I compared populations of the muricid gastropod Urosalpinx cinerea from its native Atlantic and introduced Pacific ranges, examining its responses to major abiotic and biotic environmental factors. Specifically, I assessed its ability to right itself across a range of winter temperatures (Chapter 1), and its behavioral responses to cues from potential introduced range predators (Chapter 2). These studies represent the first phenotypic comparisons between introduced and native populations of U. cinerea, as well as the first comparisons between U. cinerea living in different parts of the introduced range. Taken together, these studies emphasize the value of combining biogeographic comparisons with experimental approaches to explore the evolutionary and ecological dynamics of biological invasions.
Chapter 1: Temperature sensitivity of righting response in Urosalpinx cinerea from the native and introduced range. Anticipating the ecological consequences of anthropogenic climate change and biological invasions for marine ecosystems requires understanding how changing climate regimes affect ecologically relevant behaviors in introduced species. I compared the temperature sensitivity of righting response speed, a behavior related to overall movement and important to surviving dislodgment and evading predators, between native and introduced populations of U. cinerea. Such comparisons are essential to detecting whether introduced phenotypes have diverged from native range counterparts and have rarely been performed among marine species. Righting speed of U. cinerea from two native range bays (in Connecticut and Delaware, USA) and three introduced range bays (in Washington and California, USA) was tested under three temperature treatments spanning winter conditions across much of its range (5°C, 10°C, 15°C) and at 20°C, a temperature previously identified as optimal for feeding and reproduction in the native range. Snails took significantly longer to right themselves as temperatures dropped from 20°C to 5°C, with the greatest temperature sensitivity in the interval from 10°C to 5°C. However, there were no geographic differences, with snails from all regions responding similarly; therefore, local environmental conditions are likely to determine U. cinerea activity levels across seasons. Since the interval of greatest temperature sensitivity coincides with winter minimum water temperatures in the introduced range, warmer winters brought on by global climate change could allow U. cinerea to be more active throughout the year, with potential concomitant impacts on native oysters and other prey species.
Chapter 2: Detection of predation risk cues in Urosalpinx cinerea from the native and introduced ranges. Determining the factors governing the success of introduced predators is key to predicting and managing their impacts. By exploring how an introduced predator uses cues to detect predation risk from top predators in the introduced range, and by comparing individuals from the native and introduced range, we can gain insight into the roles of predator recognition and naiveté in introductions. This study measured cue recognition in U. cinerea, and examined how snails collected from several populations in the native and introduced ranges responded to chemical cues from two crab predators and injured conspecifics. Both native and introduced range U. cinerea responded to Cancer antennarius and Carcinus maenas kairomones, and to conspecific alarm cues. This is the first report of native range individuals of an introduced species demonstrating a pre-existing ability to recognize chemical cues from an introduced range predator with which they had no prior experience. U. cinerea may have benefitted from similarity between their native community and the resident community in their introduced range, as they were capable of recognizing ostensibly unfamiliar crab predators, possibly by relying on common cues or on generalization from predators U. cinerea evolved with in their native range. The ability to avoid disadvantages of novelty may aid the successful establishment of many introduced species.
|Commitee:||Grosholz, Edwin D., Holyoak, Marcel|
|School:||University of California, Davis|
|School Location:||United States -- California|
|Source:||MAI 51/03M(E), Masters Abstracts International|
|Subjects:||Ecology, Conservation, Behavioral Sciences|
|Keywords:||Biogeography, Climate change, Invasive species, Non-consumptive effects, Predator-prey, Risk assessment|
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