An Evolutionary Arms Race: Speed and Hunting in The African Savannah

By Maryna Mullerman ’20

running_cheetah.jpg

Figure 1. Researchers analyzed various performance characteristics of savannah predator-prey pairs.

Prey must run faster than predators to avoid getting killed, while predators must overwhelm prey to avoid starving. There have been numerous studies published on predator-prey relationships, but little research has analyzed high-speed savannah animal locomotion. Alan M. Wilson and researchers from the Royal Veterinary College at the University of London aimed to analyze the locomotor characteristics in two predator-prey pairs: the lion-zebra pair and the cheetah-impala pair. The researchers hypothesized that predators had to be more athletic to follow the unpredictable movements of their prey.

The animals were found in Botswana, Southern Africa with a nonpredetermined sample size. All animals were sedated adult species consisting of nine lions, five cheetahs, seven zebras, and seven impalas. Front and hind leg and body lengths were measured, and biopsies were taken from biceps femoris muscles. Muscle power was very temperature-dependent, so fibers were activated using temperature changes. Fiber power was measured by exposing samples to four different force-control events. Performance classifications such as maximum muscle power output, animal acceleration and deceleration, turning ability, and stride frequency of prey were compared to those of their predators. Global Positioning System/Inertial Navigation System (GPS-INS) processing was used to track live animal activity, position, and velocity for navigational equations.

The model produced possible position profiles for predators and prey in the two-stride chase. The initial hypothesis was supported by fiber analysis, revealing that predators had 20% higher muscle fiber power, 37% greater acceleration, and 72% greater deceleration capacity than their prey. For velocity and stress at peak power, no significant differences were found. Researchers concluded that lower-power muscle fibers found in prey species were more economical and advantageous for their survival, while high prey speed resulted in high capture probability. Slower-moving herbivores were able to make unpredictable turns and use more escape options.

The researchers supported their hypothesis and emphasized the importance of predator-prey relationships for the relative equilibrium of the ecosystem. The study could be improved by increasing sample size and analyzing more predator-prey pairs such as the leopard-gazelle pair. Further research can explore the other features in predator-prey relationships that contribute to coexistence.

 

References:

  1. A.Wilson, et. al, Biomechanics of predator – prey arms race in lion, zebra, cheetah and impala. Nature 0, (2018). doi: 10.1038/nature25479.
  2. Image retrieved from: https://www.google.com/search?q=running+cheetah&safe=strict&rlz=1C1CHBF_enUS698US698&tbs=sur:fc,imgo:1,isz:l&tbm=isch&source=lnt&sa=X&ved=0ahUKEwiSg5OH1ZHZAhXNmVkKHdjEBuIQpwUIIA&biw=1707&bih=844&dpr=1.13#imgrc=r3g7vkPK1N0C0M
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