Observational evidence that maladaptive gene flow reduces patch occupancy in a wild insect metapopulation.
Theory predicts that dispersal throughout metapopulations has a variety of consequences for the abundance and distribution of species. Immigration is predicted to increase abundance and habitat patch occupancy, but gene flow can have both positive and negative demographic consequences. Here, we address the eco-evolutionary effects of dispersal in a wild metapopulation of the stick insect Timema cristinae, which exhibits variable degrees of local adaptation throughout a heterogeneous habitat patch network of two host-plant species. To disentangle the ecological and evolutionary contributions of dispersal to habitat patch occupancy and abundance, we contrasted the effects of connectivity to populations inhabiting conspecific host plants and those inhabiting the alternate host plant. Both types of connectivity should increase patch occupancy and abundance through increased immigration and sharing of beneficial alleles through gene flow. However, connectivity to populations inhabiting the alternate host-plant species may uniquely cause maladaptive gene flow that counters the positive demographic effects of immigration. Supporting these predictions, we find the relationship between patch occupancy and alternate-host connectivity to be significantly smaller in slope than the relationship between patch occupancy and conspecific-host connectivity. Our findings illustrate the ecological and evolutionary roles of dispersal in driving the distribution and abundance of species.
Animal and Plant Sciences, University of Sheffield, Sheffield, S10 2TN, United Kingdom.|Ecology and Evolutionary Biology, University of Connecticut, Storrs, Connecticut, 06269.
Timothy E
TE
Farkas
Metapopulation Research Centre, Biosciences, University of Helsinki, Helsinki, 00014, Finland.|Neuroscience and Biomedical Engineering, Aalto University, Aalto, FI-00076, Finland.
Tommi
T
Mononen
Animal and Plant Sciences, University of Sheffield, Sheffield, S10 2TN, United Kingdom.|Department of Biology, University of North Carolina, Durham, North Carolina, 27599.
Aaron A
AA
Comeault
Animal and Plant Sciences, University of Sheffield, Sheffield, S10 2TN, United Kingdom.
Patrik
P
Nosil
D063147:Animal Distribution; D000818:Animals; D002140:California; D017753:Ecosystem; D051456:Gene Flow; D007313:Insecta / Q000235:genetics / Q000502:physiology*; D011157:Population Dynamics
Connectivity; eco-evolutionary dynamics; extinction; gene flow; maladaptation; metapopulation