RT Journal Article
SR Electronic
T1 Isolation and Gene Flow in a Speciation Continuum in Newts
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 095877
DO 10.1101/095877
A1 M. Pabijan
A1 P. Zieliński
A1 K. Dudek
A1 M. Stuglik
A1 W. Babik
YR 2016
UL http://biorxiv.org/content/early/2016/12/21/095877.abstract
AB The evolution of reproductive isolation is a prolonged process that fosters genetic exchange between differentiating metapopulation lineages. Gene flow between incipient species provides an opportunity to quantify and understand the impact of gene flow on the accumulation of divergence along the speciation continuum. Here we delimit taxa, reconstruct phylogeny and infer gene flow in newts of the Lissotriton vulgaris species complex based on 74 nuclear markers sequenced for 127 populations. Using several species delimitation and phylogenetic methods, we recovered nine allo- and parapatric taxa, and obtained a partially resolved phylogeny. Approximate Bayesian Computation modeling detected historical and recent gene flow between several taxa, including non-sister pairs. Gene flow among taxa in Central Europe (L. v. ampelensis, L. v. meridionalis, two morphologically cryptic taxa within L. v. vulgaris) suggests that these lineages are non-independent and possibly in the process of merging in some areas. Three southern lineages (L. v. graecus, L. v. kosswigi, L. v. lantzi) have acquired the population genetic hallmarks of independent species, whereas the status of L. v. schmidtleri remains uncertain. We identified hybridization, causing extensive haplotype sharing between non-sister lineages, as an important source of genealogical discordance, positively misleading multispecies coalescent-based species tree methods. We also obtained strong statistical support for widespread mtDNA introgression, suggested by previously observed discordance between mtDNA phylogeny and morphology. Our study shows that distinct metapopulation lineages along the speciation continuum can exchange nontrivial amounts of genes and emphasizes an urgent need for effective methods accounting for gene flow in species tree reconstruction.