Data for: Plastic maternal effects of social density on reproduction and fitness in the least killifish, Heterandria formosa

Environmental parental effects, also known as transgenerational
plasticity, are widespread in plants and animals. Less well known is
whether those effects contribute to maternal fitness in the same manner in
different populations. We carried out a multi-generational laboratory
experiment with females drawn from two populations of the Least Killifish,
Heterandria formosa, to assess transgenerational plasticity in
reproductive traits in response to differences in social density and its
effects on maternal fitness. In the first and second generations,
increased density decreased reproductive rate and increased offspring size
in females from both populations. There were complicated patterns of
transgenerational plasticity on maternal fitness that differed between
females from different populations. Females from a population with
historically low densities whose mothers experienced lower density had
higher fitness than females whose mothers experienced higher density,
regardless of their own density. The opposite pattern emerged in females
from the population with historically high densities: females whose
mothers experienced higher density had higher fitness than females whose
mothers experienced lower density. This transgenerational plasticity is
not anticipatory but might be considered adaptive in both populations if
providing those “silver spoons” enhances offspring fitness in all
environments.