Genomic sweep and potential genetic rescue during limiting environmental conditions in an isolated wolf population

Abstract

Genetic rescue, in which the introduction of one or more unrelated individuals into an inbred population results in the reduction of detrimental genetic effects and an increase in one or more vital rates, is a potentially important management tool for mitigating adverse effects of inbreeding. We used molecular techniques to document the consequences of a male wolf ( Canis lupus ) that immigrated, on its own, across Lake Superior ice to the small, inbred wolf population in Isle Royale National Park. The immigrant's fitness so exceeded that of native wolves that within 2.5 generations, he was related to every individual in the population and his ancestry constituted 56 per cent of the population, resulting in a selective sweep of the total genome. In other words, all the male ancestry (50% of the total ancestry) descended from this immigrant, plus 6 per cent owing to the success of some of his inbred offspring. The immigration event occurred in an environment where space was limiting (i.e. packs occupied all available territories) and during a time when environmental conditions had deteriorated (i.e. wolves' prey declined). These conditions probably explain why the immigration event did not obviously improve the population's demography (e.g. increased population numbers or growth rate). Our results show that the beneficial effects of gene flow may be substantial and quickly manifest, short-lived under some circumstances, and how the demographic benefits of genetic rescue might be masked by environmental conditions.

Efficient mitigation of founder effects during the establishment of a leading-edge oak population

“…The strong reproductive dominance of tree T1 during the initial stage of population establishment is likely to leave a strong imprint on the future genetic composition and diversity of the study population [32,33]. In addition, most of the corresponding seedlings must have been mothered by this tree, considering that eight of the nine F 2 recruits sired by immigrant pollen had been mothered by tree T1.…”

Evolutionary rescue in vertebrates: evidence, applications and uncertainty

“…As population growth is a function of the number of individuals that survive and reproduce, quantifying the effect of 'new genes' on the probability of persistence is critical to evaluate the population-scale consequences of changes in the distribution of adaptive traits. It should be noted, however, that the effectiveness of genetic rescue is reduced if deteriorating ecological conditions persist (see [61] for example).…”

Hybridization as a facilitator of species range expansion

“…As indicated above, one such factor is admixture among conspecific populations, which can increase standing genetic variation and generate novel, adaptive combinations resulting in enhanced adaptability at the range edge [27,28,32,33,58]. Nevertheless, lack of genetic variation in peripheral populations and lack of new beneficial mutations can still restrict the extent to which genetic exchange among conspecific populations enhances their adaptability at the range edge [57,59].…”