Chapter Summary

• Behavioural ecology is concerned with how an animal's response to a particular stimulus or situation is influenced by its ecology and evolution. Molecular data have improved our understanding of numerous aspects of behaviour, including mating systems, sex ratio allocation and foraging behaviour.

• The basic types of animal mating systems are monogamy, polygamy (polyandry, polygyny and polygynandry), and promiscuity. These can be differentiated on the basis of whether or not social bonds are formed and, if so, how many males and females are included.

• Molecular data can identify extra-pair fertilizations (EPFs) through parentage analysis. Potential biological parents can be excluded if they are genetically incompatible with the offspring. If too few adults can be excluded to allow the identification of parents, a maximum likelihood analysis of genotypes can be used to assign the most likely biological parent.

• Molecular evidence for EPFs has shown that both sexes, whether monogamous or polygamous, will often copulate with partners with which they share no social bond. One outcome of this is that social monogamy seldom translates into genetic monogamy.

• Parentage analysis has revealed a lot of information about pre- and post-copulatory mate choice, and has provided support for both the good genes hypothesis and the genetic compatibility hypothesis.

• Kin selection can be a plausible explanation for social breeding if helpers are related to recipients. The relatedness between individuals can be estimated on the basis of within-individual and within-population allele frequencies.

• Sex-linked molecular markers tell us that various taxonomic groups, including birds, frogs and social insects, are able to adaptively manipulate the sex ratio of their offspring. In social insects this can lead to conflict between queens and workers because haplodiploidy results in relatedness asymmetries.

• Sex-biased dispersal is extremely widespread. In mammals, males are more likely to disperse than females, whereas the opposite is true in birds. This may be done to minimize local competition or to avoid inbreeding. Sex-biased dispersal can be inferred from relatedness values, assignment tests, comparisons of FST from both males and females, or comparisons of FST from uniparentally versus biparentally inherited markers.

• Foraging behaviour can be studied by genotyping prey remains from guts or faeces. If combined with individual-specific genotypes, this can provide detailed information on individual feeding preferences. Identifying prey can have practical applications in biological control programmes or conservation biology.

• Molecular data can also provide us with information on foraging patterns, e.g. they may tell us how far individuals travel and what routes they follow in their search for food and other resources.

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