hiphop: Improved paternity assignment among close relatives using a simple exclusion method for biallelic markers

Kinship analysis and pedigree reconstruction by RAD sequencing in cattle

Kinship and pedigree, used for estimating inbreeding, heritability, selection, and gene flow, are useful for breeding and animal conservation. However, as the size of crossbred populations increases, inaccurate generation and parentage assignment in livestock farms increase. Restriction-site-associated DNA sequencing is a cost-effective platform for single nucleotide polymorphism (SNP) discovery and genotyping. Here, we performed a kinship analysis and pedigree reconstruction for Angus and Xiangxi yellow cattle. A total of 975 cattle, including 923 offspring with 24 known sires and 28 known dams, were sampled and subjected to SNP discovery and genotyping. The identified SNP panel included 7,305 SNPs capturing the maximum difference between paternal and maternal genome information, allowing us to distinguish F1 from F2 generations with 90% accuracy. In conclusion, we provided a low-cost and efficient SNP panel for kinship analyses and the improvement of local genetic resources, which are valuable for breed improvement, local resource utilization, and conservation.

A sex skew in life-history research: the problem of missing males

Life-history strategies are diverse. While understanding this diversity is a fundamental aim of evolutionary biology and biodemography, life-history data for some traits-in particular, age-dependent reproductive investment-are biased towards females. While other authors have highlighted this sex skew, the general scale of this bias has not been quantified and its impact on our understanding of evolutionary ecology has not been discussed. This review summarizes why the sexes can evolve different life-history strategies. The scale of the sex skew is then discussed and its magnitude compared between taxonomic groups, laboratory and field studies, and through time. We discuss the consequences of this sex skew for evolutionary and ecological research. In particular, this sex bias means that we cannot test some core evolutionary theory. Additionally, this skew could obscure or drive trends in data and hinder our ability to develop effective conservation strategies. We finally highlight some ways through which this skew could be addressed to help us better understand broad patterns in life-history strategies.

Hybridization decreases native cutthroat trout reproductive fitness

Examining natural selection in wild populations is challenging, but crucial to understanding many ecological and evolutionary processes. Additionally, in hybridizing populations, natural selection may be an important determinant of the eventual outcome of hybridization. We characterized several components of relative fitness in hybridizing populations of Yellowstone cutthroat trout and rainbow trout in an effort to better understand the prolonged persistence of both parental species despite predictions of extirpation. Thousands of genomic loci enabled precise quantification of hybrid status in adult and subsequent juvenile generations; a subset of those data also identified parent-offspring relationships. We used linear models and simulations to assess the effects of ancestry on reproductive output and mate choice decisions. We found a relatively low number of late-stage (F3+) hybrids and an excess of F2 juveniles relative to the adult generation in one location, which suggests the presence of hybrid breakdown decreasing the fitness of F2+ hybrids later in life. Assessments of reproductive output showed that Yellowstone cutthroat trout are more likely to successfully reproduce and produce slightly more offspring than their rainbow trout and hybrid counterparts. Mate choice appeared to be largely random, though we did find statistical support for slight female preference for males of similar ancestry. Together, these results show that native Yellowstone cutthroat trout are able to outperform rainbow trout in terms of reproduction and suggests that management action to exclude rainbow trout from spawning locations may bolster the now-rare Yellowstone cutthroat trout.

Genetic variance in fitness indicates rapid contemporary adaptive evolution in wild animals

The rate of adaptive evolution, the contribution of selection to genetic changes that increase mean fitness, is determined by the additive genetic variance in individual relative fitness. To date, there are few robust estimates of this parameter for natural populations, and it is therefore unclear whether adaptive evolution can play a meaningful role in short-term population dynamics. We developed and applied quantitative genetic methods to long-term datasets from 19 wild bird and mammal populations and found that, while estimates vary between populations, additive genetic variance in relative fitness is often substantial and, on average, twice that of previous estimates. We show that these rates of contemporary adaptive evolution can affect population dynamics and hence that natural selection has the potential to partly mitigate effects of current environmental change.