Molecular evidence using enzyme and RAPD markers for sympatric evolution in British species of Tetramesa (Hymenoptera: Eurytomidae)

Biological Journal of the Linnean Society (Impact Factor: 2.41). 11/2004; 83(4):509 - 525. DOI:10.1111/j.1095-8312.2004.00408.x

ABSTRACT Some species of the insect genus Tetramesa (Hymenoptera: Eurytomidae), which has a world-wide distribution, are morphologically very similar, both in the adult and larval stages. In the British Isles, there are 37 recorded species, all of which feed on grasses as larvae and are largely host specific. Some form galls on their hosts; others do not. We used a range of enzyme and random amplified polymorphic DNA (RAPD) markers to investigate a complex of five cryptic species occurring sympatrically in the UK, collected from seven sites in mainland England and Wales: T. calamagrostidis (von Schlechtendal), T. longicornis (Walker) and T. petiolata (Walker) infesting different grass hosts, and T. hyalipennis (Walker) s.l. comprising two-host adapted forms (labelled 1 and 2) reared from the grasses Elymus repens and E. farctus, respectively. Nine soluble enzyme systems (some known to be polymorphic in other insects) and 37 RAPD primers allowed taxonomic separation of the species. However, whilst RAPD markers were able to discriminate between the two host-adapted forms of T. hyalipennis, enzyme markers (producing phenotypic profiles in the absence of genetic crosses) could not. Upon calculating genetic distances for the RAPD data from which a cladogram of Euclidean distances (relatedness) was produced along with multivariate analysis of the data, T. longicornis was shown to be the most ‘basal’ species, and most related to T. hyalipennis s.l.; T. calamagrostidis and T. petiolata were found to be more distantly related to these species but most closely related to each other. The two forms of T. hyalipennis s.l. appear to be the most closely related of any of the species investigated, probably diverging the most recently. From this data, and since the populations examined were all sympatric without obvious physical barriers to reproduction, it can be concluded that some degree of sympatric evolution has occurred, most obviously in the case of the host-adapted forms of T. hyalipennis. If so, this complex of species could be another rare example of sympatric speciation in insects. Further research using more sophisticated molecular markers such as microsatellites, amplified fragment length polymorphic markers (AFLPs) and DNA sequencing (e.g. of mtDNA and ribosomal DNA regions), in conjunction with behavioural studies, are required to further elucidate this interesting species group. © 2004 The Linnean Society of London, Biological Journal of the Linnean Society, 2004, 83, 509–525.

0 0
  • Source
    [show abstract] [hide abstract]
    ABSTRACT: Surveys of tropical insects are increasingly uncovering cryptic species - morphologically similar yet reproductively isolated taxa once thought to comprise a single interbreeding entity. The vast majority of such species are described from a single location. This leaves us with little information on geographic range and intraspecific variation and limits our ability to infer the forces responsible for generating such diversity. For example, in herbivorous and parasitic insects, multiple specialists are often discovered within what were thought to be single more generalized species. Host shifts are likely to have contributed to speciation in these cases. But when and where did those shifts occur, and were they facilitated by geographic isolation? We attempted to answer these questions for two cryptic species within the butterfly Cymothoe egesta that were recently discovered on different host plants in central Cameroon. We first used mtDNA markers to separate individuals collected on the two hosts within Cameroon and then extended our analysis to incorporate individuals collected across the entire pan-Afrotropical range of the original taxon. To our surprise, we found that the species are almost entirely allopatric, dividing the original range and overlapping only in the narrow zone of West-Central Africa where they were first discovered in sympatry. This finding, combined with analyses of genetic variation within each butterfly species, strongly suggests that speciation occurred in allopatry, probably during the Pleistocene. We discuss the implications of our results for understanding speciation among other cryptic species recently discovered in the tropics and argue that more work is needed on geographic patterns and host usage in such taxa.
    Molecular Ecology 09/2009; 18(17):3639-51. · 6.28 Impact Factor
  • Source
    [show abstract] [hide abstract]
    ABSTRACT: The cursor complex is a group within the Akodon genus of South American rodents, formed by Akodon cursor and A. montensis. Correct distinction between these two species is of great importance since they can harbor different Hantavirus strains. These species are only distinguishable by means of karyotypic or internal anatomic features, requiring dissection; recently, some other genetic methods have become available. We developed RAPD markers capable of distinguishing between A. cursor and A. montensis. Samples included 42 individuals of A. cursor from four localities and 16 individuals of A. montensis from two localities. Fifty-five bands, 41 of which were polymorphic, were analyzed. A principal component analysis showed that this set of markers could successfully distinguish between the two species, mainly based on three RAPD bands. The number of bands in each population was compared within a 95% confidence interval as a measure of intraspecific variability. The A. cursor populations were found to have marked genetic structure across the study area (AMOVA; F(ST )= 0.21), which in part might be because of the relatively limited dispersal capabilities of this species. Species-specific bands, with potential for species identification, were identified.
    Genetics and molecular research: GMR 01/2011; 10(4):2881-92. · 0.99 Impact Factor
  • [show abstract] [hide abstract]
    ABSTRACT: Eupelmus vesicularis (Retzius) is considered to be a widespread and polyphagous parasitoid recorded from more than 200 hosts. The aim of this study was to determine whether two colour forms of the putative species represent two different morphs of a single species or a pair of cryptic species. Three different methods – morphometric analysis, allozyme electrophoresis and evaluation of host preferences – were used to investigate the existence of two cryptic species. Bivariate and multivariate analyses clearly indicate two species that are also distinguishable electrophoretically at the Idh-2, G6pdh, Me, Pgm and Xdh loci. The evaluation of host preferences indicates some overlap in host range between the two species.
    Journal of Natural History. 05/2010; 44(17-18):1113-1129.

Full-text (2 Sources)

Available from
Jun 19, 2013