Mitochondrial haplotype variability of brown trout populations from Northwestern Iberian Peninsula, a secondary contact area between lineages

Abstract

Previous studies using mitochondrial markers and microsatellites revealed a new highly differentiated Atlantic lineage of brown trout in the Iberian Peninsula mainly confined to the Upper Duero Basin. Data suggest that Duero lineage (DU) hybridizes with previously described Atlantic (AT) lineages in that basin. However, nuclear and cytogenetic data suggest another hybrid zone between divergent lineages might be present in the Miño Basin, another Atlantic drainage located to the north. Here, we extend those studies by analyzing the mitochondrial haplotype variability of brown trout populations from northwestern Spain, a poorly studied area, to obtain an accurate picture of the distribution of DU. Results show that the DU haplotype is fixed in several isolated populations from the upper course of the Miño River and its main tributary the Sil River. DU haplotype co-occurs with two related AT haplotypes in the Miño Basin revealing a new secondary contact zone. The identification of both longtime stable populations of DU and several other populations showing introgression with widespread AT lineages will be useful for the management and conservation of such an endemic lineage.

Management units of brown trout from Galicia (NW: Spain) based on spatial genetic structure analysis

“…1). The distribution of the presumed oldest Atlantic haplotype, named as Duero haplotype by Machordom et al (2000), seems to be restricted to the upper course of the river in both basins, while the lower course is dominated by more widely distributed Atlantic haplotypes (Martínez et al 2007;Bouza et al 2008). Relatively high genetic divergence among metapopulations from Duero Basin was confirmed by using allozymes and microsatellite markers (Bouza et al 2001;Martínez et al 2007).…”

“…In total, 901 brown trout (Salmo trutta) individuals collected in 30 different locations from 18 river basins from Machordom et al 2000;Martínez et al 2007) and in Miño and Sil Rivers (lighter shading;Bouza et al 2008). The detailed map of Galicia shows mitochondrial haplotypic frequencies for each population as chart diagrams (Duero haplotype: black; Atlantic haplotypes: grey and white; Bouza et al 2008).…”

“…The detailed map of Galicia shows mitochondrial haplotypic frequencies for each population as chart diagrams (Duero haplotype: black; Atlantic haplotypes: grey and white; Bouza et al 2008). The six studied regions R1-R6 are indicated.…”

“…Two different mitochondrial lineages of brown trout co-occur in northwest of Spain including Galicia (Martínez et al 2007;Bouza et al 2008). Particularly, they are present in high frequencies in Miño and Duero Basins (see Fig.…”

Genetic structure of the cisco (Coregonus albula L.) from lakes of glacial origin in northern Poland

“…The investigated species include Clupea harengus [17], Salmo trutta [18,19] C. peled [20] andmigration rate and its impact on the genetic structure of the population require an exact genetic characterization.…”