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Locally differentiated cryptic pigmentation in the freshwater isopod Asellus aquaticus
A Hargeby1, J Stoltz, J Johansson
1Limnology, Department of Ecology, Lund University, Lund, Sweden. anders.hargeby@limnol.se
Journal of Evolutionary Biology
|April 22, 2005
Summary
Freshwater isopods, Asellus aquaticus, exhibit cryptic pigmentation matching their environment. This adaptation shows local differentiation in coloration, driven by habitat differences and promoting genetic diversity.
Area of Science:
- Ecology
- Evolutionary Biology
- Animal Behavior
Background:
- Background colour matching in animals suggests cryptic pigmentation.
- The freshwater isopod Asellus aquaticus is a suitable model organism for studying cryptic coloration.
Purpose of the Study:
- To investigate the relationship between Asellus aquaticus pigmentation and background darkness in various aquatic habitats.
- To determine if Asellus populations differentiate in pigmentation based on local substrate characteristics.
Main Methods:
- Studied pigmentation of Asellus aquaticus across 29 lakes, wetlands, and ponds in Southern Sweden.
- Correlated Asellus pigmentation with substrate darkness.
- Analyzed pigmentation differences in populations inhabiting areas with contrasting substrate types.
Main Results:
- Asellus pigmentation was significantly correlated with substrate darkness across all studied localities.
- Populations in areas with two distinct substrate types showed differentiated pigmentation.
- Pigmentation generally increased with body size, but this relationship varied among localities.
Conclusions:
- Findings provide evidence for cryptic pigmentation in Asellus aquaticus.
- Local adaptation and selection pressures have led to differentiation in pigmentation on a small spatial scale.
- Habitat heterogeneity appears to promote genetic diversity within Asellus populations.