Article

Molecular and chemical characters to evaluate species status of two cuckoo bumblebees: Bombus barbutellus and Bombus maxillosus (Hymenoptera, Apidae, Bombini)

Systematic Entomology (Impact Factor: 2.55). 07/2011; DOI: 10.1111/j.1365-3113.2011.00576.x

ABSTRACT Many methods, based on morphological, molecular or chemical characters, have been used to address the question of species taxonomic status. Integrative taxonomy aims to define stronger supported taxonomic hypotheses by considering complementary datasets from different characters. By following an integrative approach, the present study includes molecular, chemical and morphological criteria to establish the taxonomic status of two rare and doubtful cuckoo bumblebee taxa: Bombus (Psithyrus) barbutellus and Bombus (Psithyrus) maxillosus. These two sympatric taxa are discriminated by few morphological criteria (mainly wing darkness and hair length). We used these morphological character diagnoses to establish an a priori status of our samples (23 specimens). We developed a combined molecular dataset from one nuclear gene, elongation factor 1α (EF-1α), and one mitochondrial gene, cytochrome c oxidase subunit I (COI ), spanning 1623 bp, and a chemical dataset of sexual marking pheromones (73 compounds). The molecular data were subjected to maximum-likelihood and Bayesian phylogenetic inference under partitioned model and maximum parsimony. The chemical data were analysed by clustering and the two-group k-means method to test divergences between the two species. The resulting phylogenetic trees show no consistent divergence between the two taxa. Moreover, we found no divergence in the sexual marking pheromones in the clustering and two-group k-means analyses. These converging results support the conspecificity of both taxa. Nonetheless, our determinations using the traditional morphological criteria separated our samples into two taxa. We conclude that the morphological criteria seem to relate to intraspecific variations: B. maxillosus is regarded as a syn.n. of B. barbutellus.

Download full-text

Full-text

Available from: Patrick Lhomme, Jul 15, 2015
1 Follower
 · 
235 Views
  • Source
    • "Corsican B. pascuorum is considered as similar to its continental parents according to a lack of divergence (Table 2). These results agree with most of previous studies (see Rasmont & Adamski, 1996; Lecocq et al. 2011, 2013b). "
    [Show abstract] [Hide abstract]
    ABSTRACT: Many islands are biodiversity hotspots that host numerous endemic species. Unfortunately, insular faunas suffer from high rates of extinction and endangerment, and numerous conservation plans have been developed for their protection. These conservation plans are often assessed on the basis of occurrence and proportion of endemic taxa. However, delimitations of species and subspecies are still confusing and controversial. From a practical point of view, these disagreements make it difficult for government agencies and non-governmental organizations to initiate conservation measures. The present study develops a pragmatic integrative taxonomic approach on the basis of molecular and eco-chemical criteria. This method is applied to the insular bumblebee fauna of Corsica. For each taxon, the differentiation of Corsican taxa from the nearest related allopatric parents is characterized using genetic markers and the chemical composition of cephalic labial gland secretions. Phylogenetic analyses, Bayesian implementation of the general mixed Yule-coalescent approach, and comparative chemical studies show that two Corsican taxa can be considered as endemic species while five others can be considered as subspecies. Regardless of the taxonomic assessment the method facilitates diagnosis of evolutionarily significant units and rank taxa according to their distinctiveness. International Union for Conservation of Nature red lists are reconsidered according to the new taxonomic hypothesis for Corsican bumblebees. Modifications in species assessments are proposed. The present approach provides useful data sets for policy-makers and conservation organizations.
    Animal Conservation 06/2015; 18(3):236–248. DOI:10.1111/acv.12164 · 2.52 Impact Factor
  • Source
    • "Few recent studies have used a multisource approach to gather different lines of evidence of speciation in order to draw strongly supported taxonomic hypotheses for bumblebees (e.g. Bertsch et al. 2005; Lecocq et al. 2011). This type of approach combines taxonomic tools from different areas, such as geometric morphometric, genetics and chemistry to obtain to a more informed consensus. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Delimitation of closely related species is often hindered by the lack of discrete diagnostic morphological characters. This is exemplified in bumblebees (genus Bombus). There have been many attempts to clarify bumblebee taxonomy by using alternative features to discrete morphological characters such as wing shape, DNA, or eco-chemical traits. Nevertheless each approach has its own limitations. Recent studies have used a multisource approach to gather different lines of speciation evidence in order to draw a strongly supported taxonomic hypothesis in bumblebees. Yet, the resulting taxonomic status is not independent of selected evidence and of consensus methodology (i.e. unanimous procedure, majority, different weighting of evidence). In this paper, we compare taxonomic conclusions for a group of taxonomically doubtful species (the B. lapidarius-group) obtained from the four commonly used lines of evidence for species delimitation in bumblebees (geometric morphometric of wing shape, genetic differentiation assessment, sequence-based species delimitation methods, and differentiation of cephalic labial gland secretions). We ultimately aim to assess the usefulness of these lines of evidence as components of an integrative decision framework to delimit bumblebee species. Our results show that analyses based on wing shape do not delineate any obvious cluster. In contrast, nuclear/mitochondrial, sequence-based species delimitation methods, and analyses based on cephalic labial gland secretions are congruent with each other. This allows setting up an integrative decision framework to establish strongly supported species and subspecies status within bumblebees.
    Zoologica Scripta 02/2015; 44:281-297. DOI:10.1111/zsc.12107 · 2.92 Impact Factor
  • Source
    • "Therefore, the present more feasible bioassays should be extended to all taxa included in B. terrestris and coupled with other eviden ce (i.e. integrative taxonomy; Lecocq et al. 2011; 2014) and possibly other reproductive traits to conclude to pre-mating isolation. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Many species display local variations in pre-mating signals and in mating preferences. This may lead to discrimination against potential foreign mates that may ultimately lead to reproductive isolation. However, the extent to which population differentiation in mating cues affects the species recognition has received little empirical support. Here we investigate the consequence of geographic differentiation in male reproductive traits on female preferences to these traits in Bombus terrestris. We characterise (1) the geographic differentiation in male cephalic labial gland secretions (CLGS), a key trait for mate attraction and (2) the preference of virgin females to the CLGS of different subspecies. Our results show geographic CLGS differences parallel with divergences in female preferences for these secretions. This geographic CLGS differentiation in males, along with female preference for sympatric males could lead to or reflect a premating isolation among subspecies.
    Apidologie 02/2015; early view. DOI:10.1007/s13592-015-0349-y · 1.54 Impact Factor
Show more