tailieunhanh - Lake Trout Ecosystems in a Changing Environment - Chapter 2

Lịch sử và quá trình tiến hóa của hồ cá hồi trong hồ Lá chắn: những thách thức trong quá khứ và tương lai Bằng chứng cho thấy rằng hồ cá hồi có khả năng phát triển đáp ứng với những thay đổi môi trường gây ra bởi những sự kiện đóng băng trong thời kỳ Pleistocene. Sau khi rút lui của các tấm băng hà cuối cùng, hồ cá hồi recolonized phạm vi hiện tại của họ từ refugia nhiều. Dân cư trong các hồ khiên phương bắc có nguồn gốc từ ít nhất sáu nhóm refugial, với sự đóng. | chapter two History and evolution of lake trout in Shield lakes past and future challenges Chris C. Wilson Ontario Ministry of Natural Resources Nicholas E. Mandrak Department of Fisheries and Oceans Contents Introduction Evolutionary history Glacial refugia and historical genetics peering into the past Postglacial dispersal Secondary contact among refugial groups Genetic structure of modern populations Species interactions and anthropogenic disturbances Research needs Conclusion References Introduction Evidence suggests that lake trout likely evolved in response to environmental changes caused by glaciation events during the Pleistocene era. Following the retreat of the last ice sheets lake trout recolonized their present range from multiple refugia. Populations in Boreal Shield lakes are descended from at least six refugial groups with the greatest contributions from Mississippian and Atlantic sources. Secondary contact among these separate lineages was a significant source of genetic diversity enabling adaptation to local environments. Suprisingly little is known about the diversity and adaptive structure of inland lake trout populations. There is some evidence of local adaptation among inland populations and stocking strains as well as differential fitness between native and stocked lake trout. 2004 by CRC Press LLC However many issues regarding lake trout adaptation and fitness remain unresolved. In addition the biological characteristics of lake trout make them extremely vulnerable to natural and anthropogenic disturbances which present significant management challenges to ensure their persistence. Lake trout have often been described as a glacial relict a holdover from the Ice Age that lives primarily in deep cold-water habitats. The species has certainly been intimately associated with glacial events and is perhaps better adapted to the past than the present. The fascination of anglers and biologists with lake trout may in part stem from the prehistoric .