ORCID Profile
0000-0003-2152-3153
Current Organisations
University of Cambridge
,
University of Oxford
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Publisher: University of Chicago Press
Date: 12-2014
DOI: 10.1086/678399
Abstract: We provide the first evidence for interspecific warfare in bees, a spectacular natural phenomenon that involves a series of aerial battles and leads to thousands of fatalities from both attacking and defending colonies. Molecular analysis of fights at a hive of the Australian stingless bee Tetragonula carbonaria revealed that the attack was launched by a related species, Tetragonula hockingsi, which has only recently extended its habitat into southeastern Queensland. Following a succession of attacks by the same T. hockingsi colony over a 4-month period, the defending T. carbonaria colony was defeated and the hive usurped, with the invading colony installing a new queen. We complemented our direct observations with a 5-year study of more than 260 Tetragonula hives and found interspecific hive changes, which were likely to be usurpation events, occurring in 46 hives over this period. We discuss how fighting swarms and hive usurpation fit with theoretical predictions on the evolution of fatal fighting and highlight the many unexplained features of these battles that warrant further study.
Publisher: Springer Science and Business Media LLC
Date: 23-03-2011
DOI: 10.1038/NATURE09831
Publisher: Wiley
Date: 11-1998
Publisher: Wiley
Date: 03-09-2015
DOI: 10.1111/EEN.12250
Publisher: Elsevier BV
Date: 07-2009
Publisher: Wiley
Date: 05-1998
Publisher: Proceedings of the National Academy of Sciences
Date: 30-04-2018
Abstract: Cooperative interactions among species—mutualisms—are major sources of evolutionary innovation. However, despite their importance, two species that formerly cooperated sometimes cease their partnership. Why do mutualisms break down? We asked this question in the partnership between arbuscular mycorrhizal (AM) fungi and their plant hosts, one of the most ancient mutualisms. We analyze two potential trajectories toward evolutionary breakdown of their cooperation, symbiont switching and mutualism abandonment. We find evidence that plants stop interacting with AM fungi when they switch to other microbial mutualists or when they evolve alternative strategies to extract nutrients from the environment. Our results show vital cooperative interactions can be lost, but only if successful alternatives evolve.
Publisher: The Company of Biologists
Date: 2004
DOI: 10.1242/JEB.00733
Abstract: Floral volatiles play a major role in plant–insect communication. We examined the influence of two volatiles, phenylacetaldehyde andα-pinene, on the innate and learnt foraging behaviour of the moth Helicoverpa armigera. In dual-choice wind tunnel tests, adult moths flew upwind towards both volatiles, with a preference for phenylacetaldehyde. When exposure to either of these volatiles was paired with a feeding stimulus(sucrose), all moths preferred the learnt odour in the preference test. This change in preference was not seen when moths were exposed to the odour without a feeding stimulus. The learnt preference for the odour was reduced when moths were left unfed for 24 h before the preference test. We tested whether moths could discriminate between flowers that differed in a single volatile component. Moths were trained to feed on flowers that were odour-enhanced using either phenylacetaldehyde or α-pinene. Choice tests were then carried out in an outdoor flight cage, using flowers enhanced with either volatile. Moths showed a significant preference for the flower type on which they were trained. Moths that were conditioned on flowers that were not odour-enhanced showed no preference for either of the odour-enhanced flower types. The results imply that moths may be discriminating among odour profiles of in idual flowers from the same species. We discuss this behaviour within the context of nectar foraging in moths and odour signalling by flowering plants.
Publisher: Wiley
Date: 12-2001
Publisher: Wiley
Date: 18-07-2017
DOI: 10.1111/EEN.12433
Publisher: Wiley
Date: 11-05-2005
DOI: 10.1111/J.1420-9101.2005.00900.X
Abstract: We studied host selection and exploitation, two crucial aspects of parasite ecology, in Achrysocharoides parasitoid wasps, which show remarkable host specificity and unusual offspring sex allocation. We estimated a molecular phylogeny of 15 Achrysocharoides species and compared this with host (plant and insect) phylogenies. This tri-trophic phylogenetic comparison provides no evidence for cospeciation, but parasitoids do show phylogenetic conservation of the use of plant genera. Patterns of sequence ergence also suggest that the parasitoids radiated more recently (or evolved much faster) than their insect hosts. Three main categories of brood production occur in parasitoids: (1) solitary offspring, (2) mixed sex broods and (3) separate (split) sex broods. Split sex broods are very rare and virtually restricted to Achrysocharoides, while the other types occur very widely. Our phylogeny suggests that split sex broods have evolved twice and provides evidence for a transition from solitary to mixed sex broods, via split sex broods, as predicted by theory.
Publisher: Cold Spring Harbor Laboratory
Date: 04-01-2018
DOI: 10.1101/242834
Abstract: Cooperative interactions among species, termed mutualisms, have played a crucial role in the evolution of life on Earth. However, despite key potential benefits to partners, there are many cases where two species cease to cooperate, and mutualisms break down. What factors drive the evolutionary breakdown of mutualism? We examined the pathways towards breakdowns of the mutualism between plants and arbuscular mycorrhizal (AM) fungi. Using a comparative approach, we identify ~25 independent cases of complete mutualism breakdown across global seed plants. We found that breakdown of cooperation was only stable when host plants either: (i) partner with other root symbionts or (ii) evolve alternative resource acquisition strategies. Our results suggest that key mutualistic services are only permanently lost if hosts evolve alternative symbioses or adaptations. Cooperative interactions among species – mutualisms – are major sources of evolutionary innovation. However, despite their importance, two species that formerly cooperated sometimes cease their partnership. Why do mutualisms breakdown? We asked this question in the partnership between arbuscular mycorrhizal (AM) fungi and their plant hosts, one of the most ancient mutualisms. We analyse two potential trajectories towards evolutionary breakdown of their cooperation, symbiont switching and mutualism abandonment. We find evidence that plants stop interacting with AM fungi when they switch to other microbial mutualists or when they evolve alternative strategies to extract nutrients from the environment. Our results show vital cooperative interactions can be lost - but only if successful alternatives evolve.
Publisher: Elsevier BV
Date: 08-1997
Abstract: In haplodiploid species, the presence of unmated (virgin) females that can produce only haploid male offspring may have several important effects on a range of phenomena such as reproductive strategies, the transmission of parasitic chromosomes and the evolution of eusociality. The strength of these effects will depend upon the prevalence of virgin females. Two theories make conflicting predictions concerning the importance of factors that should be associated with increased levels of virginity, emphasizing either the degree of local mate competition or brood size. In this paper, a model is presented which predicts that, under conditions of local mate competition, the prevalence of virginity should be negatively correlated with the average number of offspring developing in a patch. The different predictions were then tested using data from 53 species of fig wasps representing 15 genera from four continents. Across species, the estimated prevalence of virginity was significantly inversely related to brood size, but showed no correlation with sex ratio (an index of local mate competition), supporting the predictions of our model. Qualitatively similar results were found when a formal comparative analysis was carried out using a morphologically and molecularly based phylogeny.
Publisher: Elsevier BV
Date: 04-2008
DOI: 10.1016/J.JTBI.2007.11.009
Abstract: Learning can allow in iduals to increase their fitness in particular environments. The advantage to learning depends on the predictability of the environment and the extent to which animals can adjust their behaviour. Earlier general models have investigated when environmental predictability might favour the evolution of learning in foraging animals. Here, we construct a theoretical model that predicts the advantages to learning using a specific biological ex le: oviposition in the Lepidoptera. Our model includes environmental and behavioural complexities relevant to host selection in these insects and tests whether the predictions of the general models still hold. Our results demonstrate how the advantage of learning is maximised when within-generation variability is minimised (the local environment consists mainly of a single host plant species) and between-generation variability is maximised (different host plant species are the most common in different generations). We discuss how our results: (a) can be applied to recent empirical work in different lepidopteran species and (b) predict an important role of learning in lepidopteran agricultural pests.
Publisher: American Association for the Advancement of Science (AAAS)
Date: 12-08-2011
Abstract: Plants and their associated fungi reward partners that offer the best resources to sustain mutualism in complex systems.
Publisher: Elsevier BV
Date: 08-2008
Publisher: Wiley
Date: 11-1998
DOI: 10.1046/J.1365-294X.1998.00467.X
Abstract: Wolbachia form a group of intracellular bacteria that alter reproduction in their arthropod hosts. Two major phylogenetic sub isions (A and B) of Wolbachia occur. Using a polymerase chain reaction assay we surveyed for the A and B group Wolbachia in 82 insect species from two temperate host-parasitoid communities (food webs) and a general collection of Lepidoptera caught at a light trap. One host-parasitoid community was based around leaf-mining Lepidoptera, and the other around Aphids. We found that: (i) 22.0% of insects s led were infected with Wolbachia and (ii) the prevalence and type (A or B) of Wolbachia infection differed significantly between communities and taxonomic groups. We obtained DNA sequences from the ftsZ gene for the group B Wolbachia found in six leaf-mining species and one of their parasitoids, as well as four of the Lepidoptera caught by a light trap. Taken together, the results of our survey and phylogenetic analyses of the sequence data suggest that host-parasitoid transfer of Wolbanchia is not the major route through which the species we have examined become infected. In addition, the Wolbachia strains observed in five leaf-mining species from the same genus were not closely related, indicating that transfer between species has not occurred due to a shared feeding niche or cospeciation.
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Stuart West.