Sexual selection and the African lion's mane.

Author: West, Peyton McLean

Awarding University: University of Minnesota, USA

Level : PhD

Year: 2003

Holding Libraries: University Microfilms International ;

Subject Terms: Ecology/Tsavo National Park, Kenya/Lions/Hair/Diet/Global warming/ ;

Pages: 0

Advisors: Adviser: Packer, Craig

Abstract:

This thesis explores the role of sexual selection in the evolution of the African lion's mane and the general relationship between sexual selection and environmental factors. Using a combination of demographic, behavioral, photographic and serological records, playback and dummy experiments, and infrared thermography, I investigated the costs and benefits associated with the mane in the Serengeti National Park and Ngorongoro Crater, Tanzania and Tsavo East National Park, Kenya from 1996-2001. The mane does not appear to confer significant protection during fights. The mane area was not a specific target of attacks, and injuries to the mane area were not associated with higher mortality than other injuries. Within the mane area, regions that were most frequently attacked were not the regions associated with greater hair length and/or darkness in the manes of adult males. Mane characteristics were related to aspects of male condition and functioned as signals to conspecifics. Mane length decreased with serious injury, and mane darkness increased with age, foraging success and serum testosterone. Male lions were intimidated by long and dark manes, while females found darker manes more attractive and benefited from their preference through increased reproductive success. Infrared thermography demonstrated a relationship between temperature and mane characteristics. The surface temperatures of maned males were higher than those of females and darker-maned males were significantly hotter than those with lighter manes. Darker-maned males also suffered higher proportions of abnormal sperm and reduced food intake in hotter weather. The heat-related costs of the mane suggest that predicted increases in global temperature may have a significant impact on mane morphology. Males in hotter climates are often maneless, and average mane size and darkness across populations may begin to decline. Climate change may have far-reaching implications for sexual selection not only through direct temperature costs but also through indirect mechanisms such as nutrition. An exploration of the relationship between mineral nutrition and sexual selection suggests that many sexually-dimorphic traits are influenced by minerals, particularly calcium, phosphorus, copper and zinc, and suggests that the size and color of these morphological traits may also vary in response to global climate change.