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STRONG SELECTION AGAINST HYBRIDS MAINTAINS A NARROW CONTACT ZONE BETWEEN MORPHOLOGICALLY CRYPTIC LINEAGES IN A RAINFOREST LIZARD
Author(s) -
Singhal Sonal,
Moritz Craig
Publication year - 2012
Publication title -
evolution
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.84
H-Index - 199
eISSN - 1558-5646
pISSN - 0014-3820
DOI - 10.1111/j.1558-5646.2011.01539.x
Subject(s) - biology , hybrid zone , cline (biology) , evolutionary biology , biological dispersal , phylogeography , range (aeronautics) , ecology , incipient speciation , species complex , disequilibrium , reproductive isolation , natural selection , panmixia , context (archaeology) , genetic structure , population , phylogenetics , genetic variation , gene flow , phylogenetic tree , genetics , paleontology , medicine , materials science , sociology , gene , ophthalmology , composite material , demography
Phenotypically cryptic lineages comprise an important yet understudied part of biodiversity; in particular, we have much to learn about how these lineages are formed and maintained. To better understand the evolutionary significance of such lineages, we studied a hybrid zone between two morphologically cryptic phylogeographic lineages in the rainforest lizard, Lampropholis coggeri . Analyzing a multilocus genetic dataset through cline inference, individual‐based methods and population measures of disequilibrium and using simulations to explore our genetic results in context of theoretical expectations, we inferred the processes maintaining this hybrid zone. We find that these lineages meet in a hybrid zone that is narrow ( ≈ 400 m) relative to inferred dispersal rate. Further, the hybrid zone exhibits substantial genetic disequilibrium and sharply coincident and largely concordant clines. Based on our knowledge about the region’s biogeography, the species’ natural history, and our simulation results, we suggest that strong selection against hybrids structures this system. As all clines show a relatively narrow range of introgression, we posit that this hybrid zone might not yet be in equilibrium. Nonetheless, our results clearly show that phylogeographic lineages can evolve substantial reproductive isolation without concomitant morphological diversification, suggesting that such lineages can constitute a significant component of evolutionary diversity.