Identification of metapopulation dynamics among Northern Goshawks of the Alexander Archipelago, Alaska, and Coastal British Columbia

Abstract

Northern Goshawks occupying the Alexander Archipelago, Alaska, and coastal British Columbia nest primarily in old-growth and mature forest, which results in spatial heterogeneity in the distribution of individuals across the landscape. We used microsatellite and mitochondrial data to infer genetic structure, gene flow, and fluctuations in population demography through evolutionary time. Patterns in the genetic signatures were used to assess predictions associated with the three population models: panmixia, metapopulation, and isolated populations. Population genetic structure was observed along with asymmetry in gene flow estimates that changed directionality at different temporal scales, consistent with metapopulation model predictions. Therefore, Northern Goshawk assemblages located in the Alexander Archipelago and coastal British Columbia interact through a metapopulation framework, though they may not fit the classic model of a metapopulation. Long-term population sources (coastal mainland British Columbia) and sinks (Revillagigedo and Vancouver islands) were identified. However, there was no trend through evolutionary time in the directionality of dispersal among the remaining assemblages, suggestive of a rescueeffect dynamic. Admiralty, Douglas, and Chichagof island complex appears to be an evolutionarily recent source population in the Alexander Archipelago. In addition, Kupreanof island complex and Kispiox Forest District populations have high dispersal rates to populations in close geographic proximity and potentially serve as local source populations. Metapopulation dynamics occurring in the Alexander Archipelago and coastal British Columbia by Northern Goshawks highlight the importance of both occupied and unoccupied habitats to long-term population persistence of goshawks in this region.

Population genomic analyses reveal a highly differentiated genetic cluster of northern goshawks (Accipiter gentilis laingi) in Haida Gwaii

“…within the last 20,000 years or so) population differentiation between Haida Gwaii and elsewhere and the occasional gene flow from other regions to Haida Gwaii. Second, our data do not reveal a higher amount of inbreeding in Haida Gwaii, as inbreeding coefficients range from -0.0621 to 0.278 which is within the range in other populations ( Supporting Table 11 and Supporting Figure 11) and consistent with previous estimates (Sonsthagen et al, 2012). This suggests inbreeding is not presently a major concern.…”

“…A haplotype network of the mtDNA data (Figure 4 and Supporting Table 8) illustrates that only two haplotypes were present in HG-a result consistent with the findings of Sonsthagen et al (2012). One of these was unique to HG and found in 5 out of 7 HG samples, and the other was found in a few individuals in Alaska (both AA and AK).…”

“…Previous genetic research in northern goshawks was inconclusive in terms of clarifying the range of laingi. Sonsthagen et al (2012) concluded that patterns in both mitochondrial DNA and microsatellites were consistent with gene flow among sites along the BC coast and southeast Alaska, but the study did not include northern goshawks from outside of this region. Most analyses of genetic variation in a conservation context have used a small set of molecular markers (e.g., mitochondrial DNA, which is inherited as a single unit from the mother; or a small number, e.g.…”

Spatio‐temporal variation in European starling reproductive success at multiple small spatial scales

“…; Sonsthagen et al. ), territorial species (e.g., Nystrand et al. ), or distinct habitat types (e.g., Ozgul et al.…”

“…Many empirical studies aiming to quantify spatial variation in demography focus on populations that comprise distinct geographical or biological subunits, and hence where a priori spatial subdivisions appear obvious to observers (Saracco et al 2010). For example, many studies consider archipelagos (e.g., Saether et al 1999;Sonsthagen et al 2012), territorial species (e.g., Nystrand et al 2010), or distinct habitat types (e.g., Ozgul et al 2006;Russell and Ruffino 2011). However, such analyses do not quantify demographic variation within these coarse subunits.…”