Discussion Multilocus analyses revealed that genotypes could be assigned to northern T. jerichonana and southern lineages that occupied the NEPR and PAR regions of the southeastern Pacific ridge system. Connecting segments of the SEPR axis represented a region of and intergradation between the two lineages (Fig. 5). The significant cytonuclear disequilibrium (CND) observed between and mtDNA genes at SEPR also ATPsα indicated admixture in this region, although no significan was found at Latitudinal HSP. clines that produced an IBD-like signal were observed, as previously reported for (). COI exhibited an identical signal because the mitochondrial genes are coupled in the Cytb non-recombinant mitochondrial genome. In addition, two independent nuclear genes, and also exhibited IBD-like signals, though the slopes of on latitude HSP ATPsα, ΦST were shallower (Fig. 4). Stepping-stone dispersal (SSD) among discrete vent fields could create the IBD-like signals (). Strong selection gradients also could result in a convergence of clines among independent loci (), although there was no evidence of selection on any locus examined. The geochemical composition of vent effluents can vary greatly on very small spatial scales (), but the extremes of these local conditions are very broad. In contrast, the temperatures and salinities of ambient (non-vent) seawater are relatively homogeneous at depths occupied by (2235–2747 m). T. jerichonana The Refuge/re-invasion hypothesis A regional extinction event (or events) followed by secondary invasion of the SEPR axis with colonists from NEPR and PAR refugia could have generated the T. jerichonana observed patterns. According to the refuge/re-invasion hypothesis, the NEPR and PAR
Discussion Multilocus analyses revealed that T. jerichonana genotypes could be assigned to northern and southern lineages that occupied the NEPR and PAR regions of the southeastern Pacific ridge system. Connecting segments of the SEPR axis represented a region of and intergradation between the two lineages (Fig. 5). The significant cytonuclear disequilibrium (CND) observed between ATPsα and mtDNA genes at SEPR also indicated admixture in this region, although no significan was found at HSP. Latitudinal clines that produced an IBD-like signal were observed, as previously reported for COI (). Cytb exhibited an identical signal because the mitochondrial genes are coupled in the non-recombinant mitochondrial genome. In addition, two independent nuclear genes, HSP and ATPsα, also exhibited IBD-like signals, though the slopes of ΦST on latitude were shallower (Fig. 4). Stepping-stone dispersal (SSD) among discrete vent fields could create the IBD-like signals (). Strong selection gradients also could result in a convergence of clines among independent loci (), although there was no evidence of selection on any locus examined. The geochemical composition of vent effluents can vary greatly on very small spatial scales (), but the extremes of these local conditions are very broad. In contrast, the temperatures and salinities of ambient (non-vent) seawater are relatively homogeneous at depths occupied by T. jerichonana (2235–2747 m). The Refuge/re-invasion hypothesis A regional extinction event (or events) followed by secondary invasion of the SEPR axis with T. jerichonana colonists from NEPR and PAR refugia could have generated the observed patterns. According to the refuge/re-invasion hypothesis, the NEPR and PAR
tevnia_ms_revision_20150401.docx