Open AccessThe modality of nine Triturus newt hybrid zones assessed with nuclear, mitochondrial and morphological data
Author(s) -
Arntzen Jan W.,
Wielstra Ben,
Wallis Graham P.
Publication year - 2014
Publication title -
biological journal of the linnean society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.906
H-Index - 112
eISSN - 1095-8312
pISSN - 0024-4066
DOI - 10.1111/bij.12358
Subject(s) - biology , introgression , transect , hybrid zone , gene flow , evolutionary biology , triturus , nuclear gene , reproductive isolation , mitochondrial dna , zoology , ecology , population , genetics , genetic variation , gene , demography , sociology
The shape of hybrid zones provides insight into genetic isolation between the evolutionary lineages involved: the greater the limitation to gene flow, the farther along the unimodal to bimodal continuum. We study hybrid zone modality in a group of closely related species at a variety of levels of genetic divergence. We explore the degree and the geography of hybridization in 12 transects of Triturus newts, for nine of the ten secondary contact zones in E urope, using nuclear and mitochondrial encoded genetic data and morphological characteristics. Species status is verified by examining the correlation between the three marker systems in a geographical context. At 40 allozyme loci, two transects classify as unimodal, three as bimodal and two as intermediate, while the signal for hybridization is weak or absent in five transects. One zone studied in duplicate was classified as intermediate in one region and as bimodal in another region. mt DNA introgression is frequent and extends beyond nuclear introgression in two transects. Morphology provides additional evidence for hybridity, including one transect for which the signal of nuclear gene flow is weak. Compared to simulations allowing panmixia, the observed allozyme transitions at contact zones show a deficit of backcrossing to various degrees. Over all transects, there is a weak negative relationship between the level of hybridization and allozyme genetic distance for species pairs, consistent with B ateson– D obzhansky– M uller effects. This observation, based upon highly comparable data for a single genus, supports conclusions derived from analyses over a wide variety of other taxa. © 2014 The Authors. Biological Journal of the Linnean Society published by John Wiley & Sons Ltd on behalf of T he L innean S ociety of L ondon, Biological Journal of the Linnean Society , 2014, 113 , 604–622.