Bayesian species delimitation reveals generalist and specialist parasitic wasps on Galerucella beetles (Chrysomelidae): sorting by herbivore or plant host

Abstract

BackgroundTo understand the ecological and evolutionary consequences of species interactions in food webs necessitates that interactions are properly identified. Genetic analyses suggest that many supposedly generalist parasitoid species should rather be defined as multiple species with a more narrow diet, reducing the probability that such species may mediate indirect interactions such as apparent competition among hosts. Recent studies showed that the parasitoid Asecodes lucens mediate apparent competition between two hosts, Galerucella tenella and G. calmariensis, affecting both interaction strengths and evolutionary feedbacks. The same parasitoid was also recorded from other species in the genus Galerucella, suggesting that similar indirect effects may also occur for other species pairs.MethodsTo explore the possibility of such interactions, we sequenced mitochondrial and nuclear genetic markers to resolve the phylogeny of both host and parasitoid and to test the number of parasitoid species involved. We thus collected 139 Galerucella larvae from 8 host plant species and sequenced 31 adult beetle and 108 parasitoid individuals.ResultsThe analysis of the Galerucella data, that also included sequences from previous studies, verified the five species previously documented as reciprocally monophyletic, but the Bayesian species delimitation for A. lucens suggested 3–4 cryptic taxa with a more specialised host use than previously suggested. The gene data analyzed under the multispecies coalescent model allowed us to reconstruct the species tree phylogeny for both host and parasitoid and we found a fully congruent coevolutionary pattern suggesting that parasitoid speciation followed upon host speciation.ConclusionUsing multilocus sequence data in a Bayesian species delimitation analysis we propose that hymenopteran parasitoids of the genus Asecodes that infest Galerucella larvae constitute at least three species with narrow diet breath. The evolution of parasitoid Asecodes and host Galerucella show a fully congruent coevolutionary pattern. This finding strengthens the hypothesis that the parasitoid in host search uses cues of the host rather than more general cues of both host and plant.

Differences in Cellular Immune Competence Explain Parasitoid Resistance for Two Coleopteran Species

“…parviclava derived from G. calmariensis were used, which might suggest that the parasitoids have adapted to this host species, thereby explaining the low parasitism success in G. pusilla . On the other hand, parasitoids hatching from G. pusilla do not seem to be genetically differentiated from parasitoids hatching from G. calmariensis [21]. Moreover, the parasitism experiments have later been repeated several times with parasitoids hatching from G. pusilla with the same general results (L. Fors et al, in prep).…”

Revision ofCognettia(Clitellata, Enchytraeidae): re-establishment ofChamaedrilusand description of cryptic species in thesphagnetorumcomplex

“…Nevertheless, such cryptic lineages may differ in certain ecological and physiological properties (e.g. Hamb€ ack et al, 2013;Sattler et al, 2007;Sturmbauer et al, 1999), but this variation is likely to be ignored if the species taxonomy is not fully resolved (Feckler et al, 2013). The use of inadequate taxonomy makes it almost impossible to interpret and compare results involving such species complexes, as it is not known if the same cryptic species has been investigated.…”

Species delimitation in northern European water scavenger beetles of the genus Hydrobius (Coleoptera, Hydrophilidae)

“…BPP is increasingly used to delimit species (e.g. Bochkov et al 2014; De Crop et al 2014; Derkarabetian and Hedin 2014; Guillin et al 2014; Hamback et al 2013), but as of to date few studies have used the guide tree-free BPP v3.0 on empirical data.…”