Genetic divergence and origin of Mediterranean populations of the River Blenny Salaria fluviatilis (Teleostei : Blenniidae)
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| Authors: | Perdices, A; Doadrio, I; Côté, IM; Machordom, A; Economidis, P; Reynolds, JD |
| Year: | 2000 |
| Journal: | Copeia : 723-731 |
| Title: | Genetic divergence and origin of Mediterranean populations of the River Blenny Salaria fluviatilis (Teleostei : Blenniidae) |
| Abstract: | The current distribution of the River Blenny Salaria (= Blennius) fluviatilis, one of the two freshwater representatives of a large, cosmopolitan marine fish family, poses an interesting biogeographical problem because this species inhabits widely separate circum-Mediterranean watersheds. Potential scenarios of its dispersal were examined using allozyme analysis of several populations from the Iberian and Greek peninsulas. Based on Nei genetic distances, the most divergent populations were the populations inhabiting lakes, Lake Trichonis in Greece, and Ruidera Lakes in Spain. Their high divergence suggests their early isolation from the main ingroup populations. In contrast, low genetic distances were found among river populations regardless of geographic location. There was a correlation between genetic distance and geographic distance among Iberian river populations, suggesting that dispersal following the colonization of fresh water occurred via the sea to nearby, unconnected river basins. The ancestor of S. fluviatilis may have been a euryhaline species, allowing incursions into fresh water and subsequent dispersal via the sea. This dispersal scenario could theoretically be combined with multiple colonization episodes. The two old lake populations shared a unique allele at the Pgdh-A locus in high frequency with its closest relative S. pave, which was absent from other populations. This may indicate two initial incursions into fresh water by a wide-ranging marine ancestor that possessed this allele. Differential selection on this allele in lake habitats or convergence are less likely possibilities. Thus, the present distribution of S. fluviatilis appears to stem from a combination of "raceme" origins (i.e., more than one colonization episode) and subsequent dispersal and divergence in new watersheds. |
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