Allometric Slopes Not Underestimated by Ordinary Least Squares Regression: A Case Study with <i>Enchenopa</i> Treehoppers (Hemiptera: Membracidae)

Al-Wathiqui, Nooria; Rodrı́guez, Rafael L.

doi:10.1603/an10185

Cited by 27 publications

(18 citation statements)

References 13 publications

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“…; O'Connor et al. ; Al‐Wathiqui and Rodríguez ; Taskinen and Warton ; Hansen and Bartoszek ). Our model provides additional insight into this controversy, which we discuss in the Supporting Information.…”

Section: Model and Resultsmentioning

confidence: 99%

Cryptic individual scaling relationships and the evolution of morphological scaling

et al. 2016

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Morphological scaling relationships between organ and body size-also known as allometries-describe the shape of a species, and the evolution of such scaling relationships is central to the generation of morphological diversity. Despite extensive modeling and empirical tests, however, the modes of selection that generate changes in scaling remain largely unknown. Here, we mathematically model the evolution of the group-level scaling as an emergent property of individual-level variation in the developmental mechanisms that regulate trait and body size. We show that these mechanisms generate a "cryptic individual scaling relationship" unique to each genotype in a population, which determines body and trait size expressed by each individual, depending on developmental nutrition. We find that populations may have identical population-level allometries but very different underlying patterns of cryptic individual scaling relationships. Consequently, two populations with apparently the same morphological scaling relationship may respond very differently to the same form of selection. By focusing on the developmental mechanisms that regulate trait size and the patterns of cryptic individual scaling relationships they produce, our approach reveals the forms of selection that should be most effective in altering morphological scaling, and directs researcher attention on the actual, hitherto overlooked, targets of selection.

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Section: Model and Resultsmentioning

confidence: 99%

Cryptic individual scaling relationships and the evolution of morphological scaling

et al. 2016

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“…The RMA allometry analysis of the various female genital measurements resulted in no consistent pattern. However, OLS regressions, which are seen as more appropriate to analyse scaling relationships according to current knowledge (Al‐Wathiqui & Rodríguez, ; Voje & Hansen, ; Rodríguez et al . ), suggested hypo‐allometry for all the genital dimensions.…”

Section: Discussionmentioning

confidence: 99%

One size fits all? Determinants of sperm transfer in a highly dimorphic orb‐web spider

Assis

Foellmer

2016

J of Evolutionary Biology

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The evolutionary significance of widespread hypo-allometric scaling of genital traits in combination with rapid interspecific genital trait divergence has been of key interest to evolutionary biologists for many years and remains poorly understood. Here, we provide a detailed assessment of quantitative genital trait variation in males and females of the sexually highly dimorphic and cannibalistic orb-weaving spider Argiope aurantia. We then test how this trait variation relates to sperm transfer success. In particular, we test specific predictions of the one-size-fits-all and lock-and-key hypotheses for the evolution of genital characters. We use video-taped staged matings in a controlled environment with subsequent morphological microdissections and sperm count analyses. We find little support for the prediction of the one-size-fits-all hypothesis for the evolution of hypo-allometric scaling of genital traits, namely that intermediate trait dimensions confer highest sperm transfer success. Likewise, our findings do not support the prediction of the lock-and-key hypothesis that a tight fit of male and female genital traits mediates highest sperm transfer success. We do, however, detect directional effects of a number of male and female genital characters on sperm transfer, suggesting that genital trait dimensions are commonly under selection in nature. Importantly, even though females are much larger than males, spermatheca size limits the number of sperm transferred, contradicting a previous hypothesis about the evolutionary consequences of genital size dimorphism in extremely size-dimorphic taxa. We also find strong positive effects of male body size and copulation duration on the probability of sperm transfer and the number of sperm transferred, with implications for the evolution of extreme sexual size dimorphism and sexual cannibalism in orb weavers.

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“…We measured traits with the program ImageJ (Rasband 1997(Rasband -2009). Repeatability of body and genitalia traits was C0.98 (see also Al-Wathiqui and Rodríguez 2011).…”

Section: Methodsmentioning

confidence: 99%

Genotype × environment interaction is weaker in genitalia than in mating signals and body traits in Enchenopa treehoppers (Hemiptera: Membracidae)

Rodrı́guez

Al-Wathiqui

2011

Genetica

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Theory predicts that selection acting across environments should erode genetic variation in reaction norms; i.e., selection should weaken genotype × environment interaction (G × E). In spite of this expectation, G × E is often detected in fitness-related traits. It thus appears that G × E is at least sometimes sustained under selection, a possibility that highlights the need for theory that can account for variation in the presence and strength of G × E. We tested the hypothesis that trait differences in developmental architecture contribute to variation in the expression of G × E. Specifically, we assessed the influence of canalization (robustness to genetic or environmental perturbations) and condition-dependence (association between trait expression and prior resource acquisition or vital cellular processes). We compared G × E across three trait types expected to differ in canalization and condition-dependence: mating signals, body size-related traits, and genitalia. Because genitalia are expected to show the least condition-dependence and the most canalization, they should express weaker G × E than the other trait types. Our study species was a member of the Enchenopa binotata species complex of treehoppers. We found significant G × E in most traits; G × E was strongest in signals and body traits, and weakest in genitalia. These results support the hypothesis that trait differences in developmental architecture (canalization and condition-dependence) contribute to variation in the expression of G × E. We discuss implications for the dynamics of sexual selection on different trait types.

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Allometric Slopes Not Underestimated by Ordinary Least Squares Regression: A Case Study with Enchenopa Treehoppers (Hemiptera: Membracidae)

Cited by 27 publications

References 13 publications

Cryptic individual scaling relationships and the evolution of morphological scaling

Cryptic individual scaling relationships and the evolution of morphological scaling

One size fits all? Determinants of sperm transfer in a highly dimorphic orb‐web spider

Genotype × environment interaction is weaker in genitalia than in mating signals and body traits in Enchenopa treehoppers (Hemiptera: Membracidae)

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