Climate refugia for three Afromontane forest‐dependent bird species in south‐eastern South Africa

Abstract

Aim Pleistocene climate shifts were influential in shaping biodiversity patterns for forest‐dependent species. Within southern Africa, palaeoclimatic shifts possibly homogenised subtropical Afromontane forest biodiversity, yet these forests continue to harbour unique diversity. For the three songbird species with different natural histories, we investigated the refugial role of subtropical Afromontane and scarp forests and explored specifically how palaeoclimatic events impacted genetic connectivity among forest patches. Location Maputaland‐Pondoland‐Albany Biodiversity Hotspot, south‐eastern South Africa. Taxon Batis capensis, Phylloscopus ruficapilla and Pogonocichla stellata. Methods Mitochondrial control region sequences and microsatellite data were used to assess genetic diversity and population structure among 406 birds. Demographic change was inferred using Bayesian skyline plots (BSPs), and approximate Bayesian computations (ABCs) were used to identify gene flow trends among putative refugia. Environmental niche models (ENMs) were used to infer past occurrence probabilities. Results Species BSPs supported regional presence predating the Last Glacial Maximum (21 kya) and indicated post‐glacial population expansions. ABC modelling revealed that present‐day gene flow trends emerged largely during the current interglacial (<12 kya), suggesting that thermal maxima promote regional forest expansion. The north‐eastern source of gene flow in all the three species suggested a post‐glacial influx from refugia further north, while southern scarp forests sustained secondary source populations for B. capensis and P. ruficapilla. High gene flow signatures from south‐western forests in B. capensis and especially P. stellata alluded to hidden source populations in the under‐surveyed southern Afrotemperate forests—the southernmost Afromontane forest bloc. ENMs corroborated both scarp and southern Afrotemperate forests as glacial refugia and demonstrated persistent regional population presence over the past 120 kya. Main Conclusions The population genetics and palaeodistribution of the three bird species indicate their regional persistence throughout the late Pleistocene, suggesting that Afromontane and scarp forests of south‐eastern South Africa served as refugia for subtropical African avian forest biota.

Habitat opening fostered diversity: impact of dispersal and habitat‐shifts in the evolutionary history of a speciose afrotropical insect group

“…1, 3). African highlands (Supporting information for a detailed map) along the Eastern corridor probably acted as altitudinal refugia during the cycles of expansion and contraction of the savannas (Plana 2004, Couvreur et al 2021), resulting in the connection and isolation of related species in highland refugia among both forest‐ and arid‐adapted lineages (Menegon et al 2014, Huntley and Voelker 2017, Portillo et al 2018, Mulvaney et al 2022, Dagallier et al 2023). This hypothesis is supported by: 1) the fact that Sesamiina species endemic to the African highlands belong to distinct lineages (e.g.…”

Evolution, systematics and historical biogeography of Palparini and Palparidiini antlions (Neuroptera: Myrmeleontidae): Old origin and in situ diversification in Southern Africa

“…Although the adults of some species are sometimes caught at high elevations (up to 2000 m), most palparine and palparidiine species only thrive at lower elevations where they can find the sandy areas that are required for the development of their larvae. Because of the latter, it is also difficult to determine whether these reliefs potentially acted as climatic refugia for Palparini during cycles of rainforest fragmentation and reconnection over the past 7 Myr, as it has been shown for different groups adapted to closed or open habitats (Bryja et al, 2017; Huntley & Voelker, 2017; Menegon et al, 2014; Mulvaney, Cherry, & Matthee, 2022; Portillo et al, 2018; Tolley et al, 2011).…”

Habitat Opening Fostered Diversity: Impact of Dispersal and Habitat-shifts in the Diversification of a Speciose Afrotropical Insect Group

“…Within this heterogeneous environment, an array of dispersal, vicariance, reverse colonization events, and in situ speciation events within East Africa are inferred during the last 7 million years (Myr) (Figures 1, 3). African highlands (see Appendix S.4.3 for a detailed map) along the Eastern corridor probably acted as altitudinal refugia during the cycles of expansion and contraction of the savannas (Plana 2004;Couvreur et al 2021), resulting in the connection and isolation of related species in highland refugia among both forest-and arid-adapted lineages (Menegon et al 2014, Huntley and Voelker 2017, Portillo et al 2018, Mulvaney et al 2022, Dagallier et al 2023. This hypothesis is supported by: (i) the fact that Sesamiina species endemic to the African highlands belong to distinct lineages (e.g., Se.…”