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History cleans up messes: The impact of time in driving divergence and introgression in a tropical suture zone
Author(s) -
Singhal Sonal,
Bi Ke
Publication year - 2017
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/evo.13278
Subject(s) - introgression , biology , lineage (genetic) , allopatric speciation , evolutionary biology , divergence (linguistics) , range (aeronautics) , coalescent theory , genome , phylogenetics , genetics , gene , population , linguistics , philosophy , demography , materials science , sociology , composite material
Contact zones provide an excellent arena in which to address questions about how genomic divergence evolves during lineage divergence. They allow us to both infer patterns of genomic divergence in allopatric populations isolated from introgression and to characterize patterns of introgression after lineages meet. Thusly motivated, we analyze genome‐wide introgression data from four contact zones in three genera of lizards endemic to the Australian Wet Tropics. These contact zones all formed between morphologically cryptic lineage‐pairs within morphologically defined species, and the lineage‐pairs meeting in the contact zones diverged anywhere from 3.1 to 5.8 million years ago. By characterizing patterns of molecular divergence across an average of 11K genes and fitting geographic clines to an average of 7.5K variants, we characterize how patterns of genomic differentiation and introgression change through time. Across this range of divergences, we find that genome‐wide differentiation increases but becomes no less heterogeneous. In contrast, we find that introgression heterogeneity decreases dramatically, suggesting that time helps isolated genomes “congeal.” Thus, this work emphasizes the pivotal role that history plays in driving lineage divergence.