DOI: 10.5061/dryad.bc578
title: Data from: Historical biogeography resolves the origins of endemic Arabian toad lineages (Anura: Bufonidae): evidence for ancient vicariance and dispersal events with the Horn of Africa and South Asia

description: Background: The Arabian Peninsula is home to a unique fauna that has
 assembled and evolved throughout the course of major geophysical events,
 including the separation of the Arabian Plate from Africa and subsequent
 collision with Eurasia. Opportunities for faunal exchanges with particular
 continents occurred in temporally distinct periods, and the presence of
 African, Western Eurasian, and South Asian derived taxa on the Arabian
 Peninsula signifies the complexity of these historical biogeographic
 events. The six true toad species (family Bufonidae) endemic to Arabian
 Peninsula present a considerable taxonomic and biogeographic challenge
 because they are part of a global bufonid radiation, including several
 genera surrounding the Arabian Peninsula, and difficult to discriminate
 morphologically. As they could be derived from African, Western Eurasian,
 or South Asian toad groups, elucidating their evolutionary relationships
 has important implications for historical biogeography. Here, we analyze a
 global molecular data set of 243 bufonid lineages, with an emphasis on new
 sampling from the Horn of Africa, Western Eurasia, South Asia, and the
 Arabian Peninsula, to reconstruct the evolutionary relationships of the
 Arabian species. We produce a robust time-calibrated phylogeny to infer
 the biogeographic history of this group on and around the Arabian
 Peninsula. Results: Our phylogenetic analyses indicate two of the endemic
 Arabian toad species, “Bufo” tihamicus and “Bufo” arabicus, evolved
 independently within the African genus Amietophrynus. We confirm the
 Arabian species Duttaphrynus dhufarensis is of South Asian origin, but do
 not find evidence for the Asian genus Duttaphrynus being present in the
 Horn of Africa, discrediting a previously proposed Asian bufonid dispersal
 event to Africa. We also do not find evidence of the African genus
 Amietophrynus occurring in South Asia, suggesting that unlike many other
 vertebrate taxa, toads have not used the Arabian Peninsula as a
 stepping-stone for trans-continental dispersal. Our divergence dating
 estimates strongly suggest the formation of the Red Sea drove simultaneous
 divergences between two of the Arabian species (A. tihamicus comb. nov.
 and A. arabicus comb. nov.) and their xclosest mainland African relatives
 in the Early Miocene. We estimate the divergence of D. dhufarensis with
 its closest South Asian relatives occurred in the mid to Late Miocene,
 suggesting the temporary or permanent land connections between the Arabian
 plate and Eurasia facilitated dispersal of this lineage to the Arabian
 Peninsula. Conclusions: The Arabian bufonid assemblage, despite being
 comparatively depauperate with respect to surrounding continents,
 exemplifies the faunal pattern of the Arabian Peninsula, namely being a
 complex admixture of African, Western Eurasian, and South Asian elements.
 The historical biogeographic patterns exhibited by Arabian toads and their
 allies are concordant with studies of other vertebrate taxa, building
 support for the role of major geological events in driving simultaneous
 vicariance and dispersal events around the Arabian Peninsula. Although
 many taxa or groups exhibiting disjunct Afro-Arabian distributions appear
 to have dispersed more recently from the Horn of Africa via a southern
 land bridge or overwater dispersal, both Amietophrynus tihamicus and A.
 arabicus likely represent true African relicts resulting from vicariance
 associated with the Red Sea formation, a pattern that so far is rare among
 the vertebrate species investigated.
description: Analysis_1_lognormalInput file for BEAST v1.8.1 for Analysis 1Analysis_1_lognormal_consensusAnalysis 1 consensus treeAnalysis_2_normalInput file for BEAST v1.8.1 for Analysis 2.Analysis_2_normal_consensusConsensus tree for Analysis 2.Analysis_3_exponentialInput file for BEAST v1.8.1 for Analysis 3.Analysis_3_exponential_consensusConsensus tree for Analysis 3.