Evolution of chinook salmon (Oncorhynchus tshawytscha) populations in New Zealand: pattern, rate, and process.

摘要: Chinook salmon, Oncorhynchus tshawytscha, from the Sacramento River, California, USA were introduced to New Zealand between 1901 and 1907, colonized most of their present-day range within about 10 years. The populations now vary in phenotypic traits typically used differentiate salmon natural range: growth freshwater at sea, age maturity, dates return fresh water reproduction, morphology, reproductive allocation. This paper reviews a large research program designed determine relative contributions plasticity genetic adaptation this variation, an effort understand processes underlying evolution new populations. We found strong evidence trait divergence 30 generations, particularly rate, date return, output, with plausible adaptive bases for these differences. Importantly, we also demonstrated not only basis post-release survival but higher survival, hence fitness, population released its established site compared another same site. conclude that different rivers probably resulted initially (e.g., habitat-specific rates, effects upriver migration on ovarian investment). Philopatry (homing natal streams) combined rapid distinct breeding periods restrict gene flow, facilitating other traits. suggest addition resulting random founder effects, may arise during very early stages colonization when original colonists are non-random, pre-adapted subset source population. ‘favored founders effect’ immediately improves fitness Overall, reveals complex interplay environmental controls over behavior, physiology life history characterize differentiation, process has taken place repeatedly