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Big brains reduce extinction risk in Carnivora.
1Department of Biology, Stanford University, Stanford, USA. abelson@alumni.stanford.edu.
Oecologia
|October 26, 2019
Summary
Mammal extinction risk is linked to brain size. Species with lower relative encephalization (RE), a measure of brain size relative to body mass, faced higher extinction risks, especially smaller carnivorans.
Area of Science:
- Paleontology
- Evolutionary Biology
- Zoology
Background:
- Understanding mammalian extinction vulnerability requires novel approaches beyond traditional life history traits.
- Wildlife behavior offers a potentially unifying perspective on species persistence and extinction.
- The fossil record provides limited direct behavioral data, necessitating proxies like relative encephalization (RE).
Purpose of the Study:
- To investigate the role of relative encephalization (RE) and body size in carnivoran extinction risk over geologic time.
- To determine if brain size, as a proxy for behavior, influences extinction patterns in mammals.
- To explore interactions between RE and body size in predicting extinction vulnerability.
Main Methods:
- Analysis of the order Carnivora, focusing on 224 species from 40 to 0.012 million years ago.
- Utilizing relative encephalization (RE) as a proxy for behavior, calculated by controlling for body mass and phylogeny.
- Employing Cox proportional-hazards models to assess extinction risk based on RE and body size.
Main Results:
- Carnivoran species with reduced relative encephalization (RE) exhibited significantly higher risks of extinction.
- An interaction effect was observed: RE had the most substantial impact on extinction risk for smaller-bodied species.
- These findings highlight the importance of brain size in long-term mammalian survival.
Conclusions:
- Relative encephalization (RE) is a critical factor in understanding extinction dynamics within the order Carnivora over geological timescales.
- Behavioral proxies like RE can illuminate extinction patterns not evident from life history traits alone.
- Conservation strategies may benefit from considering cognitive traits alongside ecological and life history factors.
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