Inconsistent phylogeographic pattern between a sperm dependent fish and its host: in situ hybridization vs dispersal

Abstract

BackgroundCo-dispersal of sperm-dependent hybrids and their sexual relatives is expected to result in consistent spatial patterns between assemblages of hybrids and genetic structure of parental species. However, local hybridization events may blur this signal as assemblages could be organized under different connectivity constraints. This study aims at testing the hypothesis of local hybridization events by comparing the assemblage of hybrid fish Chrosomus eos-neogaeus to the genetic diversity of one of its parental species, Chrosomus eos.ResultsAn extensive survey performed on a total of 132 sites located in two regions of Southern Quebec (West-Qc and East-Qc) revealed a distinct organization of hybrid lineages. One of the six hybrid lineages detected in West-Qc is widespread throughout this region resulting in a low α-diversity (1.38) and β-diversity (4.35). On the other hand, 36 hybrid lineages were detected in East-Qc and displayed narrow geographic distributions leading to a high α-diversity (2.30) and β-diversity (15.68). In addition, the C. eos multilocus haplotype of several of these hybrids is assigned to their respective sympatric C. eos population. Finally, contrasting with hybrids, the paternal species C. eos displayed a higher ρST in West-Qc (0.2300) than in East-Qc (0.0734).ConclusionThe unusually high diversity of hybrid lineages in East-Qc as well as the spatial organization and the close genetic relationship with C. eos sympatric populations support the hypothesis that multiple hybridization events occurred in situ. These findings coupled to the near absence of the maternal species Chrosomus neogeaus suggest that the decline of this species could be the trigger event at the origin of the high rates of spontaneous hybridization in this region.Electronic supplementary materialThe online version of this article (doi:10.1186/s12862-016-0754-5) contains supplementary material, which is available to authorized users.

Inferring responses to climate warming from latitudinal pattern of clonal hybridization

“…The very high diversity of lineages and their restricted distribution are consistent with the hypothesis that hybridization events occurred locally. Genetic analyses provided another support to this hypothesis as the multilocus genotype of hybrids from RI, YA, and SF networks matched that of C. eos sympatric populations, one of the species involved in hybridization (Vergilino et al, ).…”

“…This striking result contrasts with diversity from the other regions of North America surveyed so far. Previous studies reported a single or a very low number of widespread lineages per region (Angers & Schlosser, ; Doeringsfeld, Schlosser, Elder, & Evenson, ; Elder & Schlosser, ; Goddard et al, ; Vergilino et al, ). Such a low diversity in very large areas is typical of mtDNA diversity of species that colonized regions covered by the ice sheet during the Pleistocene (Bernatchez & Wilson, ).…”

“…We analyzed a total of 51 sites along a 500‐km‐long transect, from 45°02′ to 48°29′ north (Figure , Table ). Of these, 19 sites are representative of the southernmost hydrographic networks of the southeastern Quebec: Richelieu R. (RI), Yamaska R. (YA), and Saint Francois R. (SF) sampled in previous studies (Leung, Breton, & Angers, ; Vergilino et al, ). Nine of these 19 sites were a pool of geographically close sites located in the same network and harboring the same hybrid assemblage, to avoid over‐representation of these assemblages representing the same local hybridization events.…”

“…Chrosomus neogaeus first reproduces in early spring, while C. eos reproduces later (Das & Nelson, ). The hybrid lineages analyzed so far were always the result of reproduction between late C. neogaeus females and early C. eos males, since all hybrids detected so far harbor the maternally inherited mitochondrial DNA of C. neogaeus (Angers & Schlosser, ; Binet & Angers, ; Goddard et al, ; Vergilino et al, ). Hybrids are known to display an intermediate reproduction period between that of C. neogaeus and C. eos .…”

Effects of mitonuclear combination and thermal acclimation on the energetic phenotype

“…Thereafter, mtDNA of all individuals was discriminated between C. eos (wild type) and C. neogaeus (cybrid). Because several C. neogaeus haplotypes were present in cybrids of this lake (Vergilino, Leung, & Angers, 2016), these individuals were further discriminated to select a single cybrid mitotype (Mississippian, A‐IV). The genetic identification is further described below.…”