Studies in the field of behavioral and reproductive biology have proved that courtship is of great importance in the population of guppy (Poecilia reticulate). In this courtship male guppies are known to attract females by displaying their body. Females are known to attract to males with large body contour, much colorful fins and with greater courtship display. In the time of courtship, male guppy expands its fins and repeatedly moves its body from back of head to tail end in a ‘S’-shaped posture.
This posture is called ‘Sigmoid display’.
This colorful display helps them to attract females that lead to copulation and ultimately to forma a new generation. So, guppies are much colorful though this coloration attracts predators (Evans et al. 2001). What do you think is responsible for the variation in color from one generation to the next? Variation in color from one generation to the next in guppy population depends upon the probable crossing between the available parents. Availability of parent depends on the predator pattern in their habitat.
Some predator prefers colorful prey and some avoids them.
So, the second case will develop a guppy population with more colorful males. But in the second case, a population will be formed devoid of colorful males. So, natural selection as well as predation pattern is responsible for the variation in color of male guppies from one generation to the next. Select a hypothesis from the Sex and the Single Guppy Web activity or come up with your own and record it here. None of the hypothesis stated in the site regarding the cause behind guppy coloration is solely acceptable.
In my view, natural selection of parents, predation pattern and habitat environment are the controlling factors for the pattern of coloration of guppy population. Habitat environment determines what type of predator should be available, predator types determines the prey type (predators may prefer colorful guppy or they can avoid them). This chain will determine the coloration status of a generation. Ultimately two parents are selected by natural selection. Thus a new generation is formed.