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Evolution: sex and cannibalism in redback spiders.
1School of Biological Sciences, University of East Anglia, Norwich NR4 7TJ, UK. m.gage@uea.ac.uk
Current Biology : CB
|August 23, 2005
Summary
Female redback spiders evolved two sperm storage organs for paternity choice. Males counter-adapted with an abdominal mechanism to improve survival and insemination after cannibalism.
Area of Science:
- Evolutionary Biology
- Animal Behavior
- Reproductive Strategies
Background:
- Sexual cannibalism is observed in female redback spiders.
- This behavior influences mating dynamics and reproductive success.
Purpose of the Study:
- To investigate the evolutionary adaptations in female redback spiders related to sperm storage.
- To understand male counter-adaptations to maximize paternity in the context of sexual cannibalism.
Main Methods:
- Analysis of female reproductive anatomy, focusing on sperm storage organs.
- Observation and analysis of male mating behaviors and survival post-cannibalism attack.
- Examination of male anatomical adaptations, specifically the abdominal constricting mechanism.
Main Results:
- Female redback spiders possess two distinct sperm storage organs, enabling post-copulatory mate choice.
- Males have evolved an abdominal constricting mechanism that enhances their survival and mating success.
- This male adaptation increases the likelihood of inseminating both female sperm storage sites.
Conclusions:
- The study reveals a complex co-evolutionary arms race between male and female redback spiders.
- Female sperm storage organs facilitate paternity choice, while male adaptations ensure insemination and survival.
- These findings highlight the intricate evolutionary pressures shaping reproductive strategies in this species.