PMC

Filled circles represent first nests and open circles represent second nests. Elevated testosterone concentration did not predict cuckoldry rate. Cuckoldry rate was, however, negatively related to ventral plumage colour. A regression line is presented for the negative relationship between cuckoldry rate and ventral plumage colour.

Total difference between the heritability estimates using the genetic pedigree in comparison to the social pedigree. Titles illustrate EPP scenario: (A) EPM trait increases EPP, (B) social father trait decreases cuckoldry, (C) combination of i and ii, (D) difference between EPM and social father increases cuckoldry, and (E) difference between EPM and social father decreases cuckoldry, (see Methods for details). Vertical lines indicate standard error whereas mid‐point represents the mean. Difference is expressed as difference from input heritability and proportion difference (%) is shown in Figs. S1 and S2, respectively. The x‐axis shows the strength of the scenario (i.e., strength of relationship between the trait and EPP) which refers to β from equation . This is analogous to a linear standardized selection gradient for scenarios [i], [ii], and [iii] (Supporting Information).

The genealogical links between self and different categories of cousins. (a) A self and its mother's sister's (MoSis) children. (b) A self and its mother's brother's (MoBro) children. (c) A self and its father's sister's (FaSis) children. (d) A self and its father's brother's (FaBro) children. The dashed line indicates that within-pair paternity might be reduced due to cuckoldry.

Squares encompass females paired with either Mate Guarding (MG) or Parental Care (PC) males, with MG-paired females leaving the mating pool each time step. Females not in squares have paternity shared among Multiple Mating (MM) males. The dotted arrow represents some paternity given to MM males through cuckoldry.