Genetic structure and diversity of the Iberian populations of the freshwater blenny Salaria fluviatilis (Asso, 1801) and its conservation implications

Diversity and biogeography of Mediterranean freshwater blennies (Blenniidae, Salaria)

“…Thus, the relatively old, strongly differentiated Guadiana river lineage could represent a vestigial haplotype that survived the initial cold periods at the beginning of the Pleistocene. Retention of ancient polymorphism has been reported in freshwater blennies previously (Méndez et al., 2019; Perdices et al., 2000), and shared haplotypes between individuals from the Guadiana river and other southern lineages (e.g., Verde River; Figure 3a) could be the result of the proximity of these two locations or because of the effects of the LGM in the Iberian Peninsula (Méndez et al., 2019). A secondary connection of Iberian populations with North African lineages likely explains the distinct Algerian–Verde lineage and has also been documented in other freshwater fishes of the region (Casal‐López & Doadrio, 2018), but recent gene flow through marine dispersion should also not be ruled out in this context.…”

“…one month) larval phase of freshwater blennies (Gil et al., 2010) could facilitate dispersal over larger geographical scales; however, thus far no larvae of S. fluviatilis have been found in marine environments. Nonetheless, haplotype sharing between Spanish and Israeli populations has been documented previously in the marine sister species S. pavo (Almada et al., 2009) and there is also some evidence of more recent migration across marine environment between extant S. fluviatilis populations (Laporte, Perrier, et al., 2016; Méndez et al., 2019). Interestingly, the Turkish samples from the Aegean are more closely related to the North Oriental basin populations than to the Middle East lineages, which coincides with a major biogeographic barrier in the Southern Anatolian freshwater ecoregion (Economou et al., 2007; Zogaris & Economou, 2017).…”

“…This highlights the vulnerability of this species on islands (Ferrito & Tigano, 1996; Zogaris et al., 2015) and many peninsular inland waters as well (Barbieri et al., 2015). Above all, patchily distributed freshwater blenny populations on islands and within small coastal river basins harbour their own genetic lineages, which are susceptible to droughts that could lead to genetic bottlenecks and run risks of losing genetic variation due to increased inbreeding and genetic drift (Méndez et al., 2019).…”

“…Thus, the relatively old, strongly differentiated Guadiana river lineage could represent a vestigial haplotype that survived the initial cold periods at the beginning of the Pleistocene. Retention of ancient polymorphism has been reported in freshwater blennies previously (Méndez et al, 2019;Perdices et al, 2000), and shared haplotypes between individuals from the Guadiana river and other southern lineages (e.g., Verde River; Figure 3a) could be the result of the proximity of these two locations or because of the effects F I G U R E 4 Phylogeographic and cluster analyses for each of the major three geographical areas, (a) Occidental basin, (b) North Oriental basin and (c) the Middle East, using the d-loop datasets. Each of the three figures includes the results obtained from (left) the Bayesian phylogeographic and ecological clustering (BPEC), (right) the z-values (i.e., surface plot heights that reflect the genetic distance) of the genetic landscape shape interpolation analysis (AIS), and (a and b below, c right) heatmaps showing the individual assignment probability for each cluster (as rows for a and b, columns for c) revealed by hierarchical Bayesian analysis of population structure (hierBAPS).…”

“…Shaded areas of the BPEC analyses show the 50% probability density contours of each population cluster. Coloured dots represent major catchments or geographical areas of the LGM in the Iberian Peninsula (Méndez et al, 2019). A secondary connection of Iberian populations with North African lineages likely explains the distinct Algerian-Verde lineage and has also been documented in other freshwater fishes of the region (Casal-López & Doadrio, 2018), but recent gene flow through marine dispersion should also not be ruled out in this context.…”