DOI: 10.5061/dryad.k8199
title: Data from: Demographic mechanisms of inbreeding adjustment through extra-pair reproduction

description: 1. One hypothesis explaining extra-pair reproduction is that socially
 monogamous females mate with extra-pair males to adjust the coefficient of
 inbreeding (f) of extra-pair offspring (EPO) relative to that of
 within-pair offspring (WPO) they would produce with their socially paired
 male. Such adjustment of offspring f requires non-random extra-pair
 reproduction with respect to relatedness, which is in turn often assumed
 to require some mechanism of explicit pre-copulatory or post-copulatory
 kin discrimination. 2. We propose three demographic processes that could
 potentially cause mean f to differ between individual females' EPO
 and WPO given random extra-pair reproduction with available males without
 necessarily requiring explicit kin discrimination. Specifically, such a
 difference could arise if social pairings formed non-randomly with respect
 to relatedness or persisted non-randomly with respect to relatedness, or
 if the distribution of relatedness between females and their sets of
 potential mates changed during the period through which social pairings
 persisted. 3. We used comprehensive pedigree and pairing data from
 free-living song sparrows (Melospiza melodia) to quantify these three
 processes and hence investigate how individual females could adjust mean
 offspring f through instantaneously random extra-pair reproduction. 4.
 Female song sparrows tended to form social pairings with unrelated or
 distantly related males slightly less frequently than expected given
 random pairing within the defined set of available males. Furthermore,
 social pairings between more closely related mates tended to be more
 likely to persist across years than social pairings between less closely
 related mates. However, these effects were small and the mean relatedness
 between females and their sets of potential extra-pair males did not
 change substantially across the years through which social pairings
 persisted. 5. Our framework and analyses illustrate how demographic and
 social structuring within populations might allow females to adjust mean f
 of offspring through random extra-pair reproduction without necessarily
 requiring explicit kin discrimination, implying that adjustment of
 offspring f might be an inevitable consequence of extra-pair reproduction.
 New theoretical and empirical studies are required to explore the general
 magnitude of such effects and quantify the degree to which they could
 facilitate or constrain long-term evolution of extra-pair reproduction.
description: PairsData_DryadThis file contains data required for the basic descriptive analysis of social pairing in relation to kinship.NewMalesPairings_DryadThis file contains data required for the analysis of social pairing in relation to kinship between females and the 'new males' set of potential mates.AllMalesPairings_DryadThis file contains data required for the analysis of social pairing in relation to kinship between females and the 'all males' set of potential mates.PairPersistence_DryadThis file contains data required for the analysis of social pair persistence in relation to kinship.ChangeMeanK_DryadThis file contains data required for the analysis of changing mean kinship within the duration of females' social pairings.