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Abstract The effective population size (Ne) 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).
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ABSTRACT Mass extinctions change global ecosystems, and the end‐Triassic mass extinction was hypothesized to have precipitated the rise of dinosaur dominance, with dinosaurs filling resource zones of eliminated large‐bodied reptilian lineages. This replacement has been explicitly hypothesized for theropod dinosaurs, and the eastern North American theropod footprint record suggests an increase in maximum body size across the Triassic‐Jurassic boundary. Without taking ontogenetic stage in account, the maximum size of the rare large Triassic theropods worldwide supports this hypothesis, with the size of the largest individuals corresponding to the largest Triassic theropod tracks. However, both morphological data and histological examination suggest that known large‐bodied Triassic theropods are represented by immature individuals still growing rapidly at the time of death, indicating that the maximum body size of Triassic theropods was much larger than that a strict reading of the body fossil record would suggest. The size increase recorded in the sediments of eastern North America is not part of a global trend. Instead of a simple ecological replacement of non‐dinosaurian archosaurs by dinosaurs, the rise in theropod dinosaurian ecological dominance was an extended process across the end of the Late Triassic into the Jurassic. Anat Rec, 303:1158–1169, 2020. © 2019 Wiley Periodicals, Inc.