Many organisms, including plants in the Asteraceae family, have dimorphic dispersal modes that enable some offspring to disperse while other offspring are retained in the maternal environment. In heterogeneous environments, maternal individuals may gain a fitness advantage if the proportion of their offspring that disperse varies with environmental context. Using a simple metapopulation matrix model framework to describe two habitat types that differ in suitability, we calculate metapopulation growth rates given a range of variable and fixed dispersal strategies. Our model is parameterized with life-history data from populations of musk thistle, Carduus nutans.
Results/Conclusions
Assuming equal proportions of suitable and unsuitable habitat, and no penalty for dispersal, variable dispersal strategies generally perform better than fixed strategies, and the gain increases as the suitability of the poorer habitat decreases. Further, we discuss field studies of context-dependent dimorphic dispersal, and the implications for the spread of invasive species in heterogeneous environments.
