How many moths must a sloth carry off for the sloth to rely on the moths?

Three Toed Sloth

Is it easier being green? Photo by Bas Boemsaat.

Sloths are weird critters. Cute, in a certain light, but mostly weird. They’re members—with armadillos and anteaters—in a superorder of mammals called the Xenarthra, which are united by a unique form of multi-jointed vertebrae. Their diet consists mostly of leaves, which are poor quality food, and hard to digest. Fortunately, they also have one of the slowest, lowest-energy lifestyles of any mammal, using heavily modified limbs to hang upside down from branches while they browse, their most recent meal fermenting in their guts.

David Attenborough got up close with a sloth—which he calls a “mobile compost heap”—in The Life of Mammals. He also observes one of the sloth’s weirdest behaviors: to answer the call of nature, it climbs all the way down to the ground.

Why do sloths go to all that trouble—and risk—just to poop? Well, according to a recent paper in Proceedings of the Royal Society, they do it to feed poop-eating moths that help cultivate nutritious algae in their fur. No, but really.

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Ed Yong on mind-controlling parasites

Here at Nothing in Biology Makes Sense, we’re fascinated by all the weird, baroque ways that living things influence and coevolve with each other—so Ed Yong’s new TED talk about mind-controlling parasites is right up our alley. Just like his writing—currently on display at National Geographic‘s Phenomena, among many other venues—it’s a compendium of nifty natural history punctuated with highly educational gross-outs and the occasional black-belt level pun.

The cost of attracting pollinators is … attracting everyone else

Flowers of Dalechampia scan dens, with key measurements indicated. Figure 1 of Perez-Barrales et al. (2013).

Flowers of Dalechampia scandens, with key measurements indicated. Figure 1 of Perez-Barrales et al. (2013).

Flowers that rely on animal pollinators to remix their genetic material have evolved a tremendous diversity of strategies for attracting those pollinators—from beguiling scents to elaborate visual displays to pretending to be a lady pollinator.

But there’s a downside to making a big, showy display to attract pollinators—you might also attract visitors who have less helpful intentions than gathering up some pollen and moving on to the next flower. Showy flowers might attract animals that steal the rewards offered to pollinators—or they might attract animals that eat the flowers themselves, or the developing seeds created by pollination. So the evolution of attractive floral displays might very well be a compromise between attracting the right visitors, and attracting the wrong ones.

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Before they hatch, these lizards are tailored to whatever habitat they’re in

Closed-litter Rainbow-skink (Carlia longipes)

Carlia longipes, looking right at home on a rock. Photo by berniedup.

Whether the weather be cold, or whether the weather be hot
we’ll be adapted whatever the weather, whether you like it or not.

Life is risky for a newly hatched lizard. You have to make your way in a habitat you’ve never seen before, full of all sorts of larger animals that think you’d make a decent snack, if maybe not a full meal. Wouldn’t it be nice if you could’ve been preparing for the conditions you’ll meet out there even before you crack through that shell?

Well, for one species of skinks, it looks like this may be exactly what happens. A recent paper in The American Naturalist makes the case that rainbow skinks (Carlia longipes) develop in their eggs to match the habitat conditions around their nest—based on the temperature of the nest.

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Natural History in the -omics era

This post is a guest contribution by Michael Harvey, graduate student in Robb Brumfield‘s lab at the Museum of Natural Science at Louisiana State University. Mike studies avian evolution, phylogenomics, and Neotropical ornithology. 

Blackwater river…approximate Bayesian computation…dawn song…genomic islands…wing chord…target DNA enrichment…

My life as an evolutionary biologist straddles two worlds. I study the comparative phylogeography of Amazonian birds, and on the one hand my research involves laboratory and computational methods that push the limits of new technologies and analytical techniques, and on the other, expeditions to the tropics that are nearly indistinguishable from the natural history work conducted by Victorian era biologists. I am a PhD student at Louisiana State University, and for most of the year my work is in the lab and at my desk. For several months of the year, however, my work is general ornithological collecting expeditions to the Amazon Basin.

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Friday Coffee Break, St. Patty’s Style

Irish Coffee

Every Friday at Nothing in Biology Makes Sense! our contributors pass around links to new scientific results, or science-y news, or videos of adorable wildlife, that they’re most likely to bring up while waiting in line for a latte.

First of all, my deepest apologies for the lateness of this post.  As you may know I am a 4th year medical student and today was Match Day and I was deep in the throws of celebrating the completion of 4 years of medical education as well as learning where I will be training for the next three years in Family Medicine.   So, without further adieu, your links for this week.

CJ decided to that there were too many good links and had to share several.  First, as a skater herself she found an article relating to transmission of skin flora between close team mates and those competing in roller derby.  Next she decided to share how the sequester is going to affect science jobs and the next few years could be difficult.  But finally, a cool post on five animals that could possibly take over the world, which makes me look at spiders a little closer now.

Next, Jeremy likes the fact that new evidence from the Mars rover is favorable to the possibility of conditions that could have sustained life on the red planet.

From Sarah, some very cool slow mo predator vs. prey footage.  Gotta say this is pretty awesome!  She also found some up close and personal pics of jumping spiders.

From Noah, a video documenting several scientists as they inventory one of the worlds most biodiverse locations, the Yasuni Biosphere Reserve.

Finally, in the spirit of March Madness, from Devin comes a battle of the Mammals. “Mammal March Madness from the Mammal’s Suck blog. Although the tournament is purely fictional, the facts and natural history information given out during the extended live tweet rounds are amazing. The first rounds are already complete, but tune in for the exciting finals. Live action via twitter: @Mammals_Suck and general info via the website:”

The Molecular Ecology Online Forum

Cross-posted from Denim and Tweed.

Remember the Molecular Ecologist symposium I attended as part of the 2012 Evolution meetings in Ottawa? Well, there’s going to be a sequel, launching Wednesday in convenient online format.

The Molecular Ecologist will be hosting speakers from the Ottawa symposium in a live-chat on the blog, starting at 9 a.m. US Central Time and running until noon (that’s 3-6 p.m. GMT, for those of us located outside North American). We’re trying out a live-chat service called CoverItLive, which will let readers follow the coversation and submit questions and/or comments directly from the blog — test runs have gone pretty smoothly, and I’m excited to see how this works as a medium for scientific discussion.

If you want to review the Ottawa symposium beforehand, check out the archived material at the Molecular Ecology websited. To indicate your interest and submit questions in advance, e-mail Molecular Ecology Managing Editor Tim Vines; otherwise, just join us Wednesday morning at The Molecular Ecologist.◼

A post about lizards on islands. But not the ones you’re probably thinking of.

Yemen Socotra Felletti 48_00

Socotran Adenium obesum

Evolutionary biologists are fascinated by islands. There are a number of reasons for this. Islands systems can act as natural evolutionary experiments. They are small, less biodiverse, and isolated, so their biota can often be treated as simplified models of more complex mainland ecosystems (e.g. Darwin’s finches on the island Daphne Major). Ecologically similar islands can also act as replicates, with related taxa playing out the same evolutionary scenarios over and over again in isolation (e.g. Caribbean Anolis). Or they can act as life preservers, providing isolated strongholds for ancient evolutionary lineages that have long been extinct in the rest of the world (e.g. the Tuatara of New Zealand).

The Socotra archipelago is a particularly interesting, but poorly studied island system. Socotra consists of four islands in the Indian Ocean. It is extremely isolated (150 miles from the horn of Africa, 240 miles from the Arabian Peninsula) yet it has a continental origin. That means it was once part of the supercontinent Gondwana and suggests that some species may have lived there since it first became an island (~17.6 million years ago). Socotra has a very high level of endemism, with 37% of its plant species and 90% of its reptiles occurring nowhere else. As the islands are very remote and in a politically unstable part of the world, most of this unique biodiversity has not been studied using modern techniques. The islands are rugged and mountainous, reaching 1500m elevation, and primarily classified as tropical desert, making for a fairly fantastical landscape. A recent paper by Goméz-Diaz et al. (2012) takes a broad-brush approach to characterizing a chunk of Socotra’s obscure diversity: the Hemidactylus geckos.

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Evolving invaders

This post is a guest contribution by Kathryn Turner, a PhD student at the University of British Columbia, who studies the evolution of invasive thistles. Kathryn writes about her scientific interests at the slyly named site Alien Plantation and tweets under the handle @KTInvasion.

ResearchBlogging.orgInvasive species are a big problem. A real big problem. In the US alone, invasive species cost nearly $120 billion in damages per year (Pimentel 2005). 42% of species on the Threatened and Endangered list are there primarily because of invasive species.

Which leaves us with two questions. First, most obviously, how is it that a species is able to come into a new environment that it is not adapted to, surrounded by new environmental conditions and foreign biological interactions, and thrive? Thrive so exaggeratedly, that it can out-compete and displace species which have been there for millennia, adapting precisely to those environmental conditions and biological interactions? How can an individual survive to propagate a population? How can any species accomplish this? Second, less obviously: why can’t more species do it? Humans transport animals and seeds (and spores and larvae, etc, etc) around all the time, but only 10% establish self-sustaining populations, and only 1% spread to new habitats, becoming potentially invasive; this is known as the ‘tens rule’ (Williamson 1993) – a funny ‘rule of thumb’ for which I could never quite figure out the math.

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Ecological complexity breeds evolutionary complication


ResearchBlogging.orgIt is a truth universally acknowledged in evolutionary biology, that one species interacting with another species, must be having some effect on that other species’ evolution.

Actually, that’s not really true. Biologists generally agree that predators, prey, parasites, and competitors can exert natural selection on the other species they encounter, but we’re still not sure how much those interactions matter over millions of years of evolutionary history.

On the one hand, groups of species that are engaged in tight coevolutionary relationships are also very diverse, which could mean that coevolution causes diversity. But it could be that the other way around: diversity could create coevolutionary specificity, if larger groups of closely-related species are forced into narower interactions to avoid competing with each other.

Part of the problem is that it’s hard to study a species evolving over time without interacting with any other species—how can we identify the effect of coevolution if we can’t see what happens in its absence? If only we could force some critters to evolve with and without other critters, and compare the results after many generations …

Oh, wait. That is totally possible. And the results have just been published.

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