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

Abstract

Environments are heterogeneous in space and time, and the permeability of landscape and climatic barriers to gene flow may change over time. When barriers are present, they may start populations down the path toward speciation, but if they become permeable before the process of speciation is complete, populations may once more merge. In Southern Africa, aridland biomes play a central role in structuring the organization of biodiversity. These biomes were subject to substantial restructuring during Plio-Pleistocene climatic fluctuations, and the imprint of this changing environment should leave genetic signatures on the species living there. Here, we investigate the role of adjacent aridland biome boundaries in structuring the genetic diversity within a widespread generalist bird, the Cape Robin-chat (Cossypha caffra).

Comparative Phylogeography of Southern African Bird Species Suggests an Ephemeral Speciation Model

“…The primary effect on this species was that as interior regions of South Africa became uninhabitable, puff adder populations were pushed to more northerly or coastal habitats, and mitochondrial clades subsequently expanded to occupy a variety of habitats, with some introgression between clades at contact zones. More recently, a study of the Cape Robin-chat [22] recovered a similar pattern wherein arid land biomes were shown to play a major role in structuring populations across southern Africa. As aridity increased in the central Nama Karoo biome, Cape Robin-chat populations became isolated in different biome refugia, which in turn led to three lineages.…”

“…This suggests either that, like puff adders, refugial isolation during glacial maxima may have driven speciation, with incipient lineages subsequently expanding to habitat-defined contact zones, or that differentiation across habitats or biomes (ecological speciation) is playing a role in generating southern African avian diversity. For birds, there is no support for a refugial pattern other than that evidenced by the Cape Robin-chat [22], and just a few studies exist [2,9,10,29,30] that might support ecological speciation.…”

“…Still another possibility is that more frequent climate perturbations have been acting to generate species in southern Africa. Recent work based on multi-proxy alluvial records has shown that ecotone changes have occurred in South Africa over the past 14 kyr [31], and several studies have used climate circulation models encompassing the past 140 kyr to determine that low climatic variability, of a degree enabling biome persistence, is strongly associated with avian species richness in the region [18,22,32]. Further, biome persistence is probably linked to reduced extinction risk [20].…”

An introduction to predictive distribution modelling for conservation to encourage novel perspectives

“…For example, warming temperatures have led to local extinctions in mountaintop communities in southeastern Peru as species shift their geographic ranges to track climate, a potential harbinger of the possible extinction of high elevation tropical species (Feeley et al, 2012;Freeman et al, 2018;Rehm & Feeley, 2016). Yet species may be more resilient than models assume; for example, genetic data indicate that many species were able to persist through dramatic climate fluctuations in the Pleistocene (Bocalini et al, 2021;Song et al, 2020;Wogan et al, 2020).…”

Sahara mustard as a major threat to desert biodiversity in the southwest United States and the need to integrate contemporary methods to understand its biology

“…For example, Andriollo et al (2018) used F IS to examine diversity across bat species and Wogan et al (2020) used this same metric to examine subpopulation differentiation in a generalist bird. A methodological clarification to the original manuscript would have ap-…”