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.
We have a new contributor today: Samuel Kornstein, who sent this just a few days ago. His notes are indented, and he has a great wildlife photography site here.
I have a bunch of wildlife photos to share. These are all from last week, taken during a family trip to Manuel Antonio and Lake Arenal in Costa Rica. The wildlife there is just incredible. Feel free to post any that you think make the cut.
The highlight was the two toed sloth sighting. My wife and I spent a morning hiking around Manuel Antonio National park with our two young kids (aged two and one), and we were hoping to find a sloth. Unfortunately we didn’t, but still had an amazing time. When we got back to our rental house, this two toed sloth was just hanging out in a tree on the property.
Referring to the photos on his website, he added this:
Photography has been a side hobby of mine for the past ten years or so, and these are some of my favorites.
I believe this is a grey throated (or dark throated) hawk, but I can’t find anything more specific. They were quite common.
Not strictly wildlife (or a great photo), but we visited a manatee rescue center where we were able to see that rare animal (Trichechus inunguis). You can see the horizontally flattened paddle-like tail. As with whale flukes, this clearly is used in vertical propulsion strokes rather than side to side like fish. This reflects the fact that aquatic mammals are derived from land mammals that flexed the spine up and down when running.
Also not really wild, guinea pigs (Cavia porcellus) are raised as food. Some in our group gave it a try, but I can’t get past a passage in a travel memoir that I read years ago describing a guinea pig roasted whole as looking like “the victim of a forest fire”.
This chinchilla (Chinchilla lanigera, I think) was living in a somewhat lower class ancient Inca house (judging from the rather crudely fitted stonework compared to the extraordinary work on things like temples and some higher class houses).
Also probably not wild, these alpacas (Vicugna pacos) were wandering free near one of the Inca sites we visited.
And this alpaca clearly is not wild, but very cute.
And a llama (Lama glama), wild or domestic I don’t know, wandered by in time to give me an excuse for including Machu Picchu in a set of purported wildlife photos.
And another “ringer” just because I really like this photo. This is at Otavalo, Ecuador, photographed during a post trip excursion connected to a visit to the Galapagos a few years ago.
Today’s contribution, photos from Peru, are from a regular, Joe Dickinson. His captions are indented.
Here is the first of two sets of wildlife photos from a recent trip to Peru that I’ve been saving until you returned from you antarctic adventure.
Not very exotic, but I think this flight of pigeons in front of the cathedral in Lima is rather striking.
Iquitos is where we boarded a boat for an Amazon cruise.
This three toed sloth ( genus Bradypus, ) has a baby clinging to her stomach.
The baby is perhaps easier to see in this shot.
This may be a Chilean rose tarantula (Grammostola rosea). At least that name seems to fit. [JAC: this species doesn’t seem to be known from Peru, so readers can help out here.]
OK, not exactly wildlife, but my wife gives some scale what I believe is a Kapoc tree (Ceiba pentandra), one of the species that can be “emergent” (extending beyond the canopy).
Another tarantula looks to me to be a different species from the one above, but I haven’t been able to find any suggestion of an ID.
This is a rather soulful looking spider monkey (genus Ateles)
The wooly monkey (genus Lagothrix) is more muscular looking but also very agile. Both, of course, have the prehensile tail characteristic of New World monkeys. I had to bite my tongue to avoid correcting our guide when he said Old World monkeys have no tail. Wrong—it’s just not prehensile. He also asserted that tarantulas are not spiders because they have ten legs rather than 8. Wrong again, they just have rather large pedipalps (mouthparts). This sort of thing always makes me worry: what else did he/she get wrong that I don’t know about.
Here, out of context, is a baboon (Old World) making rather good use of her tail.
Send those photos in, folks! I can always use more.
Reader Ralph Burgess sent some swell photos from Kruger National Park, a place I hope to visit one day. His notes are indented below:
As requested, a selection here, all from the past couple of weeks in Kruger NP. I’ve eschewed the more conventional iconic shots of lion, elephant, buffalo – I think these are some more interesting ones.
Tawny Eagles (Aquila rapax). I initially saw just the bird on the left munching on a kill, right at the limit of my lens. Just as my aging eyes managed to get him in focus, a second eagle came in to try to steal his lunch, and he launched.
Lilac-breasted Roller (Coracias caudatus). These stunning birds are common in Kruger.
Spotted Hyena (Crocuta crocuta). As I mentioned, I’d like to make a case for you to elevate the Spotted Hyena to honorary cat status. They are phylogenetically closer to cats than dogs, although some elements of morphology and niche are convergent with canines. Their traditional negative reputation in both African and Western culture is undeserved. They were notably curious and endearing animals when encountered in Kruger. They are highly intelligent with complex social structure. They are not primarily scavengers, and certainly not cowardly – they will try to fight off lions to protect their own kills. The mother in the first picture had raised several litters in a culvert, pups of various ages were present. The second picture shows an elder sibling playing at being a parent, grabbing his straying baby brother by the scruff of the neck to bring him back to safety. The last Hyena picture shows a different animal with a fresh impala kill.
White-backed vultures (Gyps africanus). There was a lot more going on here than just the traditional vulture silhouette photo. There was a snoozing pride of lions hidden close in the grass, probably protecting a recent kill, since the birds were actively moving from perch to perch trying for the best spot to monitor them. I caught a moment when several birds were in flight switching position. And I like the way the dry grass looks like the fires of hell beneath them.
Kruger is probably the best place in the world for leopard (Panthera pardus) sightings. The first is a male spraying. The second shows a smaller female trying to stop her impala kill falling out of the tree.
Chacma baboons (Papio ursinus), two modes of transport. The first shows a miserable juvenile clinging on in the rain. The second shows a baby small enough to ride underneath, with en route refreshments conveniently located.
We have a first-time poster today, Rob Knell, an evolutionary ecologist from Queen Mary University of London. His research page is here, and his “favourite animal photos” page is here. Today we have some of his favourites. His captions are indented:
I’m fortunate enough to have taught field courses in both Borneo and South Africa and so I have had a lot of opportunities to see and photograph some really amazing wildlife. Anyway, these are some of my personal favourites.
Male chacma baboon, Papio ursinus, photographed in the Kruger National park, South Africa. Shortly after I took this one of this animal’s accomplices jumped through our window and stole our biscuits.
Hummingbird hawk moth, Macroglossum stellatarum, feeding on buddleia, photographed near Toulouse, France.
Juvenile boomslang, Dispholidus typus. Found in a tree about 20m from our accommodation at a field station in Limpopo province, South Africa. [JAC: these are highly venomous snakes; a juvenile killed one of our Field Museum colleagues, Karl P. Schmidt, in 1957. See the Science Friday video here, which recounts his “death diary”, as he wrote down his symptoms without seeking medical help. A scientist to the end.] [GCM: And, look at our account of Schmidt’s death here at WEIT, and its apparent inspiration for the film The Killer Shrews.]
Lappet-faced vulture, Torgos tracheliotos. Doing the vulture thing in the Kruger Park.
Lappet-faced vulture 2: soaring over the Olifants river, Kruger National Park. That wingspan is probably between 2.5 and 3m.
Nyala male, Tragelaphus angasii, Kruger Park. Nyala are glorious animals.
Oriental Magpie-Robin, Copsychus saularis, photographed at Danum Valley field station, Sabah, Malaysian Borneo. Common as anything but still lovely birds.
Pied Kingfisher (Ceryle rudis): the largest animal that can do a powered hover, I am told. Olifants River, Kruger National Park.
I’ll put this up quickly as I’m getting ready to leave. This multiauthored paper from Current Biology (click on screenshot below; access free with legal Unpaywall app, pdf here and reference at bottom) documents that if you’re a male bonobo (Pan paniscus), having your mom around at mating time gives you a serious reproductive advantage over other males. In contrast, mothers don’t enhance the reproductive success of their sons in bonobos’ closest relatives: chimpanzees (Pan troglodytes). In both species, males remain in a group when mature (they’re “philopatric”) while the females disperse.
Using genetic tests, as well as knowledge of whether a mother was part of a group when the male was siring offspring, the authors determined, for four wild bonobo and six wild chimp colonies of various sizes (see figure below), what the likelihood was for a male to have offspring with and without his mom around. As you can see from the data below, there was a substantial advantage for bonobo males when mom was there: such males had a more than three-fold likelihood of having offspring than when mom wasn’t part of their group. And you can see that there’s no significant difference for chimps. The effect of females on the reproductive success of their daughters wasn’t measured, surely because female bonobos and chimps leave the group when they grow up and thus can’t be found.
Figure 1 (from paper): Observed average likelihood of a male to sire offspring in the presence and absence of their mothers in the group. Bonobos are represented in black and chimpanzees in grey. Circle sizes represent the number of offspring. The generally higher likelihood of a male to sire a given offspring in bonobos is due to the smaller number of males in the group compared to chimpanzees.
How does this work? From the paper:
. . . a large body of evidence suggests that bonobo mothers also behave in ways that potentially increase the paternity success of their sons. For example, bonobo mothers frequently bring their sons into close spatial proximity with estrous females, protect their sons’ mating attempts from interference by other males, interfere in the mating attempts of other males, and form coalitions with their sons to help them acquire and maintain high dominance rank.
Why not in chimps? This is probably due to the different social structure of the species: in bonobos females are more dominant and thus have the ability to control their offspring, fight off unrelated competitors, and form coalitions. As the authors say:
Such maternal behavior is more likely to be effective in bonobos, where the sexes are co-dominant and the highest ranks are consistently occupied by females, than in chimpanzees, where all adult males are dominant over all females.
Certainly it would help a female chimp’s reproductive success if she could do what bonobo moms do, but they simply don’t have the social status to permit such behavior. The genes behind their social structure have forestalled the evolution of genes for maternal helping of sons’ reproduction.
What is the evolutionary advantage of such behavior? That’s pretty clear: a female’s grandchild carries a quarter of her genes. Any gene that makes a female help her sons reproduce will be represented in more copies than alternative genes that don’t produce such helping behavior. This is just a form of kin selection: an extended form of parental care that involves not just tending your young, but helping them mate.
An unanswered question. Having your own offspring takes a lot of effort and is costly in terms of time and physiological condition, shortening your lifespan compared to not having offspring. But if you could somehow, as a female bonobo, cease reproducing, you might be able to live a lot longer and, by helping sons have offspring, pass on even more of your genes than if you kept reproducing yourself. If this tradeoff worked, you’d expect females to stop reproducing, going through a menopause but then living a long time and helping their sons find mates.
But this isn’t the case: bonobos and chimps, like nearly every other mammal, keep reproducing until they die. As far as I remember, and I may be wrong, only humans and orcas have a well recognized menopause in females.
Why don’t bonobos have it, too? Well, the tradeoff I mentioned above may not work, or perhaps there are simply no genes around that can produce menopause. Since there’s nearly always genetic variation for every trait, I suspect that the former answer is more likely: you don’t leave more genes by ceasing reproduction and helping your sons have grandchildren for you. But that’s just a guess.
A few weeks ago I had the wonderful experience of watching macaques on a rock on the beach of the Thai island Koh Larn. Until sunset there was only half an hour left but luckily the light was enough for some nice pictures.
I don’t know what species of macaque it is, so readers are welcome to provide an ID.
