Why Evolution is True is a blog written by Jerry Coyne, centered on evolution and biology but also dealing with diverse topics like politics, culture, and cats.
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.”
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
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.
[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:
I’ve just finished making a BBC World Service radio programme about the first animals. Anyone, anywhere in the world, can listen to it (it’s only 28 minutes long!) – you just have to register with the BBC (free, rapid and cost- and spam-free). Click on the pic to go to the BBC website:
The programme deals with two different ways that researchers are studying this question – by looking at fossils, and at DNA. In both cases I interview researchers and – in the case of the Ediacara – get to handle some fossils. I also ate some 600 million year embryos at Bristol University (to see what they tasted like, obviously), but we didn’t include that in the programme. . .
The fossil data relate to what are called the Ediacaran biota – strange fossils from before the Cambrian, around 570 million years ago. The fossils are very hard to interpret – they don’t look like much alive today – but an amazing technique for analysing cholesterol molecules in the rock, so organic molecules preserved for all that time, has confirmed that Dickinsonia, the thing in the picture above, was an animal. Other techniques involve looking at large numbers of Ediacaran fossils and seeing how their distribution relates to those of modern animals. All the data suggest that some of the Ediacaran weirdos were indeed animals, although we cannot know if they are the ancestors of any animal alive today.
The DNA data focuses on a different question, which DNA can answer – which of the groups of animals alive today was the first to branch off the tree of life? Traditionally there has been a straightforward answer to this: sponges, which are nerveless and tissueless. But 10 years ago comparative genomic studies dropped a bombshell – they suggested that the first group to branch off were the ctenophores or comb jellies. This has caused a huge row because it would mean either that nerves evolved twice – once in the ctenophores, and once in our ancestors, after the nerveless sponges branched off – or that the huge sponge group somehow lost the genes for producing nerves.
Many biologists (myself included) don’t like either of these options, and prefer the sponges as the first model, but the data are persistent. Or are they? I spoke to experts on both sides of this argument, which has caused quite a hoo-haa in the zoological community for the past decade.
Anyway, go ahead and have a listen – download it and listen to it on public transport or while you are exercising. NB: I made the programme with ace producer Andrew Luck-Baker.
If you are a teacher, especially if you teach animal evolution, please get your students to listen to it.
Duck update: Honey was gone this morning, though she was here with James all day yesterday. At 7:30 a.m., James was again swimming disconsolately around the pond, and even attempting to quack, though not much of a noise came out. (Previously he’d just uttered low quack-y noises, but now he opened his bill wide and tried a real quack, with pretty dire results.) I’m convinced he was mourning Honey’s absence.
Then, at 10:30, Honey was back! Lord knows where she went; this is a real emotional roller coaster, but surely presages the Big Migration. At any rate, here’s James sitting on the “bathtub” this morning waiting for his mate. He’s standing on one leg and stretching a wing. I like this picture a lot. James is a good mate and I don’t think Honey can do better:
Let’s end the week with some humorous wildlife photos, in particular the finalists from the 2008 Comedy Wildlife Photography Awards. You can see all the photos here, but I’ll put up my favorite five six. Coincidentally, three of them involve bears.
