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Smaller beetles are better scramble competitors at cooler temperatures
Jordi Moya-Laraño1, Maysaa El Tigani El-Sayyid, Charles W Fox
1Department of Entomology, University of Kentucky, S-225 Agricultural Science Building-North, Lexington, KY 40546-0091, USA. jordi@eeza.csic.es
Biology Letters
|July 20, 2007
Summary
Small male seed beetles gain a mating advantage over larger males due to quicker takeoff, especially in cooler temperatures. This temperature-dependent advantage highlights how environmental conditions influence the evolution of body size.
Area of Science:
- Evolutionary biology
- Ecological processes
- Animal behavior
Background:
- Temperature is a critical factor influencing organic evolution and ecological dynamics.
- The impact of temperature on selection pressures related to body size remains largely unexplored.
Purpose of the Study:
- To investigate if smaller seed beetles (Stator limbatus) possess an advantage over larger ones in scramble competition for mates.
- To determine if this size-related advantage is modulated by ambient temperature.
Main Methods:
- Artificial selection was used to create lines of beetles with selected large versus small body sizes.
- Scramble competition experiments were conducted to assess mating success.
- The influence of varying temperatures on male mating advantage was analyzed.
Main Results:
- In both large and small beetle lines, smaller males demonstrated a significant advantage in scramble competition.
- This advantage is attributed to the faster takeoff speed of smaller males, enabling them to reach females first.
- The intensity of selection favoring smaller male body size was substantially greater at cooler temperatures.
Conclusions:
- Male body size advantage in Stator limbatus scramble competition is temperature-dependent.
- Environmental temperature plays a crucial role in shaping the adaptive significance of body size evolution.
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