Imbalance of Predator and Prey Armament: Geographic Clines in Phenotypic Interface and Natural Selection

Toju,; Sota,

doi:10.2307/3491251

Cited by 50 publications

(120 citation statements)

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“…This suggests that a transcontinental comparison of the PA tolerance of snowshoe hares from regions home to birches with PA concentrations ranging from high to low is warranted, especially given the unprecedented spatial scale at which these terrestrial mosaics could operate relative to other previously documented consumer-resource mosaics (e.g., Thompson 2005;Thompson and Fernandez 2006;Toju and Sota 2006;Siepielski and Benkman 2007;Toju 2008). The comparison would be a transcontinental test of Thompson's (2005) geographic mosaic of coevolution hypothesis.…”

Section: Discussionmentioning

confidence: 94%

Papyriferic Acid, An Antifeedant Triterpene From Birch Trees, Inhibits Succinate Dehydrogenase From Liver Mitochondria

et al. 2009

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Papyriferic acid (PA) is a triterpene that is secreted by glands on twigs of the juvenile ontogenetic phase of resin producing tree birches (e.g., Betula neoalaskana, B. pendula) and that deters browsing by mammals such as the snowshoe hare (Lepus americanus). We investigated the pharmacology of PA as a first step in understanding its antifeedant effect. After oral administration to rats, PA and several metabolites were found in feces but not urine, indicating that little was absorbed systemically. Metabolism involved various combinations of hydrolysis of its acetyl and malonyl ester groups, and hydroxylation of the terpene moiety. The presence of a malonyl group suggested a possible interaction with succinate dehydrogenase (SDH), a mitochondrial enzyme known to be competitively inhibited by malonic acid. The effect of PA on the oxidation of succinate by SDH was examined in mitochondrial preparations from livers of ox, rabbit, and rat. In all three species, PA was a potent inhibitor of SDH. Kinetic analysis indicated that, unlike malonate, PA acted by an uncompetitive mechanism, meaning that it binds to the enzyme-substrate complex. The hydrolysis product of PA, betulafolienetriol oxide, was inactive on SDH. Overall, the evidence suggests that PA acts as the intact molecule and interacts at a site other than the succinate binding site, possibly binding to the ubiquinone sites on complex II. Papyriferic acid was potent (K(iEIS) ranged from 25 to 45 microM in the three species) and selective, as malate dehydrogenase was unaffected. Although rigorous proof will require further experiments, we have a plausible mechanism for the antifeedant effect of PA: inhibition of SDH in gastrointestinal cells decreases mitochondrial energy production resulting in a noxious stimulus, 5-HT release, and sensations of nausea and discomfort. There is evidence that the co-evolution of birches and hares over a large and geographically-diverse area in Northern Europe and America has produced marked differences in the formation of PA by birches, and the tolerance of hares to dietary PA. The present findings on the metabolic fate and biochemical effects of PA provide a rational basis for investigating the mechanisms underlying differences among populations of hares in their tolerance of a PA-rich diet.

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Section: Discussionmentioning

confidence: 94%

Papyriferic Acid, An Antifeedant Triterpene From Birch Trees, Inhibits Succinate Dehydrogenase From Liver Mitochondria

et al. 2009

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“…Studies on the camelia weevil (C. cameliae) have shown that differences in rostrum length among populations are correlated with seed coat thickness (Toju and Sota 2006b). The plant and the insect are involved in a coevolutionary race in which thick seed coats promote the development of longer rostrums and vice versa (Toju and Sota 2006b). The pressure on rostrum length is strong, as evident from the disproportionally enlarged rostrum relative to body size in populations feeding on seeds with thick seed coats (Toju and Sota 2006a).…”

Section: Introductionmentioning

confidence: 98%

“…Most species are seed parasites and their main host plants are oaks, chestnuts, hazelnut trees and camelias (Hughes and Vogler 2004b). They exhibit long legs and a vastly extended rostrum that measures up to three times their body length, particularly in the females (Hughes and Vogler 2004a;Toju and Sota 2006b). The mandibles at the terminus of the rostrum are used to drill an oviposition hole by slowly chewing a narrow opening into the thick coating of the growing seed (Desouhant et al 2000;Muñoz 2008, 2009).…”

Section: Introductionmentioning

confidence: 99%

“…Both the exaggerated legs and the extended rostrum are thought to be adaptive for oviposition into seeds of various sizes and shapes, as they may determine the kind of seeds that ovipositing females can grip and penetrate (Hughes and Vogler 2004a). Studies on the camelia weevil (C. cameliae) have shown that differences in rostrum length among populations are correlated with seed coat thickness (Toju and Sota 2006b). The plant and the insect are involved in a coevolutionary race in which thick seed coats promote the development of longer rostrums and vice versa (Toju and Sota 2006b).…”

Section: Introductionmentioning

confidence: 99%

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Complex selection on life-history traits and the maintenance of variation in exaggerated rostrum length in acorn weevils

2011

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Trophic interactions can trigger the development of exaggerated specialized characters and promote morphological diversification. For example, acorn weevils (genus Curculio) present strikingly long rostrums, which are used by females to perforate oviposition holes through the seed coat. Species exhibiting longer rostrums are known to exploit larger acorns, and therefore rostrum length is thought to be subject to selection to match the preferred acorn type. However, rostrum length is strongly correlated with body size, and morphological divergence could result from either selection on rostrum length for optimal food exploitation or from other pressures acting on body size. We collected infested acorns at oak forests where the large Curculio elephas and the small-bodied Curculio glandium co-occur. There were no interspecific differences in adult female body size to rostrum length allometric relationships, and rostrum length is equally correlated with body size in either species. MtDNA-based species identification showed that C. glandium larvae were present within acorns of all sizes, whereas C. elephas larvae were restricted to acorns above a minimum size, irrespective of oak species. Hence, exploitation of large acorns can hardly have triggered rostrum enlargement, as the small sized C. glandium adults (with short rostrums) could perforate and oviposit in both small and large acorns. Rather, increased rostrum length is probably a by-product of the larger body sizes of individuals emerging from bigger acorns, which allow increased larval size and enhance larval survival likelihood. Summarizing, when exaggerated feeding traits co-vary with other body features, interspecific morphological variability may result from contrasting selective pressures acting on these correlated characters.

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“…This view on coevolution has led to clear, testable predictions, and indeed these are taken up by an expanding range of scientists, who experimentally test these predictions in a variety of systems (e.g. Thompson 1999aThompson , b, 2009aBurdon and Thrall 1999;Lively 1999;Brodie et al 2002;Benkman et al 2003;Neuhauser et al 2003;Zangerl and Berenbaum 2003;Toju and Sota 2006). One of the central challenges is to explain the observed geographical distribution of alleles at adaptive loci in terms of selection (stabilizing, directional, disruptive or balancing) versus migration and genetic drift.…”

Section: Introductionmentioning

confidence: 94%

The potential of a population genomics approach to analyse geographic mosaics of plant--insect coevolution

2010

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A central issue in the evolutionary ecology of species interactions is coevolution, which involves the reciprocal selection between individuals of interacting species. Understanding the importance of coevolution in shaping species interactions requires the consideration of spatial variation in their strength. This is exactly what the, recently developed, geographic mosaic theory of coevolution addresses. Another major development in the study of population ecology is the introduction of the population genomics approach in this field of research. This approach addresses spatial processes through molecular methods. It is of particular interest that population genomics is especially applicable to natural populations of non-model species. We describe how population genomics can be used in the context of the geographic mosaic of coevolution, specifically to identify coevolutionary hot-spots, and to attribute genetic variation found at specific loci to processes of selection versus trait remixing. The proposed integration of the population genomics approach with the conceptual framework of the geographic mosaic of coevolution is illustrated with a few selected, particularly demonstrative, examples from the realm of insect-plant interactions.

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Imbalance of Predator and Prey Armament: Geographic Clines in Phenotypic Interface and Natural Selection

Cited by 50 publications

References 0 publications

Papyriferic Acid, An Antifeedant Triterpene From Birch Trees, Inhibits Succinate Dehydrogenase From Liver Mitochondria

Papyriferic Acid, An Antifeedant Triterpene From Birch Trees, Inhibits Succinate Dehydrogenase From Liver Mitochondria

Complex selection on life-history traits and the maintenance of variation in exaggerated rostrum length in acorn weevils

The potential of a population genomics approach to analyse geographic mosaics of plant--insect coevolution

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