Sexual size dimorphism within species increases with body size in insects

Teder, Tiit; Tammaru, Toomas

doi:10.1111/j.0030-1299.2005.13609.x

Cited by 300 publications

(326 citation statements)

References 162 publications

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“…This is equivalent to a pattern of (phylo)genetic variation in male body size being generally greater than that of females (Blanckenhorn et al, 2007b). In contrast, our results here rather agree with opposite patterns of phenotypic variance found in insects (Teder and Tammaru, 2005). Blanckenhorn et al (2007b) also found incongruent SSD patterns among species (according to Rensch's rule) vs among populations and among families within species (inconsistent with Rensch's rule) for sepsid flies with female-biased SSD, but not for scathophagid flies with male-biased SSD.…”

Section: Discussionsupporting

confidence: 82%

Effect of genomic deficiencies on sexual size dimorphism through modification of developmental time in Drosophila melanogaster

Takahashi

Blanckenhorn

2015

Heredity

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Sexual size dimorphism (SSD), a difference in body size between sexes, is common in many taxa. In insects, females are larger than males in 470% of all taxa in most orders. The fruit fly, Drosophila melanogaster is one prominent model organism to investigate SSD since its clear and representative female-biased SSD and its growth regulation are well studied. Elucidating the number and nature of genetic elements that can potentially influence SSD would be helpful in understanding the evolutionary potential of SSD. Here, we investigated the SSD pattern caused by artificially introduced genetic variation in D. melanogaster, and examined whether variation in SSD was mediated by the sex-specific modification of developmental time. To map the genomic regions that had effects on sexual wing size and/or developmental time differences (SDtD), we reanalyzed previously published genome-wide deficiency mapping data to evaluate the effects of 376 isogenic deficiencies covering a total of~67% of the genomic regions of the second and third chromosomes of D. melanogaster. We found genetic variation in SSD and SDtD generated by genomic deficiencies, and a negative genetic correlation between size and development time. We also found SSD and SDtD allometries that are not qualitatively congruent, which however overall at best only partly help in explaining the patterns found. We identified several genomic deficiencies with the tendency to either exaggerate or suppress SSD, in agreement with quantitative genetic null expectations of many loci with small effects. These novel findings contribute to a better understanding of the evolutionary potential of sexual dimorphism.

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Section: Discussionsupporting

confidence: 82%

Effect of genomic deficiencies on sexual size dimorphism through modification of developmental time in Drosophila melanogaster

Takahashi

Blanckenhorn

2015

Heredity

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“…This might also be a contributing factor to the male biased sex ratio that is often found in small populations before the extinction of that population (see Gabriel and Ferriere, 2004). It is known that females are more sensitive to environmental stress than males (Teder and Tammaru, 2005): the results of the present study suggest that part of this sensitivity is genetically based.…”

Section: Discussionmentioning

confidence: 52%

Inbreeding and extreme outbreeding cause sex differences in immune defence and life history traits in Epirrita autumnata

2007

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Empirical studies in vertebrates support the hypothesis that inbreeding reduces resistance against parasites and pathogens. However, studies in insects have not found any evidence that inbreeding compromises immune defence. Here we tested whether one generation of brother-sister mating or extreme outbreeding (mating between two populations) have an effect on innate immunity and life history traits in the autumnal moth, Epirrita autumnata. We show that the effect of inbreeding on immune response differed between the sexes: whereas in females, inbreeding significantly reduced encapsulation response against nylon monofilament ability, it did not have a significant effect on male immune response. There were also differences in the correlation of the immune response with other traits: in females increased immune response was positively correlated with large size, whereas in males immune response increased with a reduction in development time. Immune response differed significantly among families in males but not in females, both for the inbreeding and extreme outbreeding experiments. In conjunction with the observed immune responses to inbreeding, these data suggest that in males genetic variation for immune response is largely additive or non-directional with respect to dominance, whereas in females variation is much reduced and consists of directional dominance variance. Further, we show that encapsulation response against nylon monofilament is associated with the resistance against real pathogens suggesting that this widely used method to measure the strength of immune defence in insects is also a biologically relevant method.

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“…Rensch's rule (RR) states that male body size varies more than female body size, irrespective of which sex is larger. RR was originally formulated to describe the pattern seen across species within a related clade, but has since been tested within species to see if similar drivers exist at the intra-specific level [13,17]. Within a species, it predicts an increase in SSD with increasing body size in species where males are the larger sex, and a decrease in SSD with body size in species where females are larger [14,16].…”

Section: Introductionmentioning

confidence: 99%

“…Here, we specifically focus on sex-dependent differences in T-S responses, as this may ultimately help to elucidate the underlying drivers of both SSD and T-S responses. Sex-based differences in T-S responses have been considered before; while most studies have been experimental and have considered single species, the syntheses and analyses of responses by Teder & Tammaru [13] and Stillwell et al [19] on insects, have looked more broadly at differential changes in SSD with environmental conditions. We increase the amount of temperature response data considered by almost fourfold in our analysis and increase the range of species to include other Arthropoda.…”

Section: Introductionmentioning

confidence: 99%

Equal temperature–size responses of the sexes are widespread within arthropod species

2015

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Sexual size dimorphism (SSD) is often affected by environmental conditions, but the effect of temperature on SSD in ectotherms still requires rigorous investigation. We compared the plastic responses of size-at-maturity to temperature between males and females within 85 diverse arthropod species, in which individuals of both sexes were reared through ontogeny under identical conditions with excess food. We find that the sexes show similar relative (proportional) temperature-body size (T-S) responses on average. The high degree of similarity occurs despite an analysis that includes a wide range of animal body sizes, variation in degree of SSD and differences in the sign of the T-S response. We find no support for Rensch's rule, which predicts greater variation in male size, or indeed the reverse, greater female size variation. SSD shows no systematic temperature dependence in any of the 17 arthropod orders examined, five of which (Diptera, Orthoptera, Lepidoptera, Coleoptera and Calanoida) include more than six thermal responses. We suggest that the same proportional T-S response may generally have equivalent fitness costs and benefits in both sexes. This contrasts with effects of juvenile density, and food quantity/quality, which commonly result in greater size plasticity in females, suggesting these variables have different adaptive effects on SSD.

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Sexual size dimorphism within species increases with body size in insects

Cited by 300 publications

References 162 publications

Effect of genomic deficiencies on sexual size dimorphism through modification of developmental time in Drosophila melanogaster

Effect of genomic deficiencies on sexual size dimorphism through modification of developmental time in Drosophila melanogaster

Inbreeding and extreme outbreeding cause sex differences in immune defence and life history traits in Epirrita autumnata

Equal temperature–size responses of the sexes are widespread within arthropod species

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