TY - JOUR

T1 - Ancient habitat shifts and organismal diversification are decoupled in the African viper genus Bitis (Serpentes: Viperidae)

AU - Barlow, Axel

AU - Wüster, Wolfgang

AU - Kelly, Christopher M.R.

AU - Branch, William

AU - Phelps, Tony

AU - Tolley, Krystal A.

PY - 2019/6/1

Y1 - 2019/6/1

N2 - Aim: The expansion of open habitats during the mid‐Miocene has been hypothesizedas a driver of allopatric speciation for many African taxa. This habitat‐dependentmode of diversification has been implicated in the shift from C3 (e.g. forest/woodland)to C4 dominated systems (i.e. open savanna, grasslands) in a number of Africansquamates. We examined this hypothesis using a genus of African viperid snakes(Bitis) with both open habitat and forest‐dwelling representatives.Location: Africa.Methods: A comprehensive multilocus dataset was used to generate a calibratedspecies tree using a multispecies coalescent model. Individual gene trees and patternsof nuclear allele sharing were used to assess species monophyly and isolation.To test the habitat‐dependent evolution hypothesis, we generated an ancestral characterstate reconstruction for open and closed habitats using the dated phylogeny.This was related to the timing of open habitat expansion and forest/woodland contractionin Africa.Results: The genus Bitis originated in the Oligocene, with species level diversificationin the late Miocene/Pliocene. Four well‐supported clades correspond to the recognizedsubgenera Bitis, Keniabitis, Macrocerastes and Calechidna. Several previouslyunrecognized lineages potentially represent cryptic species.Main conclusions: Habitat‐dependent evolution does not appear to have been amain driver for generic level viperine diversification: the ancestral state for Bitiswas open habitat and at least one clade moved into forest in the Miocene, long afterforest had contracted and fragmented. Forest‐dependent species diversified onlyin the late Miocene, presumably as forest became further reduced in extent, fittingan allopatric model of speciation. Although our results do not favour a general patternof habitat‐dependent diversification in Bitis, cladogenesis within the subgenusCalechidna for “arenicolous” species (Bitis caudalis complex) and “rupicolous” species(B. atropos‐cornuta complex), corresponds to the aridification of southwest Africa.

AB - Aim: The expansion of open habitats during the mid‐Miocene has been hypothesizedas a driver of allopatric speciation for many African taxa. This habitat‐dependentmode of diversification has been implicated in the shift from C3 (e.g. forest/woodland)to C4 dominated systems (i.e. open savanna, grasslands) in a number of Africansquamates. We examined this hypothesis using a genus of African viperid snakes(Bitis) with both open habitat and forest‐dwelling representatives.Location: Africa.Methods: A comprehensive multilocus dataset was used to generate a calibratedspecies tree using a multispecies coalescent model. Individual gene trees and patternsof nuclear allele sharing were used to assess species monophyly and isolation.To test the habitat‐dependent evolution hypothesis, we generated an ancestral characterstate reconstruction for open and closed habitats using the dated phylogeny.This was related to the timing of open habitat expansion and forest/woodland contractionin Africa.Results: The genus Bitis originated in the Oligocene, with species level diversificationin the late Miocene/Pliocene. Four well‐supported clades correspond to the recognizedsubgenera Bitis, Keniabitis, Macrocerastes and Calechidna. Several previouslyunrecognized lineages potentially represent cryptic species.Main conclusions: Habitat‐dependent evolution does not appear to have been amain driver for generic level viperine diversification: the ancestral state for Bitiswas open habitat and at least one clade moved into forest in the Miocene, long afterforest had contracted and fragmented. Forest‐dependent species diversified onlyin the late Miocene, presumably as forest became further reduced in extent, fittingan allopatric model of speciation. Although our results do not favour a general patternof habitat‐dependent diversification in Bitis, cladogenesis within the subgenusCalechidna for “arenicolous” species (Bitis caudalis complex) and “rupicolous” species(B. atropos‐cornuta complex), corresponds to the aridification of southwest Africa.

KW - multilocus phylogenetics

KW - multispecies coalescent

KW - reptiles

KW - snakes

KW - sub-Saharan Africa

U2 - 10.1111/jbi.13578

DO - 10.1111/jbi.13578

M3 - Article

VL - 46

SP - 1234

EP - 1248

JO - Journal of Biogeography

JF - Journal of Biogeography

SN - 1365-2699

IS - 6

ER -