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DIVERGENCE IN MORPHOLOGY AND MATING SIGNALS, AND ASSORTATIVE MATING AMONG POPULATIONS OF CHORTHIPPUS PARALLELUS
J R Dagley1, R K Butlin1, G M Hewitt1
1School of Biological Sciences, University of East Anglia, Norwich, NR4 7TJ, United Kingdom.
Summary
Divergence in acoustic signals and morphology between grasshopper populations led to significant assortative mating. This rapid premating isolation suggests strong selection, even without close relatives influencing the process.
Area of Science:
- Evolutionary biology
- Speciation research
- Animal behavior
Background:
- Geographically separated populations can evolve reproductive isolation.
- Acoustic signals are crucial for mate recognition in many species.
- Morphological differences can correlate with behavioral divergence.
Purpose of the Study:
- To investigate premating isolation in grasshopper populations.
- To assess the roles of acoustic signals and morphology in reproductive isolation.
- To examine the speed and potential drivers of divergence.
Main Methods:
- Studied three geographically distinct populations of Chorthippus parallelus.
- Analyzed morphological traits, including those related to sound production.
- Measured acoustic sexual signals of males, focusing on four parameters.
- Conducted multiple-choice tests to assess assortative mating.
Main Results:
- Significant assortative mating observed between two of three population pairs.
- Divergence in three of four acoustic signal parameters noted.
- Morphological differences, including signal-related characters, were found.
- Rapid divergence suggests strong selective pressures.
Conclusions:
- Acoustic and morphological divergence contribute to premating isolation in Chorthippus parallelus.
- Observed isolation evolved rapidly, likely driven by selection.
- Selection is unlikely to be due to interactions with closely related species.
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