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Old mice, young islands and competing biogeographical hypotheses
Jeffrey L van Zant1, Michael C Wooten
1Department of Biological Sciences, Auburn University, 331 Funchess Hall, Auburn, AL 36849, USA. jvanzant@mail.ucf.edu
Molecular Ecology
|October 25, 2007
Summary
Genetic analysis of Peromyscus polionotus reveals coastal populations are older than previously thought. This finding challenges existing biogeographical models and supports a new "Shore-line Tracking" hypothesis for their evolution.
Area of Science:
- Evolutionary Biology
- Genetics
- Zoology
Background:
- Peromyscus polionotus, a rodent species from the southeastern USA, is a model for studying geographical variation and adaptive evolution.
- Previous assumptions suggested P. polionotus is young, with recent coastal population origins.
- These assumptions underpinned the prevailing "Recurrent Invasion" biogeographical hypothesis.
Purpose of the Study:
- To test the age assumptions of P. polionotus and its coastal populations.
- To evaluate the "Recurrent Invasion" biogeographical hypothesis.
- To investigate the evolutionary history and diversification patterns of P. polionotus.
Main Methods:
- Mitochondrial DNA sequencing of cytochrome b and D-loop regions (2449 bp).
- Analysis of 79 P. polionotus samples from the Florida and Alabama Gulf Coast.
- Use of Peromyscus maniculatus subspecies and P. keeni as outgroups.
Main Results:
- Cytochrome b divergence between P. maniculatus and P. polionotus was higher than anticipated.
- Three distinct genetic groups were identified within P. polionotus.
- Coastal populations (beach mice) form a monophyletic group, estimated to be approximately 200,000 years old.
Conclusions:
- The study refutes the age assumptions of P. polionotus and its coastal populations.
- Results contradict the "Recurrent Invasion" model.
- The findings support an alternative "Shore-line Tracking" hypothesis, offering a simpler explanation for observed variation.
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