Mate choice & plumage polymorphism in the feral pigeon (Columba livia) - Essay Example

Assortative mating is a process where two similar or dissimilar individuals mate where as Disassortative mating involves choosing of a partner for progeny benefits from the range of the parental genotypes. Aim of this paper is to evaluate the association of plumage polymorphism and mate choice in feral pigeons using Chi-square test. In particular, this paper analyzes the plumage colour preference as either dependent or independent in the mating process of the male and female feral pigeons. If the pigeons choose their partner in harmony with plumage colour then it is defined as dependent pairing and if they choose their partner without considering colour then it is independent pairing with respect to plumage colours.

The purpose of the study is to understand feral pigeon’s plumage based mating increases the reproductive output and extend their lifespan which are also based on environmental conditions. The colour categories used for this study are melanic, blue-grey and other colours including pale/brown pigeons. “The other colours noted in feral pigeons are faded, pale, reduced, opal, indigo, milky, pearl eye and more.” (Miller 1997). The research on feral pigeons plumage based mating is carried as described in academic handbook using Chi-square test of independence.

Chi-square test of independence tests the association between two definite variables. Colour of males’ plumage and colours of females’ plumage are the variables used in this test. The result (χ2) is then looked up on a Chi-square (χ2) table with a number of degrees of freedom (df). “We determine df for the Test of Independence by the formula df = (r-1)(c-1), where r = the number of rows and c = the number of columns.” (Yount 2006, p.6). “Chi-squared distribution table.” (The chi-squared distribution table, n.d.).

‘Expected Value’ Calculation: Using the ratios (relative frequencies) of three colour morphs in observed population, the expected values