Contrasting Genetic Structure and Diversity ofGalaxias maculatus(Jenyns, 1848) Along the Chilean Coast: Stock Identification for Fishery Management

Abstract

Galaxias maculatus (Pisces: Galaxiidae) commonly known as "puye" has a disjunct distribution along the Southern Hemisphere including landlocked and migratory populations at latitudes over 30°S in South America, Australia, Tasmania, and New Zealand. Chilean artisanal fishery of G. maculatus has become less important as a resource due to multiple factors including overexploitation, pollution, introduction of predators, and competitors. At the same time, the current conservation status of the species in Chile is still uncertain. Here, we used mtDNA control region sequences (925bp) to investigate main patterns of genetic diversity and structure in populations from 2 biogeographic areas along the Chilean coast. Extremely high levels of genetic diversity characterize the species, suggesting a low amount of influence of the last glacial cycle over its demography compared with other studies in freshwater and marine South American fishes. However, we recognized contrasting genetic patterns between the Intermediate Area (between 30°S and 42°S) and the Magellanic Province (between 42°S and 56°S). On the one hand, over a narrow geographical range (<200 km) each Intermediate Area estuarine population constitutes a different genetic unit. On the other hand, the Magellanic populations of the species exhibited low levels of differentiation in an area extending for more than 500 km. Such differences may be a consequence of different coastal configurations, oceanographic regimes, and Quaternary glacial histories. Finally, our results support the existence of different stock units for G. maculatus and this information should be integrated in future management strategies and aquaculture programs for this species.

Quaternary ice sheets and sea level regression drove divergence in a marine gastropod along Eastern and Western coasts of South America

“…habitat preferences, reproductive mode and bathymetric range). A concordance between historic biogeographic and contemporary phylogeographic patterns supports that evolutionary forces determining species distributions are also associated with spatial patterns of populations genetic structure 5,6,18,44,45 . Here we corroborate previous molecular results in the species 24,28 , and enhance our understanding of the Quaternary biogeography of the species by recognizing two clearly discriminated genetic clusters currently found in: 1) temperate areas across the Chile-Peru province, north of the 42°S in the Pacific, and 2) cold and temperate areas across the Magellan and Argentina provinces, respectively.…”

“…This break represents the southern limit for many Chile-Peru Province species and the northern border for numerous Magellan ones 13,36 . The shift in species composition recorded in marine organisms at 42°S in the southeast Pacific has been explained by changes in salinity and wave exposure 48,51 , topographical shifts of the coastline as a consequence of the increased number of fjords and channels 10,11,47 , differences in main oceanographic patterns 13,18,19,36,50 , and Quaternary glaciological histories 18,19,27,43 . In fact, this biogeographic limit coincides with the separation of the West Wind Drift into two main Pacific currents, the Humboldt Current System flowing north across the Central Chilean coast and the Cape Horn Current heading south along the Pacific Magellan margin 36,46 .…”

Historical and Contemporary Diversity of Galaxiids in South America: Biogeographic and Phylogenetic Perspectives

“…For instance, microsatellite markers revealed that G. maculatus populations from northern Patagonia exhibit higher genetic diversity and are more highly differentiated (within watersheds) that G. maculatus populations from Southern Patagonia, a pattern explained by the lesser effects of glaciations in northern than in southern Patagonia [6]. West of the Andes in Chile, DNA sequence diversity patterns indicate that estuarine G. maculatus exhibit relatively low genetic differentiation over 1500 Km of coastal waters south of 42 • S, where the glaciers reached the sea during the LGM, a pattern that contrasts with G. maculatus populations north of 42 • S [35,[44][45][46].…”

Genetics, Gene Flow, and Glaciation: The Case of the South American Limpet Nacella mytilina

“…Accordingly, a marked decline in genetic diversity through bottleneck processes or founder effects followed by population expansion is expected [103]. Evidence of such demographic processes has been recorded in several Patagonian near-shore marine species [20,24,25,34,111–116,125,126]. In contrast, little evidence of LGM ice apart from the small cirques and short (max.…”