| consequences for host-parasitoid interactions of grazing-dependent habitat heterogeneity. | 1. environmental heterogeneity can produce effects that cascade up to higher trophic levels and affect species interactions. we hypothesized that grazing-dependent habitat heterogeneity and grazing-independent host plant heterogeneity would influence directly and indirectly a host-parasitoid interaction in a woodland habitat. 2. thistles were planted randomly in 20 birch woodlands, half of which are grazed by cattle. the abundances of two species of seed herbivore and their shared parasitoid wer ... | 2006 | 16689961 |
| phylogeographic patterns of host-race evolution in tephritis conura (diptera: tephritidae). | host-race evolution is a prime candidate for sympatric speciation because host shifts must take place in the presence of both hosts. however, the geographic context in which the shift takes place may have strong allopatric or peripatric components if the primary host within a localized area is scarce or even goes extinct. inference of the relative importance of the geographic mode of speciation may be gained from phylogeographic imprints. here, we investigate the phylogeography of host races of ... | 2006 | 16499694 |
| infestation of a novel host plant by tephritis conura (diptera: tephritidae) in northern britain: host-range expansion or host shift? | the addition of a novel host plant to a phytophagous insect's diet may result in subsequent host-plant specialisation, and is believed to be a key cause for speciation in this trophic group. in northern britain, the tephritid fly tephritis conura has experienced a unique host-plant expansion, from the melancholy thistle cirsium heterophyllum to the marsh thistle c. palustre. here, we examine whether the incorporation of c. palustre in the repertoire of british t. conura flies has caused genetic ... | 2009 | 19184463 |
| the role of geographic setting on the diversification process among tephritis conura (tephritidae) host races. | we address the controversy over the processes causing divergence during speciation. host races of the fruit fly tephritis conura attack the thistles cirsium oleraceum and cirsium heterophyllum. by studying the genetic divergence of t. conura in areas where host plants are sympatric, parapatric and allopatric, we assessed the contribution of geography in driving host-race divergence. we also evaluated the relative importance of genetic drift and selection in the diversification process, by analys ... | 2006 | 16570066 |
| performance of host-races of the fruit fly, tephritis conura on a derived host plant, the cabbage thistle cirsium oleraceum: implications for the original host shift. | the thistle-infesting fruit fly tephritis conura loew (diptera: tephritidae) forms host races on the melancholy thistle, cirsium hetewphyllum (l.) hill (asterales: asteraceae) and the cabbage thistle, cirsium olemceum (l.). scop. previous research indicates that the host shift occurred from c. hetewphyllum to c. oleraceum. in this paper we address whether the host shift involved physiological adaptations by studying oviposition acceptance and survival of the two host races on the derived host c. ... | 2008 | 20302521 |