Mating patterns in an inbred Arctic carnivore

Abstract

Mating patterns are highly context-dependent and the outcome of selection pressures formed by ecological factors, inbreeding levels and access to available partners. In small and inbred populations, matings are limited by high kin encounter rates and access to mates. In this paper, we use background pedigree data to investigate mating patterns and inbreeding avoidance in an isolated and critically endangered Arctic fox (Vulpes lagopus) population. Empirical data showed avoidance of matings within natal family. Based on 35 documented matings, we only recorded two full-sibling matings and these occurred between individuals from different natal families. Matings between second-order relatives, however, occurred to the same extent as between unrelated individuals. To test how this influenced the population development of inbreeding (f), we simulated scenarios of random mating, exclusion of natal family and exclusion of individuals in already existing pair bonds. The observed development of inbreeding did not correspond the expected scenario of random mating (linear regression, r 2 = 0.354, P = 0.20), but showed a comparable outcome as the simulated development of discriminating natal family (linear regression, r 2 = 0.980, P < 0.001). We conclude that behavioural, pre-copulatory inbreeding avoidance strategies occur in this population and that exclusion of mating with natal family causes a slower increase in inbreeding levels compared to random mating. This study demonstrates how long-term monitoring, pedigree construction and simulations can generate information valuable for an in-depth understanding of both conservation genetics and behavioural ecology in threatened populations.

Genetic rescue in an inbred Arctic fox (Vulpes lagopus) population

“…This is counterintuitive as heterozygosity is expected to decrease during isolation and increase in response to gene flow. Heterozygote excess despite extended periods of isolation has been found in previous studies [13,63] and could arise by chance due to small effective population size [64] but could also be caused by inbreeding avoidance, which was recently discovered in this population [65]. The heterozygote deficiency found after immigration is likely an artefact of appeared subpopulation structure arising from the admixture event [66].…”

Resources and predation: drivers of sociality in a cyclic mesopredator

“…In the three genetically detected cases, we saw both closely related fathers (uncle–nephew) and completely unrelated individuals (a local fox and a captive bred immigrant). The relationship in the third case is unclear, since they originated from two different founders (Godoy et al 2018 ) and, as a consequence, are assumed to be unrelated. The completely unrelated fathers were observed coexisting at the den for 4 days without any signs of hostility towards each other (personal observation).…”

Low Persistence of Genetic Rescue Across Generations in the Arctic Fox (Vulpes lagopus)

“…The Scandinavian Arctic fox population has functioned as a model system to investigate inbreeding depression and genetic rescue effects under natural conditions ( Norén et al 2016 ; Godoy et al 2018 ; Hasselgren et al 2018 ). Intense hunting caused a major population bottleneck in the late 19th century ( Lönnberg 1927 ) and despite legal protection, the population failed to recover due to disruptions in natural prey cycles, as well as competition and predation of northwards expanding red foxes ( Vulpes vulpes ; Hersteinsson and MacDonald 1992 ; Angerbjörn et al 2013 ; Elmhagen et al 2017 ).…”