Mating order and reproductive success in male Columbian ground squirrels (Urocitellus columbianus)

Multiple mating by females is common in many mammalian species, often resulting in mixed paternity litters. In such mating systems, mating order, male age, and male body mass frequently play an important role in determining male reproductive success. We tested for these effects on male reproductive success in Columbian ground squirrels (Urocitellus columbianus). The mating activity of estrous females was observed, and the occurrence of sperm precedence was tested using microsatellites to determine paternity in a total of 147 litters (434 offspring), including 110 litters (334 offspring) where the mating position of individual males was determined. Females mated with up to 8 males per litter, whereas paternity analyses revealed that only the first 5 males to mate actually sired offspring. The number of offspring sired significantly decreased with position in the mating sequence, showing a strong first male advantage. The extent of this advantage diminished with an increasing number of male mating partners, indicating that sperm competition plays an important role. A male's position in the females' mating sequences was not consistent within and across seasons, suggesting that individual males did not follow distinct reproductive strategies. Rather, males of intermediate age were more successful than young and old males, when corrected for age effects; heavier males were more likely to mate first. We conclude that males gain the largest part of their seasonal reproductive output from mating first with a female due to a pronounced first male advantage but gain considerable additional fitness from mating with additional, already mated female

Seeing-good-gene-based mate choice:From genes to behavioural preferences

1. Although vertebrates have been reported to gain higher reproductive outputs by choosing mates, few studies have been conducted on threatened species. However, species recovery should benefit if natural mate choice could improve reproductive output (i.e., pair performance related to offspring number, such as increased clutch size, numbers of fertilized egg and fledglings). We assessed the evidence for major histocompatibility complex (MHC)-based mate preference in the endangered crested ibis (Nipponia nippon), and quantified the impacts of such choice on reproductive output. 2. We tested the hypothesis that crested ibis advertise “good genes” through external traits, by testing whether nuptial plumage characteristics and body morphology mediate mate choice for underlying genetic MHC variation. 3. We found differences between males and females in preferred MHC genotypes, external traits used in mate choice, and contributions to reproductive outputs. Females preferred MHC-heterozygous males, which had darker [i.e., lower total reflectance and ultraviolet (UV) reflectance] nuptial plumage. Males preferred females lacking the DABd allele at the MHC classⅡDAB locus, which had higher average body mass. DABd-free females yielded heavier eggs and more fledglings, while MHC-heterozygous males contributed to more fertilized eggs and fledglings. Fledging rate was highest when both parents had the preferred MHC genotypes (i.e., MHC-heterozygous father and DABd-free mother). Comparisons showed that free-mating wild and seminatural pairs yielded more fertilized eggs and more fledglings, with a higher fledging rate, than captive pairs matched artificially based on pedigree. 4. Conservation programs seldom apply modern research results to population management, which could hinder recovery of threatened species. Our results show that mate choice can play an important role in improving reproductive output, with an example in which an endangered bird selects mates using UV visual capability. Despite the undoubted importance of pedigree-based matching of mates in conservation programs, we show that free-mating can be a better alternative strategy

Heterozygosity-fitness correlations in a wild mammal population: accounting for parental and environmental effects

HFCs (heterozygosity–fitness correlations) measure the direct relationship between an individual's genetic diversity and fitness. The effects of parental heterozygosity and the environment on HFCs are currently under-researched. We investigated these in a high-density U.K. population of European badgers (Meles meles), using a multimodel capture–mark–recapture framework and 35 microsatellite loci. We detected interannual variation in first-year, but not adult, survival probability. Adult females had higher annual survival probabilities than adult males. Cubs with more heterozygous fathers had higher first-year survival, but only in wetter summers; there was no relationship with individual or maternal heterozygosity. Moist soil conditions enhance badger food supply (earthworms), improving survival. In dryer years, higher indiscriminate mortality rates appear to mask differential heterozygosity-related survival effects. This paternal interaction was significant in the most supported model; however, the model-averaged estimate had a relative importance of 0.50 and overlapped zero slightly. First-year survival probabilities were not correlated with the inbreeding coefficient (f); however, small sample sizes limited the power to detect inbreeding depression. Correlations between individual heterozygosity and inbreeding were weak, in line with published meta-analyses showing that HFCs tend to be weak. We found support for general rather than local heterozygosity effects on first-year survival probability, and g2 indicated that our markers had power to detect inbreeding. We emphasize the importance of assessing how environmental stressors can influence the magnitude and direction of HFCs and of considering how parental genetic diversity can affect fitness-related traits, which could play an important role in the evolution of mate choice

Social effects of territorial neighbours on the timing of spring breeding in North American red squirrels

Organisms can affect one another’s phenotypes when they socially interact. Indirect genetic effects occur when an individual’s phenotype is affected by genes expressed in another individual. These heritable effects can enhance or reduce adaptive potential, thereby accelerating or reversing evolutionary change. Quantifying these social effects is therefore crucial for our understanding of evolution, yet estimates of indirect genetic effects in wild animals are limited to dyadic interactions. We estimated indirect phenotypic and genetic effects, and their covariance with direct effects, for the date of spring breeding in North American red squirrels (Tamiasciurus hudsonicus) living in an array of territories of varying spatial proximity. Additionally, we estimated indirect effects and the strength of selection at low and high population densities. Social effects of neighbours on the date of spring breeding were different from zero at high population densities but not at low population densities. Indirect phenotypic effects accounted for a larger amount of variation in the date of breeding than differences attributable to the among‐individual variance, suggesting social interactions are important for determining breeding dates. The genetic component to these indirect effects was however not statistically significant. We therefore showcase a powerful and flexible method that will allow researchers working in organisms with a range of social systems to estimate indirect phenotypic and genetic effects, and demonstrate the degree to which social interactions can influence phenotypes, even in a solitary species.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/149549/1/jeb13437_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/149549/2/jeb13437.pd

Spatial Genetic Structure of a Symbiotic Beetle-Fungal System: Toward Multi-Taxa Integrated Landscape Genetics

Spatial patterns of genetic variation in interacting species can identify shared features that are important to gene flow and can elucidate co-evolutionary relationships. We assessed concordance in spatial genetic variation between the mountain pine beetle (Dendroctonus ponderosae) and one of its fungal symbionts, Grosmanniaclavigera, in western Canada using neutral genetic markers. We examined how spatial heterogeneity affects genetic variation within beetles and fungi and developed a novel integrated landscape genetics approach to assess reciprocal genetic influences between species using constrained ordination. We also compared landscape genetic models built using Euclidean distances based on allele frequencies to traditional pair-wise Fst. Both beetles and fungi exhibited moderate levels of genetic structure over the total study area, low levels of structure in the south, and more pronounced fungal structure in the north. Beetle genetic variation was associated with geographic location while that of the fungus was not. Pinevolume and climate explained beetle genetic variation in the northern region of recent outbreak expansion. Reciprocal genetic relationships were only detectedin the south where there has been alonger history of beetle infestations. The Euclidean distance and Fst-based analyses resulted in similar models in the north and over the entire study area, but differences between methods in the south suggest that genetic distances measures should be selected based on ecological and evolutionary contexts. The integrated landscape genetics framework we present is powerful, general, and can be applied to other systems to quantify the biotic and abiotic determinants of spatial genetic variation within and among taxa

The Victorian anti-vaccination discourse corpus (VicVaDis): construction and exploration

This article introduces and explores the 3.5-million-word Victorian Anti-Vaccination Discourse Corpus (VicVaDis). The corpus is intended to provide a (freely accessible) historical resource for the investigation of the earliest public concerns and arguments against vaccination in England, which revolved around compulsory vaccination against smallpox in the second half of the 19th century. It consists of 133 anti-vaccination pamphlets and publications gathered from 1854 to 1906, a span of 53 years that loosely coincides with the Victorian era (1837–1901). This timeframe was chosen to capture the period between the 1853 Vaccination Act, which made smallpox vaccination for babies compulsory, and the 1907 Act that effectively ended the mandatory nature of vaccination. After an overview of the historical background, this article describes the rationale, design and construction of the corpus, and then demonstrates how it can be exploited to investigate the main arguments against compulsory vaccination by means of widely accessible corpus linguistic tools. Where appropriate, parallels are drawn between Victorian and 21st-century vaccine-hesitant attitudes and arguments. Overall, this article demonstrates the potential of corpus analysis to add to our understanding of historical concerns about vaccination

Use of the national low-temperature neutron irradiation facility for fusion materials research

The National Low-Temperature Neutron Irradiation Facility (NLTNIF), now constructed and currently being evaluated, will provide high radiation intensities and special environmental and testing conditions for qualified experiments at no cost to users. The NLTNIF will be of interest for both basic and applied research on fusion reactor materials. A general description and major specifications of the facility are presented along with recent results of the performance tests. In addition, a description is given of the procedure and experimental assemblies needed to perform experiments in the NLTNIF

Characterization of the National Low-Temperature Neutron Irradiation Facility

The National Low-Temperature Neutron Irradiation Facility (NLTNIF) is now operating at the Bulk Shielding Reactor at ORNL. The facility provides high radiation intensities and special environmental and testing conditions for qualified experiments at no cost to users. A general description and major specifications of the NLTNIF are presented along with the results of performance tests. In addition, the hardware and other considerations required to perform experiments in the NLTNIF are described