Genetic Evidence of a Population Bottleneck and Inbreeding in the Endangered New Zealand Sea Lion,Phocarctos hookeri

Abstract

The New Zealand sea lion (NZSL) is of high conservation concern due to its limited distribution and its declining population size. Historically, it occupied most of coastal New Zealand, but is now restricted to a few coastal sites in southern mainland New Zealand and the sub-Antarctic Islands. NZSLs have experienced a recent reduction in population size due to sealing in the 1900s, which is expected to have resulted in increased inbreeding and a loss of genetic variation, potentially reducing the evolutionary capacity of the species and negatively impacting on its long-term prospects for survival. We used 17 microsatellite loci, previously shown to have cross-species applications in pinnipeds, to determine locus- and population-specific statistics for 1205 NZSLs from 7 consecutive breeding seasons. We show that the NZSL population has a moderate level of genetic diversity in comparison to other pinnipeds. We provide genetic evidence for a population reduction, likely caused by historical sealing, and a measure of allele sharing/parental relatedness (internal relatedness) that is suggestive of increased inbreeding in pups that died during recent epizootic episodes. We hypothesize that population bottlenecks and nonrandom mating have impacted on the population genetic architecture of NZSLs, affecting its population recovery.

The demise of a wonder: Evolutionary history and conservation assessments of the Wonder Gecko Teratoscincus keyserlingii (Gekkota, Sphaerodactylidae) in Arabia

“…This population shows a low level of genetic diversity, an excess of homozygotes, and high levels of inbreeding, all consistent with a recent founder event. Non-random mating leading to high values of F IC can be induced by bottlenecks or founder events, small population size and habitat fragmentation in natural populations (e.g., [95,96]), but it can also be the result of breeding programs on captive animals [97]. In any case, increased inbreeding may lead to the fixation of deleterious alleles and is associated with higher mortality, lower fertility and even extinction [98,99].…”

Localizing and classifying adaptive targets with trend filtered regression

“…Populations tend not to maintain constant sizes, with sizes instead fluctuating over time (Graciá et al, 2015;Osborne et al, 2016;Sherry, 2018). For example, it is widely accepted that global human populations have undergone different recent demographic events, such as more rapid expansions and more extreme bottlenecks in European and Asian populations when compared to Africans (Gravel et al, 2011;Tennessen et al, 2012).…”

Localizing and Classifying Adaptive Targets with Trend Filtered Regression

“…Populations tend not to maintain constant sizes, with sizes instead fluctuating over time (Graciá et al., 2015; Osborne et al., 2016; Sherry, 2018). For example, it is widely accepted that global human populations have undergone different recent demographic events, such as more rapid expansions and more extreme bottlenecks in European and Asian populations when compared with Africans (Gravel et al., 2011; Tennessen et al., 2012).…”