Range-wide genetic structure in the thorn-tailed rayadito suggests limited gene flow towards peripheral populations

Abstract

Understanding the population genetic consequences of habitat heterogeneity requires assessing whether patterns of gene flow correspond to landscape configuration. Studies of the genetic structure of populations are still scarce for Neotropical forest birds. We assessed range-wide genetic structure and contemporary gene flow in the thorn-tailed rayadito (Aphrastura spinicauda), a passerine bird inhabiting the temperate forests of South America. We used 12 microsatellite loci to genotype 582 individuals from eight localities across a large latitudinal range (30°S–56°S). Using population structure metrics, multivariate analyses, clustering algorithms, and Bayesian methods, we found evidence for moderately low regional genetic structure and reduced gene flow towards the range margins. Genetic differentiation increased with geographic distance, particularly in the southern part of the species’ distribution where forests are continuously distributed. Populations in the north seem to experience limited gene flow likely due to forest discontinuity, and may comprise a demographically independent unit. The southernmost population, on the other hand, is genetically depauperate and different from all other populations. Different analytical approaches support the presence of three to five genetic clusters. We hypothesize that the genetic structure of the species follows a hierarchical clustered pattern.

Extrapair paternity in two populations of the socially monogamous Thorn‐tailed RayaditoAphrastura spinicauda(Passeriformes: Furnariidae)

“…In the northern locality, rayaditos breed in a naturally fragmented relict of Valdivian temperate forest that is surrounded by a semiarid landscape (Figure 2), and that persists atop the coastal mountain range due to extensive water input from oceanic fog (del‐Val et al., 2006). This is considered a continental island population due to its isolation from other forested areas occupied by the species (Botero‐Delgadillo et al., 2020). Rayaditos from the southern population breed in extensive and rather continuous areas of sub‐Antarctic forest (Figure 2).…”

Risk‐taking behaviour relates to timing of breeding in a sub‐Antarctic rainforest bird

“…2005, Botero‐Delgadillo et al . 2017a, 2020b). There is no apparent sexual dimorphism in Rayaditos, which are socially monogamous and exhibit bi‐parental care, with females and males equally participating in nest provisioning (Moreno et al .…”

“…2005, Botero‐Delgadillo et al . 2015, 2020b). Nestbox occupation rate during 2013–15 was 20.6% (24 nests per year on average).…”

“…2014, Botero‐Delgadillo et al . 2017, 2020b) and then transported inside a cloth bag to a field‐portable aviary located c . 60 m from the capture site for measuring exploratory behaviour (Botero‐Delgadillo et al .…”

Female extra‐pair behavior is not associated with reduced paternal care in Thorn‐tailed Rayadito

“…We collected data from nest boxes during two consecutive breeding seasons, from October to late December 2014 and 2015. We monitored 220 nest boxes that were installed in three large young patches of Magellanic forest, as part of a long‐term study of the breeding biology of Thorn‐tailed Rayadito (Botero‐Delgadillo, Poblete & Vásquez, 2015; Botero‐Delgadillo, Quirici, Poblete, Acevedo, et al., 2020; Botero‐Delgadillo, Quirici, Poblete, Ippi, et al., 2020). Nest box occupation by rayaditos during 2014 and 2015 corresponded to 15% ( n = 33) and 11.4% ( n = 25), respectively.…”