Turnover and post‐bottleneck genetic structure in a recovering population of Peregrine Falcons Falco peregrinus

Abstract

Dispersal is a process that increases genetic diversity and genetic connectivity of populations. We studied the turnover rate of breeding adults and genetic population structure to estimate dispersal in Peregrine Falcons in Finland. We used relatedness estimates among Finnish Peregrine Falcons over a 5‐year period, genotyping over 500 nestlings with 10 microsatellite loci to reveal the rate of turnover. Our results reveal a high turnover rate (21.7%) that does not seem to be correlated with the breeding success of the previous year. The extent of population genetic structure and diversity, and possible signs of the population crash during the 1970s, was assessed with a reduced dataset, excluding relatives. We found genetic diversity to be similar to previously studied falcon populations (expected heterozygosity of 0.581) and no population genetic structuring among our sampled populations. We did not find a genetic imprint of the past population bottleneck that the Finnish Peregrine population experienced. We conclude that high dispersal rates are likely to have contributed to maintaining genetic diversity across the landscape, by mixing individuals within the species’ distribution in Finland and thus preventing genetic structuring and negative effects associated with the population decline in the 1970s.

Conservation genetics of regionally extinct peregrine falcons (Falco peregrinus) and unassisted recovery without genetic bottleneck in southern England

“…Ponnikas et al (2017), using 10 microsatellite loci, also found similar heterozygosity values and no genetic bottlenecks, but they found higher allelic richness in peregrine falcons from Finland than in the UK populations reported here, and no genetic structure. They concluded that the genetic diversity could have been maintained through high dispersal rates across Finland without reintroductions, thus preventing genetic structuring of populations and the negative effects of the population decline due to the use of organochlorine pesticides, but that the effective population size was low and genetic monitoring is needed (Ponnikas et al 2017).…”

“…Successful breeding, good dispersal capabilities and inter-population connectivity are fundamental for preventing inbreeding depression and subsequent loss of genetic diversity (Frankham 2015; Ponnikas et al 2017). As evidenced by our population genetics and phylogeographic study, results broadly indicated that there was no overall loss of genetic diversity or signature of a population bottleneck, although some genetic diversity indices showed lower genetic variation in the post-pesticide population (UK-post) than in the pre-pesticide population (UK-pre).…”

“…Despite UK peregrines possessing no migratory behavioural traits, it is a species of innate dispersal and colonising capability (Smith et al 2015; McGrady et al 2017; Ponnikas et al 2017). Individuals dispersing from other refugial areas, such as Cornwall, Cumbria, Wales and Scotland (Crick and Ratcliffe 1995; Horne and Fielding 2002; Franklin and Everitt 2009), but genetically similar to the historical population, could have contributed to the Sussex peregrine population – however, we lack the necessary samples to test this hypothesis.…”

A century of genetic variation inferred from a persistent soil‐stored seed bank

“…This would help overcome limitations set by shifts in abundance over time (Jarrell et al., ) and low germination rates, particularly for reconstituting cohorts from deeper (i.e., >16 cm) soil layers. Reconstituting cohorts from finer scale depth intervals could also minimize discontinuities (i.e., time steps) and thus offer a stronger basis for examining dynamic demographic processes like population turnover (Ponnikas, Ollila, & Kvist, ). It may be possible to increase sample sizes by increasing germination rates, although trials so far conducted suggest that methodological modifications may only lead to marginal improvements (Gentile, ).…”

Genetic variability in Peregrine Falcon populations of the Western Palaearctic region

“…Molecular analyses of variable microsatellite markers and mitochondrial DNA supported the conservation actions taken in North Europe and North America (Nesje et al 2000a, Tordoff & Reding 2001, Jacobsen et al 2008, Johnson et al 2010, Ponnikas et al 2017, and the investigation of the genetic relationships among many subspecies, including some of remote oceanic islands (Nesje et al 2000b, Talbot et al 2011, White et al 2013b, Bell et al 2014. In Mediterranean areas of Western Palaearctic region, corresponding to most of F. p. brookei range, the past population collapse was less extended.…”