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Hybridization dynamics between sympatric species of trout: loss of reproductive isolation
Author(s) -
BETTLES C. M.,
DOCKER M. F.,
DUFOUR B.,
HEATH D. D.
Publication year - 2005
Publication title -
journal of evolutionary biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.289
H-Index - 128
eISSN - 1420-9101
pISSN - 1010-061X
DOI - 10.1111/j.1420-9101.2005.00935.x
Subject(s) - biology , sympatric speciation , reproductive isolation , hybrid , evolutionary biology , sympatry , hybrid zone , mating , sexual selection , zoology , population , genetics , genetic variation , gene flow , botany , gene , demography , sociology
Abstract Although reinforcement should enhance reproductive barriers in sympatric species, sympatric trout species do hybridize. Using mitochondrial and nuclear species markers, we investigated hybridization directionality, hybrid mating biases, and selection against hybrids in 13 sympatric cutthroat and rainbow trout populations on Vancouver Island, Canada. Approximately 50% of the genotyped fish were hybrid (F1 or higher‐order) and populations ranged from very recent (all F1 hybrids) to extremely advanced higher‐order hybridization. Overall, interbreeding was reciprocal, although some populations showed directional hybridization. Pronounced cytonuclear disequilibrium in post‐F1 hybrids indicated a remarkable mating bias not previously reported, which is most likely because of behavioural reproductive preferences. Selection against hybrids was observed in only two populations, indicative of extrinsic selection. Two populations were ‘hybrid swarms’, with a complete loss of reproductive isolation. The complex hybridization dynamics in this system represent a valuable natural experiment of the genetic and evolutionary implications of recent and on‐going interspecific hybridization.

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