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Profound Effects of Population Density on Fitness-Related Traits in an Invasive Freshwater Snail
Journal article   Open access   Peer reviewed

Profound Effects of Population Density on Fitness-Related Traits in an Invasive Freshwater Snail

Nicholas Zachar and Maurine Neiman
PloS one, Vol.8(11), pp.e80067-e80067
11/21/2013
DOI: 10.1371/journal.pone.0080067
PMCID: PMC3836992
PMID: 24278240
url
https://doi.org/10.1371/journal.pone.0080067View
Published (Version of record) Open Access

Abstract

Population density can profoundly influence fitness-related traits and population dynamics, and density dependence plays a key role in many prominent ecological and evolutionary hypotheses. Here, we evaluated how individual-level changes in population density affect growth rate and embryo production early in reproductive maturity in two different asexual lineages of Potamopyrgus antipodarum , a New Zealand freshwater snail that is an important model system for ecotoxicology and the evolution of sexual reproduction as well as a potentially destructive worldwide invader. We showed that population density had a major influence on individual growth rate and early-maturity embryo production, effects that were often apparent even when comparing treatments that differed in population density by only one individual. While individual growth rate generally decreased as population density increased, we detected a hump-shaped relationship between embryo production and density, with females from intermediate-density treatments producing the most embryos and females from low- and high-density treatments producing the fewest embryos. The two lineages responded similarly to the treatments, indicating that these effects of population density might apply more broadly across P. antipodarum . These results indicate that there are profound and complex relationships between population density, growth rate, and early-maturity embryo production in at least two lineages of this important model system, with potential implications for the study of invasive populations, research on the maintenance of sex, and approaches used in ecotoxicology.

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