McTavish E.J.,University of Texas at Austin |
McTavish E.J.,Center for the Study of Evolution in Action |
Smith G.K.,University of Texas at Austin |
Guerrero R.F.,University of Texas at Austin |
Gering E.J.,University of Texas at Austin
Evolutionary Ecology Research | Year: 2012
Background: Female-limited colour polymorphisms occur in many species of dragonflies and damselflies. Often one female morph appears male-like in coloration (androchromes) whereas one or more others are distinct from males (gynochromes). These androchromes are hypothesized to be male-mimics, thereby avoiding the harassment of excessive male mating attempts. Organism: The damselfly Ischnura ramburii, Rambur's forktail, is a widespread New World species with androchrome and gynochrome females. It was introduced to the Hawaiian Islands in the mid-1970s and females were thought to be exclusively gynochromatic there. Questions: How do males and females differ in their flight apparatus? Do females with different colour morphologies also differ in flight morphology? Hypothesis: Because male-like coloration is sometimes associated with male-like flight behaviours, androchrome females should have more male-like wings than gynochrome females. Methods: We caught individuals of I. ramburii in the field from seven populations on three of the Hawaiian Islands and three populations in Texas (part of its native range). Using digitized wing and body images, we compared body size, wing size, and wing shape between sexes, between female morphs, and among geographic regions. Results: Male I. ramburii are smaller than females and have smaller, more slender wings. Although androchromes are absent from the Big Island of Hawaii, both androchrome and gynochrome females are common on Oahu and Kauai. Androchrome females are indistinguishable from gynochrome females in all aspects of their flight apparatus except for forewing size, which is smaller than that of gynochromes and thus more-male like. Wing shape and size vary geographically. Body- and wing-size differences between males and females are consistent across regions, although the degree and direction of sexual dimorphism in wing shape are not. © 2012 Emily Jane McTavish.
Foster J.A.,University of Idaho |
Foster J.A.,Center for the Study of Evolution in Action |
Moore J.,Quantitative Medicine
Pacific Symposium on Biocomputing 2011, PSB 2011 | Year: 2011
Recent advances in sequencing technologies have made is possible, for the first time, to take a thorough census of the microbial species present in a given environment. This presents a particularly exciting opportunity since bacteria and archea comprise the dominant forms of life on earth, and since they are vital to human health and to the wellbeing of our environment. However, the bioinformatics for interpreting these very large sequence datasets are not fully developed. This session presents recent work supporting the computational analysis of microbiome data. © 2011 World Scientific Publishing Co. Pte. Ltd.
While there has been much speculation regarding brain size and intelligence, a new paper published in the journal Proceedings of the National Academy of Sciences confirms that species with brains that are large relative to their bodies are more intelligent. This research "represents a novel and rigorous experimental test of the relationship between brain size and problem-solving ability, using mammalian carnivores as our test group," said Kay Holekamp, an integrative biologist at Michigan State University (MSU), and senior author of the paper. "Our results show that having a larger brain really does improve an animal's ability to solve a problem it has never encountered before." Brain size is often used as a proxy for cognitive ability. Whether brain size can predict cognitive ability in animals has frequently been questioned, however, mainly because of the lack of any experimental evidence, Holekamp added. To tackle this lack of scientific data, Sarah Benson-Amram, a scientist at the University of Wyoming and the paper's first author, and collaborators traveled to nine U.S. zoos and presented 140 animals from 39 mammalian carnivore species with a novel problem-solving task. The study included polar bears, arctic foxes, tigers, river otters, wolves, spotted hyenas and some rare, exotic species, such as binturongs, snow leopards and wolverines. Each animal was given 30 minutes to extract food from a metal box, closed with a bolt latch. The box was scaled to the animal's size and baited with each study animal's preferred food—red pandas received bamboo and snow leopards got steak. "Does a larger brain imply greater intelligence?" asked George Gilchrist, program director in the National Science Foundation's (NSF) Division of Environmental Biology, which funded the research along with NSF's Divisions of Biological Infrastructure and Integrative Organismal Systems. "This is a key question for those studying brain evolution. To address that question, Gilchrist said, the researchers "devised a clever puzzle that could be presented to multiple species—and discovered a strong correlation between relatively large brain size and problem-solving ability." Overall, 35 percent of the animals successfully solved the problem. The bears had an almost 70 percent success rate, and meerkats and mongooses were the least successful, with no individuals from their species solving the problem. "This study offers a rare look at problem-solving in carnivores, and the results provide important support for the claim that brain size reflects an animal's problem-solving abilities as well as enhance our understanding of why larger brains evolved in some species," Benson-Amram said. The study also showed that neither manual dexterity nor living in larger social groups improved problem-solving success. "A hypothesis that has garnered much support in primate studies is 'the social brain hypothesis,' which proposes that larger brains evolved to deal with challenges in the social domain," said Holekamp, who is affiliated with NSF's BEACON Center for the Study of Evolution in Action. The hypothesis posits that intelligence evolved to enable animals to anticipate, respond to, and perhaps even manipulate the actions of others in their social groups, Holekamp said. "If the social brain hypothesis can predict success at solving non-social problems, then we would expect that species that live in larger social groups should be more intelligent," Holekamp said. "However, we did not find any support for that prediction in this study." Explore further: Hyenas that think outside the box solve problems faster
Sullivan J.,University of Idaho |
Sullivan J.,Center for the Study of Evolution in Action |
Demboski J.R.,Denver Museum of Nature and Science |
Bell K.C.,University of New Mexico |
And 5 more authors.
Heredity | Year: 2014
Increasing data have supported the importance of divergence with gene flow (DGF) in the generation of biological diversity. In such cases, lineage divergence occurs on a shorter timescale than does the completion of reproductive isolation. Although it is critical to explore the mechanisms driving divergence and preventing homogenization by hybridization, it is equally important to document cases of DGF in nature. Here we synthesize data that have accumulated over the last dozen or so years on DGF in the chipmunk (Tamias) radiation with new data that quantify very high rates of mitochondrial DNA (mtDNA) introgression among para-and sympatric species in the T. quadrivittatus group in the central and southern Rocky Mountains. These new data (188 cytochrome b sequences) bring the total number of sequences up to 1871; roughly 16% (298) of the chipmunks we have sequenced exhibit introgressed mtDNA. This includes ongoing introgression between subspecies and between both closely related and distantly related taxa. In addition, we have identified several taxa that are apparently fixed for ancient introgressions and in which there is no evidence of ongoing introgression. A recurrent observation is that these introgressions occur between ecologically and morphologically diverged, sometimes non-sister taxa that engage in well-documented niche partitioning. Thus, the chipmunk radiation in western North America represents an excellent mammalian example of speciation in the face of recurrent gene flow among lineages and where biogeography, habitat differentiation and mating systems suggest important roles for both ecological and sexual selection. © 2014 Macmillan Publishers Limited All rights reserved.
Rosenblum E.B.,University of Idaho |
Rosenblum E.B.,University of California at Berkeley |
Rosenblum E.B.,Center for the Study of Evolution in Action |
Sarver B.A.J.,University of Idaho |
And 8 more authors.
Evolutionary Biology | Year: 2012
Understanding the rate at which new species form is a key question in studying the evolution of life on earth. Here we review our current understanding of speciation rates, focusing on studies based on the fossil record, phylogenies, and mathematical models. We find that speciation rates estimated from these different studies can be dramatically different: some studies find that new species form quickly and often, while others find that new species form much less frequently. We suggest that instead of being contradictory, differences in speciation rates across different scales can be reconciled by a common model. Under the "ephemeral speciation model", speciation is very common and very rapid but the new species produced almost never persist. Evolutionary studies should therefore focus on not only the formation but also the persistence of new species. © 2012 The Author(s).