Genetic diversity and mate selection in a reintroduced population of gray wolves

The genetic composition of an individual can markedly affect its survival, reproduction, and ultimately fitness. As some wildlife populations become smaller, conserving genetic diversity will be a conservation challenge. Many imperiled species are already supported through population augmentation efforts and we often do not know if or how genetic diversity is maintained in translocated species. As a case study for understanding the maintenance of genetic diversity in augmented populations, I wanted to know if genetic diversity (i.e., observed heterozygosity) remained high in a population of gray wolves in the Rocky Mountains of the U.S. > 20 years after reintroduction. Additionally, I wanted to know if a potential mechanism for such diversity was individuals with below average genetic diversity choosing mates with above average diversity. I also asked whether there was a preference for mating with unrelated individuals. Finally, I hypothesized that mated pairs with above average heterozygosity would have increased survival of young. Ultimately, I found that females with below average heterozygosity did not choose mates with above average heterozygosity and wolves chose mates randomly with respect to genetic relatedness. Pup survival was not higher for mated pairs with above average heterozygosity in my models. The dominant variables predicting pup survival were harvest rate during their first year of life and years pairs were mated. Ultimately, genetic diversity was relatively unchanged > 20 years after reintroduction. The mechanism for maintaining such diversity does not appear related to individuals preferentially choosing more genetically diverse mates. Inbreeding avoidance, however, appears to be at least one mechanism maintaining genetic diversity in this population.

Low-Stress Livestock Handling Protects Cattle in a Five-Predator Habitat

Given the ecological importance of top predators, societies are turning to non-lethal methods for coexistence. Coexistence is challenging when livestock are released within wild predator habitats, even when people supervise or use lethal methods. We report a randomized, controlled design to evaluate low-stress livestock handling (L-SLH), a form of range riding, to deter grizzly (brown) bears, gray wolves, cougars, black bears, and coyotes in Southwestern Alberta. The treatment condition was supervision by two newly hired and trained range riders and an L-SLH practicing range rider. This treatment was compared against a baseline pseudo-control condition of the single experienced range rider working alone. Cattle experienced zero injuries or deaths in either condition. We infer that inexperienced range riders trained and supervised by an experienced rider did not raise or lower the risk to cattle. Also, predators did not shift to the cattle herds protected by fewer range riders. Pending experimental evaluation of other designs, we recommend use of L-SLH.

The Japanese wolf is most closely related to modern dogs and its ancestral genome has been widely inherited by dogs throughout East Eurasia

The Japanese wolf (Canis lupus hodophilax Temminck, 1839) was a subspecies of the gray wolf that inhabited the Japanese Archipelago and became extinct 100-120 years ago. In this study, we determined the whole genomes of nine Japanese wolves from the 19th- early 20th centuries and 11 Japanese dogs and analyzed them along with both modern and ancient wolves and dogs. Genomic analyses indicate that the Japanese wolf was a unique subspecies of the gray wolf that was genetically distinct from both modern and ancient gray wolves, lacking gene flow with other gray wolves. A Phylogenetic tree that minimizes the effects of introgression shows that Japanese wolves are closest to the dog monophyletic group among the gray wolves. Moreover, Japanese wolves show significant genetic affinities with East Eurasian dogs. We estimated the level of introgression from the ancestor of the Japanese wolves to the ancestor of East Eurasian dogs that had occurred in the transitional period from the Pleistocene to the Holocene, at an early stage after divergence from West Eurasian dog lineages. Because of this introgression, Japanese wolf ancestry has been inherited by many dogs through admixture between East Eurasian dog lineages. As a result of this heredity, up to 5.5% of modern dog genomes throughout East Eurasia are derived from Japanese wolf ancestry.

Ranchers' Perspectives on Participating in Non-lethal Wolf-Livestock Coexistence Strategies

Potential impacts to rural livelihoods by large carnivores, such as gray wolves (Canis lupus), increase economic liability and fear among residents, resulting in social conflicts over wildlife issues. Strategies have been developed to promote non-lethal predator management in rural communities, but there is limited understanding of why ranchers choose to participate in such programs. We conducted semi-structured interviews (n = 45) of ranchers in Washington state, United States, asking open-ended questions to explore their perspectives on conflict mitigation. Interviews were analyzed using Grounded Theory. Ranchers mentioned five broad types of mitigation strategies: state agency intervention (i.e., calling the state agency in charge of wolf management to request either compensation or lethal wolf removal), biological measures (e.g., use of guard animals), physical measures (e.g., fences), human interference (cowboys and cowgirls), and indirect measures (e.g., husbandry practices). Motivations for participating in non-lethal mitigation strategies included previous positive interactions with wildlife agency officials, an understanding of the importance of wolves to the ecosystem, and clearly outlined guidelines on how to deal with wolf interactions. Barriers that hindered rancher participation included disdain for regulation both regarding the Endangered Species Act and the state's requirements for accessing damage compensation, which were perceived to be extensive and over-reaching. Negative attitudes toward wolf recovery included fear of wolves and perceived damage that wolves inflict on rural lives and livelihoods. Ranchers' motivations and perceived barriers for participating in mitigation strategies included sociopolitical and economic factors. Thus, we suggest that in addition to mitigating economic loss, wildlife managers address the intangible social costs that deter ranchers' participation in mitigation strategies through continued dialogue.

The effects of age, sex, weight and breed on canid methylomes

Unlike genomes, which are static throughout the lifespan of an organism, DNA methylomes are dynamic. To study these dynamics we developed quantitative models that measure the effect of multiple factors on DNA methylomes including, age, sex, weight and genetics. We conducted our study in canids, which prove to be an ideal species to assess epigenetic moderators due to their extreme variability in size and well-characterized genetic structure. We collected buccal swabs from 217 canids (207 domestic dogs and 10 gray wolves) and used targeted bisulfite sequencing to measure methylomes. We also measured genotypes at over one thousand single nucleotide polymorphisms (SNPs). We found that DNA methylomes are strongly associated with age, enabling the construction of epigenetic clocks. We also show that methylomes are strongly impacted by sex, weight and sterilization status, leading to accurate predators of these factors. Methylomes are also affected by genetics and we observe multiple associations between SNP loci and methylated CpGs. Finally, we show that several factors moderate the relationship between epigenetic ages and real ages, such as body weight, which increases epigenetic aging. In conclusion, we demonstrate that the plasticity of DNA methylomes is impacted by myriad genetic and physiological factors, and that DNA methylation biomarkers are accurate predictors of age, sex and sterilization status.

Breeding displacement in gray wolves (Canis lupus): Three males usurp breeding position and pup rearing from a neighboring pack in Yellowstone National Park

Gray Wolves (Canis lupus) are territorial, group living carnivores that live in packs typically consisting of a dominant breeding pair and their offspring. Breeding tenures are relatively short and competitive, with vacancies usually occurring following a breeder’s death, and are often filled by unrelated immigrants or by relatives of the previous breeder. The frequency and conditions of active breeder displacements are poorly understood. Position changes in the dominance hierarchy are common yet rarely documented in detail. We describe a turnover in male breeding position in a wolf pack by males from a neighboring pack in mid-summer 2016 in Yellowstone National Park. Over the course of two months, three males from the Mollie’s pack displaced the breeding male of the neighboring Wapiti Lake pack, joined the pack’s two adult females, and subsequently raised the previous male’s four approximately three-month old pups. In the four years following the displacement (2017 to 2020), at least one of the intruding males has successfully bred with the dominant female and most years with a subordinate female (who was one of the pups at the time of displacement). The pack reared pups to adulthood each year. Male breeding displacements are likely influenced by male-male competition and female mate choice. These changes are the result of individuals competing to improve breeding position and may lead to increased pack stability and greater reproductive success. We report in detail on the behavior of a closely observed breeding displacement and we discuss the adaptive benefits of the change.