High genetic diversity in the blue-listed British Columbia population of the purple martin maintained by multiple sources of immigrants

Abstract

To assess genetic diversity in the blue-listed purple martin (Progne subis) population in British Columbia, we analysed mitochondrial control region sequences of 93 individuals from British Columbia and 121 individuals collected from seven localities of the western and eastern North American subspecies P. s. arboricola and P. s. subis, respectively. Of the 47 haplotypes we detected, 34 were found exclusively in western populations, and 12 were found only in eastern populations. The most common eastern haplotype (25) was also found in three nestlings in British Columbia and one in Washington. Another British Columbia nestling had a haplotype (35) that differed by a C to T transition from haplotype 25. Coalescent analysis indicated that these five nestlings are probably descendents of recent immigrants dispersing from east to the west, because populations were estimated to have diverged about 200,000-400,000 ybp, making ancestral polymorphism a less likely explanation. Maximum likelihood estimates of gene flow among all populations detected asymmetrical gene flow into British Columbia not only of rare migrants from the eastern subspecies in Alberta but also a substantial number of migrants from the adjacent Washington population, and progressively lower numbers from Oregon in an isolation-by distance pattern. The influx of migrants from different populations is consistent with the migrant-pool model of recolonization which has maintained high genetic diversity in the small recovering population in British Columbia. Thus, the risk to this population is not from genetic erosion or inbreeding following a severe population crash, but from demographic stochasticity and extinction in small populations.

Genetic structure in remnant populations of an endangered cyprinodontid fish, Orestias ascotanensis, endemic to the Ascotán salt pan of the Altiplano

“…These springs might be connected near the center of the salt pan during the rainfalls that characterized the ''Altiplano winter'' (usually December to February). The resulting gene flow would maintain high variability as expected for partially isolated subpopulations (Wright 1969;Chesser et al 1993;Baker et al 2008;Reid et al 2008).…”

Countering criticisms of single mitochondrial DNA gene barcoding in birds

“…To test the resolving power of COI in detecting within‐species divergence with small samples normally analysed by investigators, we compared DNA barcodes with short control region sequences obtained previously from purple martins ( Progne subis ), as reported in Baker et al . (2008), and from little blue penguins ( Eudyptula minor ).…”

“…(2008), and from little blue penguins ( Eudyptula minor ). For the latter we used primers ND6LR (5′‐GCCCCCCGAGAYAACCCCCG‐3′, Oliver Haddrath) and LBPCRH (5′‐AATGAGAATGTYMYTGTATACGGRTAT‐3′, Kristen Choffe) to amplify a 350‐bp fragment from the hypervariable 5’ end of the control region using the same amplification and sequencing protocols as for purple martins (Baker et al . 2008, GenBank Accession nos FJ589573–FJ589632).…”

Characterization of 10 polymorphic microsatellite markers for the purple martin, Progne subis

“…subis) and western populations (P.s arboricola) of purple martins have been in decline since the mid-20th century (Laughlin and Kibbe 1985;Zeransksi and Baptist 1990;Veit and Petersen 1993;Hunt 2003). They have suffered severe range-wide declines associated with the loss of territory due to nesting site competition with european starlings (Stutnus vulgaris) and house sparrows (Passer domesticus;Brown 1981;Baker et al 2008). Data from the Breeding Bird Survey indicates a range decline of 0.6% per year, with the decline concentrated in eastern North America (0.9%; Sauer et al 2004).…”

“…Data from the Breeding Bird Survey indicates a range decline of 0.6% per year, with the decline concentrated in eastern North America (0.9%; Sauer et al 2004). Even though the species as a whole does not have IUCN status, certain populations have been Red-listed as late as 2006, and are currently Blue-listed or vulnerable (Baker et al 2008). Purple martins are particularly vulnerable to population decline because they are dependent on humans to provide nesting cavities (Copley et al 1999).…”