Fine-scale genetic structure in the critically endangered red-fronted macaw in the absence of geographic and ecological barriers

Abstract

Behavioural and socio-cultural traits are recognized in the restriction of gene flow in species with high cognitive capacity and complex societies. This isolation by social barriers has been generally overlooked in threatened species by assuming disrupted gene flow due to population fragmentation and decline. We examine the genetic structure and ecology of the global population of the Critically Endangered red-fronted macaw (Ara rubrogenys), an endemic species to the inter-Andean valleys of Bolivia. We found a fine-scale genetic structuring in four genetic clusters. Genetic diversity was higher in wild compared to captive-bred macaws, but similar to that of captive wild-caught macaws. We found no clear evidence of severe genetic erosion in the population in recent decades, but it was patent in historic times, overlapping with drastic human habitat transformation and macaw persecution over millennia. We found no evidence of geographical and ecological barriers, owing to the high dispersal ability, nesting and foraging habits between genetic clusters. The lack of genetic intermixing despite long-distance foraging and seasonal movements suggests recruitment in natal colonies and other social factors reinforcing philopatry-related genetic structure. Conservation efforts should be specifically focussed on major threats in each genetic cluster as independent conservation units, and also considered in ex-situ management.

Predicting the Future Distribution of Ara rubrogenys, an Endemic Endangered Bird Species of the Andes, Taking into Account Trophic Interactions

“…Despite its restricted range, the population is structured in genetic clusters with low or null gene flow among them, despite that some colonies are separated by few tens of kilometers, that there are no ecological barriers and that macaws make larger daily and seasonal movements for feeding. Therefore, it is highly improbable that the species could colonize very distant areas in its future niche suitability [81].…”

Breeding and global population sizes of the Critically Endangered Red-fronted MacawAra rubrogenysrevisited

“…Further, Ridgely (1981; also see Lanning 1991) reported that several hundred Red-fronted Macaws were trapped annually for the international pet trade in the late 1970s (most likely continuing at the same rate through to at least the early 1980s), which could add up to well over 1,000 birds removed from the wild population during this period. Blanco et al (2021), however, found no clear evidence of strong genetic erosion in the population as a whole during recent decades, but rather during the last centuries or millennia, possibly coinciding with the expansion of the Incan Empire in the 15 th century and concomitant intense habitat transformation in Bolivia's inter-Andean dry valleys. Today, main threats to the species are continued habitat loss and degradation (due to forest conversion to agriculture, overgrazing, domestic and industrial firewood cutting), nest-poaching and trapping of adults for local and national pet supply and persecution of the species by local farmers as a crop pest, fuelling a presumed on-going rapid population decline (Tella et al 2013, Pires et al 2016, BirdLife International 2021b.…”

Advancing Genetic Methods in the Study of Parrot Biology and Conservation

“…In contrast, no geographical or ecological barriers were found for the Red-fronted Macaw Ara rubrogenys across inter-Andean valleys in Bolivia. This suggests that social factors might reinforce their philopatry-related genetic structure, as cliffs with nest sites are not continuously distributed across the landscape [206]. Landscape genetics was also used to study the historical and current distributions of the Crimson Rosella Platycercus elegans complex, showing that population expansion followed by secondary contact and hybridization might be responsible for their present genetic structure [207].…”