Evolution 2010 Day 3 (June 27th)

A big boat that counterbalances the pendulum at the Oregon Convention Center

I began the second full day of talks at Evolution 2010 presiding over the only education session in the entire meeting, a session which also included my talk for the meeting. It is a bit surprising that our session, which was forced to start at 8 am on a Sunday, was the only one dedicated to actually delivering evolutionary biology to students. It is not that I would like the number of education sessions to be comparable to the fifteen dedicated to adaptation or the thirteen focused on phylogeography: I realize that this was primarily a meeting about scientific research. But somehow the fact that so few people are attending the meeting to speak about their work as educators is of concern; at similar meetings such as the annual meeting of the Ecological Society of America, there are usually numerous education-oriented talks and workshops. While the number of education talks was a bit worrisome, attendance at these talks was not: there was a large and interactive audience throughout the session.

Kristin Jenkins (in proxy for scheduled speaker Jory Weintraub) led off the session with her talk “Evolution Education Resources from the National Evolutionary Synthesis Center”. Jenkins was one of several people at the meeting representing the education and outreach arm of NESCent, the National Evolutionary Synthesis Center. NESCent is primarily funded by the National Science Foundation (NSF), so their mission is not only to foster synthetic understanding in evolution, but also to meet NSF’s “broader impacts” criteria through education and outreach. NESCent accomplishes this through the formation of education working groups, the support of postdocs working specifically on educational issues, organizing workshops aimed at expanding the participation of under-represented groups in evolutionary biology, and providing professional development in education for scientists. They also seek to act as a collection point for valuable curricula produced outside of NESCent, collaborate with a website called Understanding Evolution, organize symposia for secondary school biology teachers, and help support the celebration of Darwin Day. Based on Jenkins’ presentation, it seems like anyone with an interest in improving the educational work they do in evolutionary biology should be participating in some part of NESCent’s education and outreach effort.

Jenkins also delivered the second talk of the education session, “Promoting the adoption of an evolutionary theme in biology courses”. She described NESCent’s contributions to the Introductory Biology Project, which aims to integrate evolutionary content into first-year biology courses. Introductory biology curricula are notoriously idiosyncratic, with different schools taking widely different approaches to introducing their first-year students to the major, so what NESCent is trying to do is to provide curricula that allows for the creation of “evolutionary context” in subjects commonly taught in introductory biology courses. As an example, Jenkins talked about the Krebs Cycle (something most of us were forced to memorize at some point in our lives) and how the fact that it is a highly conserved metabolic pathway can be used to teach evolutionary concepts. NESCent is currently collecting these kinds of “evolutionary extensions” to the introductory biology curriculum, and Jenkins encouraged anyone with suggested ideas to contact her. She also mentioned the possibility of creating an electronic textbook which would aid these efforts, a proposal that seemed to interest many in attendance.

In his talk “Measuring students’ evolutionary understanding: context, coherence, and competence”, Ross Nehm challenged educators undertaking empirical study of their students’ evolutionary understanding to perform more meaningful tests. The study of students’ misconceptions has been a major focus of research into science education, and in evolutionary biology students seem to come with a host of persistent wrong ideas about how evolution works. Many studies have tried to identify where these misconceptions are most rampant and assess the effectiveness of various methods for providing students with the correct conceptual understandings, but Nehm has some pretty major concerns about how these studies are being executed. He identified three key areas in which most studies of evolutionary misconceptions fall short: context, coherence, and competence. Considering context is important because evidence shows that students’ understanding is often limited to the example in which they learned a concept, so if we don’t test their understanding across contexts we are not necessarily getting an accurate picture of the breadth of their understanding. Similarly, we want their understanding to be coherent, meaning that concepts can be used stably across a diversity of problems and not just within the narrow confines of a particular question. Finally, we want students to have competence, which Nehm defined as the deep and robust integration of concepts. Throughout his talk he suggested that the quality of educational research on student misconceptions of evolutionary biology needs to improve greatly; in particular, he expressed concern that the use of “concept inventories” (which measure the number of concepts students can rattle off) fail to assess whether students have achieved competence by demonstrating coherent understanding within a variety of contexts.

Meghan Rector, a graduate student in Ross Nehm’s laboratory, presented the next talk entitled “Evolutionary ‘pressures’: Biologists’ conceptions and students’ misconceptions”. She provided some really interesting commentary on the role that language plays in the maintenance of evolutionary misconceptions. In particular she focused on “multivalent terms”, words like “selection”, “adapt”, and “pressure” recruited from everyday language to have specific meaning in the field of evolutionary biology. This problem really hit home for me, as I have learned that I have to very specifically point out to my students that adaptation in common usage is not really all that analogous to what evolutionary biologists mean by an “adaptation”; failure to make this distinction results in confusion about whether evolution is a LaMarckian or Darwinian process. To research the nature of how multivalent terms lead to confusion, Rector used a computer algorithm to characterize and inventory students’ misuse of the “force metaphor” associated with the use of the word “pressure” to describe the process of selection. She found that misconceptions arising from the use of the force metaphor were rampant, suggesting that evolutionary education must be crafted to supplant metaphor with mechanism.

Ross Nehm (in proxy for scheduled speaker Erica Crespi) provided the next talk (“Desegregating evolution in the curriculum: genomics to the rescue!”), which described work within a consortium of liberal arts colleges to better integrate evolution into introductory biology courses. Most textbooks mimic the deficient mental models of evolution maintained by students in that they present evolution as a separate, segregated subject rather than as a concept integrated across all biological topics. Interestingly, Nehm took issue with the oft-quoted “Nothing in Biology Makes Sense Except in the Light of Evolution” argument of Dobzhansky; Nehm contends that students have no problem understanding narrow biological concepts without any evolutionary framework, and it is a broader understanding of evolution that suffers from the lack of integrative teaching. He then described how the program called Teaching Big Science at Small Colleges uses a series of “Inquiry-based Integrated Instructional Units” to integrate evolutionary understanding across a broad curriculum with a genomic theme.

Norman Johnson spoke next about Nature Publishing Group’s Scitable education portal, where he maintains a blog called “Watching the Detectives”. Scitable functions as an access point for non-scientists with interest in the world of scientific research. Currently focused heavily on topics related to genetics, the site includes many well-organized articles on subjects ranging from the most general to fairly specific. Teachers will find that site valuable, as it contains many well-written articles that can be used to “build your own classroom”. It also functions as a social network, allowing users to sign in and interact with the editors and contributors. Johnson reported that Nature is currently trying to expand the content provided on Scitable, and encouraged those interested in contributing to contact the editors.

Next I delivered my talk, “Sex, Play, and Music: Reaching Non-majors Through Short Courses in Evolution”. If you are interested, I have posted a PDF of the presentation here.

The final talk in the education session (“College students’ misconceptions about population genetics”) was given by Joel Abraham, who represented SimBiotic Software. Abraham described the challenges associated with getting students to think about evolution at the population-level. For instance, SimBiotic offers a virtual lab called EvoBeaker: Sickle-Cell Alleles, which teaches students about the sickle-cell anemia polymorphism. To understand how to better design the lab to displace student misconceptions, Abraham used a diagnostic multiple-choice test that included wrong answers designed to identify student misconceptions to assess the understanding of 563 students. The results showed that significant misunderstandings persist, and suggest challenges that the virtual labs must overcome in order to foster stronger student understanding.

In addition to the education session, there was also a lunchtime Education Outreach Workshop entitled “Developing Science Education Outreach Projects with Local Teachers” sponsored by Kristin Jenkins of NESCent and Louise Mead of the National Center for Science Education. Mead and Jenkins gave an overview of opportunities to work within the public schools as well as different “informal science education” settings (museums, zoos) were outreach can occur. They reviewed six principles for planning quality workshops for teachers as well as how to make sure the workshop integrates science standards that have become focus of education. After this brief presentation, we broke into groups to discuss challenges and ideas we have for realizing our own outreach projects.

There's lots of movement between sessions as participants hustle between talks in different sessions

Beyond the evolutionary focus of the day I also attended an eclectic mix of talks during the morning and afternoon. John Orcutt spoke about geographical patterns in mammalian body size in his talk “Mammal body size and paleoclimatic change: a new perspective on an old debate”. Bergmann’s Rule suggests that overall mammalian body size increases with lower temperatures and precipitation and higher degrees of seasonality. Orcutt wanted to know how how Bergmann’s hypothesized abiotic drivers of body mass patterns compared with biotic drivers like competition, predation, and net primary productivity, so he exposed an exceptionally complete fossil record of dental measures (from squirrels, dogs, and horses) and paleoclimatic data derived from Oregon’s Columbia Plateau to a regression analysis. What he found was that climate data alone do a poor job of predicting trends in body size, suggesting that biotic as well as abiotic factors are likely involved in these trends.

Urban ecology does not get the attention it needs and deserves and urban evolution… well, let’s just say that there is not even such a subject out there. But Jason Munshi-South does just this kind of work in white-footed mice. In his talk “Landscape genetics of white-footed mice (Peromyscus leucopus) in New York City”, he presented results from a survey of mouse diversity across New York City parks. What he found was that although mice maintain significant local fixation of microsatellite genetic markers and high overall diversity, the divergence pattern between mice found in Queens, Manhattan, and the Bronx cannot be resolved. This is pretty phenomenal because the corridors between ideal parkland habitat can be pretty narrow and circuitous, and Queens is separated from the Bronx and Manhattan by water. Munshie-South plans to use landscape analysis to understand how patterns of migration might be maintaining sufficient gene flow to prevent divergence.

There was only one talk on cooperation on this day, but it was a good one. In his talk  “Good Neighbor, bad neighbor: Song sparrows retaliate against aggressive rivals based on direct experience and reputation”, Caglar Akҫay used direct field measurements to the “dear enemy” effect in territorial birds. The “dear enemy” effect, first proposed by James Fisher in 1954, suggests that paradoxically territorial birds may be less rather than more aggressive towards their nearest neighbors, even though they compete most directly with these neighbors. This tolerance of neighbors may be a means of reducing aggression, but it also may be a form of coalition maintenance providing collective defense against invaders. In a really neat set of experiments, Akҫay used audio playback of territorial calls to manipulate how resident birds view their neighbors. His playback simulated two different kinds of bad neighbors: those who were too aggressive to the residents, and those who were insufficiently aggressive towards invaders. Akҫay found that both kinds of bad neighbors were subject to more aggression. This suggests that residents follow a “tit-for-tat” strategy in dealing with their neighbors, but also punish their neighbors for not contributing to communal defense. This finding is fascinating because it shows that these birds maintain a fairly complex and nuanced sense of “justice” in dealing with their neighbors.

My quest to attend as many talks on the evolution of sex and reproduction continued with two more talks. The first, “Mating, pair formation, and sexual conflict in the Gloomy Octopus” by Peter Godfrey-Smith, focused on a group of octopi that reproduce using a “hectocotylized arm” that allows males to deliver their spermatophores to females. Using pictures taken in the field, Godfrey-Smith sought to understand diversity in male copulatory strategies, which can vary from a direct, grappling attempt to mount to a tentative and careful reach. In directly approaching females, males may lower their risk of predation (females are often hidden in protected rock dens) but increase the chance that the female will cannibalized the hectocotylized arm, rendering him reproductively dead. If the female looks dangerous, the male may opt to expose himself to predation and go for the more conservative “reach delivery” of his spermatophore. Although Godfrey-Smith’s sample size was very small, this initial pilot study suggests that the size of the females may dictate the male strategy.

Stephanie Kamel presented a talk entitled “Multiple mating and family conflict in a marine snail” that revealed the kind of trouble that certain mating systems can get you into. Female snails of the focal species (which I did not catch) engage in multiple matings, so polyandry is common. This sets up increased conflict between offspring, who Kamel has shown engage in cannibalistic brood reduction during simultaneous development in egg capsules. Only 2.5% of fertilized eggs survive to hatching, and they do so by eating their siblings before their siblings eat them. To make things more complicated, males provide parental care by carrying egg capsules on their shells, which allows them to potentially carry eggs from multiple females. But don’t forget that those females have also mated with multiple males, so any male who accepts eggs could be subject to parasitism by other males. Kamel has shown that carrying eggs is costly, both in terms of caloric cost and predation risk, so getting another male to carry eggs you fertilized should be greatly rewarded. Clearly life is not simple for these snails, and Kamel plans to unravel more of these intra-sexual, inter-sexual, and intra-generational conflicts.

Poster sessions are always exciting if not a bit overwhelming and I got to check out a few really interesting posters. Erik Hanschen’s poster “Experimental Evolution of Cooperation in Colicigenic Bacteria” showed interesting results of “tragedy of the commons” experiments in bacteria that produce a toxin that is used to kill competitors. Strains of Esterichia coli that produce the colicin have three components that underlie the adaptation: a gene for the toxin, a gene conferring immunity to the toxin, and a gene that allows for lysis. The lysis gene suggests just how altruististic this trait is: individuals lyse themselves in order to release the toxin into the environment, aiding its clonal compatriots by poisoning competitors. When suicide is part of the trait it is ripe for exploitation by a mutant, and apparently a mutation to the toxin gene allows cheaters to prosper on the efforts of altruists. Pretty quickly the colicin-producing trait is lost in the population. Erik’s work showed that this loss is faster in liquid (non-viscous medium) but also lost on growth plates (viscous medium), apparently because the toxin does not stay local on the plate. But he also found that different colicin-producing variants respond differently in these experimental arenas, and sometimes colicin production is not lost and can even be gained. Obviously further work needs to be done to explain how the cooperative production of colicin is maintained, both in these lab arenas and hopefully in the natural world. The existence of wildtype colicin-producing bacteria suggests that the tragedy of the commons is not occurring under all ecological conditions.

There were also a couple of posters on the topography of interaction networks, a topic I wrote about in my coverage of the 2009 ESA meeting. These networks are used to represent the positive and negative interactions between species in a particular community. Research has shown that these networks are not the result of random assembly, and show stereotypical patterning depending on what kind of network it is (between mutualists, predators and their prey, or parasites and their hosts) I got to speak to Marcelo Borges for awhile about his poster “The Structure of Parasite-Host Interaction Networks”. He performed an analysis of the degree of nestedness found in parasite-host networks. Unlike mutualistic networks, parasite-host networks do not appear to be highly nested, although methodological difficulties still seem to exist in exactly how to accurately measure nestedness.

Portland has a certain sense of humor to it, in this case manifested as images of famous Oregon falls over the conference center urinals