Microgeographic genetic isolation in chub (Cyprinidae: Squalius cephalus) population of the Durance River: estimating fragmentation by dams

Abstract

Weirs and dams are wide spread throughout the world's river systems. The most direct effect of these barriers is the limitation of organism movements, i.e., the alteration of connectivity by fragmentation of the aquatic habitat. Whereas the impact of fragmentation on migratory fish species has been well studied, insights on nonmigratory species are still needed. In particular, knowledge on the effects of dams on cyprinid populations at the watershed scale is lacking. Therefore, we studied the genetic structure of eleven chub (Squalius cephalus) samples lined up in the highly fragmented Durance River (France). Using five microsatellite loci, we show that even if the overall genetic differentiation is low, isolation by distance does occur and that genetic diversity increases from upstream to downstream. Dams seem to participate jointly with waterway distance in the explanation of this pattern. However more precise conclusions cannot be made. Guidance for future studies are given.

Isolation by distance and non-identical patterns of gene flow within two river populations of the freshwater fish Rutilus rutilus (L. 1758)

“…Although these areas are vulnerable to bottlenecking, the same signal is compatible with a scenario of re-colonisation post-extirpation (Hänfling and Weetman 2006). IBD is expected in riverine freshwater fishes but it is not universally found in all river populations (Hänfling et al 2004;Dehais et al 2010;Hamilton et al 2014), corroborating our findings. The strength of IBD may also vary over generations, complicating biological interpretation of snapshot estimates (Junge et al 2011).…”

“…2) and are consonant with estimates observed in this species in the UK, exhibiting significant overlap between mean and variances in heterozygosity and allelic richness across all surveyed Thames sub-populations (Hamilton et al 2014). Concordance of diversities is also to be found in European roach (Demandt 2010) and in European coarse fish generally (e.g., Dehais et al 2010). Each microsatellite locus shows a similar statistical distribution of allele frequencies in either river (Fig S1).…”

“…3), although estimates of mean N e between the two rivers were unaffected. Overall, genetic structuring among sub-populations was low, consistent with patterns of neutral genetic variation observed across coarse fishes (e.g., Dehais et al 2010;Blanchet et al 2010). However, MWP and TH are significantly divergent to warrant individual attention.…”

Genetic diversity of pacu for restocking programs in the Tietê and Grande rivers, Brazil

“…Dams and Hydroelectric Power Plants (HPP) do not to allow WPs of migratory fish to pass upstream to reach their reproduction locations (DEHAIS et al, 2010). The study by Makrakis et al (2007Makrakis et al ( ) from 1997Makrakis et al ( to 2005 in the Paraná River Basin in Brazil, Paraguay and Argentina observed a migratory path for Piaractus mesopotamicus stretching up to 422 km (26.4 km/day).…”

Analyses of Genetic Variation in Populations of Oregon Chub, a Threatened Floodplain Minnow in a Highly Altered Environment

“…Cyprinid species are found in a number of different geographic regions and habitat types, and populations face many threats to their persistence including habitat fragmentation (Alo and Turner 2005;Skalski et al 2008;Dehais et al 2010), alterations in the natural hydrologic regime (Platania 1991;Scheerer 2002), conversion of habitat to agricultural and urban areas (Waite and Carpenter 2000), and introductions of nonnative species that compete with and prey upon native cyprinids (Platania 1991;Simon and Markle 1999;Matthews and Marsh-Matthews 2007). As a result of these threats, many cyprinid species are presently threatened, endangered, or declining in abundance.…”