Life-history traits of comb jellies (Mnemiopsis) invaded to European waters start reproducing at a body mass 100 times less than in mother populations. This is consistent with predictions from a simple fitness optimization model
Species establishing outside their natural range, negatively impacting local ecosystems, are of increasing global concern. They often display life-history features characteristic for r-selected populations with fast growth and high reproduction rates to achieve positive population growth rates (r) in invaded habitats. The paper demonstrates substantially earlier maturation at a 2 orders of magnitude lower body mass at first reproduction in invasive compared to native populations of the comb jelly Mnemiopsis leidyi. Empirical results are corroborated by a theoretical model for competing life-history traits that predicts maturation at the smallest possible size to optimize r, while individual life-time reproductive success (R0), optimized in native populations, is near constant over a large range of intermediate maturation sizes. We suggest that high variability in reproductive tactics in native populations is an underappreciated determinant of invasiveness, acting as substrate upon which selection can act during the invasion process.
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Jaspers C, Marty L, Kiørboe t (2017) Selection for life-history traits to maximize population growth in an invasive marine species. Global Change Biol. In press. DOI: 10.1111/gcb.13955. Available online