Islands in the sky

About fifteen years ago, I fulfilled a lifelong dream to go to Ecuador, a country I've been fascinated with since I was a kid.  I'm a fanatical birder, and that tiny country is home to no less than one-sixth of the world's nine-thousand-odd bird species, including over three hundred different kinds of hummingbirds.  (Where I live, in upstate New York, we have exactly one, and it's only here in the summer.)

It was when I was reading up on the hummingbirds in the Ecuadorian bird guide before leaving on the trip that I noticed something odd.  A number of the species had extremely narrow ranges.  A good example is the exquisite Violet-tailed Sylph (Aglaiocercus coelestis):

[Image licensed under the Creative Commons Joseph C Boone, Violet-tailed Sylph 2 JCB, CC BY-SA 4.0]

The Violet-tailed Sylph is only found in a narrow band a couple of kilometers wide on the Pacific slope of the Andes.  North-to-south, though, its range spans over sixteen hundred kilometers.  The reason for this bizarre geographical distribution is obvious if you consider the topography; the range of the Violet-tailed Sylph, and the majority of the other hummingbirds, is driven by altitude, so their ranges run in thin strips parallel to the Andes Mountains.  A lot of it has to do with food specialization; they're nectar-feeders, and many of them have bills shaped to fit only a single species of flower.  Many tropical plants are very temperature- and moisture-sensitive, and that depends strongly on altitude, so they have equally restricted ranges.  In the case of the lovely little Sylph, its food sources are mostly found in the cloud forests that run along the mid-slope of the Andes at an elevation of about a thousand meters.

The combination of phenomenal overall biodiversity with extremely narrow ranges that you find in Ecuador draws some parallels with the fascinating ecological model called island biogeography studied in the 1960s by Robert MacArthur and E. O. Wilson.  They were trying to find patterns to explain why some islands (such as Trinidad) have extensive and diverse ecosystems, and others (such as Tristan da Cunha) have very low diversity.  They found two factors that made the most difference; island size and the proximity of the island to the nearest mainland.

The dependence on island size is easy to see; the bigger the island, the more resources there are, and the greater the number of species it can support.  The proximity factor comes from the likelihood of immigration (defined as a new species arriving and becoming established); more distant islands are farther away from a source of new species.  The math gets a little complicated, but the basic gist is that islands end up in an equilibrium between immigration and extinction, and that equilibrium results in a predictably higher number of species on larger islands that are closer to the mainland.

Where this gets interesting is that the mathematical model even works for metaphorical islands -- marshes surrounded by desert, isolated springs and lakes, hydrothermal vents on the floor of the deep ocean, and -- as with our hummingbird -- narrow ecosystems in mountain ranges that are restricted by altitude.  In fact, it's this last one that got me thinking about this topic in the first place; last week, a really cool study by a team led by Martha Kandziora of Charles University (Prague) looked at diversity in African "sky islands," ecosystems high up on mountains that are defined by cold temperatures, low rainfall, and harsh sunlight.  The authors write:

Tropical alpine floras are renowned for high endemism, spectacular giant rosette plants testifying to convergent adaptation to harsh climates with nightly frosts, and recruitment dominated by long-distance dispersal from remote areas.  In contrast to the larger, more recent (late Miocene onward) and contiguous expanses of tropical alpine habitat in South America, the tropical alpine flora in Africa is extremely fragmented across small patches on distant mountains of variable age (Oligocene onward)...  Although some of the mountains are old... most lineages appear to have colonized the afroalpine during the last 5 or 10 My.  The accumulation of species increased exponentially toward the present.  Taken together with recent reports of extremely low intrapopulation genetic diversity and recent intermountain population divergence, this points to a young, unsaturated, and dynamic island scenario.  Habitat disturbance caused by the Pleistocene climate oscillations likely induced cycles of colonization, speciation, extinction, and recolonization.

One of the things driving the study is that these regions are seriously threatened by anthropogenic climate change.  While species like the Violet-tailed Sylph could potentially respond to warming trends by moving farther up-slope, the African sky islands have nowhere to go.  If the climate gets significantly hotter, the great likelihood is that these ecosystems with their unique and bizarre flora will simply disappear.

Tragic to think that we're losing biodiversity and in many cases only poorly understand what's being lost.  Perhaps these odd species with their extreme specialization and tiny ranges don't have much impact on our day-to-day lives, but without them, we would live in a sadly impoverished world.

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A botanical mystery

One of the most pernicious tendencies in human thought is our arrogance.  The attitude that we know all there is to know, understand the universe, have it all figured out, has led to more oversights, blunders, and outright idiocy than anything else I can think of.

What's striking is how often our intuition about things turns out to be wrong.  Consider, for example, the following question: of all the species currently alive on Earth, what percent of them are known to science -- identified, observed, collected, or studied?

The best estimate we have, from a 2011 study that appeared in PLoS Biology, blew my mind, and as a 32-year veteran of teaching biology, I was ready for an answer lower than my expectation.  You ready?

Fourteen percent.

The study estimated the total number of species on Earth at 8.7 million, 86% of which are unknown to science.  This is staggering.  We are fooling around with our climate and ecosystems, bulldozing our way through our own living space, and potentially destroying millions of species we didn't even know existed.

To be fair, our ignorance about the organisms we share the planet with is at least in part not our fault.  If, like me, you live in a comfortable home with amenities and no particular need to venture off into the wilderness, it would be easy to think that our familiar surroundings are all there is.  The truth is a little humbling, and far more interesting.  I remember my first trip to Hawaii, back in 2003, when we spent our time on the lovely island of Kauai.  While we were there, we took a boat trip out to the Na Pali Coast, a stunning terrain that has a few narrow sandy beaches, but almost immediately beyond them wrinkles up into mountains that are in places damn near vertical.

Carol and I at Na Pali

The guide on the boat told us something that I found astonishing; large parts of Waimea Canyon and Koke'e Parks, which lie inland from Na Pali, are completely unexplored.  Not only is it too steep for roads to be built, you can't even land a helicopter.  Hiking might be possible, but it's densely forested.  The combination has made the interior of these parks one of the few places in the United States where we can say with fair confidence that no human being has ever stood.

Add to that the fact that even more unexplored than some of the remote terrestrial regions are the deep oceans.  I've heard it said we know more about the terrain of the Moon than we do about the floor of the deep ocean -- I don't know if that's true, but it sure sounds plausible.

I'd like to consider, though, a more positive thought; that our lack of knowledge of other species on Earth means there is a lot out there that we could still potentially learn.  And sometimes that happens through unexpected channels.  In fact, the reason this whole topic comes up is because of an article last week in Atlas Obscura about a British botanist and biological artist named Marianne North (24 October 1830-30 August 1890), who traveled all over the world painting native plants in intricate detail -- and who captured an image of at least one plant nobody could identify.

The painting in question was made in Sarawak, one of two states of Malaysia that are on the island of Borneo.  Sarawak is a bit like Kauai; inhabited at the perimeter, but with an inland of rugged terrain and dense, nearly impenetrable forest.  Well, this kind of thing didn't stop North, who made some exquisite paintings of plants in Sarawak, including this one:

[Image is in the Public Domain]

The plant with the blue berries was unidentified -- some botanists thought it might be a member of the tropical genus Psychotria (in the coffee family, Rubiaceae).  But something about that didn't ring true.  None of the 1,582 catalogued species of Psychotria has blue berries -- all the known ones are red or pink -- and the arrangement of the leaves didn't look quite right.  So either (1) this one was an anomaly, (2) North painted the plant inaccurately, or (3) the identification was wrong.

Option (1) was a little far-fetched, but not outside the realm of possibility.  Option (2) struck most knowledgeable people as outright impossible; North was known for her absolute painstaking attention to minute detail.  So botanist and illustrator Tianyi Yu decided (3) had to be correct.  But how to find a single species of plant in an overgrown wilderness on the island of Borneo, which had avoided detection by other scientists for over a century?

Yu had a brainstorm; maybe it hadn't completely flown under the radar.  He decided to spend some time in the herbarium at Kew Gardens.  If you are ever in England, Kew is a must-see; it is home to one of the most amazingly complete collection of plants in the world, and is also stunningly beautiful, especially in spring and summer.  The herbarium contains collections of preserved plants stretching back to its founding in the middle of the nineteenth century, and currently houses over eight million specimens.

So saying it was a needle in a haystack is an understatement.  Yu had one thing going for him; North had been not only a meticulous artist, she was also conscientious about writing down where her paintings had been made.  This one was labeled "Matang Forest, Sarawak," and since the Kew specimens are catalogued not only by species but by location, it significantly narrowed down Yu's search.

And he found it.  A sprig of it was collected in 1973 and sent back to Kew, but was unidentified.  Yu studied both the specimen and North's painting, and concluded that it was a member of the genus Chassalia -- also in Rubiaceae, so the guess of Psychotria hadn't been that far off.

Further analysis by botanists confirmed Yu's surmise.  As the person who identified it as a previously-unrecorded species, Yu was given the honor of naming it.

And last year, it went down in the taxonomic records as Chassalia northi, in recognition of Marianne North's contributions to the field of botany.

So out there on the island of Borneo is a little shrub with white flowers and blue berries that we now have a name for because of a nineteenth-century adventurer/scientist/artist, a happenstance collection from 1973, and a diligent modern botanist determined to put the pieces together.  Just showing that we can still pick away at the sphere of our own ignorance -- but only if we are first willing to admit that there is a lot we still don't know about the world we live in.

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Out of sight, out of mind

Humans have amazingly short memories.

I suppose that there's at least some benefit to this.  Unpleasant events in our lives would be far, far worse if the distress we experienced over them was as fresh every single day as it was the moment it happened.  That's the horror of PTSD; the trauma gets locked in, triggered by anything that is even remotely similar, and is re-experienced over and over again.

So it's probably better that negative emotions lose their punch over time, that we simply don't remember a lot of what happens to us.  But even so, I kind of wish people would keep important stuff more in mind, so we don't repeat the same idiotic mistakes.  Santayana's quote has almost become a cliché -- "Those who don't remember the past are doomed to repeat it" -- but part of the saying's sticking power is its tragic accuracy.

The reason this comes up is because of some research out of Oxford University that appeared in the journal Trends in Ecology and Evolution this week.  A team led by Ivan Jarić looked at the phenomenon of extinction -- but framed it a bit differently than you may have seen it, and in doing so, turned the spotlight on our own unfortunate capacity for forgetting.

There are various kinds of extinction.  Extirpation is when a species is lost from a region, but still exists elsewhere; mountain lions, for example, used to live here in the northeastern United States, but were eradicated in the late nineteenth and early twentieth century (the last confirmed sighting was in Maine in 1938).  They're still holding their own in western North America, however.  Functional extinction is when the population is reduced so much that it either no longer has much impact on the ecosystem, or else would not survive in the wild without signification conservation measures, or both.  Sadly, the northern white rhinoceros, the northern right whale, and the south China tiger are all considered functionally extinct.  

Extinct in the wild is exactly what it sounds like; relict populations may exist in captivity, but it's gone from its original range.  Examples include the beautiful scimitar oryx, the Hawaiian crow, and the franklinia tree (collected in the Altamaha River basin in Georgia in 1803 and never seen in the wild since).  Such species may be reintroduced from captive breeding, but it tends to be difficult, expensive, and is often unsuccessful.

Then there's global extinction.  Gone forever.  There has been some talk about trying to resuscitate species for which we have remains that have intact DNA, Jurassic Park-style, but the hurdles to overcome before that could be a reality are enormous -- and there's an ongoing debate about the ethics of bringing back an extinct species into a changed modern world.

The new research, however, considers yet another form of extinction: societal extinction.  This occurs when a population is reduced to the point that people basically forget it ever existed.  It's amazing both how fast, and how completely, this can happen.  Consider two bird species from North America -- the passenger pigeon (Ectopistes migratorius) and the Carolina parakeet (Conuropsis carolinensis) -- both of which were common in the wild, and both of which went completely extinct, in 1914 and 1918 respectively.

Illustration of the passenger pigeon by naturalist Mark Catesby (1731) [Image is in the Public Domain]

Actually, "common" is a significant understatement.  Up until the mid-nineteenth century, passenger pigeons were the most common bird in North America, with an estimated population of five billion individuals.  Flocks were so huge that a single migratory group could take hours to pass overhead.  Carolina parakeets, though not quite that common, were abundant enough to earn the ire of fruit-growers because of their taste for ripe fruit of various kinds.  Both species were hunted to extinction, something that only fifty years earlier would have been considered inconceivable -- as absurd-sounding as if someone told you that fifty years from now, gray squirrels, robins, house sparrows, and white-tailed deer were going to be gone completely.

What is even more astounding, though, is how quickly those ubiquitous species were almost entirely forgotten.  In my biology classes, a few (very few) students had heard of passenger pigeons; just about no one knew that only 150 years ago, there was a species of parrot that lived from the Gulf of Mexico north to southern New England, and west into the eastern part of Colorado.  As a species, we're amazingly good at living the "out of sight, out of mind" principle.

The scariest part of this collective amnesia is that it makes us unaware of how much things have changed -- and are continuing to change.  Efforts to conserve the biodiversity we still have sometimes don't even get off the ground if when the species is named, the average layperson just shrugs and says, "What's that?"  Consider the snail darter (Percina tanasi), a drab little fish found in freshwater streams in the eastern United States, that became the center of a firestorm of controversy when ecologists found that its survival was jeopardized by the Tellico Dam Hydroelectric Project.  No one but the zoologists seemed to be able to work up much sympathy for it -- the fact that it wasn't wiped out is due only to the fact that a population of the fish was moved to neighboring streams that weren't at risk from the dam, and survived.  (It's currently considered "threatened but stable.")

"It is important to note that the majority of species actually cannot become societally extinct, simply because they never had a societal presence to begin with," said study lead author Ivan Jarić, in an interview with Science Daily.  "This is common in uncharismatic, small, cryptic, or inaccessible species, especially among invertebrates, plants, fungi and microorganisms -- many of which are not yet formally described by scientists or known by humankind.  Their declines and extinctions remain silent and unseen by the people and societies."

Which is honestly kind of terrifying.  It's bad enough to lose species that are, as it were, right in front of our eyes; how many more are we losing that are familiar names only to biologists, or aren't even yet known to science?  And keep in mind that little-known doesn't mean unimportant.  There are plenty of "uncharismatic, small, cryptic, or inaccessible species" that are pretty damn critical.  One that springs to mind immediately are mycorrhizae, a group of underground fungi that form a symbiotic relationship with plant roots.  The relationship is mutually beneficial; the plant has its capacity to absorb minerals and water greatly increased, and the fungus gets a home and a source of food.  By some estimates, 95% of plant species have a mycorrhizal partner, and some -- notably orchids -- are completely dependent on it, and die if they are separated from their fungal symbiont.  Even plants that aren't entirely reliant on them benefit from the relationship; there is increasing evidence that adding mycorrhizal spores to an ordinary vegetable garden can decrease dependence on chemical fertilizers, improve drought resistance, and increase crop yield (some experiments have seen it as much as double).

Incredibly cool.  But not what most of us would consider "charismatic."  I doubt, for example, that micrographs of mycorrhizae will ever usurp the wolves and eagles and elephants on the pages of the calendars we hang on our walls.  I mean, I would buy one, but I suspect I'm in the minority.

What this highlights to me is that we need to fight this tendency to overlook or forget about the organisms in our world that aren't obvious -- the rare, the small, the hidden.  The fact that their plight is not as obvious as the whales and the elephants and the tigers doesn't mean they're unimportant.  We need to become conscious of what's around us, and committed to protecting it.  Another comparison that's become almost a cliché is comparing biodiversity to a tapestry, but the symbolism is apt.

Pull out enough threads, and the entire thing comes to pieces.

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Floral invaders

I used to ask a question to my biology classes, during the unit on ecology: what are the only two commonly-eaten fruits that are native to North America?

Some of the most frequent wrong answers -- and where those plants are actually native:

• Apples ("American as apple pie," right?)  Nope, native to Europe, brought over in the early seventeenth century by the French settlers of eastern Canada and now naturalized across the continent.
• Peaches, apricots, and pears -- native to central Asia.
• Plums -- native to China (although there are a few wild North American plum varieties, they're not the ones you ever see in the grocery store).
• Kiwi fruit -- native to east Asia.
• Cherries, strawberries, blackberries, and raspberries -- native to Europe.
• Citrus fruits -- native to southern Asia and Australia.
• Pineapples -- native to South America.
• Bananas -- native to southeast Asia, Papua-New Guinea, and Australia.

Some students -- knowing their botany -- thought I was being tricky and had in mind plants whose product are fruits in the botanical sense, but not to be found in the fruit section of the grocery store, like cucumbers (south Asia) and tomatoes (Central and South America), but no.

The only two commonly-consumed fruits that are native to North America are blueberries and cranberries.  (Squash is also an example, if you count introductions that preceded European colonization; they were widely used by Indigenous Americans, but even they originally came from Mexico and Central America.)

It might be especially hard to believe this apropos especially of blackberries and raspberries, which have gone wild and in many places (like my back yard) form nearly impenetrable thorny thickets of vines.  We have the birds to thank for this; birds consume the berries and then carry the seeds far and wide, a dispersal strategy that is effective enough that both species are now found in every state in the continental United States and every province of Canada.

[Image is in the Public Domain]

Well, so what?  Why does this matter?  The problem is the degree to which non-native (or exotic) species have infiltrated ecosystems -- and changed them.  I could just as well used garden flowers as my example group, but most high school students know fruits way better than flowers.  And I'm ignoring what might be the single most common group of exotic plants in the United States, so ubiquitous that we hardly even think about them; the various common species of lawn grasses.

There are two commonly-cited problems with non-natives. Certainly the best known is that when exotic organisms take hold, they can outcompete and replace native species.  The most successful exotics are the ones that are ecological generalists, able to utilize a wide variety of resources and habitats, and those have especially taken hold in the disturbed ecosystems of cities; consider where you are most likely to find dandelions, burdock, pigeons, house sparrows, and rats, for example.  A second is the accidental introduction of pests that end up destroying native organisms -- three we're constantly fighting here in the northeastern United States are Japanese beetles, the spotted lanternfly, and the emerald ash borer.  (Once again, there's another example in this category you may not have thought about -- feral cats, which take a tremendous toll on native birds.  But I'm guessing the cat lovers in my readership won't appreciate my labeling cats as "exotic pests...")

A third, and less-explored, aspect of the transport of species into new regions is homogenization.  Enough new introductions, and previously diverse and unique ecosystems start looking very much alike.  This was the subject of a paper last week in Nature Communications by a team led by Qiang Yang of the University of Konstanz (Germany), detailing a way to quantify this loss of uniqueness.  

The authors write:

Regional species assemblages have been shaped by colonization, speciation and extinction over millions of years.  Humans have altered biogeography by introducing species to new ranges.  However, an analysis of how strongly naturalized plant species (i.e. alien plants that have established self-sustaining populations) affect the taxonomic and phylogenetic uniqueness of regional floras globally is still missing.  Here, we present such an analysis with data from native and naturalized alien floras in 658 regions around the world.  We find strong taxonomic and phylogenetic floristic homogenization overall, and that the natural decline in floristic similarity with increasing geographic distance is weakened by naturalized species.  Floristic homogenization increases with climatic similarity, which emphasizes the importance of climate matching in plant naturalization.  Moreover, floristic homogenization is greater between regions with current or past administrative relationships, indicating that being part of the same country as well as historical colonial ties facilitate floristic exchange, most likely due to more intensive trade and transport between such regions.  Our findings show that naturalization of alien plants threatens taxonomic and phylogenetic uniqueness of regional floras globally.  Unless more effective biosecurity measures are implemented, it is likely that with ongoing globalization, even the most distant regions will lose their floristic uniqueness.

The problem is, halting this trend is going to be tough.  In a lot of ways, that ship has already sailed.  We can act on local scales -- like my wife's and my effort to convert a section of our property into a native wildflower meadow -- but there has already been too much pot-stirring to have a chance of separating the mixture back to its original configuration of ingredients.  It may be that the best we can do is to mitigate the damage to the extent we can; replacing lawn, choosing to plant natives, removing unwanted exotics when you find them -- and keeping your cats indoors. 

And, of course, remember the somewhat encouraging truth that even introduced species can eventually come into equilibrium with the natives.  European Starlings, introduced into North America in the late nineteenth century, had multiplied into such enormous numbers that in many regions they were the most common bird around, but in the last fifty years have declined to more reasonable (and stable) numbers.  (The only scary thing about this is that we don't have a clear idea of why they've declined -- by some estimates, to fifty percent of the total population in 1970 -- and scarier still, there's been a commensurate decline in native species during the same time frame.)

But the harsh fact is that we've already made irreparable changes to the world's ecosystems, and that's not going to stop any time soon.  The important thing now is to learn from past mistakes -- and do what we can to protect what's still left of our beautiful and unique biodiversity.

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One of my favorite writers is the inimitable Mary Roach, who has blended her insatiable curiosity, her knowledge of science, and her wonderfully irreverent sense of humor into books like Stiff (about death), Bonk (about sex), Spook (about beliefs in the afterlife), and Packing for Mars (about what we'd need to prepare for if we made a long space journey and/or tried to colonize another planet).  Her most recent book, Fuzz: When Nature Breaks the Law, is another brilliant look at a feature of humanity's place in the natural world -- this time, what happens when humans and other species come into conflict.

Roach looks at how we deal with garbage-raiding bears, moose wandering the roads, voracious gulls and rats, and the potentially dangerous troops of monkeys that regularly run into humans in many places in the tropics -- and how, even with our superior brains, we often find ourselves on the losing end of the battle.

Mary Roach's style makes for wonderfully fun reading, and this is no exception.  If you're interested in our role in the natural world, love to find out more about animals, or just want a good laugh -- put Fuzz on your to-read list.  You won't be disappointed.

[Note: if you purchase this book using the image/link below, part of the proceeds goes to support Skeptophilia!]

The kites fly again

The iconic movie Jurassic Park has provided us with quite a number of quotable lines:

"I hate it when I'm always right."

"Clever girl."

"That is one big pile of shit."

"See?  Nobody cares."

"Hold onto your butts."

But as someone who has studied (and taught) evolution for decades, none of them has stuck in my mind like Ian Malcolm's pronouncement, "Life... uh... finds a way."

This short sentence sums up something really profound; however the Earth's ecosystems are damaged, they always bounce back.  Even after the catastrophic Permian-Triassic Extinction -- which by some estimates wiped out 90% of the existing taxa on Earth -- there was a recovery and rediversification.

Note that I'm not saying that means it was a good thing.  The end Permian extinction event was, it is believed, caused by an unimaginably huge series of volcanic eruptions, followed by a major spike in the carbon dioxide content of the atmosphere -- leading to a jump in the global temperature and catastrophic oceanic anoxia.

So yeah.  "Life survived" doesn't mean it'd have been a fun event to live through.  But it should give us hope that the damage humans can do to the Earth as a whole is, in the grand scheme of things, short-lived.

As an encouraging example of this, take a recent study out of the University of Florida on snail kites.  These birds, related to hawks and falcons, are serious food specialists; they eat only one species of snail, found in salt marshes like the Everglades (and also parts of Central America; I first saw snail kites in Belize).  When things are stable, being a specialist is a good thing -- you pretty much corner the market on a particular resource, like the South American hummingbird species whose bills are shaped to fit one and only one species of flower.  The snail kite's food finickiness is this same sort of thing, and as long as the Everglades was undamaged and had an abundant supplies of snails, all was well.

[Image licensed under the Creative Commons Bernard DUPONT from FRANCE, Snail Kite (Rosthramus sociabilis) Poconé, Mato Grosso, CC BY-SA 2.0]

But when the environment is rapidly changing, either through human effects or because of natural events, being a specialist is seriously precarious.  When a new species of snail -- the island apple snail -- was introduced to the Everglades, its larger size and voracious appetite outcompeted the native snails, and the snail kites were in trouble because their bills weren't large and heavy enough to tackle the bigger prey.

Snail kites were already on the Endangered Species List, given that the Everglades has been massively damaged by human activity.  This, it seemed, might be the death blow to the Florida population of this striking bird.

But... life, uh, finds a way.

The snail kite, in a near-perfect reenactment of the bill diversification in Darwin's finches in the Galapagos, had a variety of bill sizes.  Genetic diversity, despite their extreme specialization.  Before the introduction of the island apple snail, bill size probably didn't make much difference, positive or negative, to the individual birds.  But now, large bills were a serious advantage.  The birds with the biggest bills could tackle the larger snail species -- meaning they had a copious food source that their smaller-billed cousins couldn't utilize.

And in the thirteen years since the introduction of the island apple snail, the average bill size has gone up dramatically -- and the overall population is rebounding.

"Beak size had been increasing every year since the invasion of the snail from about 2007,” said Robert Fletcher, who co-authored the study.  "At first, we thought the birds were learning how to handle snails better or perhaps learning to forage on the smaller, younger individual snails...  We found that beak size had a large amount of genetic variance and that more variance happened post-invasion of the island apple snail.  This indicates that genetic variations may spur rapid evolution under environmental change."

As I said earlier, this is not meant to give the anti-environmental types another reason to say, "Meh, we don't have to change what we're doing, things'll be okay regardless."  Most species aren't as fortunate as the snail kites, already having the genetic diversity to cope with a sudden change.  Much more likely, if we keep doing what we're doing, the specialist species in the world will simply be wiped out.

Whether we'll be able to survive in such a changed world remains to be seen.

But one thing is nearly certain; even if we catastrophically damage the global ecosystem, it will rebound eventually.  Which is hopeful, as far as it goes.  Even after Homo sapiens is another fossilized footnote in the Earth's geological history, life will persist -- once more generating, in Darwin's immortal words, "endless forms most beautiful and most wonderful."

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 Many of us were riveted to the screen last week watching the successful landing of the Mars Rover Perseverance, and it brought to mind the potential for sending a human team to investigate the Red Planet.  The obstacles to overcome are huge; the four-odd-year voyage there and back, requiring a means for producing food, and purifying air and water, that has to be damn near failsafe.

Consider what befell the unfortunate astronaut Mark Watney in the book and movie The Martian, and you'll get an idea of what the crew could face.

Physicist and writer Kate Greene was among a group of people who agreed to participate in a simulation of the experience, not of getting to Mars but of being there.  In a geodesic dome on the slopes of Mauna Loa in Hawaii, Greene and her crewmates stayed for four months in isolation -- dealing with all the problems Martian visitors would run into, not only the aforementioned problems with food, water, and air, but the isolation.  (Let's just say that over that time she got to know the other people in the simulation really well.)

In Once Upon a Time I Lived on Mars: Space, Exploration, and Life on Earth, Greene recounts her experience in the simulation, and tells us what the first manned mission to Mars might really be like.  It makes for wonderful reading -- especially for people like me, who are just fine staying here in comfort on Earth, but are really curious about the experience of living on another world.

If you're an astronomy buff, or just like a great book about someone's real and extraordinary experiences, pick up a copy of Once Upon a Time I Lived on Mars.  You won't regret it.

[Note: if you purchase this book using the image/link below, part of the proceeds goes to support Skeptophilia!]

An alpine gem in China

In order to produce new species -- so goes the evolutionary model -- you need two things: isolation (splitting off the population that will eventually become the new species from the parent population) and selection (environmental conditions that favor different traits in the splinter population than the ones favoring the parent population).  Given those two, and sufficient time, sooner or later you'll have two (or more) separate species.

The classic example of this, of course, is the group of birds called "Darwin's finches," that evolved from a parent population of tanagers from mainland South America (their closest relative is the Dull-colored Grassquit of Colombia, Ecuador, and Peru) something on the order of two million years ago.  Once arrived in the islands, they thereafter fragmented to fill the available niches in a process that has been nicknamed adaptive radiation.

So split off a population and give it some new conditions to contend with, and you'll end up with new species.  Which is what happened to a whole ecosystem's worth of species thirty million years ago -- leading to one of the most biodiverse spots on Earth.

New research into the genetics of the dozens of unique species in the Hengduan Mountains and Qinghai Plateau of western China has given us a fascinating lens into this process.  In "Ancient Orogenic and Monsoon-Driven Assembly of the World’s Richest Temperate Alpine Flora," by Wen-Na Ding, Robert Spicer, and Yao-Wu Xing of the Chinese Academy of Sciences and Richard Ree of Chicago's Field Museum, we read about a biotic province created by mountain building that not only raised the elevation (and thus lowered the average temperature), but altered wind currents to create monsoons -- and isolated the populations trapped there from their relatives on the other side of the mountain range.

"The theory is, if you increase the ruggedness of a landscape, you're more likely to have populations restricted in their movement because it's harder to cross a deeper valley than a shallow valley," said study co-author Richard Ree, in an interview with Science Daily.  "So any time you start increasing the patchiness and barriers between populations, you expect evolution to accelerate...  The combined effect of mountain-building and monsoons was like pouring jet fuel onto this flame of species origination.  The monsoon wasn't simply giving more water for plants to grow, it had this huge role in creating a more rugged topography.  It caused erosion, resulting in deeper valleys and more incised mountain ranges."

This all started back in the Oligocene Epoch, thirty million years ago, and the area has been pretty well isolated ever since.  The result is plants like the Himalayan lantern (Agapetes lacei):

.... which you wouldn't guess is a relative of rhododendrons and azaleas; the alpine monkshood (Aconitum gymnandrum):

... the gorgeous little Paraquilegia microphyllum:

... and literally hundreds of others, species found there and nowhere else on Earth.

The remoteness and general inaccessibility of the area has limited the human impact (fortunately), but scientists are rightly concerned with the effects that climate change will have on these subalpine valleys and plateaus.  Even if we're not directly damaging the ecosystem, our actions elsewhere imperil it, just as our out-of-control fossil fuel use has led to the thawing of the Arctic and the threat of ice sheet collapse in Antarctica -- the latter of which recent research has suggested could add three meters to the average sea level over a very short period, with catastrophic consequences.

But for now, let's just focus on this pristine gem of an ecosystem, and marvel at the processes that created it.  Once again, we see the truth of Darwin's words, with which he ended The Origin of Species: "There is grandeur in this view of life, with its several powers, having been originally breathed into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved."

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This week's Skeptophilia book recommendation is a fun and amusing discussion of a very ominous topic; how the universe will end.

In The End of Everything (Astrophysically Speaking) astrophysicist Katie Mack takes us through all the known possibilities -- a "Big Crunch" (the Big Bang in reverse), the cheerfully-named "Heat Death" (the material of the universe spread out at uniform density and a uniform temperature of only a few degrees above absolute zero), the terrifying -- but fortunately extremely unlikely -- Vacuum Decay (where the universe tears itself apart from the inside out), and others even wilder.

The cool thing is that all of it is scientifically sound.  Mack is a brilliant theoretical astrophysicist, and her explanations take cutting-edge research and bring it to a level a layperson can understand.  And along the way, her humor shines through, bringing a touch of lightness and upbeat positivity to a subject that will take the reader to the edges of the known universe and the end of time.

[Note: if you purchase this book using the image/link below, part of the proceeds goes to support Skeptophilia!]

Pieces of the mosaic

The diversity you find among birds is really remarkable.

There are differences in bill shape, from the weird angled beaks of flamingos, to the longer-on-the-bottom fish skewers of skimmers, to the absurd (and aptly-named) spoonbills and shoebills, to the pelicans -- about whom my dad taught me a limerick when I was little:

A wonderful bird is the pelican.
His bill can hold more than his bellican.
He can stash in his beak
All his food for the week,
But I really don't see how the hellican.

Yeah, it's kind of obvious where I got my sense of humor from.

Of course, it doesn't end there.  The impossibly long toes of the South American jacanas (called "lilytrotters" because they can walk on the floating leaves of waterlilies).  The phenomenal wingspan of the albatross.  The insane plumage of the birds-of-paradise.

And the colors.  Man, the colors!  Even in my decidedly non-tropical home we have some pretty amazing birds.  The first time I saw an Indigo Bunting, I was certain that one of my sons had put a blue plastic bird on the bird feeder just to rattle my chain.  There couldn't be a real bird that was that fluorescent shade of cobalt.

Then... it moved.

But nothing prepared me for the colors I saw on my visits to Ecuador, especially amongst the birds of the tanager family.  There are hundreds of species of tanagers in that tiny little country, and because they often travel in mixed foraging flocks, you can sometimes see twenty or thirty different species in the same tree.  These include the Green-headed Tanager:

[Image licensed under the Creative Commons Lars Falkdalen Lindahl (User:Njaelkies Lea), Green-headed Tanager Ubatuba, CC BY-SA 3.0]

The Black-capped Tanager:

[Image licensed under the Creative Commons Joseph C Boone, Black-capped Tanager JCB, CC BY-SA 4.0]

And the Flame-faced Tanager:

[Image licensed under the Creative Commons Eleanor Briccetti, Flame-faced Tanager (4851596008), CC BY-SA 2.0]

Being a biologist, of course the question of how these birds evolved such extravagant colors is bound to come up, and my assumption was always that it was sexual selection -- the females choosing the most brightly-colored males as mates (in this group, as with many bird species, the males are usually vividly decked out and the females are drab-colored).  If over time, the showiest males are the most likely to get lucky, then you get sexual dimorphism -- the evolution of different outward appearances between males and females.  (This isn't always so, by the way.  Most species of sparrows, for example, have little sexual dimorphism, and even experienced birders can't tell a male from a female sparrow by looking.)

The truth is, however, this is an oversimplified explanation, which I suppose I should expect given how long I've been in science.  Nature is both way more complex and way more interesting than we usually expect.  Just this week a paper was released in the journal BMC Evolutionary Biology that looks at another group of birds that look like someone went nuts with a paint-by-number set -- the Australasian lorikeets.

Lorikeets are in the parrot family, and even by comparison to other parrot species they're ridiculously flamboyant.  Take a look, for example, at the aptly-named Rainbow Lorikeet:

[Image licensed under the Creative Commons Dick Daniels (http://carolinabirds.org/), Rainbow Lorikeet RWD, CC BY-SA 3.0]

The researchers, Brian Smith, Glenn Seeholzer, and Jon Merwin of the American Museum of Natural History's Department of Ornithology, were curious about how lorikeets balance being bright enough to attract mates while not being so showy they attract the attention of predators -- the latter being in no short supply in Australia and New Guinea, where the birds are found.  Using spectral analyses of museum specimens encompassing nearly the entire diversity of lorikeets, Smith, Seeholzer, and Merwin found out a few things that were absolutely fascinating:

• Virtually all the color diversity in lorikeets is on the underside -- breast, abdomen, and front of the face.  The backs of almost all species are plain green -- making them camouflaged from above and less visible to predators like hawks.
• Some of the range of colors they do have is invisible to the human eye.  A number of species have pigments that reflect strongly in the ultraviolet region of the spectrum, which is visible to birds but not to us -- and presumably, not to many non-avian predators either.  So they can be as flashy as they want in the ultraviolet and still not attract attention from hungry carnivores.
• Each of the patches is under the control of a different set of genes and thus can be selected independently, meaning different species of lorikeets can diverge in terms of the facial color while remaining similar in the coloration on the back and abdomen -- something called "mosaic evolution."

"The range of colors exhibited by lorikeets adds up to a third of the colors birds can theoretically observe," Merwin said.  "We were able to capture variation in this study that isn't even visible to the human eye.  The idea that you can take color data from museum specimens, infer patterns, and gain a larger understanding of how these birds evolved is really amazing."

Of course, I wondered if the same forces might be involved in the evolution of two groups I've actually seen in the wild, hummingbirds and the aforementioned tanagers.  It certainly seems to fit the same pattern -- a wide range of eye-catching colors on the front of the body, and -- especially in the hummingbirds -- largely green on top.

But that's just a guess.  It certainly opens up an interesting line of inquiry into the evolution of other bird groups.  And -- perhaps -- will end up explaining a great many of the other pieces of the biodiversity mosaic.

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One of my favorite people is the indefatigable British science historian James Burke.  First gaining fame from his immensely entertaining book and television series Connections, in which he showed the links between various historical events that (seen as a whole) play out like a centuries-long game of telephone, he went on to wow his fans with The Day the Universe Changed and a terrifyingly prescient analysis of where global climate change was headed, filmed in 1989, called After the Warming.

One of my favorites of his is the brilliant book The Pinball Effect.  It's dedicated to the role of chaos in scientific discovery, and shows the interconnections between twenty different threads of inquiry.  He's posted page-number links at various points in his book that you can jump to, where the different threads cross -- so if you like, you can read this as a scientific Choose Your Own Adventure, leaping from one point in the web to another, in the process truly gaining a sense of how interconnected and complex the history of science has been.

However you choose to approach it -- in a straight line, or following a pinball course through the book -- it's a fantastic read.  So pick up a copy of this week's Skeptophilia book of the week.  You won't be able to put it down.

[Note: if you purchase this book using the image/link below, part of the proceeds goes to support Skeptophilia!]

The danger of comfort

There is nothing as dangerous as our attitude that if something isn't bothering us right here and right now, it can effectively be ignored.

It's what is behind the phenomenon that doctors rail against, that if you're feeling good at the moment, there's no reason to have an annual physical.  I say this with a degree of wry amusement because I'm a doctor avoider myself, but at least I acknowledge how foolish that approach is.  There are large numbers of illnesses that if caught early and treated are not really that serious, but if left untreated long enough can kill you.  I was just chatting a couple of days ago with a friend about a mutual acquaintance who had ignored increasingly severe headaches for weeks, and ultimately died of a ruptured cerebral aneurysm that probably would have been operable -- at the age of 41.

Scale that attitude up, and you have our current approach to the global environment.

Every time you look at the news you see more alarm bells about the current state of the natural world.  Just in the last two weeks, we've had the following:

• A study at the University of Sussex showing that the world's biodiversity is falling far faster than previous models had estimated
• A paper in Nature with new data about mass loss from the Greenland ice sheet, projecting the displacement of forty million people worldwide from coastal flooding and incursion of seawater in the next eighty years
• A rather horrifying study from the University of California-San Diego detailing more accurate estimates of microplastics in the ocean -- bits of effectively non-biodegradable debris suspended in seawater, with unknown long-term effects on ecosystems -- and found that the average concentration was 8.3 million pieces of microplastic per cubic meter of water, on the order of six orders of magnitude higher than previous measurements

But here I sit in my comfortable office in rural upstate New York.  It's a clear December morning, the sky is a pristine pale blue, the tilled cornfield across the road dusted with snow.  There are birds at the feeders, a hawk is kiting high overhead, my dogs are snoozing in a patch of sunlight after an early morning's romp.  I have a cup of hot coffee, a fire in the wood stove.

All's well with the world.  Right?

Certainly looks like it is.

[Image licensed under the Creative Commons Pranjal kukreja, Adventure-clouds-environment-672358, CC BY-SA 4.0]

We're geared to respond to how our personal conditions are in the moment, so stories like the ones I mentioned above have a hard time gaining any traction in our consciousness.  I consider myself more environmentally-conscious than a lot of people (and for cryin' in the sink, I just spent the morning researching serious problems with the global ecology) and I still have a hard time feeling viscerally alarmed by it, the way I would if there was a forest fire headed this way or a chemical spill was killing all the fish in my pond or smog was making it impossible to breathe without a filter mask.

There's really no difference, though, between the three problems in the news and the three hypothetical ones I just mentioned -- or if there is, it's a matter of scale.  The three papers I referenced above are orders of magnitude more serious than any of the three local ones I listed.  If a wildfire went out of control and burned my house down, it would be a tragedy for me.  But the three papers I described are disasters in the making that affect not just one person, nor even a single community, but the entire world.

And for most people, they elicit nothing more than a shrug of the shoulders.

It doesn't help, of course, that the current government of the United States is actively involved in perpetuating this attitude, and (worse) spreading scientific misinformation.  For some of the perpetrators it's done with malice aforethought, because of the influence of money from the fossil fuel lobby and others like it, but for some -- like Donald Trump -- it's a combination of the "who cares, I'm doing fine" attitude with outright willful stupidity.  Take, for example, this direct quote from Trump's speech to a Turning Point USA (a conservative student group) rally just two days ago:

I never understood wind.  I know windmills very much, I have studied it better than anybody.  I know it is very expensive.  They are made in China and Germany mostly, very few made here, almost none, but they are manufactured, tremendous — if you are into this — tremendous fumes and gases are spewing into the atmosphere.  You know we have a world, right?  So the world is tiny compared to the universe.  So tremendous, tremendous amount of fumes and everything.  You talk about the carbon footprint, fumes are spewing into the air, right spewing, whether it is China or Germany, is going into the air...  A windmill will kill many bald eagles.  After a certain number, they make you turn the windmill off, that is true.  By the way, they make you turn it off.  And yet, if you killed one, they put you in jail.  That is okay.  But why is it okay for windmills to destroy the bird population?

Watching a video of this speech, it was hard to escape two conclusions: (1) Donald Trump is the single stupidest person ever elected to public office, and (2) the fact that there are still a significant number of supporters of this man's policies, who apparently still think he's the best president ever, makes me despair for the future of the human race.

When I taught Environmental Science, I was up front about my goal -- to widen students' perspective from what's right in front of them, to their homes, to their communities, to their nation, and finally to the entire world.  So much of what we're doing wrong lately -- or failing to do -- is purely because we only care, and act, on what is right before our faces.

So I'm glad that I've got a beautiful morning to enjoy, clean air, a warm and safe place for myself and my family and pets.  But I can't let that lull me into the Panglossian attitude that "all is for the best in the best of all possible worlds."  In the current conditions -- with ecological perils everywhere, and a government that combines complicity and ignorance -- complacency is the deadliest danger of all.

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As technology has improved, so has our ability to bring that technology to bear on scientific questions, sometimes in unexpected ways.

In the fascinating new book Archaeology from Space: How the Future Shapes Our Past, archaeologist Sarah Parcak gives a fascinating look at how satellite photography has revolutionized her field.  Using detailed photographs from space, including thousands of recently declassified military surveillance photos, Parcak and her colleagues have located hundreds of exciting new sites that before were completely unknown -- roads, burial sites, fortresses, palaces, tombs, even pyramids.

These advances are giving us a lens into our own distant past, and allowing investigation of inaccessible or dangerous sites from a safe distance -- and at a phenomenal level of detail.  This book is a must-read for any students of history -- or if you'd just like to find out how far we've come from the days of Heinrich Schliemann and the excavation of Troy.

[Note: if you purchase this book using the image/link below, part of the proceeds goes to support Skeptophilia!]

Insect rebound

I vividly recall my first visit to the American Museum of Natural History in Washington, DC, perhaps fifteen years ago.  Having a fascination for evolutionary biology and paleontology, I was thrilled to take a walk down the hallway with exhibits of each biological taxon, in phylogenetic order -- put simply, all the groups of living things in the order they come on the family tree of life.

So I'm walking up the hall, and things are progressing the way I'd expect -- bacteria to protozoans to plants to primitive animals, and within Kingdom Animalia, jellyfish to flatworms to roundworms to more complex invertebrates, and then on to fish, amphibians, reptiles, birds, and mammals.

But that wasn't the end of the hall.  The usual approach to the "Great Tree of Life" -- with, of course, mammals at the top of the heap and humans at the top of the mammals, as befits the pinnacle of evolution -- wasn't applied here.  If you progress past mammals, you're into Phylum Arthropoda, those animals with jointed legs and an exoskeleton, which include arachnids, crustaceans, centipedes, millipedes, and the most successful creatures on Earth...

... insects.

Being that it's the end of summer in upstate New York, I can verify that insects are highly successful life forms, given that there are millions of mosquitoes in my back yard alone, every single one of which divebombs my wife whenever she goes outside.  Something about Carol just attracts biting insects.  In fact, she claims that I bring her along to tropical destinations just to draw the mosquitoes away from me.

Which is not true.  Honestly.

In all seriousness, there is incredible diversity amongst insects, and many taxonomists believe that the number of insect species outnumbers all other kinds of animals put together.  Just beetles by themselves -- Order Coleoptera -- represents over 400,000 species, or about 25% of the total animal biodiversity on Earth.

This is the origin of the famous story about biologist J. B. S. Haldane, who was not only a vocal proponent of evolution but was an outspoken atheist.  Haldane frequently had hecklers show up at his talks, and one such asked him at the end, "So, Professor Haldane, what has your study of biology told you about the nature of God?"

Without missing a beat, Haldane replied, "All I can say is that he must have an inordinate fondness for beetles."

Metallic Shield Bug (Scutiphora pedicellata) from Australia [Image licensed under the Creative Commons Benjamint444, Metallic shield bug444, CC BY-SA 3.0]

It's curious that such a diverse and ubiquitous group still has a great many questions unresolved about its origins.  It's known that the big jump in insect diversity came after the Permian-Triassic Extinction of 252 million years ago, the "Great Dying" that wiped out (by some estimates) 95% of life on Earth.  There's a common pattern that a sudden burst of species formation always follows a mass extinction, but in this case, because of a poor fossil record following the event, it's been hard to connect later biodiversity to speciation amongst the survivors.

We just got a huge boost in what we know about insect evolution because of the discovery of a fossil deposit in China dating from 237 million years ago, or only ("only!") fifteen million years after the extinction itself.  The site had eight hundred fossils representing 28 different insect families that had survived the bottleneck, including the ancestors of modern beetles, flies, and cockroaches.

The study, done jointly by Zheng Daran and Wang Bo of the State Key Laboratory of Paleobiology and Stratigraphy in Nanjing, China and Chang Su-Chin of the University of Hong Kong, is only a preliminary analysis of the fossils at the site, and has already helped to connect the dots between pre-Permian-Triassic insects and more modern ones.  As Elizabeth Pennisi, senior correspondent for Science magazine, writes:

The sites underscore that this burst of evolution took place much earlier than researchers had thought, particularly for water-loving insects.  Among the remains are fossil dragonflies, caddisflies, water boatmen, and aquatic beetles.  Until now, paleontologists had thought such aquatic insects didn’t diversify until 130 million years ago.  These insects—which include both predators and plant eaters—helped make freshwater communities more complex and more productive... moving them toward the ecosystems we see today.

It's always fascinating when we add something to our knowledge of past life, and even more impressive when it's about one of the most diverse groups that has ever existed.  Seeing how life rebounded after the Permian-Triassic Extinction should also give us hope -- that even after a cataclysm, the survivors can still come back and rebuild Earth's biodiversity.

Or, as Ian Malcolm put it in Jurassic Park, "Life finds a way."

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This week's Skeptophilia book recommendation is part hard science, part the very human pursuit of truth.  In The Particle at the End of the Universe, physicist Sean Carroll writes about the studies and theoretical work that led to the discovery of the Higgs boson -- the particle Leon Lederman nicknamed "the God Particle" (which he later had cause to regret, causing him to quip that he should have named it "the goddamned particle").  The discovery required the teamwork of dozens of the best minds on Earth, and was finally vindicated when six years ago, a particle of exactly the characteristics Peter Higgs had described almost fifty years earlier was identified from data produced by the Large Hadron Collider.

Carroll's book is a wonderful look at how science is done, and how we have developed the ability to peer into the deepest secrets of the universe.

[If you purchase the book from Amazon using the image/link below, part of the proceeds goes to supporting Skeptophilia!]