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Poor genetic differentiation but clear cytoform divergence among cryptic species in Simulium damnosum complex ( D iptera: S imuliidae)
Author(s) -
OFORKA LINDA C.,
ADELEKE MONSURU A.,
ANIKWE JOSEPH C.,
HARDY NATE B.,
MATHIAS DERRICK K.,
MAKANJUOLA WINIFRED A.,
FADAMIRO HENRY Y.
Publication year - 2018
Publication title -
systematic entomology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.552
H-Index - 66
eISSN - 1365-3113
pISSN - 0307-6970
DOI - 10.1111/syen.12256
Subject(s) - biology , species complex , evolutionary biology , gene flow , coalescent theory , genetic divergence , chromosomal inversion , sympatric speciation , genetic variation , genetics , phylogenetics , gene , chromosome , genetic diversity , karyotype , population , phylogenetic tree , demography , sociology
A complex cryptic species taxonomy has been developed for the flies that vector Onchocerca volvulus L euckart in A frica. This taxonomy names cytoforms of Simulium damnosum T heobald s.l. based on chromosomal inversion polymorphisms. Researchers have linked variation in cytoforms to variation in geographical distributions and biological traits, but have failed to demonstrate that many of these cytoforms are differentiated genetically or morphologically. This may be explained by recent divergence and incomplete lineage sorting of ancestral polymorphisms. Alternatively, it may be the outcome of ongoing gene flow, with inversions maintaining sets of co‐adapted alleles and selection driving inversion frequency differences across habitats. Here, our goals were to test species delimitations in the S. damnosum complex, and determine if the poor differentiation between these species is better explained by the ancestral polymorphisms or gene‐flow hypotheses. Geometric morphometric analysis and more intensive genetic sampling of populations in N igeria only reinforced the lack of clear divergence among S. damnosum complex cytoforms. By contrast, the first statistical estimates of evolutionary relationships based on chromosomal inversion polymorphism data revealed clear signs of divergence, which lends support to the ancestral polymorphisms hypothesis. But the latter analyses may be biased by non‐neutral evolution of inversion polymorphisms; more rigorous tests of cytoform‐based species hypothesis will require deeper sampling across populations and neutral genetic markers along with explicit modelling of genetic isolation and migration.