In socially monogamous species, male reproductive success consists of ‘within-pair’ offspring produced with their socially-paired mate(s), and ‘extra-pair’ offspring produced with additional females throughout the population. Both reproductive pathways offer distinct opportunities for selection in wild populations, as each is composed of separate components of mate attraction, female fecundity, and paternity allocation. Identifying key sources of variance and covariance among these components is a crucial step towards understanding the reproductive strategies that males use to maximize fitness both annually and over their lifetimes. We use 16 years of complete reproductive data from a population of black-throated blue warblers (Setophaga caerulescens) to partition variance in male annual and lifetime reproductive success, and thereby identify if the opportunity for selection varies over the lifetimes of individual males and what reproductive strategies likely favor maximum lifetime fitness. The majority of variance in male reproduction was attributable to within-pair success, but the specific effects of individual components of variance differed between total annual and total lifetime reproductive success. Positive overall lifetime covariance between within-pair and extra-pair components indicates that males able to maximize within-pair success, particularly with double-brooding females, likely achieve higher overall lifetime fitness via both within-pair and extra-pair reproductive pathways.

Data for 'Variance in within-pair reproductive success influences the opportunity for selection annually and over the lifetimes of males in a multi-brooded songbird'
Germain, Hallworth, Kaiser, Sillett, Webster, Evolution 2021.

This file contains all male Black-throated blue warblers present in our study area at Hubbard Brook Experimental Forest from 1999-2015.

For each entry (male-year), the identity, number of broods, number of offspring per brood, and number of young sired by the focal male are listed for all social and extra-pair females. Where males have multiple socially-paired females, data for each social female is presented in a separate row.

Key to variables: