Host body size, not host population size, predicts genome-wide effective population size of parasites Doña Reguera, Jorge Johnson, Kevin P. Coevolution Heterozygosity Infrapopulation Lice Phthiraptera Funding was provided by US NSF DEB-1342604, DEB-1925487 and DEB-1926919 grant awards to K.P.J., and European Commission grant H2020-MSCA-IF-2019 (INTROSYM:886532) to JD. The effective population size (N-e) of an organism is expected to be generally proportional to the total number of individuals in a population. In parasites, we might expect the effective population size to be proportional to host population size and host body size, because both are expected to increase the number of parasite individuals. However, among other factors, parasite populations are sometimes so extremely subdivided that high levels of inbreeding may distort these predicted relationships. Here, we used whole-genome sequence data from dove parasites (71 feather louse species of the genus Columbicola) and phylogenetic comparative methods to study the relationship between parasite effective population size and host population size and body size. We found that parasite effective population size is largely explained by host body size but not host population size. These results suggest the potential local population size (infrapopulation or deme size) is more predictive of the long-term effective population size of parasites than is the total number of potential parasite infrapopulations (i.e., host individuals). 2023-07-14T11:59:17Z 2023-07-14T11:59:17Z 2023-06-05 journal article Jorge Doña , Kevin P Johnson, Host body size, not host population size, predicts genome-wide effective population size of parasites, Evolution Letters, 2023;, qrad026. [https://doi.org/10.1093/evlett/qrad026] https://hdl.handle.net/10481/83750 10.1093/evlett/qrad026 eng info:eu-repo/grantAgreement/EC/H2020/886532 http://creativecommons.org/licenses/by/4.0/ open access Atribución 4.0 Internacional Oxford University Press