You’ve got to hand it to the geeks and nerdlings over at ScienceDaily.com!
Yesterday’s headline really caught my eye.
Survival of the Prettiest: Sexual Selection Can Be Inferred from the Fossil Record
The article begins, “Detecting sexual selection in the fossil record is not impossible, according to scientists writing in Trends in Ecology and Evolutionthis month, co-authored by Dr Darren Naish of the University of Southampton.”
The term “sexual selection” refers to the evolutionary pressures that relate to a species’ ability to repel rivals, meet mates and pass on genes. We can observe these processes happening in living animals but how do paleontologists know that sexual selection operated in fossil ones?
(Sexual dimorphism in the pterosaur Darwinopterus [Image by Mark Witton])
Historically, palaeontologists have thought it challenging, even impossible, to recognise sexual selection in extinct animals. Many fossil animals have elaborate crests, horns, frills and other structures that look like they were used in sexual display but it can be difficult to distinguish these structures from those that might play a role in feeding behaviour, escaping predators, controlling body temperature and so on.
However in their review, the scientists argue that clues in the fossil record can indeed be used to infer sexual selection.
“We see much evidence from the fossil record suggesting that sexual selection played a major role in the evolution of many extinct groups,” says Dr Naish, of the University’s Vertebrate Palaeontology Research Group.
“Using observations of modern animal behaviour we can draw analogies with extinct animals and infer how certain features improve success during courtship and breeding.”
(Above image of sexual selection in dinosaurs may not be 100% accurate)
Modern examples of sexual selection, where species have evolved certain behaviours or ornamentation that repel rivals and attract members of the opposite sex, include the male peacock’s display of feathers, and the male moose’s antlers for use in clashes during mating season.
Whilst these features might have had multiple uses, the authors conclude that sexual selection should not be ruled out.
“Some scientists argue that many of the elaborate features on dinosaurs were not sexually selected at all,” adds Dr Naish, who is based at the National Oceanography Centre, Southampton.
“But as observations show that sexual selection is the most common process shaping evolutionary traits in modern animals, there is every reason to assume that things were exactly the same in the distant geological past.”
- Robert J. Knell, Darren Naish, Joseph L. Tomkins, David W.E. Hone. Sexual selection in prehistoric animals: detection and implications. Trends in Ecology & Evolution, 2013; 28 (1): 38 DOI: 10.1016/j.tree.2012.07.015
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