Category: animals

Do seahorses validate “queerness”? The naturalistic fallacy committed by the Sussex Wildlife Trust

January 21, 2022 • 11:15 am

Every day I get six or seven links from readers about the infestation of society by performative brands of DEI (i.e., “wokeness”). The links are often distressing and depressing, but I have to tell readers “I’m sorry, but I can’t write about everything!”

But when I am compelled by the laws of physics to write about something is when people try to bend biology to fit their ideological narrative. The most egregious example of this is the claim that there is no such thing as a sexual binary in humans and other animals, which is just wrong. Males have small mobile gametes (that’s the definition), and females big and immobile ones. Just like my Drosophila, about 99.99% of humans are either male or female by this definition. Hermaphrodites or other intermediates are not “other sexes”; they are developmental anomalies. (That’s not a slur on human intermediates; it’s a statement that you get the very rare intermediates only when development slips off the rails that have evolved to ensure a sexual binary.)

These attempts to refer to nature as a way of validating human behavior, morality, or ideology is, of course, an example of the “naturalistic fallacy,” usually described as the fallacy of saying “what’s seen in nature is good in humans.” And it’s a dumb fallacy, because a lot of animals behave in nature in ways that we would consider immoral in our own species. (Chimps, for example, attack other bands of chimps and rip individuals apart while they’re still alive. Some spider females kill and eat males after mating.) We can’t look to nature for morality, because, at bottom, nature is amoral, for animals don’t have the capacity to argue and make considered judgments about how to behave. Often “considerate” behavior towards others is the evolutionary product of reciprocal altruism or kin selection.

So when the Sussex Wildlife Trust tries to use the pregnancy of male seahorses as a justification for “queerness”, as they do below, they’re committing the naturalistic fallacy. The reason we shouldn’t discriminate against non-cis people is because discrimination is wrong and hurtful, not because male seahorses (and, by the way, male pipefish and sea dragons, contra the tweet below) get pregnant. Mallard drakes sometimes kill females during forced copulation, which in humans is the equivalent of rape. Does that make rape okay? You get my point.

Here’s the tweet. The original has been deleted (I wonder why?) but here’s a screenshot of the original:

 

Now a bit of biology before we go on to the associated article.  Seahorses have a fascinating mating and breeding system. They’ve evolved so that the males largely take care of the eggs. (In many species, males do at least half the tending and rearing). In seahorses, pipefish, and sea dragons, this occurs by males sequestering the eggs in their kangeroo-like pouches, fertilizing them there, and sequestering them until hatching.  (This may be a way to increase offspring number by favoring those individuals who protect their reproductive investment by protecting fertilized eggs.)

The important thing is that, in seahorses, sea dragons, and pipefish, the females produce eggs faster than the males can put them in their pouches, so females are always looking around for an “empty” male. Because—unlike in most animals—females are thus competing for males’ attention, and sexual selection is reversed. It’s the opposite of what happens in most other species, in which males compete to fertilize females. This is why, if there is sexual dimorphism in seahorses, it’s the females who are more elaborately decorated and with more secondary sexual characteristics. (See also here.)

Note that the males, while they take care of fertilized eggs and in that sense are pregnant, are still males, as they produce sperm rather than eggs. So you could say that “males get pregnant”, but that’s not the same thing as transsexual men who can sometimes get pregnant, nor does seahorse pregnancy somehow show that transmale pregnancy is “okay” or “moral”. It IS perfectly okay, but not because you find it in some marine species.

I like to show students the video below of a male seahorse giving birth, which looks almost as laborious and painful as labor in human females. This form of reproduction, given the female’s rapid rate of producing eggs, may have evolved to protect eggs and embryos from predation. We just don’t know.

What we do know is that males have a form of pregnancy, but this says nothing one way or the other about transsexual pregnancy in humans. The pregnant seahorses are neither queer nor transsexual, but males, and there’s no morality in the fishes (yes, seahorses, sea dragons, and pipefish are “fish”).

I wouldn’t have written all this if reader Al, who was steamed, sent me this associated link from the Sussex Wildlife Trust news (click on screenshot to read).  Now I’m not going to go after this very hard, as I want to just reiterate the naturalistic fallacy and how it’s used as a justification or valorization of human behavior. And yes, pregnant seahorses do show that animal behavior is diverse and unexpected.  But pregnant male seahorses remain males, and they’re not “queer,” either, as the author seems to imply in her piece.

But the seahorses are used to somehow buttress the insecurity of a woman trying to come out as queer.

A few quotes:

As a keen zoology undergraduate who adored, almost worshipped, Darwin’s theory of evolution, I couldn’t quite come to terms with his theory of sexual selection. It really didn’t add up as I was tentatively stepping out of the queer closet back in 1996. I lived and breathed evolutionary theory but where did I fit in? A deviation? An anomaly? A kink in the genetic spiral of life? So, of course, I started studying the evolution of sex and soon discovered how incredibly diverse and fascinating the plant and animal kingdoms (more like queendoms or even queerdoms) really are in terms of gender and sexuality.

. . . .In the plant world too there is a whole host of queerness to explore. In fact bisexual flowers are described as “perfect”, having both male and female reproductive structures. Examples include roses and lilies but also the horse chestnut, highlighted in a wonderful project by the Queer Botany Society at the Walthamstow Marshes SSSI.

Now, with my work for the Sussex Kelp Restoration Project much of my favourite flagship “queer” marine species are linked directly to our conservation work here on the Sussex Coast. For example bottlenose dolphins who are known to engage in homosexual behaviour and sex for fun, again thought to increase social bonding and cooperation. The black seabream which are all born female and change to male at maturity (known as protogynous hermaphrodites). And finally the incredible seahorse species that in my opinion can claim the throne of the animal drag-kingdom in having the only true reversed pregnancy.

I’m sure Darwin would agree that rather than it all being about nature versus nurture we should focus more on nurturing our true nature, that part of us that is wild and free and far from binary. Wouldn’t it be dull if everything were so very black and white
 life and love is in fact gloriously technicolour thanks to evolution’s rainbow.

Now people can find solace where they will, but I think it’s misguided to look to nature to validate a behavior in humans. For every mammalian species that shows homosexual behavior, there are a dozen who don’t.  (Do those show that homosexuality is “unnatural, ergo wrong?” Of course not!) And homosexuality in humans, which often involves attraction solely to members of your own sex, is not at all the same thing as homosexual behavior in dolphins. For when a the male wants offspring, he knows where to go. Should a rapist find validation by studying ducks?

The last sentence of the piece above, referring to “evolution’s rainbow,” is likely a reference to Joan Roughgarden’s Evolution’s Rainbow, a book-length attempt to justify human non-cis-ness by looking at animals (Roughgarden is a transsexual woman). I reviewed it for the Times Literary Supplement in 2004. My review is no longer online but I have a copy and will send it to those who want to read it. Here’s the last part of my review (it was mixed: I found Roughgarden’s descriptions of behavior being very good but her moral “lessons” untenable). Yet the warning about the naturalistic fallacy is apparently is as relevant today as it was when I wrote this 18 years ago:

But regardless of the truth of Darwin’s theory, should we consult nature to determine which of our behaviours are to be considered normal or moral? Homosexuality may indeed occur in species other than our own, but so do infanticide, robbery and extra-pair copulation.  If the gay cause is somehow boosted by parallels from nature, then so are the causes of child-killers, thieves and adulterers. And given the cultural milieu in which human sexuality and gender are expressed, how closely can we compare ourselves to other species? In what sense does a fish who changes sex resemble a transgendered person? The fish presumably experiences neither distressing feelings about inhabiting the wrong body, nor ostracism by other fish. In some baboons, the only males who show homosexual behaviour are those denied access to females by more dominant males. How can this possibly be equated to human homosexuality?

The step from “natural” to “ethical” is even riskier. As the philosopher G. E. Moore argued, identifying what is good or right by using any natural property is committing the “naturalistic fallacy”: there is no valid way to deduce “ought” from “is”. If no animals showed homosexual behaviour, would discrimination against gay humans be more justified? Certainly not. Roughgarden’s philosophical strategy is as problematic as her biological one.

Roughgarden believes that evolutionary biologists, with their enthusiasm for the “classical” gender roles of the neo-Darwinian theory of sexual selection, are partly responsible for society’s unease with gay and transgendered people. She is wrong. This theory is powerful and largely correct. Yes, there are nuances of behaviour that require special explanation, or that we don’t yet understand. But nobody, least of all Darwin, ever claimed that evolutionary biology is characterized by ironclad laws. Our field is not physics. Nevertheless, some generalizations, such as the pervasive competition of males for females, can be powerful and useful.

Yet in the end, all of this is irrelevant to the gay and transgendered community’s genuine concerns about repressive social attitudes. Rather than wringing her hands about the theories embraced by her biological colleagues, Joan Roughgarden might consider visiting a school board meeting deep in the American Bible Belt. There, ironically, she would find where opposition to a sexually diverse society really thrives, as does opposition to the very theory she is partly lambasting, Darwinism. It is not the intellectuals who are the problem; it’s the anti-intellectuals.

Nature, as varied as it is, can be used to “validate” any human behavior, therefore it can validate NO human behaviors.

Oldest evidence for animals found? New sponge-like fossil is 890 million years old, several hundred million years older than next oldest animal

July 29, 2021 • 9:15 am

First, we have to know what biologists mean by “animals”. In brief, they are multicellular organisms comprising eukaryotic cells (“true cells” with a nucleus and nuclear membrane, as well as organelles like mitochondria). Or, to be more specific, I’ll give the Wikipedia definition:

Animals (also called Metazoa) are multicellular, eukaryotic organisms in the biological kingdom Animalia. With few exceptions, animals consume organic material, breathe oxygen, are able to move, can reproduce sexually, and go through an ontogenetic stage in which their body consists of a hollow sphere of cells, the blastula, during embryonic development.

Long before animals existed, living organisms existed, but these were cyanobacteria (“blue green algae”) and other microbes, not regarded as animals. The first cyanobacteria date back about 3.5 billion years, only a billion years after the Earth formed. The cyanobacteria are identified in fossil stromatolites—layered reef-like structures formed by the accretion of bacteria. Stromatolites are still forming in some places on Earth, like Shark Bay, Australia.

But when did the first metazoan, or “animal” appear? For that you can use either fossil or molecular evidence.

The earliest fossil scientists regard as an animal is Dickinsonia from the Ediacara fauna, dated about 540 million years ago.  Scientists think it’s an animal because its lipid biomarkers, which you can extract from fossils and the sediments above and below them, include cholesteroids, compounds found exclusively in animals. Dickinsonia is known only from imprints, like the one below, and its affinities are a mystery.

Dickinsonia

Molecular data, from which you can construct a phylogenetic tree of living animal groups and then extrapolate backwards, have shown that animals probably originated between 650 and 850 million years ago, but we have no animal fossils from that period. Those trees also show that perhaps the earliest animal was similar to sponges, for sponges seem to be the most “basal” animals—those that branched off the animal tree before other groups. This makes sponges the “sister group” of all other animals.

Now a new paper in Nature by Elizabeth C. Turner of Laurentian University in Canada has pushed the oldest animal fossil back a long way: several hundred million years—to 890 million years ago! And, in fact, the fossil shows features of early sponges, verifying the molecular conclusions.

Now not all paleobiologists agree that what Turner found is an animal—some say the structures observed may have a microbial origin—but Turner herself is pretty confident, as are some other paleontologists. So let’s take this conclusion as “likely, but not certain”. Surely further work will either strengthen or weaken Turner’s evidence.

You can access Turner’s paper by clicking on the screenshot below, or downloading the pdf here. The reference is at the bottom of this post.

Investigating the Little Dal Reef Formation in Northwestern Canada, itself a kind of stromatolite, Turner collected rocks between 1992 and 2018, and, in thin sections of those rocks, observed “vermiform” (worm-shaped) microstructures filled with calcite “spar”, or calcium carbonate crystals. These tube-like structures join and divide in a branching network, just like the tubules of modern sponges, some of which have a calcite skeleton. (The tubules of modern sponges allow them to circulate water through their bodies, getting food and oxygen.) These wormlike structures are surrounded in the fossils by a calcite “groundmass”, which may be the external body of the sponge.

Here’s what Turner says about these interconnecting tubules and why she regards them as early sponges:

The shape, size, branching style and polygonal meshworks of the Little Dal vermiform tubules closely resemble both spongin fibre networks of modern keratosan sponges (Fig. 2a–c) and vermiform microstructure either demonstrated or interpreted to be sponge-derived in diverse Phanerozoic microbial, reefal and non-reefal carbonate rocks. The compositional and textural homogeneity of the microspar groundmass supports an origin through permineralization of a pre-existing biological substance, rather than incremental accumulation of detrital sediment or microbial carbonate that passively incorporated complexly anastomosing tubular microfossils. Variable preservation and association with geopetal peloid accumulations are familiar aspects of Phanerozoic sponge taphonomy In previous work, detailed comparison of the three-dimensional characteristics of vermiform microstructure with branching cylindrical organism types yielded no convincing alternative to the sponge interpretation

Here are subfigures (a)-(b) of her Figure 2 showing the fossil network compared to that of a modern sponge (c), with the captions below (click photo to enlarge).

(From Fig. 2 of the paper): a, Well-preserved vermiform microstructure exhibits a polygonal meshwork of anastomosing, slightly curved, approximately 30-ÎŒm-diameter tubules embedded in calcite microspar (KEC25). Scale bar, 500 ÎŒm. b, Enlarged rectangle from a, showing branching tubules forming three-dimensional polygons intersected at various angles by the thin section; clear calcite crystals, about 10–20 ÎŒm in width, fill tubules in groundmass of more finely crystalline calcite (dark grey). Scale bar, 50 ÎŒm. c, Three-dimensional fragment of spongin skeleton from a modern keratosan sponge, illustrating its branching and anastomosing network of fibres (incident light). Scale bars, 100 ÎŒm (main panel), 20 ÎŒm (inset).

There are other pictures as well, but the first two are the heart of the matter. You may not think they look like much, but they do show the interconnecting, ramifying tubules with the light-colored calcite crystals typical of some groups of sponges. The area where these putative fossils are found is 890 million years old.  And these fossils are older than the next oldest and indisputable sponge fossils by 350 million years!

Turner hypothesizes that these early organisms couldn’t compete with the reef-building cyanobacteria, but were able to find “oxygen oases” to use the oxygen produced by the cyanobacteria. The association of these putative sponges with oxygen-producing bacteria may be one piece of evidence that these are indeed metazoans, which of course require oxygen.

As I said, some paleobiologists disagree about whether these are animals. You can hear a ten-minute Nature-sponsored discussion with Turner, some supporters, and some doubters here. I highly recommend that you listen to this short but lucid discussion.

One other point: these organisms must have survived at least one of the periods of extensive glaciation and freezing known as “Snowball Earth“, when the entire planet was either completely frozen or almost covered with ice except for some open water. (The most extensive was between 700 and 600 million years ago.)  In the linked article, author Laura Poppick says this about that period:

What did life on Earth look like at the time, and how did it change as a consequence of these events?

There were certainly bacteria and there were also algae and unicellular primitive animals, or protists.

There is also evidence that the first multicellular animals originated at this time, probably something like sponges.

Well, according to Turner, the first multicellular animals, probably something like sponges, originated nearly 200 million years earlier than this.

Stay tuned to see how the dispute about the nature of these fossils progresses. Are they animals or simply remnants of bacterial activity? As Turner says in the interview, “We are quite confident” that these are spongelike animals. “It’s almost,” she adds, “a no-brainer.”

And here’s Turner in the field:

(From source): Elizabeth C. Turner, geology professor at Laurentian University, conducting geological fieldwork on northern Baffin Island in 2012. (Supplied photo/Laurentian University)

_______________

Turner, E.C. 2021. Possible poriferan body fossils in early Neoproterozoic microbial reefs. Nature (2021). https://doi.org/10.1038/s41586-021-03773-z

Readers’ wildlife photos

May 7, 2021 • 9:06 am

By Greg Mayer

The following photos were sent to me by a colleague, and were taken during a trip to Costa Rica during December, 2011- January, 2012. We’ll start with the crocodiles of Rio Grande de Tarcoles, which are an attraction for both Costa Rican and foreign tourists, who gather at the highway bridge to see the many large crocodiles gathered there. I was told on one of my visits there that there used to be some sort of slaughterhouse or rendering plant, and that the offal was dumped in the river, which initially attracted the crocodiles. People now feed them, although I think this is officially discouraged.

American Crocodile, Crocodylus acutus, Rio Grande de Tarcoles, Costa Rica, January 2012.
American Crocodile, Crocodylus acutus, Rio Grande de Tarcoles, Costa Rica, January 2012.
American Crocodile, Crocodylus acutus, Rio Grande de Tarcoles, Costa Rica, January 2012.

She also saw crocodiles on a trip to Tortuguero.

American Crocodile, Crocodylus acutus, on boat trip to Tortuguero, Costa Rica, January 2012.

Also at Tortuguero was this heron, a widespread species which is also found in the southeastern US, breeding at least as far north as New York.

Yellow-crowned Night Heron, Nyctanassa violacea, Tortuguero, Costa Rica, January 2012.

A visit to the area of Fortuna revealed a couple of species of mammals. This is a normally colored Mantled Howler Monkey,

Non-blonde Mantled Howler Monkey, Alouatta palliata, N of Fortuna, Costa Rica, January 2012.

while this one is “blonde”; I’ve never seen a howler of this color myself.

Blonde Mantled Howler Monkey, Alouatta palliata, N of Fortuna, Costa Rica, January 2012.

There were also bats.

Proboscis Bats, Rhynchonycteris naso, N of Fortuna, Costa Rica, January 2012.

And last but not least, because they are practically honorary cats, a squirrel from Volcan Poas.

Variegated Squirrel, Sciurus variegatoides, Volcan Poas, Costa Rica, December, 2011.

How different languages depict dog and cat sounds

March 1, 2021 • 2:30 pm

I was asking my French-Canadian friend Anne-Marie (the travel guide) if the French use “vau vau” as the spelling for the dog barking that Americans write as “bow wow”, and she said no, that the French spelling is “wouf wouf”. Well, that’s close enough, but then I thought that someone should compile a list of all the different languages’ spelling of what we spell as “bow wow” (alternatively, “woof, woof”) or, for cats, “meow”.  Foolish me—I should have known that there are tons of such lists on the Internet. Anne-Marie called my attention to two of them.

Take this one from BarkPost: which gives sixteen national versions of “bow wow”. I’ll show just three that struck me:

Meong-meong? Seriously? But in the video below, which gives not the written but the verbal renditions, you can hear native speakers from 70 countries give their national versions of dog and cat noises. It IS “meong meong”!  What you can conclude is that, in general, most people hear dog noises the same way, but there are some odd variants. But there is much less international variation of cat sounds (why?). Note, though, that Thailand is very odd!

One-off: a melanistic emperor penguin! (+ leucistic lagniappe)

November 23, 2020 • 1:30 pm

Well, I’ll be! IFL Science highlighted the presence in Antarctica of the only melanistic penguin I’ve ever heard of. We’ve all seen or heard of melanistic squirrels and jaguars or leopards (both called “black panthers”); it’s a genetic trait and can be either dominant (one gene copy and you’re black) or recessive (two copies required). But penguins?

For a panoply of melanistic species, go here, and click on the screenshot to read the article:

The one-minute BBC video is below, and though I worried this penguin may be subject to predation or lack of potential mates, the IFL Science article (and the video) says it’s doing fine:

Adult emperors have black heads and wings, gray backs, and white bellies, with their distinctive yellow-orange markings around the neck. This particular penguin spotted when the Dynasties team were filming the Emperor episode in Antarctica, is almost entirely black, but does have the odd patch of white on its chest and wing tips, and a splash of yellow around its neck.

Sometimes, sadly, it’s not good to stand out in a crowd, though. The mutation can make animals with melanism more easy to spot by predators. In this penguin’s case, not just because it may be more visible on the ice, but because penguins’ white bellies make them look invisible to predators swimming below by helping them blend in with the light from the surface.

Though, as the BBC points out, this one isn’t doing too badly, having survived into adulthood.

In fact, according to the BBC the penguin is doing just fine. Filmed amongst hundreds of its besuited brethren and looking healthy, it appeared to show signs of looking for a mate while huddling for warmth with the other penguins.

It looks lonely to me, but maybe I’m just anthropomorphizing.

UPDATE: Reader Bill Turner sent this photo, taken by his wife Yvette, and added the caption,

“Your post today on a melanistic Emperor penguin prompted me to send the attached photos of a leucistic gentoo, taken at the Chilean Captain Arturo Prat Base on Greenwich Island on 24 December 2018. The bird was, apparently, quite a familiar sight around the island.”

I hope this white bird found a mate, too.

h/t: Nicole

Asiatic lioness adopts leopard cub

February 28, 2020 • 9:00 am

by Greg Mayer

A paper just published by Dheeraj Mittal and colleagues in Ecosphere reports an Asiatic lioness (Panthera leo persica) that adopted a leopard (Panthera pardus) cub, nursing and feeding it along with its own two cubs for six weeks.

Asiatic lioness, leopard cub, and lion cub in the Gir Forest, India. Photo by D. Mittal.

As WEIT readers know, Asiatic lions survive in only a single relict population in Gujarat in northwestern India, where they coexist with leopards (but not tigers, which have been extirpated in Gujarat). As the only lions in all of Asia, they are carefully monitored by Indian wildlife biologists, and in December 2018 they spotted the leopard cub in the company of the lions. From the paper:

Contrary to the accepted understanding of lion–leopard interactions, in December 2018, we came across an adult free-ranging Asiatic lioness (Panthera leo persica) taking care of a leopard cub (P. pardus fusca) in addition to her own young cubs in the Gir forests of Gujarat, Western India (Fig. 1A). Over the course of the next one and a half months,we intimately monitored this lioness that was recorded to nurse the leopard cub and rear it as her own (Fig. 2). The leopard cub (a male of~2 months with characteristic blue haze in its eyes that indicated its very young age; Fig. 1B) was always found to be associated with the lioness: suckling from her, feeding from kills that she made, and playing with its foster siblings (Fig. 2). The prolonged duration and the ecological context of the observed foster care between these two sympatric and competing felids are bizarre and stimulate intriguing behavioral questions.

The New York Times interviewed one of Mittal’s co-authors, Stotra Chakrabarti of the University of Minnesota.

“The lioness took care of him like one of her own,” nursing him and sharing meat that she hunted, Dr. Chakrabarti said.

His new siblings, too, were welcoming, playing with their spotty new pal and occasionally following him up trees. In one photo, the leopard pounces on the head of one of his adoptive brothers, who is almost twice his size and clearly a good sport. “It looked like two big cubs and one tiny runt of the litter,” Dr. Chakrabarti said.

He has been studying the park’s lions for nearly seven years. This unlikely association “was surely the most ‘wow’ moment I’ve come across,” Dr. Chakrabarti said. His fellow researchers with an Asiatic lion conservation project in India, some who have been watching the big cats for decades, had “also not seen anything like this,” he said.

Sadly, the leopard cub was found dead after about six weeks. An autopsy revealed that it died of a congenital femoral hernia; it had not been abandoned or killed by the lions, and, given its condition, it was probably doomed from the start.

From an evolutionary perspective, rearing an allospecific cub would not be advantageous. Indeed, leopards and lions are competitors, and will kill one another as opportunity arises.  But, to paraphrase Yoda, the Baby Schema is strong with this one, and the juvenile features of essentially all amniotes that elicit the “awwww” response in humans seems to work in lions, too. It leads in this instance to what Mittal el al. call a nonadaptive ‘reproductive error’.

Mittal, D, S. Chakrabarti, S.B. Khambda, and J.K. Bump. 2020. Spots and manes: the curious case of foster care between two competing felids. Ecosphere 11(2):e03047. pdf

Readers’ wildlife photos: Stunning animal architecture

January 28, 2020 • 8:00 am

Nicky Bay is a superb photographer of small animals. I don’t think he’s technically a “reader” of this site, but I wanted to put his pictures under this category. Nicky has a Flickr site here, a Twitter page here, and a website, Macro Photography in Singapore, here. I’ve featured his photography three times on this website (here, here, and here).

He recently had a wonderful post called “5 Mysterious Structures From The World’s Smallest Architects,” but I’ll give the link below the fold. First I want you to guess what kind of creature made these structures. Nicky let me use the photos, which are copyrighted and cannot be reproduced without permission.

1.)  A log cabin made of twigs:

2.) A “jungle tent” made of leaves:

3.) Cage fortress!

4.)  Poop barricade!

5.) Web tower. 

Click on “read more” to see the answers:

Continue reading “Readers’ wildlife photos: Stunning animal architecture” →

Darwin and the Falklands

December 1, 2019 • 8:30 am

[JAC: Greg wrote about Darwin, oceanic islands, and the Falkland Islands fox about six years ago, and gives the link to that post below. But I thought I’d add the link here at the top as well, because it’s a very informative summary of how islands buttressed Darwin’s theory of evolution, as well a discussion about how a fox could have colonized the distant Falkland Islands.]

by Greg Mayer

Jerry’s back from his southern sojourn now, and may have made some posts from Chicago by the time you see this, but as he settles back in I thought it would be good to recall the lessons that another famous evolutionary biologist learned in the Falklands. Although we all associate Darwin with the Galapagos, his visit to the Falklands (also during the Beagle voyage) supplied an important bit of evidence in his thinking about islands, and the phenomena of island life were crucially important components in his argument for evolution.

Darwin was a bit perplexed by the Falklands. In many ways they seemed like oceanic islands—islands never connected to a continent, which had received their biota from across the seas by what Darwin called “occasional means of transport”. There was only a single native species of land mammal on the Falklands: the Falkland Islands fox, which was clearly related to South American foxes. (South America has a modest radiation of canids, which are variously called dogs, foxes, or wolves in English). The mammal fauna was thus depauperate (few species); disharmonious (lacking major ecological or taxonomic groups); and showed affinity to the fauna of the nearest continent (the effect of distance)—all of these are characteristics of oceanic islands.

Canis antarcticus, by George Waterhouse, from the Zoology of the Beagle. The increasing human population, and consequent increased disturbance and hunting, led to the extinction of the Falklands fox by the late 1800s.

How the fox got to the Falklands is an issue that concerned Darwin, but that’s not what I think was most important. (The issue of how they arrived, and when, was largely solved a few years ago, and we discussed it here at WEIT: the short answer is that lowered sea levels during the last glacial maximum greatly shortened the distance to the continent, and the fox came across, perhaps floating on ice floes, as Arctic foxes do.) The problems that the Falklands helped Darwin with most was why oceanic faunas were depauperate and disharmonious. Darwin’s evolutionary hypothesis was that it was difficulties of dispersal that led to oceanic faunas being apparently “undercreated”.

But there was an obvious alternative explanation: the ecological conditions on the islands are unsuitable for a species-rich, harmonious, fauna, despite seemingly appropriate physical environmental conditions. The oceanic faunas were not “undercreated”, but inhabited by the ecologically appropriate species.

These competing explanations are easily tested by introducing exotic species to the island, and seeing how they fare. If they become established, then the cause of their absence is a failure of dispersal, not a failure of environmental suitability. This is where the Falklands helped Darwin, I think. The Galapagos in the 1830s were still nearly pristine, but the Falklands showed him the fauna of an island with little direct habitat disturbance, and a small human population. But the people who had settled the Falklands brought their animals with them. At the time of his visit, Darwin recorded wild populations of cattle, horses, pigs, rabbits, rats, and mice, with cats, dogs and sheep coming later. The Falklands were thus quite capable of supporting a diverse and harmonious mammalian fauna; the mammals just needed help getting there!

So we can see that exotic mammals of all sorts do quite well in the Falklands, and that Darwin’s evolutionary hypothesis is thus supported. Although I’ve read up on the Falklands, Jerry’s visit there is the first by anyone I know, and he has provided firsthand reports on, and pictures of, the exotic mammals. So here again is a bovine, the Belted Galloway:

and a dog:Jerry tells me that sheep are “all over the place there!”, but, unfortunately, he didn’t get any pix of them. So here’s one that I found on the Internet, by Jeremy Richards, who has also sagely captioned it:

The Falklands’ dominant species, together © Jeremy Richards