Cotton, S., Fowler, K., and Pomiankowski, A. 2004. Do sexual ornaments demonstrate heightened condition-dependent expression as predicted by the handicap hypothesis? Proceedings: The Royal Society 271:771-783. Doi: 10.1098/rspb.2004.2688
The authors of this review made a compilation of 65 experiments carried out by other scientists and analyzed each of their methods to determine if their results are viable. Ultimately, many of these results claimed that sexual ornaments are condition-dependent; however, there were few well-designed experiments. They say there are three aspects that must be included in the experimental procedure of future studies focusing on the condition-dependence of male sexual ornaments. These include making a comparison of the traits (comparing sexual vs non-sexual traits), controlling for the effect of body size, and experimentally manipulating the condition to suite what would be encountered in the natural environment (not only having two extremes). This review is very applicable to any individual formulating an experiment proposal; it highlights which aspects of the procedure are often overlooked, and those that can create doubt in the results if not manipulated properly.
Cotton, S., Small, J., and Pomiankowski, A. 2006. Sexual selection and condition-dependent mate preferences. Current Biology 16:R755-R765. Doi 10.1016/j.cub.2006.08.022
There is a current hypothesis that female mate preference is condition-dependent; this review provides multiple examples of situations in which this hypothesis is supported. It also proposes that high quality females show the strongest mate preferences. This is thought to be because higher quality females have more to gain from being choosy, and are better able to pay the costs of discrimination. One test suggested in this review that is worth looking into is to determine if there is a positive relationship between female preference and total female fitness.
Hall, J. C. 1994. The mating of a fly. Science 264(5166):1702-1714
The varying kinds of pleiotropic mutations that can occur in courtship genes are investigated in detail in this paper; they can play a role in sensory, learning, and rhythm mutations resulting in defective courtship. Gynandromorph flies, which are chromosomally both female and male, can be turned into all-male flies by making them homozygous for the transformer (tra) mutation. The sex of these gynandromorphs can be manipulated by rearing conditions; XX flies with the tra-2 gene can be reared as a female at low temperatures, but heating the flies at a later life stage can turn off the gene. This is informative because this study makes it clear that these flies can easily be manipulated by their environment.
Hingle, A. Fowler, K., and Pomiankowski, A. 2001. The effect of transient food stress on female mate preference in the stalk-eyed fly Crytodiopsis dalmanni. Proceedings: The Royal Society. Doi: 10.1098/rspb.2001.1647
It is likely that condition is linked to fecundity and body size, which is why it’s not much of a leap to suggest that mate choice may be subject to condition dependence. Stalk-eyed flies were placed under nutritional stress (fed a sucrose diet), which has been shown to reduce egg laying in Drosophila melanogaster. Female stalk-eyed flies that were fed corn (their normal food) showed a preference for large-eyespan males while sucrose-fed females showed a much weaker preference for large-eyespan males. Providing the sucrose-fed females with normal food can reverse the effect of a sucrose diet on female preference. It didn’t matter whether females were fed sucrose then corn, or corn then sucrose, when the females were on the sucrose diet, there was a decrease in their preference. Also, females on a sucrose diet tended to have fewer mature and developing eggs; this is also reversible.
Jennions, M. D., Backwell, P., and Passmore, N. I. 1995. Repeatability of mate choice: the effect of size in the African painted reed frog, Hyperolius marmoratus. Animal Behaviour 49:181-186
This article highlights the fact that differences in between-population female preferences exist; however, little is known about within-population variation. The purpose of this study was to determine repeatability of mate choice in female reed frogs. One of their more interesting discoveries was a correlation between the female preference and body size. They suspect that body size can affect the females’ ability to distinguish between calls of varying frequencies.
Ritchie, M. G. 2000. The inheritance of female preference functions in a mate recognition system. Proceedings: Biological Sciences 267(1441):327-332
This article examines the inheritance of male song and female preference functions in the bush cricket, as well as the role of mate recognition systems. A mate recognition system is made up of the signals and preferences unique to a species that are involved in communication and choice of sexual partners. A female preference function is determined by the frequency with which females chooses a specific trait. The female preference function did not match up with male song in this experiment, suggesting that the preference function could exert directional selection on the male bush crickets.
Ritchie, M. G., Saarikettu, M., Livingstone, S., and Hoikkala, A. 2001. Characterization of female preference functions for Drosophila montana courtship song and a test of the temperature coupling hypothesis. Evolution 55(4):721-727
The way in which environmental conditions affect the consistency of female preference functions is widely unstudied. In this paper, they examine whether ‘temperature coupling’ of male song and female preference occurs in Drosophila montana (ie – is coordination maintained between the male and female aspects of this communication system in a changing environment?). This experiment did not focus on the effects of rearing conditions – all flies were reared at 20°C. It was determined that there was no temperature coupling occurring in this mating system.
Rosvall, K. 2011. Intrasexual competition in females: evidence for sexual selection? Behavioural Ecology. Doi: 10.1093/beheco/arr106
There is currently a debate over whether traits that influence female-female competition are sexually selected. Several hypotheses are presented in this review as to why female-female competition exists and whether it was adaptive or not. Various reasons for the existence of intrasexual competition are laid out and determined to either be sexually selected or a result of natural selection.
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