Specialization: Species Property or Local Phenomenon?

Fox, Laurel R.; Morrow, P. A.

doi:10.1126/science.211.4485.887

Cited by 781 publications

(578 citation statements)

References 117 publications

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“…The differential ability of plants to attract natural enemies may even be responsible for further dietary specialization of herbivores exploiting specific plant taxa like the Cruciferae (Yano, 1994). For example, opposing choices at the plant-level could benefit the herbivore and lead to enemy-free space shaping host-parasitoid interactions (Fox and Morrow, 1981;Fox and Eisenbach, 1992;Bigger and Fox, 1997;Gratton and Welter, 1999;Oppenheim and Gould, 2002). If host-parasitoid interactions in ecosystems are to be understood, foraging behavior of parasitoids must be studied in relation to inter-and intraspecific variation in plant-derived infochemicals.…”

Section: Introductionmentioning

confidence: 99%

Variation In Plant Volatiles and Attraction Of The ParasitoidDiadegma semiclausum(Hellén)

et al. 2005

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Abstract-Differences in allelochemistry of plants may influence their ability to attract parasitoids. We studied responses of Diadegma semiclausum (Hellén), a parasitoid of the diamondback moth (Plutella xylostella L.), to inter-and intraspecific variation in odor blends of crucifers and a non-crucifer species. Uninfested Brussels sprout (Brassica oleracea L. gemmifera), white mustard (Sinapis alba L.), a feral Brassica oleracea, and malting barley (Hordeum vulgare L.) were compared for their attractivity to D. semiclausum in a Y-tube bioassay. Odors from all plants were more attractive to the parasitoid than clean air. However, tested against each other, parasitoids preferred the volatile blend from the three cruciferous species over that of malting barley. Wasps also discriminated between uninfested crucifers: mustard was as attractive as feral B. oleracea, and both were more attractive than Brussels sprout. Attractivity of uninfested plants was compared with that of plants infested by larvae of the host P. xylostella. Host-infested mustard and Brussels sprout were more attractive than uninfested conspecifics. Interestingly, the volatile blends of uninfested white mustard and infested Brussels sprout were equally attractive. We also compared the volatile composition of different plant sources by collecting headspace samples and analysing them with GC-MS. Similarities of volatile profiles were determined by hierarchic clustering and non-metric scaling based on the Horn-index. Due to the absence of several compounds in its blend, the volatile profile of barley showed dissimilarities from blends of crucifers. The odor profile of white mustard was distinctly different from the two Brassicaceae. * To whom correspondence should be addressed. E-mail: tibor.bukovinszky@wur.nl Feral Brassica oleracea odor profile was different from infested Brussels sprout, but showed overlap with uninfested Brussels sprout. Odor blends from infested and uninfested Brussels sprout were similar, and mainly quantitative differences were found. D. semiclausum appears to discriminate based on subtle differences in volatile composition of odor blends from infested and uninfested plants.

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Section: Introductionmentioning

confidence: 99%

Variation In Plant Volatiles and Attraction Of The ParasitoidDiadegma semiclausum(Hellén)

et al. 2005

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“…Although host specificity can vary to some degree among different populations of the same parasite species across its geographical range, it still represents a true character of a parasite species, being less variable within parasite species than among parasite species (Krasnov et al 2004 a). This suggests that the level of host specificity is subjected to natural selection rather than merely reflecting the local restrictions caused by a variety of ecological, morphological, chemical and/ or genetic factors (Fox and Morrow, 1981).…”

Section: Introductionmentioning

confidence: 99%

“…From an evolutionary perspective, selection for higher or lower levels of host specificity (or, in a broader sense, ecological specialization) is affected by a variety of both parasite (=forager)-related and host (=resource)-related factors (Fox and Morrow, 1981 ;Futuyama and Moreno, 1988 ;Fry, 1996 ;Desdevises et al 2002). In particular, the models of Ward (1992) suggested that species tend to specialize on predictable resources, i.e.…”

Section: Introductionmentioning

confidence: 99%

Resource predictability and host specificity in fleas: the effect of host body mass

et al. 2006

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Ecological specialization is hypothesized to result from the exploitation of predictable resource bases. For parasitic organisms, one prediction is that parasites of large-bodied host species, which tend to be long-lived, should specialize on these hosts, whereas parasites of small host species, which represent more ephemeral and less predictable resources, should become generalists. We tested this prediction by quantifying the association between the level of host specificity of fleas and the mean body mass of their mammalian hosts, using published data from 2 large, distinct geographical regions (South Africa and northern North America). In general, we found supporting evidence that flea host specificity, measured either as the number of host species exploited or their taxonomic distinctness, became more pronounced with increasing host body mass. There were, however, some discrepancies among the results depending on the different measures of host specificity, the geographical region studied, or whether we used the raw values or phylogenetically independent contrasts. These are discussed with respect to other forces acting on the evolution of host specificity in parasites, as well as in the context of the regions' contrasting evolutionary histories. Overall, though, our findings indicate that the exploitation of large-bodied, and therefore long-lived, host species has promoted specialization in fleas, most likely because these hosts represent predictable resources.

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“…They may also be cryptic, as host adaptation may be behaviorally or physiologically rather than morphologically based. Not for nothing were herbivorous insects focal subjects for early discussions of sibling species [7,8] and later evaluations of intraspecific ecological heterogeneity [23]. These many International Journal of Ecology 3 sources of variation led to terminological confusion and a need for clear distinctions [10].…”

Section: The Kinds Of Biological Variationmentioning

confidence: 99%

Of “Host Forms” and Host Races: Terminological Issues in Ecological Speciation

Funk

2012

International Journal of Ecology

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Successful communication and accurate inferences in science depend on the common understanding and consistent usage of the terms we apply to concepts of interest. Likewise, new terminology is required when important concepts have gone unnamed. Here, I focus on terminological issues about biological variation and ecological speciation, especially in herbivorous insects but also more generally. I call for the more restricted use of concepts that have sometimes been misapplied, and thus caution against synonymizing ecological speciation with sympatric speciation and the unwarranted invocation of "host races" to describe herbivorous insect differentiation. I also call for the qualified application of terms for different kinds of biological variation and for host range when confronting uncertainty. Among other "missing terms" introduced here is "host form," a generic term describing any case of host-associated differences for which current evidence does not allow diagnosis of the specific kind of variation. Embracing the use of host form should free host race from its current overapplication. Finally, I present a case study in which Neochlamisus leaf beetle populations previously described as host forms are hereby declared to be host races, based on accumulated evidence supporting each of the associated criteria.

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Specialization: Species Property or Local Phenomenon?

Cited by 781 publications

References 117 publications

Variation In Plant Volatiles and Attraction Of The ParasitoidDiadegma semiclausum(Hellén)

Variation In Plant Volatiles and Attraction Of The ParasitoidDiadegma semiclausum(Hellén)

Resource predictability and host specificity in fleas: the effect of host body mass

Of “Host Forms” and Host Races: Terminological Issues in Ecological Speciation

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