Conservation genetics as a management tool: The five best-supported paradigms to assist the management of threatened species

Abstract

About 50 y ago, Crow and Kimura [An Introduction to Population Genetics Theory (1970)] and Ohta and Kimura [Genet. Res. 22, 201–204 (1973)] laid the foundations of conservation genetics by predicting the relationship between population size and genetic marker diversity. This work sparked an enormous research effort investigating the importance of population dynamics, in particular small population size, for population mean performance, population viability, and evolutionary potential. In light of a recent perspective [J. C. Teixeira, C. D. Huber, Proc. Natl. Acad. Sci. U.S.A. 118, 10 (2021)] that challenges some fundamental assumptions in conservation genetics, it is timely to summarize what the field has achieved, what robust patterns have emerged, and worthwhile future research directions. We consider theory and methodological breakthroughs that have helped management, and we outline some fundamental and applied challenges for conservation genetics.

Inbreeding depression in an outbred nine-spined stickleback (Pungitius pungitius) population

“…Although our estimates present relatively wide confidence intervals and vary among the genomic estimators used, the order of magnitude and range of the inbreeding loads reported here is on par with severe loads previously reported from some natural populations [73][74][75][76]. This has important conservation implications [77] as the results suggest that large-sized populations may be at a high risk of extinctions if rapid decline in population size or habitat fragmentation would increase the probability of inbred mating.…”

Climate adaptation and vulnerability of foundation species in a global change hotspot

“…Overall, we present new insights into climate adaptation, its predicted disruption by climate change, and the implications for partly sympatric foundation species that enhance biodiversity in a sentinel region for climate change impacts. Identifying so-called evolutionarily significant units worth conserving for their genetic uniqueness, adaptive significance, and risk of decline, is one of the most pressing challenges facing us today, and a necessary step in developing proactive conservation strategies (Foden et al, 2019; Smith et al, 2014; Willi et al, 2022). Our findings advance that goal by identifying sister Galeolaria species as lineages on distinct adaptive trajectories linked to climate, that seemingly share little gene flow (and hence little scope to gain neutral diversity or climate-adaptive variants from one another), and are predicted to fare differently in future climates.…”

“…Geographic ranges are shifting as species move to track tolerable climatic conditions, and abundances are changing within ranges as populations adapt, or grow maladapted and thereby vulnerable, to the climates they face (Pecl et al, 2017; Scheffers et al, 2016). Understanding current ranges, whether species harbour (and exchange) different genetic variants involved in climate adaptation, and how such variants are distributed across landscapes undergoing rapid climate change, is therefore key to predicting responses to future change and informing conservation strategies (Teixeira & Huber, 2021; Willi et al, 2022). This remains challenging for many species, especially those that are cryptic or unsuited to traditional ways of inferring adaptation and persistence (reciprocal transplants, multi-generation breeding experiments, etc.).…”

“…Over time, species lines may blur, or species that are less vulnerable to climate change may displace species that are more so, at a net cost to biodiversity (Román-Palacios & Wiens, 2020; Todesco et al, 2016). From this perspective, multi-species assessments of genomic vulnerability may help to identify whether genetic lineages are on distinct (and potentially adaptive) evolutionary pathways linked to climate, and could therefore warrant separate management to conserve their genetic uniqueness (Willi et al, 2022).…”

“…Combining such assessments with insights from neutral genomic variation, moreover, allows population structures and species barriers to be explored from both neutral and adaptive perspectives, with differing implications for population dynamics, species range shifts, and management actions under climate change (Hohenlohe et al, 2021;Kardos et al, 2021;Willi et al, 2022).…”