31° South: The physiology of adaptation to arid conditions in a passerine bird

Abstract

Arid environments provide ideal ground for investigating the mechanisms of adaptive evolution. High temperatures and low water availability are relentless stressors for many endotherms, including birds; yet birds persist in deserts. While physiological adaptation probably involves metabolic phenotypes, the underlying mechanisms (plasticity, genetics) are largely uncharacterized. To explore this, we took an intraspecific approach that focused on a species that is resident over a mesic to arid gradient, the Karoo scrub‐robin (Cercotrichas coryphaeus). Specifically, we integrated environmental (climatic and primary productivity), physiological (metabolic rates: a measure of energy expenditure), genotypic (genetic variation underlying the machinery of energy production) and microbiome (involved in processing food from where energy is retrieved) data, to infer the mechanism of physiological adaptation. We that found the variation in energetic physiology phenotypes and gut microbiome composition are associated with environmental features as well as with variation in genes underlying energy metabolic pathways. Specifically, we identified a small list of candidate adaptive genes, some of them with known ties to relevant physiology phenotypes. Together our results suggest that selective pressures on energetic physiology mediated by genes related to energy homeostasis and possibly microbiota composition may facilitate adaptation to local conditions and provide an explanation to the high avian intraspecific divergence observed in harsh environments.

Biome stability predicts population structure of a southern African aridland bird species

“…Despite this biome‐genetic diversification relationship, few empirical studies have evaluated the role of temporal habitat stability (i.e., habitat persistence through time) in structuring genetic diversity. Most genetic studies on South African aridland birds have focused on species complexes where parapatric speciation across biome boundaries has given rise to habitat specialist species (Oatley, Voelker, Crowe, & Bowie, 2012; Ribeiro, Lloyd, & Bowie, 2011; Ribeiro, Lopes, & Bowie, 2012; Ribeiro et al, 2019).…”

A rather dry subject; investigating the study of arid-associated microbial communities

“…al. demonstrate that metagenomic investigation can be a crucial component of well-rounded research into the life and adaptation of an arid-adapted animal, along with environmental, metabolic and genomic investigations [32]. Arid environments could offer a very useful proof of concept for this philosophical approach, with clear environmental influences and comparatively simple living communities.…”

“…There have been comparatively few environmental microbiology studies on arid environments though in the hunt for extremophiles and pharmaceutically useful compounds there have been some focussed investigations of particular locations [28][29][30][31]. Animal-associated microbiota research has often been a component of a larger investigation into a particular host species [32] rather than a systemic approach considering the microbiome as a feature of animal life in arid environments.…”

Phylogeographical history of the Olive Woodpecker Dendropicos griseocephalus, a species widely distributed across Africa

“…2018; Cercotrichas coryphaeus , Ribeiro et al . 2011, 2019; C. signata , Ribeiro et al . 2014; Acrocephalus baeticatus/scirpaceus , Olsson et al .…”