Historic hybridization and persistence of a novel mito-nuclear combination in red-backed voles (genus Myodes)

<p>Abstract</p> <p>Background</p> <p>The role of hybridization in generating diversity in animals is an active area of discovery and debate. We assess hybridization across a contact zone of northern (<it>Myodes rutilus</it>) and southern (<it>M. gapperi</it>) red-backed voles using variation in skeletal features and both mitochondrial and nuclear loci. This transect extends approximately 550 km along the North Pacific Coast of North America and encompasses 26 populations (n = 485). We establish the history, geographic extent and directionality of hybridization, determine whether hybridization is ongoing, and assess the evolutionary stability of novel genomic combinations.</p> <p>Results</p> <p>Identification of <it>M. rutilus </it>and <it>M. gapperi </it>based on the degree of closure of the post-palatal bridge was concordant with the distribution of diagnostic nuclear MYH6 alleles; however, an 80 km zone of introgressed populations was identified. The introgressant form is characterized by having mitochondrial haplotypes closely related to the northern <it>M. rutilus </it>on a nuclear background and morphological characteristics of southern <it>M. gapperi</it>.</p> <p>Conclusion</p> <p>Introgression appears to have been historic as pure populations of <it>M. rutilus </it>are now isolated to the north from introgressants or pure <it>M. gapperi </it>by the LeConte Glacier. As we do not find pure <it>M. rutilus </it>or <it>M. gapperi </it>individuals throughout the distribution of the introgressant form, it appears that the introgressants are a self-sustaining entity not requiring continued hybridization between pure parental forms to generate this novel combination of characters.</p

The Heather Vole, Genus Phenacomys, in Alaska

Four specimens of heather vole (genus Phenacomys) collected in the coastal mountains of Southeast Alaska document the first Recent records of this vole in Alaska. Alternative hypotheses on the relationship of these newly-discovered populations to extant and historical populations are outlined, and additional studies proposed

The complexities of female mate choice and male polymorphisms: Elucidating the role of genetics, age, and mate-choice copying

Genetic, life history, and environmental factors dictate patterns of variation in sexual traits within and across populations, and thus the action and outcome of sexual selection. This study explores patterns of inheritance, diet, age, and mate-choice copying on the expression of male sexual signals and associated female mate choice in a phenotypically diverse group of Schizocosa wolf spiders. Focal spiders exhibit one of two male phenotypes: ‘ornamented’ males possess large black brushes on their forelegs, and ‘non-ornamented’ males possess no brushes. Using a quantitative genetics breeding design in a mixed population of ornamented/non-ornamented males, we found a strong genetic basis to male phenotype and female choice. We also found that some ornamented males produced some sons with large brushes and others with barely visible brushes. Results of diet manipulations and behavioral mating trials showed no influence of diet on male phenotype or female mate choice. Age post maturation, however, influenced mate choice, with younger females being more likely to mate with ornamented males. A mate-choice copying experiment found that, following observations of another female’s mate choice/copulation, virgin mature females tended to match the mate choice (ornamented vs. non-ornamented males) of the females they observed. Finally, analyses of genetic variation across phenotypically pure (only one male phenotype present) vs. mixed (both phenotypes present) populations revealed genetic distinction between phenotypes in phenotypically-pure populations, but no distinction in phenotypically-mixed populations. The difference in patterns of genetic differentiation and mating across geographic locations suggests a complex network of factors contributing to the outcome of sexual selection

The complexities of female mate choice and male polymorphisms: Elucidating the role of genetics, age, and mate-choice copying

Genetic, life history, and environmental factors dictate patterns of variation in sexual traits within and across populations, and thus the action and outcome of sexual selection. This study explores patterns of inheritance, diet, age, and mate-choice copying on the expression of male sexual signals and associated female mate choice in a phenotypically diverse group of Schizocosa wolf spiders. Focal spiders exhibit one of two male phenotypes: ‘ornamented’ males possess large black brushes on their forelegs, and ‘non-ornamented’ males possess no brushes. Using a quantitative genetics breeding design in a mixed population of ornamented/non-ornamented males, we found a strong genetic basis to male phenotype and female choice. We also found that some ornamented males produced some sons with large brushes and others with barely visible brushes. Results of diet manipulations and behavioral mating trials showed no influence of diet on male phenotype or female mate choice. Age post maturation, however, influenced mate choice, with younger females being more likely to mate with ornamented males. A mate-choice copying experiment found that, following observations of another female’s mate choice/copulation, virgin mature females tended to match the mate choice (ornamented vs. non-ornamented males) of the females they observed. Finally, analyses of genetic variation across phenotypically pure (only one male phenotype present) vs. mixed (both phenotypes present) populations revealed genetic distinction between phenotypes in phenotypically-pure populations, but no distinction in phenotypically-mixed populations. The difference in patterns of genetic differentiation and mating across geographic locations suggests a complex network of factors contributing to the outcome of sexual selection

First Records of the Southern Red-backed Vole, Myodes gapperi, in the Yukon

Twenty Southern Red-backed Voles, Myodes gapperi, were collected in July 2004 in the LaBiche River valley of southeastern Yukon. Specimens were identified using morphological characteristics and analysis of cytochrome b gene sequences. These are the first records of this species in the Yukon. No Northern Red-backed Voles, M. rutilus, were collected and it is not known whether the two species are sympatric or parapatric in the Yukon. Further survey work is needed in southeastern Yukon to better delineate the extent of the northwestern range of this species and the extent, if any, of introgression with M. rutilus

The Development of Self-Efficacy to Work with Suicidal Clients

Suicide is a public health crisis which counselors must be prepared to address. In this grounded theory study, the researchers advance a model to show how counselors develop self-efficacy to work with suicidal clients. Counselor educators may use this model to improve programmatic training and supervision of students

Mammal Fleas (Siphonaptera: Ceratophyllidae) New for Alaska and the Southeastern Mainland Collected During Seven Years of a Field Survey of Small Mammals

Ten taxa of mammal fleas were among 124 collection records from 12 host species (one shrew, nine rodents and two carnivores), at 72 localities on the southeastern Alaska mainland in 1989 and during an extensive survey of mammals in 1992-1995 and 1997-1999. Megabothris asio megacolpus (Jordan) ex Microtus pennsylvanicus (Ord), Malaraeus telchinus (Rothschild) ex Peromyscus keeni (Rhoads) and Clethrionomys gapperi (Vigors) are new fleas for Alaska. Orchopeas caedens (Jordan) ex Tamiasciurus hudsonicus (Erxleben) is a new flea for southeastern Alaska. Synaptomys borealis (Richardson) is a new host record for Opisodasys k. keeni (Baker). The other six taxa of fleas collected were Hystrichopsylla dippiei spinata Holland, H. o. occidentalis Holland, Catallagia charlottensis (Baker), Ceratophyllus ciliatus protinus Jordan, Megabothris abantis (Rothschild) and Opisodasys vesperalis (Jordan). Of these, H. o. occidentalis, C. charlottensis and M. abantis have seven new host records for the southeastern Alaska mainland. Distribution patterns of the fleas and their host relationships in North America are discussed

The hidden land use cost of upscaling cover crops

Cover cropping is considered a cornerstone practice in sustainable agriculture; however, little attention has been paid to the cover crop production supply chain. In this Perspective, we estimate land use requirements to supply the United States maize production area with cover crop seed, finding that across 18 cover crops, on average 3.8% (median 2.0%) of current production area would be required, with the popular cover crops rye and hairy vetch requiring as much as 4.5% and 11.9%, respectively. The latter land requirement is comparable to the annual amount of maize grain lost to disease in the U.S. We highlight avenues for reducing these high land use costs

Tacky cyclic olefin copolymer: a biocompatible bonding technique for the fabrication of microfluidic channels in COC

Cyclic olefin copolymer (COC) is widely used in microfluidics due to its UV-transparency{,} its biocompatibility and high chemical resistance. Here we present a fast and cost-effective solvent bonding technique{,} which allows for the efficient bonding of protein-patterned COC structures. The bonding process is carried out at room temperature and takes less than three minutes. Enzyme activity is retained upon bonding and microstructure deformation does not occur