Data for: Multi-generational fitness effects of natural immigration indicate strong heterosis and epistatic breakdown in a wild bird population

The fitness of immigrants and their descendants produced within recipient populations fundamentally underpins the genetic and population dynamic consequences of immigration. Immigrants can in principle induce contrasting genetic effects on fitness across generations, reflecting multi-faceted additive, dominance, and epistatic effects. Yet, full multi-generational and sex-specific fitness effects of regular immigration have not been quantified within naturally structured systems, precluding inference on underlying genetic architectures and population outcomes. We used four decades of song sparrow (Melospiza melodia) life-history and pedigree data to quantify fitness of natural immigrants, natives, and their F1, F2, and backcross descendants, and test for evidence of non-additive genetic effects. Values of key fitness components (including adult lifetime reproductive success and zygote survival) of F1 offspring of immigrant-native matings substantially exceeded their parent mean, indicati..., These data come from the long-term song sparrow field study on Mandarte Island, BC, Canada (latitude 48.6329°, longitude -123.2859°). The data provided here are sufficient to replicate the analyses presented in the above paper, and are therefore a restricted subset of the full Mandarte dataset., , # Data for: Multi-generational fitness effects of natural immigration indicate strong heterosis and epistatic breakdown in a wild bird population

This file is associated with the manuscript \"Multi-generational fitness effects of natural immigration indicate strong heterosis and epistatic breakdown in a wild bird population\" (Submitted to American Naturalist in March, 2023)

Authors: Lisa Dickel, Peter Arcese, Lukas F. Keller, Pirmin Nietlisbach, Debora Goedert, Henrik Jensen, Jane M. Reid

Study population: Song sparrow (Melospiza melodia) of XOX DEL (English name Mandarte island), British Columbia, Canada, (latitude 48.6329, longitude 123.2859, 0.06 km)

All code was written by Lisa Dickel and Jane M. Reid

Data collection was planned and overseen by P. Arcese, and P. Nietlisbach, L. F. Keller and J. M. Reid contributed to fieldwork.

## Study summary

Data used come from a long-term study of song sparrows on Mandarte Island.

In these analyses we tested for fitness differences in dif...