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2014 American Society of Naturalists Awards Source: The American Naturalist, Vol. 185, No. 1 (January 2015), pp. iii-v Published by: The University of Chicago Press for The American Society of Naturalists Stable URL: http://www.jstor.org/stable/10.1086/679278 . Accessed: 27/11/2015 05:11 Your use of the JSTOR archive indicates your acceptance of the Terms & Conditions of Use, available at . http://www.jstor.org/page/info/about/policies/terms.jsp

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2014 American Society of Naturalists Awards Sewall Wright Award Mark Kirkpatrick

The Sewall Wright Award honors a senior but still active investigator who is making fundamental contributions to the Society’s goals, namely, promoting the conceptual unification of the biological sciences. This year’s recipient is Mark Kirkpatrick, professor in the Department of Integrative Biology at the University of Texas, Austin. Because of his emphasis on synthesis of theory and data, he follows closely in the footsteps of Sewall Wright. Further, many of Mark’s most influential articles have been published in The American Naturalist. Much of Mark’s research builds on topics first explored by Wright. Quite specifically, he has explored Wright’s metaphor of an adaptive landscape. For example, in an early article, he derived the conditions under which peak shifts on the phenotypic adaptive landscape can result from changes in population variation. But his similarities with Wright are far more general because he also collaborates with empiricists to both analyze data sets and develop theory that has strong empirical underpinnings. Mark has made major contributions to several different areas, including the theory of sexual selection, the evolution of continuously varying traits, the determinants of range limits, and the evolution of sex-determining mechanisms and chromosomal inversions, as we describe in the next few paragraphs. Early in the 1980s, he and Russell Lande (an earlier recipient of the Sewall Wright Award) simultaneously and independently built genetic models of runaway sexual selection. Mark formalized the population genetic conditions necessary for the self-accelerating interaction between genes for female choice and male reproductive traits that can potentially create the enormous phenotypic differences between the sexes. He codiscovered the famous “line of equilibria,” arising from the interaction of natural and sexual selection with random genetic drift. This is one of the first genetic mechanisms shown to initiate and contribute to rapid evolution of sexual isolation. These findings helped transform sexual selection from a rather dormant field into one of the fastest-growing research areas in population biology. What seems to have happened next is that many empiricists were unsure of the arbitrariness of divergence predicted by these models, and it was largely left to Mark to develop a series of quantitative genetic models that assessed various verbal arguments. He

showed that female preferences are expected to evolve to maximize direct fitness benefits rather than preferring “sexy” males that provide few benefits (such as a good territory). The culmination of this work was an article published with Nick Barton that derived a fundamental equation that summarizes, for empiricists, the quantities that must be measured to assess the efficacy of female choice based on good genes as a force for preference evolution. Their conclusion is that the strength of indirect selection is likely to be generally weak, although plausibly influential in the absence of any direct effect on female fitness. In a second contribution, Mark developed models of sexual selection in monogamous species (with Steve Arnold and Trevor Price). One of the emergent results from these models was a solution to the question of how a trait can be heritable, show a positive selection differential, and yet not evolve, a point first illustrated by R. A. Fisher in a cryptic table in his book The Genetical Theory of Natural Selection (Clarendon Press, 1930). These findings have gone on to stimulate a large area of research that evaluates competing theories for the presence of persistent directional selection in natural populations. Mark continues to work on sexual selection. Incorporating increasingly sophisticated quantitative genetic models, he has recently focused on the theory of reinforcement, exploring how conspecific mate preferences may be strengthened as a result of selection against hybrids. For example, these models show how sexual selection itself can generate reinforcement when mate choice is directed against hybrids. As hybridization becomes rare, selection against hybridization becomes weaker, so it is not generally obvious how the process of complete speciation can be achieved; recent theory he has developed (again in collaboration) illustrates some conditions that can lead to complete assortment. Most empirical research in quantitative genetics relies on measuring a few traits and calculating the genetic correlation matrix between them. However, many traits obviously vary continuously and, in principle, are described by an infinite number of points and, hence, a genetic correlation matrix of infinite dimensions. Mark developed the first models to describe evolution of these traits and how they might be best empirically studied. Importantly,

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his methods for measuring shape and shape transformations rest on an underlying genetic model, rather than focusing exclusively on the phenotype. On the basis of both theory and data, he is involved in the ongoing debate about whether genetic constraints (heritability and genetic correlations) play a major role (his position) or a minor role in limiting the trajectory of phenotypic evolution. Mark’s article with Barton on limits to a species ecological range received the President’s Award for best article in The American Naturalist in 1997. Here, the modeled constraint was not limited genetic variation but migration opposing selection. They modeled the process, first suggested verbally by Haldane and Mayr, that gene flow from the center of a species range can disrupt adaptation at the edge. This seminal work has inspired other theoreticians to extend the basic model to include species interactions, such as competition and predation, and (in Mark’s case, in particular) how limited genetic variation at the limit can affect expansions. It has also led to a resurgence of experimental studies measuring gene flow and selection at the limits of species ranges and consideration of other factors that may set species range limits. The emerging areas of Mark’s research focus on the evolution of sex-determining mechanisms and chromosomal inversions. A 2006 article in Genetics (with Barton) showed how inversions more generally spread if they encompass at least two loci with alleles that are in migrationselection balance. A 2007 article in Nature (with Sander van Doorn) showed how a new sex-determining locus can be favored if it arises near a locus segregating for sexually antagonistic variation (i.e., one allele favored more in

males and the other in females). An important finding is the role of linkage, and in particular an inversion that captures the sexually antagonistic allele and the sex-determining locus may play the key initial step. These findings are stimulating a huge amount of work on the role of inversions in speciation. Both these new areas of Mark’s research exemplify the importance he attributes to empirical tests. For example, he is working with Katie Peichel on sex-determining mechanisms in sticklebacks and with Diego Ayala and Rafael Guerrero on mosquito inversions, in an attempt to parameterize and test the models that have merged from his theoretical work. Outside of his research, Mark is actively engaged in preservation of Austin’s open spaces, and one of his prouder achievements was the drawing up of the petition to list the Barton Springs salamander as an endangered species. Mark is a naturalist and adventurer. He is happy to regale one with tales of sinking deep into snowdrifts in Ladakh, swimming with rays in Hawaii, or plodding across a Gala´pagos lava field in search of the elusive woodpecker finch. His world bird list is none too shabby for a theoretician. His appreciation for nature permeates his theory. For these reasons, we believe he is the ideal recipient of this year’s Sewall Wright Award.

Michael J. Wade, Chair, on behalf of the Sewall Wright Award Committee: Ilkka Hanski, Judith L. Bronstein, and Maria Servedio

E. O. Wilson Naturalist Award Craig Benkman

The American Society of Naturalists is pleased to announce that Craig Benkman, professor and Robert Berry chair of ecology in the Department of Zoology and Physiology at the University of Wyoming, has received the 2014 E. O. Wilson Naturalist Award. Through thousands of hours of detailed natural history observations, often in remote locations, Craig has made important contributions to our understanding of the evolutionary consequences of species interactions. In particular, his landmark studies of crossbills and pines provide clear evidence that coevolution can be a powerful mechanism through which adaptation occurs across expansive spatial scales.

Craig is one of the great naturalists of our age. Decades of year-round field study, aviary experiments, and quantitative synthesis have permitted the rigorous testing of ideas—perhaps most notably John Thomson’s geographic mosaic of coevolution—that have excited the imagination of scientists for years. As far as we are aware, his studies provide the only clear case of a “coevolutionary cascade,” in which a predator (squirrel) drives morphological evolution of a prey species (conifer cones) that, in turn, underlies evolutionary shifts in a second predator (crossbills). The result is an unusually satisfying synthesis between ecological and evolutionary processes in a natural system,

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evidenced by its inclusion in many undergraduate and specialized texts. Craig is best known for his studies that link the foraging behavior of crossbills to the population biology of both the birds and the trees they exploit and to the diversifying natural selection on birds’ beaks and tree cones. His work provides rare estimates of rugged fitness landscapes in nature, here produced by trade-offs in beak morphology affecting crossbills’ ability to extract seeds from cones, which gives advantages to specialization. In one of his classic articles, he and then undergraduate Anna Lindholm employed an elegant experiment to recapitulate the intermediate steps in the origin of an evolutionary novelty, that is, the crossed bill of the crossbill. They shaved off the crossed parts of the beak and measured foraging efficiency on different cones as it grew back. Craig and his students have also linked divergence to exploit different cone types to rapid evolution of reproductive isolation, by studying how contact calls between individuals foraging on the same cone type are used in flock cohesion and individual recognition. When binoculars and a field notebook have not been sufficient to answer the questions at hand, Craig and collaborators have embraced new molecular technologies. Most recently, this has been to use next-generation sequencing as a foundation for marker development and population genomics approaches to understanding coevolution and, more specifically, to understand the genotypic basis for serotiny (the retention of seeds in the cone, an important fire defense) in lodgepole pine. Having used genomic methods to show serotiny is heritable, he and his former graduate student Matt Talluto recently investigated how fire frequency and squirrel predation interact to dramatically affect vegetation at the landscape scale. The density of lodgepole pine seedlings following fire can vary from 0 to more than 2.5 million per hectare. It turns out that squirrels select against serotiny because it provides a yearround food resource for them. In places where squirrels are common, lodgepole pine recruitment is low, with ramifying effects through the whole ecosystem. Craig’s contribution to the next generation of naturalists is exemplified not only by his research but also by his efforts to identify and protect species of conservation concern. And it is here that one can see most clearly how deeply he understands nature and, more generally, how important research is to an understanding of threats to biodiversity. In the best example, he showed some time ago that the locally restricted South Hills, Idaho, crossbill

has evolved a deep beak in a coevolutionary arms race with the lodgepole pine, triggered by the absence of squirrels. Squirrel absence has resulted in a large serotinous cone crop. Increase in the crossbill’s beak depth, and divergence in its calls have made this a quite distinctive form, which some authors (including Craig) have suggested should be elevated to species rank. The South Hills crossbill has declined by more than 80% since 2003. From his knowledge of the system, Craig has concluded that this is a consequence of increasing numbers of hot summer days, causing the serotinous cones to open and prematurely shed their seeds. Craig received his undergraduate degree at the University of California at Berkeley and a master’s degree at Northern Arizona University, where he worked with Russ Balda on the ecology and evolution of interactions between red squirrels, Clark’s nutcrackers, and limber pine. His PhD dissertation, conducted with Ron Pulliam at the State University of New York at Albany, was a comprehensive study of the foraging ecology of crossbills. The collective ornithological knowledge of Balda and Pulliam surely provided Craig with an exciting introduction to the interface between natural history and evolutionary ecology. Craig’s own students display similar passion and talent for natural history and have clearly profited from his exemplary studies in which fundamental questions in evolutionary biology are investigated through interacting species. As is the case with our best naturalists, Craig recognizes the importance, and the enjoyment, of pure natural history. The first thing he does when getting to a new place is to head outside with his binoculars and make natural history observations, on which he sometimes publishes. For example, as a result of a short trip to Hawaii, he published a one-page note on the foraging behavior of the rare ‘Akepa, a Hawaiian passerine with a crossed bill similar to those of North American crossbills. Craig’s ability to combine the time-honored practice of natural history with modern approaches to the study of ecological and evolutionary questions exemplifies our society’s goal, which is to enhance the conceptual unification of the biological sciences. It makes him a worthy recipient of the 2014 E. O. Wilson Award.

Douglas W. Schemske, Chair, on behalf of the E. O. Wilson Award Committee: Bernard L. Crespi and Rosemary Grant

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2014 American Society of Naturalists awards.

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