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.

A team of evolutionary microbiologists has performed exactly the experiment I outlined above. The study’s lead author is Diane Lawrence, a Ph.D. student in the lab of Timothy Barraclough, who is listed as senior author.

For the experiment, the team isolated five bacterial species, of very different lineages, from pools of water at the bases of beech trees—ephemeral pockets of habitat for all sorts of microbes that break down woody debris, dead leaves, and other detritus. They cultured the bacteria on tea made from beech leaves, in vials containing either a single species, or all five species, and let them evolve for eight weeks—several dozens of bacterial generations. In a particularly clever twist on standard experimental evolution methods, they also used nuclear magnetic resonance (NMR) to identify the carbon compounds in sterilized tea that had been “used up” by the bacterial cultures, and compared the compounds in fresh beech tea to determine what the bacteria were eating.

The foot of a beech tree.

And, maybe not surprisingly, the bacterial species’ evolution with company turned out to be quite a bit from their evolution alone. Left alone, most of the species evolved a faster growth rate. This is a common result in experimental evolution, because the process of transferring evolving bacteria to fresh growth medium—”serial transfers” that were performed fifteen times over the course of the experimetn—can create natural selection that favors fast-growing mutants. But, grown all together in the same tube, species that had evolved faster growth rates in the solo experiment evolved slower growth instead.

To find out what had evolved in the multi-species tubes, the team tested the growth of the bacterial species on beech tea that had been used to grow one of the other species, then sterilized. The original, ancestral strains of bacteria generally had negative effects on each others’ growth—they lived on similar compounds in the beech tea, and so their used tea wasn’t very nourishing for the other species. The same thing occurred with the strains that had evolved alone, only stronger, which makes sense in light of the increased growth rates, which would’ve depleted the growth medium faster.

But the interactions among the strains of the different bacterial species that had evolved together was strikingly different. Many of them actually made the tea more nutritious for other species in the evolved community. That is, some of the bacteria had evolved the capacity to eat the waste products of another species that was evolving with them. Using the NMR method to track changes in the presence of different carbon compounds in the tea before and after use provided confirmation that the co-evolved species were using, and producing, complementary sets of resources.

In short, the evolving community didn’t simply become more diverse—it evolved new kinds of mutually beneficial relationships between species that began as competitors.

Beech leaves—yum?

That evolutionary shift toward mutual benefit had a significant impact on the bacterial community as a whole, too. Lawrence et al. assembled new communities of bacteria extracted from the end-point of the group evolution experiment, and compared their carbon dioxide production, a proxy for overall metabolic activity, to that of a community assembled from bacteria extracted from the end point of the solo-evolution experiments. The community of co-evolved bacteria produced significantly more carbon dioxide, suggesting they were collectively able to make more use out of the growth medium.

So that’s a pretty nifty set of results, I have to say. But I’m also left wondering what it tells us more generally. In both Lawrence et al.‘s paper, and in accompanying commentary by Martin Tucotte, Michael Corrin, and Marc Johnson, there’s a fair bit of emphasis on the unpredictability of the result. Lawrence et al. write, in their Discussion section,

The way in which species adapted to new conditions in the laboratory when in monoculture—the setting assumed for many evolutionary theories and experiments—provided little information on the outcome of evolution in the diverse community.

And, as Corrin et al. note,

These results imply that predictions constructed from single-species experiments might be of limited use given that most species interact with many others in nature.

So … evolution went differently under different conditions? That isn’t exactly a shocking revelation. The fact that this is one of the study’s major conclusions is a symptom of how little experimental work has actually tested the effects of multiple species on evolution. One experiment I’ve discussed previously on my own blog, Denim and Tweed, focused on the joint effects of predators and competitors on microbes that live in pitcher plant pitfalls, similarly emphasized the fact that it wasn’t possible to predict the evolutionary effects of predators and competitors together based solely on their individual effects. Work in this line of inquiry is hanging at the point of establishing that complex conditions lead to complex results.

What I’d really like to know—and I think all the authors of both the paper and the commentary would agree with me on this—is how we can begin to make general predictions about community evolution beyond, “it depends what we put in at the start.” It may be that we’ll need a lot more studies like this current one before we can start to identify common processes, and more interesting trends.◼

References

Turcotte, M., Corrin, M., & Johnson, M. (2012). Adaptive evolution in ecological communities. PLoS Biology, 10 (5) DOI: 10.1371/journal.pbio.1001332

Lawrence, D., Fiegna, F., Behrends, V., Bundy, J., Phillimore, A., Bell, T., & Barraclough, T. (2012). Species interactions alter evolutionary responses to a novel environment. PLoS Biology, 10 (5) DOI: 10.1371/journal.pbio.1001330

It doesn’t make much sense that U.S. citizens, whose taxes fund most of the basic science in this country, are then expected to pay upwards of $50 for a single PDF copy of a journal article presenting government-funded research results. The National Institutes of Health already requires that research it funds be archived online and accessible to the general public free of charge—why not expand that to all government-funded research? And hey, there’s a way to suggest exactly that out to the man in charge: a petition on WhiteHouse.gov.

We believe in the power of the Internet to foster innovation, research, and education. Requiring the published results of taxpayer-funded research to be posted on the Internet in human and machine readable form would provide access to patients and caregivers, students and their teachers, researchers, entrepreneurs, and other taxpayers who paid for the research. Expanding access would speed the research process and increase the return on our investment in scientific research.

The highly successful Public Access Policy of the National Institutes of Health proves that this can be done without disrupting the research process, and we urge President Obama to act now to implement open access policies for all federal agencies that fund scientific research.

It needs 25,000 virtual signatures within 30 days before it’ll get any meaningful attention, so sign this thing and then start badgering all your online “friends” about it, why don’t you? Especially the jerks who keep filling your update stream with branded product promotions and/or time-sucking adorable cat videos and/or news about how they’ve just spent real money for a virtual cow—post this directly on their “walls,” if those are even still a thing, with or without a witty and/or pleading comment appended.

I mean, it’s Monday morning; it’s not like you’re going to get do anything else for the benefit of humanity in the next minute or two, you slacker.

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.

Simone is in the field at beautiful White Sands, New Mexico, and blogging about it.

The setting is White Sands, NM – an island of gypsum dunes slowly transforming and shifting through the Chihuahuan Desert. The protagonists are three species of small white lizards inhabiting these dunes. The story is recent and rapid evolution: changing ecology, natural selection, and speciation. Our attempt, as field biologists, is to tell that story.

Noah points us to NASA’s satellite images of the Columbia Glacier in southeastern Alaska, which, like a lot of glaciers these days, is getting smaller.

In 1986, the glacier’s terminus was just a few kilometers north of Heather Island. By 2011, it had retreated more than 20 kilometers (12 miles) to the north, moving past Terentiev Lake and Great Nunatak Peak. As the glacier has retreated, it has also thinned substantially, as shown by the expansion of brown bedrock areas. Rings of freshly exposed rock, known as trimlines, are prominent in the later image. Since the 1980s, the glacier has lost about half of its total thickness and volume.

Devin suggests a recent editorial in Science on the need to connect people with graduate-level science expertise to high school science education.

At any one time, there are thousands of U.S. Graduate Students with strong Science expertise and an interest in education who would be more than qualified to stem the critical shortage of secondary chemistry, physics, earth sciences, and biology teachers, but who will most likely never set foot in a high-school (precollege) classroom.

Sarah points out that the BBC has a treasure trove of video on adaptations for defense against predators. (The one titled “snake in the grass” is especially great. —Jeremy)

Maybe if you have that cup of coffee outdoors, you’ll do better next allergy season?

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.

 Our mission is to publish for the scientific community high quality images of all the world’s ant species. As of May of 2012, AntWeb has 77510 ant images, of 18508 specimens representing over 8304 species. AntWeb provides tools for submitting images, specimen records, annotating species pages, and managing regional species lists.

One type of gammaproteobacteria , calledAcinetobacter, was singled out as being “strongly linked to the development of anti-inflammatory molecules”.

“Basically, our study showed that the more you had of this particular gammaproteobacteria on your skin then you had a immunological response which is known to suppress inflammatory responses ( to pollen, animals etc).”

Understanding the history of species is critical to understanding evolutionary processes and for making predictions about how biodiversity will fare in a rapidly changing climate. Information about how species are related (phylogeny) and how their populations have responded to past climate change (historical demography) can inform us about the conditions under which they have evolved and adapted, and how they might respond to changes currently under way.

Modern scientists get at these questions by examining two types of data: the fossil record and patterns of DNA sequence variation. The fossil record is relatively straightforward. You find a fossil in location X. You identify it as species Y and you use some method to (e.g. radiocarbon dating) to infer it was there at time Z. Making inferences from DNA sequence variation, by contrast, involves complex, computer-intensive statistical analyses, and the field is in a state of tumultuous, rapid advance.

A fascinating case study that involves the integration of fossils and DNA sequence data, and illustrates the ways in which rapid statistical advances are changing our understanding of species’ evolutionary histories is that of the origin of the polar bear (Ursus maritimus).

For decades, it has been thought that polar bears arose relatively recently (50-150 thousand years ago) from brown bears (Ursus arctos) and rapidly specialized to forage on polar ice. Kurtén (1964) believed they were derived from Siberian brown bear populations. This was originally informed by the fossil record, with older polar bear fossils having never been found.

With the advent of accessible DNA sequencing technology, researchers confirmed the hypothetical relationship of polar and brown bears as sister species and further found that the polar bear lineage actually seemed to be nested within brown bear lineages, with polar bears being most closely related to brown bears from the Admiralty, Baranof and Chichagof islands in southeast Alaska (Talbot and Shields 1996). Although the hypothesis of a Siberian origin appeared to be rejected, the statistics of the day did not allow for a rigorous estimate of timing from molecular data.

For a variety of technical reasons, studies in the early days of molecular genetics used primarily mitochondrial DNA (mtDNA) for historical inference. MtDNA has a few quirks that differentiate it from the rest of the genome: it is maternally inherited and it does not recombine. These quirks have an important consequence for studies based on it: the whole mitochondrial genome has a single story to tell, and that story is matrilineal.

You can see how this limitation might play out in phylogenetic inference if you consider attempting to use mtDNA to trace a person’s ancestry. Take me, for example. Of my eight great-grandparents, seven of them are irish, but my mother’s mother’s mother is German. As a consequence, 7/8 of my genome is expected to be of Irish origin, and the other 1/8 (plus mtDNA) Germanic. Given a sufficient database for comparison, if we sequenced a random set of genes from throughout my genome, we would discover this. If we only sequenced mtDNA, however, we would only see my German ancestry. As we sequenced more and more mtDNA, we would become more certain that I was of German descent, and be able to identify with greater precision which state and perhaps which town my great^5-grandmother hailed from. What we would not see, however, is that 7/8ths of the freely recombining, bi-parentally inherited genes contributed to my nuclear genome by my numerous non-maternal ancestors would tell a multitude of other stories, each of them tracing their own ancestries back to the Emerald Isle.

This limitation of relying on a single genetic locus (in this case mtDNA) remains important when inferring the histories of whole species on the scale of thousands to hundreds of thousands of generations, and in the late 1990′s and early 2000′s, researchers started to become aware of this fact. In spite of this knowledge, laboratory and analytical obstacles remained that prevented researchers from gathering and appropriately analyzing DNA sequence from many nuclear genes. Meanwhile, analytical developments began to occur that allowed the use of dated fossils in combination with DNA sequences to estimate the timing of branching events in phylogenetic trees and technical advances allowed DNA to be extracted and sequenced from “sub-fossil” remains over 100 thousand years old.

In light of these challenges and developments, researchers doubled down on mtDNA sequencing. They gathered full mitochondrial genomes from extant bear populations as well as fossils and used sophisticated time-calibrated analyses to hone in precisely on date that polar bears diverged from their brown bear ancestors. In perhaps the pinnacle of this work, Lindqvist et al. (2010) sequenced the mitochondrial genome of a 130-110 thousand year old polar bear jawbone and used that information to infer that polar bears diverged from the brown bears of southeast Alaska 152 thousand years ago. Because the fossil that supplied the ancient DNA shared modern polar bear morphology, the work suggested that after the split, the polar bear lineage underwent a spectacularly rapid evolutionary change, adapting morphologically and physiologically and expanding across the arctic region in 20-30 thousand years to become the polar bears we know today.

From 2008 to 2010, a series of algorithms were published that could take data from multiple genes and infer the history of whole populations, a drastic improvement over previous methods that could only identify the history of single genes (e.g. mtDNA). With these methods in mind, a group of researchers gathered data from 14 nuclear genes for multiple extant brown and polar bear populations (Hailer 2012). When they analyzed these data they found them to be inconsistent with mtDNA in both the branching pattern and the timing of branching. That is to say, the new data analyzed with the new method suggested that polar bears diverged far earlier than previously thought (around 600 thousand years ago) and that they were no longer closely related to the southeast Alaska population, but rather to the common ancestor of all brown bear populations.

The authors posit that the most likely explanation for the drastic incongruence between genes is introgressive hybridization. It is likely that some time in the last 100 thousand years, polar bears hybridized with brown bears, and that brown bear mitochondrial DNA spread throughout polar bear populations and became fixed.

This new information changes the interpretation of polar bear evolution in three important ways. First, the older origin of Ursus maritimus obviates the need to invoke extremely rapid evolution to explain the appearance of the remarkably well adapted polar bear. Second, it means that polar bears have persisted throughout many pleistocene glacial cycles, implying that they have been historically resilient to drastic changes in the polar environment. Finally it has been hypothesized that large scale mitochondrial introgression can result from drastic demographic processes, such as rapid expansion of restricted populations. In the case of polar bears, this implies that they may have been subject to drastic range contractions and expansions in the past.

Given the winding path technology and statistics have taken us on toward understanding the evolution of polar bears, and the current pace of innovation, we can only assume that the parts of the story we know now are still incomplete, and in ways that we may not yet understand. In the future, we can expect to learn in greater detail about demographic changes, such as the timing and extent of aforementioned population size shifts, and perhaps more importantly about how polar bears have adapted to climate change in the past, and how they might in the future.

Citations:

Hailer, F., V. E. Kutschera, et al. (2012). “Nuclear Genomic Sequences Reveal that Polar Bears Are an Old and Distinct Bear Lineage.” Science 336(6079): 344-347.

Kurten, B. 1964. The evolution of the polar bear,  Ursus maritimus Phipps. Acta
Zoologica Fennica 108:1–30.

Lindqvist, C., S. C. Schuster, et al. (2010). “Complete mitochondrial genome of a Pleistocene jawbone unveils the origin of polar bear.” Proceedings of the National Academy of Sciences.

Talbot, S. L. and G. F. Shields (1996). “A Phylogeny of the Bears (Ursidae) Inferred from Complete Sequences of Three Mitochondrial Genes.” Molecular Phylogenetics and Evolution 5(3): 567-575.

You could look at this in two ways. On one hand, the ants are susceptible to theft by other insects that can exploit their effective traps.  Alternatively, the traps are doubly effective because they allow the ants to eat not only the insects that blunder into the trap, but those that try to feed from them. It’s a trap for thieves as well as passers-by.

 As the group headed out along the walkway, Ginger noticed a gull acting strangely a short distance ahead of her. The bird was on the inside of the breakwater, where the water is clear and can be quite still. The gull appeared to be feeding on something underwater, but it didn’t raise its head. As they approached, they could see a red-orange shape in the water below the gull. When they got to the spot directly above the gull, they could see that it was an octopus. And Ginger’s camera was in her hand.

They say people declaring on Facebook that they are organ donors could spur others to sign up at motor vehicle departments or online registries. But these experts say Facebook could create an informal alternative to such registries that could, even though it carries less legal weight, lead to more organ donations.

This month’s issue of the Carnival of Evolution, which collects online writing about Darwin’s dangerous idea and all its variously modified descendents, is online over at John S. Wilkins’s blog Evolving Thoughts. Highlights include, but are not limited to, an attempt to trace the origin of the phrase “social Darwinism,” discussion of how sloths and turtles evolved to move slowly, and whether the diet of early humans was more healthy than ours. And there’s even a few contributions from this very blog. Go now and read the whole thing.

Religious beliefs, or more likely disbelief, tend to be a hot topic on science blogs, particularly those with a evolutionary bend.  However, when these topics come up there is often more opinion than science, which is why I was excited to see an research article in last weeks edition of Science titled ‘Analytical Thinking Promotes Religious Disbelief’ [1].  The article, authored by Will M. Gervais and Ara Norenzayan, uses a series of five studies to build a causal link between analytical cognitive processes and religious disbelief.  I thought it would be fun to delve into the science behind their audaciously titled article for my guest post here at Nothing in Biology Makes Sense.

The authors approach understanding the cognitive underpinnings of religious belief and disbelief using the dual-process theory of human thought.  This theory posits that we use two distinct and separate systems for reasoning.  The first, creatively termed System 1, is intuitive and produces a rapid response based only on prior knowledge and experience.  Previous research has found that individuals who rely more heavily on this intuitive cognitive system are more likely to believe in supernatural entities, and thus tend to have stronger religious beliefs [2]. On the other hand, System 2 is rational and produces a slower response based upon logic and reasoning that, when employed, often overrides the conclusions of System 1.  The authors hypothesize that, in contrast to System 1, this analytical cognitive system promotes religious disbelief.

Their first study establishes a correlational relationship between analytic thinking and religious belief by asking participants to answer three clever questions that have an immediate intuitive, but incorrect, answer and a correct answer that requires deeper analytical processing.  These questions, and their answers, can be found in the table below.  The study participants then answered a survey about their religious beliefs.  The results show that participants that arrive at the correct, analytical answers to the first set of questions also tend to exhibit more religious disbelief in their responses to the survey.

Excerpt from Table 1

The next four studies build a clever, and surprising, causal link between employing analytic thinking and  expressing religious disbelief. In these studies, participants either received a subtle priming stimuli intended to activate analytic thinking or a similar control stimuli.  In study 2, participants either viewed four images of Rodin’s The Thinker exhibiting a pensive pose or the control image of Discobolus of Mayron throwing a discus.  In studies 3 & 4, the participants constructed sentences from sets of words meant to induce analytical thinking, such as ‘think’, ‘reason’ or ‘ponder’, or with control words, such as ‘hammer’, ‘shoes’, and ‘jump’.  In study 5, the participants were simply asked to answer the survey in a difficult-to-read font, which has been shown to increase analytic thinking, or an easy-to-read font.  Amazingly, in all four studies, the participants exposed to the analytic stimuli showed significantly higher degrees of religious disbelief when surveyed.

source: Wikimedia

So – what do these results mean?  Does viewing intellectual art or using fancy fonts really make someone more likely to reject religious views?  In other words, can you really believe that such seemingly trivial stimuli can alter participant’s beliefs on such a personal and important topic? Making up one’s mind about the meaning of these results may be a prime example of the struggle between one’s own intuitive and analytical cognitive systems.

References:

[1] Gervais, Will M. and Ara Norenzayan (2012) Analytic Thinking Promotes Religious Disbelief. Science 336: 493-496. DOI: 10.1126/science.1215647

[2] Shenhav, Amitai, David G. Rand and Joshua D. Greene (2011) Divine Intuition: Cognitive Style Influences Belief in God. J. Exp. Psychol. Gen. DOI: 10.1037/a0025391

On the last day of April, two blog carnivals—collections of links to posts on a given topic—are freshy posted, and both are worth some of your surfing time.

First, over at Seeds Aside, is a double March/April edition of Berry-go-Round, which rounds up online writing about all things botanical, with everything from peppers to savannah treetops to electrical signalling within the tissues of carnivorous plants.

And then over at her blog on Scientopia, Scicurious is hosting an edition of the Diversity in Science Carnival devoted to “imposter syndrome,” the nagging fear of secret inferiority that almost everyone seems to feel at some point in a scientific career. Imposter syndrome can be especially troublesome for women and members of minority groups, who may not see many folks that look like them amongst their colleagues.

From Noah: New surveys of a small nature reserve in Madagascar have turned up 36 previously unknown species of frogs.

Lead author of the paper, Gonçalo M. Rosa, told mongabay.com that the reason why this forest held so many frog species “is still a mystery.” He notes that up to 24 of the species in the forest may be endemic, i.e. found no-where else in the world but in tiny Betampona [Nature Reserve].

“And that’s why these numbers are so extraordinary (especially compared with other tropical forests),” Rosa exclaims. “Betampona is also considered a botanical ‘hotspot’ with 20 of the 100 most endangered Malagasy plants found within its borders!”

The rules are simple. You must make a dance that not only captures the essence of your science but is also a cool work of art. Take a look at last year’s finalists for inspiration. Then enter the contest on the Gonzo Labs Web site. The competition is open to anyone in the sciences, broadly defined—engineers, mathematicians, and historians of science are welcome. You just need to be working on a Ph.D. or already have one. [links sic]

“There are two explanations,” Ms Grabowska-Zhang told BBC Nature.

“One: birds join their neighbours because they think: ‘My nest could be next.’

“Or they join because their neighbours have joined their [predator chasing] mobs before, and they know that if they don’t reciprocate, they’ll be left alone next time. It’s sort of great tit tit-for-tat.”

This differing characteristic could potentially predispose women to heart problems while under stress, says study leader Chester Ray. He adds that the results came as a surprise, since previous studies men have significantly less blood flow than women during the physical stress of exercise, and could explain why women tend to have more heart troubles after stressful events, such as losing a spouse. The findings also reemphasize the importance of mental stress in affecting health.

Alongside the numerous cosmetic genital procedures he offers, Dr Ostrzenski trains practitioners in procedures including ‘g-spot fat augmentation’ and ‘g-spot surgical augmentation’. [link sic]