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The evolution of body size, antennal size and host use in parasitoid wasps (Hymenoptera: Chalcidoidea): a phylogenetic comparative analysis.

Symonds MR, Elgar MA - PLoS ONE (2013)

Bottom Line: Both morphological features and identity of exploited host orders show strong phylogenetic signal, but host breadth does not.Larger body size in these wasps was weakly associated with few plant genera, and with more specialised host use, and chalcidoid wasps that parasitize coleopteran hosts tend to be larger.These results suggest there are adaptations in chalcidoid wasps that are specifically associated with host detection and exploitation.

View Article: PubMed Central - PubMed

Affiliation: Centre for Integrative Ecology, School of Life and Environmental Sciences, Deakin University, Burwood, Victoria, Australia ; Department of Zoology, University of Melbourne, Melbourne, Victoria, Australia.

ABSTRACT
Chalcidoid wasps represent one of the most speciose superfamilies of animals known, with ca. 23,000 species described of which many are parasitoids. They are extremely diverse in body size, morphology and, among the parasitoids, insect hosts. Parasitic chalcidoids utilise a range of behavioural adaptations to facilitate exploitation of their diverse insect hosts, but how host use might influence the evolution of body size and morphology is not known in this group. We used a phylogenetic comparative analysis of 126 chalcidoid species to examine whether body size and antennal size showed evolutionary correlations with aspects of host use, including host breadth (specificity), host identity (orders of insects parasitized) and number of plant associates. Both morphological features and identity of exploited host orders show strong phylogenetic signal, but host breadth does not. Larger body size in these wasps was weakly associated with few plant genera, and with more specialised host use, and chalcidoid wasps that parasitize coleopteran hosts tend to be larger. Intriguingly, chalcidoid wasps that parasitize hemipteran hosts are both smaller in size in the case of those parasitizing the suborder Sternorrhyncha and have relatively larger antennae, particularly in those that parasitize other hemipteran suborders. These results suggest there are adaptations in chalcidoid wasps that are specifically associated with host detection and exploitation.

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Antennal size and host use.Mean (±s.e.) residual antennal size for species of Chalcidoidea that do (red bars) and do not (blue bars) parasitize orders (and sub-orders) of insects. Group sample sizes are indicated above bar.
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pone-0078297-g004: Antennal size and host use.Mean (±s.e.) residual antennal size for species of Chalcidoidea that do (red bars) and do not (blue bars) parasitize orders (and sub-orders) of insects. Group sample sizes are indicated above bar.

Mentions: No measure of host breadth or specialisation predicted variation in antennal size (in models including, and hence controlling for, body size). Nor was number of plant associates a better predictor than the intercept-only model (Tables 5, 6). There was only one set of models predicting variation in relative antennal size that were convincingly better than the models: species that parasitize Hemipteran hosts tend to have larger antennae (Figure 4). The effect was more weakly apparent in the parasitization of Sternorrhyncha, and only so in the analysis using the Munro et al. phylogeny. However, the effect was stronger in species that parasitize other Hemipteran hosts (evidence ratio up to 10 in the case of the analysis using the Heraty et al. phylogeny). By contrast, there was no strong support for models linking parasitism of other host orders and antennal size (Tables 5, 6; Figure 4). There was a suggestion using the Heraty et al. phylogeny of a slightly better model indicating that egg parasitoids have relatively larger antennae (only 1.4 times better than the model). We consider this to be a result of the fact that most species that parasitize the Hemipteran suborders other than Sternorrhyncha are egg parasitoids. When we considered egg parasitism and parasitization of other Hemiptera in the same analysis (i.e. included both as predictors) the indication of larger antennae in the Hemipteran parasites remained (b = 0.152 ± 0.067 s.e.), but there was no clear indication of larger antennae in egg parasitoids generally (b = 0.052 ± 0.052 s.e.).


The evolution of body size, antennal size and host use in parasitoid wasps (Hymenoptera: Chalcidoidea): a phylogenetic comparative analysis.

Symonds MR, Elgar MA - PLoS ONE (2013)

Antennal size and host use.Mean (±s.e.) residual antennal size for species of Chalcidoidea that do (red bars) and do not (blue bars) parasitize orders (and sub-orders) of insects. Group sample sizes are indicated above bar.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3818564&req=5

pone-0078297-g004: Antennal size and host use.Mean (±s.e.) residual antennal size for species of Chalcidoidea that do (red bars) and do not (blue bars) parasitize orders (and sub-orders) of insects. Group sample sizes are indicated above bar.
Mentions: No measure of host breadth or specialisation predicted variation in antennal size (in models including, and hence controlling for, body size). Nor was number of plant associates a better predictor than the intercept-only model (Tables 5, 6). There was only one set of models predicting variation in relative antennal size that were convincingly better than the models: species that parasitize Hemipteran hosts tend to have larger antennae (Figure 4). The effect was more weakly apparent in the parasitization of Sternorrhyncha, and only so in the analysis using the Munro et al. phylogeny. However, the effect was stronger in species that parasitize other Hemipteran hosts (evidence ratio up to 10 in the case of the analysis using the Heraty et al. phylogeny). By contrast, there was no strong support for models linking parasitism of other host orders and antennal size (Tables 5, 6; Figure 4). There was a suggestion using the Heraty et al. phylogeny of a slightly better model indicating that egg parasitoids have relatively larger antennae (only 1.4 times better than the model). We consider this to be a result of the fact that most species that parasitize the Hemipteran suborders other than Sternorrhyncha are egg parasitoids. When we considered egg parasitism and parasitization of other Hemiptera in the same analysis (i.e. included both as predictors) the indication of larger antennae in the Hemipteran parasites remained (b = 0.152 ± 0.067 s.e.), but there was no clear indication of larger antennae in egg parasitoids generally (b = 0.052 ± 0.052 s.e.).

Bottom Line: Both morphological features and identity of exploited host orders show strong phylogenetic signal, but host breadth does not.Larger body size in these wasps was weakly associated with few plant genera, and with more specialised host use, and chalcidoid wasps that parasitize coleopteran hosts tend to be larger.These results suggest there are adaptations in chalcidoid wasps that are specifically associated with host detection and exploitation.

View Article: PubMed Central - PubMed

Affiliation: Centre for Integrative Ecology, School of Life and Environmental Sciences, Deakin University, Burwood, Victoria, Australia ; Department of Zoology, University of Melbourne, Melbourne, Victoria, Australia.

ABSTRACT
Chalcidoid wasps represent one of the most speciose superfamilies of animals known, with ca. 23,000 species described of which many are parasitoids. They are extremely diverse in body size, morphology and, among the parasitoids, insect hosts. Parasitic chalcidoids utilise a range of behavioural adaptations to facilitate exploitation of their diverse insect hosts, but how host use might influence the evolution of body size and morphology is not known in this group. We used a phylogenetic comparative analysis of 126 chalcidoid species to examine whether body size and antennal size showed evolutionary correlations with aspects of host use, including host breadth (specificity), host identity (orders of insects parasitized) and number of plant associates. Both morphological features and identity of exploited host orders show strong phylogenetic signal, but host breadth does not. Larger body size in these wasps was weakly associated with few plant genera, and with more specialised host use, and chalcidoid wasps that parasitize coleopteran hosts tend to be larger. Intriguingly, chalcidoid wasps that parasitize hemipteran hosts are both smaller in size in the case of those parasitizing the suborder Sternorrhyncha and have relatively larger antennae, particularly in those that parasitize other hemipteran suborders. These results suggest there are adaptations in chalcidoid wasps that are specifically associated with host detection and exploitation.

Show MeSH