Spatial turnover in host-plant availability drives host-associated divergence in a South African leafhopper (Cephalelus uncinatus)
Date
2017
Journal Title
Journal ISSN
Volume Title
Publisher
BioMed Central
Abstract
Background
The evolution of reproductive isolation between herbivorous insect populations is often initiated by shifts to novel host-plants, a process that underlies some of the best examples of ecological speciation. However, it is not well understood why host-shifts occur. Arguably the most common hypothesis is that host-shifts occur in response to competition, while a less frequently invoked hypothesis is that herbivores adapt locally to geographic differences in potential host-plant communities. Here we investigate whether geographic variation in host-plant availability is likely to have driven host-shifts in restio leafhoppers. We studied local adaptation of a camouflaged restio leafhopper species, Cephalelus uncinatus, to host-plants in the Restionaceae (restios); a family of plants with exceptional diversity in the anomalously species-rich Cape Floristic Region (CFR). To determine whether C. uncinatus experiences heterogeneous host communities across its range, we first quantified the degree of geographic overlap between C. uncinatus and each of its associated host-plant species. Then we quantified trait divergence (host preference, body size and colour) for three pairs of C. uncinatus populations found on different host-plant species differing in their degree of spatial overlap. Spectral reflectance was modelled in bird visual space to investigate whether body colour divergence in C. uncinatus corresponds to leaf sheath colour differences between restio species as perceived by potential predators.
Results
We demonstrate that C. uncinatus is forced to use different restio species in different regions because of turnover in available host species across its range. Comparisons between geographically separated populations were consistent with local adaptation: restio leafhoppers had preferences for local host-plants over alternative host-plants and matched local plants better in terms of size and colour.
Conclusions
Spatial turnover in host-plant availability has likely facilitated host-shifts in C. uncinatus. Spatial turnover in host-plant availability may be an important driver of insect diversification in the CFR and globally.
Description
CITATION: Augustyn, W. J., et al. 2017. Spatial turnover in host-plant availability drives host-associated divergence in a South African leafhopper (Cephalelus uncinatus), BMC Evolutionary Biology, 17:72, doi:10.1186/s12862-017-0916-0.
The original publication is available at http://bmcevolbiol.biomedcentral.com
The original publication is available at http://bmcevolbiol.biomedcentral.com
Keywords
Beta diversity, Restionaceae (restios) -- Cape Floristic Region, Leafhopper Cephalelus uncinatus -- Cape Floristic Region, Ecological divergence, Phytophagous insects
Citation
Augustyn, W. J., et al. 2017. Spatial turnover in host-plant availability drives host-associated divergence in a South African leafhopper (Cephalelus uncinatus), BMC Evolutionary Biology, 17:72, doi:10.1186/s12862-017-0916-0