Ever want to participate in a journal club, but just can’t seem to find the right group of people locally? Why not find the critical mass you need from colleagues online at other universities? That’s more or less what a group did recently. Last week, Rafael Maia, a PhD candidate at the University of Akron, organized an online journal club for discussing evolutionary biology.
For the first meeting, they discussed a recent Nature paper by Hugall & Stuart-Fox titled “Accelerated speciation in Colour-polymorphic birds.” The discussion was held via Google+ hangouts which worked remarkably well considering the number of participants. Be sure to check back often as they are aiming for meetings every two weeks (or more often).
If you missed the session live, you can see the recorded video by heading over to the Evolutionary Biology Online Journal Club blog.
This post is a guest contribution by Dr. Levi Morran, NIH postdoctoral fellow at Indiana University. Levi studies the role that both coevolutionary relationships and mating systems play in shaping evolutionary trajectories. His research using experimental coevolution to test the Red Queen hypothesis recently appeared in Science and was featured on NPR and the BBC.
The 40 Year-Old Virgin
In the movie, The 40 Year Old Virgin, Steve Carell’s character (the title character) asks a sex education instructor, “Is it true that if you don’t use it, you lose it?” Given the context, I’ll allow you to put the pieces together and figure out just what he was referencing with the question. But, the phrase “use it or lose it” is quite catchy isn’t it?
Surprisingly, the phrase is thought to have some relevance in the field of evolutionary genetics, particularly regarding bacterial genomes. You see, widespread gene loss and genome reduction has been observed in some strains of bacteria, particularly those that specialize in certain environments (Cramer et al. 2011; Ernst et al. 2003; Smith et al. 2006). But, how and why do bacteria “lose it”, and do they lose it because they don’t use it?
This post is a guest contribution by Amy Dapper, the proprietor of Evolve It!, a blog about (sometimes) cool (mostly) science-y things. Amy is a PhD student at Indiana University studying evolutionary theory.
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’ . 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 . 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.
Conventional wisdom suggests that pathogens and parasites are more rapidly evolving because of various reasons such as short generation time or stronger selection. Yet somehow, they have not completely won the battle against the host. Recently, a theoretical paper on coevolution in Nature caught my eye (Gilman et al., 2012). Here the authors address this paradox: “How do victim species survive and even thrive in the face of a continuous onslaught of more rapidly evolving enemies?”
Instead of treating a coevolutionary interaction between two species as the interaction of only two traits, the authors investigate the nature of an interaction among a suite of traits in each species. It’s not hard to think of a host having a fortress of defenses against attack from a parasite with an arsenal loaded with many weapons.
A paper by Morris and colleagues (2012) has generated some stir among biologists. The authors are proposing the Black Queen hypothesis to explain genomic reductions among free living interacting microbes. Rather than rehash arguments that have been made more eloquently, I’d like to just point out some informative ones
Quick summary over at the New Scientist
In depth critique by Robert T. Gonzalez
Tommy Leung also reminded me of a great review paper by Sachs et al (2011) over at TREE that is highly relevant to this debate.
What happens when two parasites infect the same host individual? Is the outcome similar to the Thunderdome: two parasites enter, one parasite leaves? Host-parasite interactions are rarely so simple. While a reductionist approach to understanding the interaction of a parasite or pathogen with its host may decompose the system to a single infection, nature is full of much more complex puzzles. Within the host, the battle itself raging between parasites (within-host competition) may have cascading effects on the host.
A recent paper on virulence caught my eye (Bashey et al., 2012) which provides an update to a very interesting result from the group a few years ago. The system includes bacterial parasites, along with parasitic nematodes, that infect insect larvae and eat/digest them from the inside out. Vigneux et al. (2008) found that when multiple parasite isolates are mixed in a host, the host mortality decreased. However, this only occurred when the isolates were not related. In the experiment, the researchers created low relatedness by mixing populations with migration. I reviewed the 2008 paper over at the Coevolvers blog, my personal science blog. The hypothesis was that chemical warfare among the parasites decreased the parasite load and reduced the negative effects on the host, virulence.
What are the evolutionary consequences of parasite superinfection (i.e. simultaneous infection by multiple parasites)? When parasites are genetically distinct, coexistence within a host generates conflict because of limited resources. How this conflict is resolved is the source of evolutionary research on the evolution of parasite life history traits such as virulence, the negative effects on the host caused by infection, and transmission mode, how parasites infect a new host. The transmission mode of a parasite is often characterized as occurring in one of two different modes: vertical or horizontal. With vertical transmission, an offspring obtains its parasites directly from its parents. In contrast, with horizontal transmission, infections occur either directly from the environment or contagiously by infection from other individuals.
My interest in the evolution of transmission mode in parasites and symbionts led me to a recent paper (Ben-Ami et al. 2011), which addresses the consequences of superinfection by two different parasites with different transmission modes of the waterflea, Daphnia magna, on virulence and parasite fecundity. Pasteuria ramosa is a castrating, horizontally transmitted, blood-infecting bacterium where spores are produced from the cadaver of the host Daphnia. Octosporea bayeri, a microsporidium, utilizes both vertical transmission to eggs and horizontal transmission via waterborne spores.