Extra-pair paternity and egg dumping in birds: life history, parental care and the risk of retaliation

Abstract

Molecular techniques have revealed striking variation among bird species in the rates of extra-pair paternity (EPP) and intraspeci c brood parasitism (IBP). In terms of the proportion of broods affected, rates of EPP and IBP vary across species from 0-95% and 0-50%, respectively. Despite a plethora of hypotheses and several careful comparative analyses, few robust correlates of this interspeci c variation have been identi ed. One explanation for this shortfall is that most comparative studies have tended to focus on contemporary ecological factors and ignored fundamental differences in reproductive biology that evolved millions of years ago. We show that, for both EPP and IBP, over 50% of interspeci c variation is due to differences among taxonomic families and orders. Therefore, we test hypotheses that predict interspeci c variation in the rate of alternative reproductive strategies should be associated with differences in life history and the form of parental care. Our analyses largely support these predictions, with high rates of reproductive cheating being associated with 'fast' life histories. High EPP rates are associated with high rates of adult mortality and reduced paternal care. High IBP rates are associated with high-fecundity rates. These patterns remain intact whether we use species as independent data points or evolutionary contrasts based on either molecular or morphological phylogenies. These results are interpreted as supporting the idea that alternative reproductive strategies are most common in taxa in which the risks of retaliation are low. We suggest a hierarchical explanation for interspeci c variation in the incidence of alternative reproductive strategies. Variation between major avian lineages in the EPP and IBP rates are determined by fundamental differences in life history and parental care that evolved many millions of years ago. Variation between populations or individuals of the same species, however, are more likely to be determined by differences in contemporary ecological and genetic factors.

Correlates of genetic monogamy in socially monogamous mammals: insights from Azara's owl monkeys

“…Among birds, EPP rates were associated with low adult mortality and low levels of male care, even when as much as 50% of interspecific variation was due to differences among taxonomic families or orders [31]. Many other factors have also been related to EPP and EGP rates in birds [32].…”

Sexual Conflict Arising from Extrapair Matings in Birds

“…As Arnold and Owens (2002) showed, about half of the variation in rates of EPP among bird species can be explained solely by the rates of adult mortality. Two factors might explain this pattern.…”

“…In extreme cases, the mismatch between the social and sexual mating systems is nothing short of spectacular; in fairywrens (Malurus species) that are socially monogamous, cooperatively breeding species with helpers, the extrapair paternity (EPP) rate can exceed 75% of all offspring and 95% of all broods (Mulder et al 1994). In socially monogamous birds, in general, the rate of EPP is typically on the order of 10% of offspring and 20% of broods (Griffith et al 2002), but variation among species, and even populations within species, is extensive (Arnold and Owens 2002;Griffith et al 2002). The occurrence of EPP has profound consequences for the evolution of social behavior, both because it alters the scope for the action of sexual selection (Webster et al 1995;Sheldon and Ellegren 1999) and because it results in males often providing parental care to offspring they have not sired (Davies et al 1992;Westneat and Sherman 1993).…”

Evolution of Paternal Investment

“…As noted, variability in male provisioning is related to the likelihood of paternity (Arnold & Owens, 2002;Møller, 2000). For many species, female cuckoldry of their social partner involves trade-offs between the risk of losing his investment versus gaining better genes and thus healthier offspring from another male (Møller & Tegelström, 1997).…”

“…The study of the attendant cost-benefit trade-offs is complicated by the evolutionary history of the species, as well as by whether paternal investment is obligate or facultatively expressed (Arnold & Owens, 2002;Clutton-Brock, 1991;Fishman, Stone, & Lotem, 2003). Obligate investment means that male care is necessary for the survival of his offspring.…”