Abstract
BackgroundIntroduced species can have profound effects on native species, communities, and ecosystems, and have caused extinctions or declines in native species globally. We examined the evolutionary response of native zooplankton populations to the introduction of non-native salmonids in alpine lakes in the Sierra Nevada of California, USA. We compared morphological and life-history traits in populations of Daphnia with a known history of introduced salmonids and populations that have no history of salmonid introductions.ResultsOur results show that Daphnia populations co-existing with fish have undergone rapid adaptive reductions in body size and in the timing of reproduction. Size-related traits decreased by up to 13 percent in response to introduced fish. Rates of evolutionary change are as high as 4,238 darwins (0.036 haldanes).ConclusionSpecies introductions into aquatic habitats can dramatically alter the selective environment of native species leading to a rapid evolutionary response. Knowledge of the rates and limits of adaptation is an important component of understanding the long-term effects of alterations in the species composition of communities. We discuss the evolutionary consequences of species introductions and compare the rate of evolution observed in the Sierra Nevada Daphnia to published estimates of evolutionary change in ecological timescales.
Highlights
Introduced species can have profound effects on native species, communities, and ecosystems, and have caused extinctions or declines in native species globally
Our results show that introductions of novel fish predators are associated with a specific pattern of phenotypic change in Daphnia populations from alpine lakes in the Sierra Nevada
Previous work in the Sierra Nevada has shown that introduced fish have caused many Daphnia populations to go locally extinct [36,37,38]
Summary
Introduced species can have profound effects on native species, communities, and ecosystems, and have caused extinctions or declines in native species globally. We examined the evolutionary response of native zooplankton populations to the introduction of non-native salmonids in alpine lakes in the Sierra Nevada of California, USA. Contemporary natural populations are faced with an unprecedented array of challenges as a direct result of anthropogenic influences on the environment. These anthropogenic influences may lead to environmental alterations that exceed the rate of change contemporary natural populations have historically experienced. When rapid environmental change occurs, the likelihood of population persistence can be enhanced through a number of mechanisms including dispersal [3], phenotypic plasticity [4], and genetic adaptation [5]. One of the most ubiquitous anthropogenic influences on ecosystems is the introduction of non-native species.
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