Date of Award

Fall 2021

Document Type

Research Project


With climate change threatening biodiversity worldwide, it is important to understand species’ physiological responses to changing thermal environments. This study examined whether thermal tolerance (measured as time to immobilization, Timm) in the zooplankton Daphnia catawba and D. schødleri varied along an elevational gradient in Western Maine. Specimens collected from five lakes were subjected to heat stress trials to look for inter-population variation. Thermal tolerance was strongly correlated with several elevation-driven lake temperature variables, with the percent of variation explained ranging from 13-37%. Daphnia from cooler, high-elevation lakes were more sensitive to elevated temperatures. While latitudinal gradients have been examined extensively, this study represents one of the first records of an elevational gradient in thermal response in Daphnia, and marks an essential first step in establishing whether local adaptation in response to changing temperatures will be possible in this system.

Included in

Biology Commons



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