scholarly journals Female‐biased gape and body‐size dimorphism in the New World watersnakes (tribe: Thamnophiini) oppose predictions from Rensch's rule

2019 ◽  
Vol 9 (17) ◽  
pp. 9624-9633 ◽  
Author(s):  
Frank T. Burbrink ◽  
India Futterman
Keyword(s):  
Body Size ◽  
New World ◽  
Rensch’S Rule ◽  
Size Dimorphism ◽  
Rensch's Rule

scholarly journals Bigger Males, Bigger Females? Pigeons’ Sexual Size Dimorphism

2020 ◽  
pp. 20-24
Author(s):  
P. M. Parés- Casanova ◽  
A. Kabir
Keyword(s):  
Body Weight ◽  
Body Size ◽  
Sexual Size Dimorphism ◽  
Wing Length ◽  
Rensch’S Rule ◽  
Size Dimorphism ◽  
Rensch's Rule ◽  
Neck Thickness ◽  
Males And Females ◽  
Domestic Pigeons

Sexual dimorphism, defined as phenotypic differences between males and females, is a common phenomenon in animals. In this line, Rensch’s rule states that sexual size dimorphism increases with increasing body size when the male is the larger sex and decreases with increasing average body size when the female is the larger sex. Domesticated animals offer excellent opportunities for testing predictions of functional explanations of Rensch’s theory. Pigeon breeds encounters many different functional purposes and selective constraints, which could influence strongly their morphology. The aim of this paper is to examine, for first time, Rensch’s rule among domestic pigeons. It was compiled a database of 12 quantitative traits (body weight, body height, beak thickness, beak length, neck length, neck thickness, wing length, rump width, tail length, tarsus length, tarsus thickness and middle toe length) for males and females of 11 different domestic pigeon breeds: Bangladesh Indigenous, Racing Homer, Turkish Tumbler, Indian Lotan, Kokah, Mookee, Indian Fantail, Bokhara Trumpeter, Bombai, Lahore and Hungarian Giant House; Rock Pigeon (Columba livia) was also considered as wild relative for comparative purposes. Comparative results between males and females showed that only body weight, wing length and neck thickness were consistent with Rensch’s rule. The rest of trait did not present correlations. Among domestic pigeons, there can appear different expressions of dimorphism according to each trait, so it must be considered that Rensch’s rule vary when considering other traits than body weight.

Evolution of sexual dimorphism in the plateau brown frog fails to obey Rensch’s rule

2022 ◽  
pp. 27-33
Author(s):  
Tong Lei Yu
Keyword(s):  
Body Size ◽  
Large Male ◽  
Large Female ◽  
Female Size ◽  
Rensch’S Rule ◽  
Size Dimorphism ◽  
Rensch's Rule ◽  
Males And Females ◽  
Brown Frog ◽  
Using Data

Rensch’s rule describes sexual size dimorphism (SSD) that decreases with increasing body size when females are larger than males and SSD that increases when males are larger than females. The plateau brown frog Rana kukunoris, a species endemic to the eastern Tibetan Plateau, exhibits female-biased size dimorphism. Using data on body size from 26 populations and age from 21 populations, we demonstrated that SSD did not increase with increasing mean female snout-vent length (SVL) when controlling for sex-specific age structure, failing to support the Rensch’s rule. Thus, we suggest that fecundity selection (favouring large female size) balances out sexual selection (favouring large male size), which results in a similar divergence between males and females body size. In addition, sex-specific age differences explained most of the variation of SSD across populations.

Testing Rensch’s rule in Acanthoscelides macrophthalmus, a seed-feeding beetle infesting Leucaena leucocephala plants

2019 ◽  
Vol 97 (4) ◽  
pp. 304-311
Author(s):  
M.N. Rossi ◽  
E.B. Haga
Keyword(s):  
Body Size ◽  
Leucaena Leucocephala ◽  
Morphological Traits ◽  
Genetic Basis ◽  
Sexual Size Dimorphism ◽  
The Body ◽  
Rensch’S Rule ◽  
Size Dimorphism ◽  
Rensch's Rule ◽  
Males And Females

Rensch’s rule states that males vary more in size than females when body size increases. The main cause of Rensch’s rule has been credited to sexual selection. However, different degrees of plasticity between the sexes have also been proven to be useful for describing variations in sexual size dimorphism, particularly within an intraspecific context. For insects, in general, this rule has rarely been tested within species. Here, we tested whether Acanthoscelides macrophthalmus (Schaeffer, 1907) (Coleoptera: Chrysomelidae: Bruchinae) followed Rensch’s rule when individuals emerged from seeds immediately after fruit collection and when they were reared for one generation, by measuring three morphological traits. Rensch’s rule was not followed for any of the morphological traits. Variations in body size were similar in males and females for bruchines that first emerged from seeds and for those that were reared for one generation. These findings suggest that environmental conditions (e.g., temperature, humidity, and seasonality) are unlikely to drive differential plasticity in males and females of this seed-feeding beetle. It is possible that changes in the body size of A. macrophthalmus have a genetic basis. However, regardless of whether variations in body size have a genetic basis, our findings provide no support for Rensch’s rule.

Pattern of sexual size dimorphism supports the inverse of Rensch’s rule in two frog species

2014 ◽  
Vol 64 (1) ◽  
pp. 87-95 ◽  
Author(s):  
Di Lu ◽  
Cai Quan Zhou ◽  
Lian Jun Zhao ◽  
Wen Bo Liao
Keyword(s):  
Body Size ◽  
Sexual Size Dimorphism ◽  
Rana Temporaria ◽  
Rensch’S Rule ◽  
Size Dimorphism ◽  
Rensch's Rule ◽  
Frog Species ◽  
Mean Size ◽  
The Common ◽  
Males And Females

Rensch’s rule describes that sexual size dimorphism (SSD) increases with body size (hyperallometry) when males are larger, and decreases with body size (hypoallometry) when males are smaller. In this paper, on the basis of mean adult body size resulting from 18 populations of the common frogRana temporariaand 24 populations of the Tibetan frogNanorana parkeri, we tested the consistency of allometric relationships between males and females with Rensch’s rule. Our results show that the variation in degree of female-biased SSD increased with increasing mean size at intraspecific levels in two species, which is consistent with the inverse of Rensch’s rule. Furthermore, we tested the hypothesis that the degree of SSD decreased with increasing altitudes. Inconsistent with the predications of our hypothesis, we found no relationships between the degree of SSD and altitude for the two species investigated. These findings suggest that females living in adverse climates in high altitudes cannot adjust their body size as plastically as males.

scholarly journals Effects of Sex and Breeding Status on Skull Morphology in Cooperatively Breeding Ansell’s Mole-Rats and an Appraisal of Sexual Dimorphism in the Bathyergidae

2021 ◽  
Vol 9 ◽  
Author(s):  
Kai R. Caspar ◽  
Jacqueline Müller ◽  
Sabine Begall
Keyword(s):  
Body Size ◽  
Morphological Differentiation ◽  
Reproductive Status ◽  
Skull Morphology ◽  
Rensch’S Rule ◽  
Size Dimorphism ◽  
Rensch's Rule ◽  
Cooperatively Breeding ◽  
Scaling Analyses ◽  
Breeding Status

African mole-rats of the genus Fukomys (Northern common mole-rats) combine a monogamous mating system and pronounced sexual size dimorphism; a pattern highly untypical for mammals. At the same time, they live in cooperatively breeding groups composed of reproductive and non-reproductive members of both sexes. How and to which degree sex and breeding status influence morphofunctional characters in eusocial mole-rats is not well characterized but essential to come to a comprehensive understanding of their peculiar social system. Here, we explore patterns of morphological differentiation in skulls of Ansell’s mole-rats (Fukomys anselli) by means of multivariate analysis of linear skull measurements combined with a 2D shape analysis of cranium and mandible. Compared to females, males display larger skulls relative to body size and show an expansion of the facial portion of the cranium, while reproductive status did not have an effect on any of the traits studied. We also show that species of Fukomys mole-rats display a scaling of relative sexual body size dimorphism in compliance to Rensch’s rule, which is deemed indicative of intense male intrasexual competition. For the bathyergid family as a whole, results of scaling analyses were more ambiguous, but also indicative of Rensch’s rule conformity. In line with genetic field data, our results point to a greater role of male-male conflicts in Fukomys than is traditionally assumed and support the notion that reproductive status does not correlate with morphofunctional segregation in these unusual rodents.

Body size, sexual size dimorphism, and Rensch's rule in adult hydropsychid caddisflies (Trichoptera: Hydropsychidae)

2003 ◽  
Vol 81 (12) ◽  
pp. 1956-1964 ◽  
Author(s):  
Jason E Jannot ◽  
Billie L Kerans
Keyword(s):  
Body Size ◽  
Sexual Size Dimorphism ◽  
Interspecific Interactions ◽  
Size Variation ◽  
Rensch’S Rule ◽  
Size Dimorphism ◽  
Selective Pressures ◽  
Rensch's Rule ◽  
Phylogenetic Inertia ◽  
Males And Females

Body size influences most biological processes from metabolic rates to the outcome of interspecific interactions. Within a species, sexual size dimorphism (SSD) reflects either differential selection on body size of males and females or phylogenetic inertia. Among taxa, SSD should decrease as body size increases when females are the larger sex — a pattern known as Rensch's rule. We examined body size, SSD, and Rensch's rule among 29 species of adult hydropsychid caddisflies (Trichoptera: Hydropsychidae) and 12 closely related caddisfly species. Females were almost always larger than males in all species examined. Body size variation among genera was greater than variance among species. In contrast, the greatest variance in SSD was among species within a genus. Contrary to Rensch's rule, the degree of SSD did not change as body size increased among genera. Observed body size patterns suggest that hydropsychid caddisfly species within a genus may be subjected to similar selective pressures during the larval stage, but this issue remains to be investigated. In addition, our data suggest that hydropsychids may violate Rensch's rule, a pattern not often reported. Our data provide a basis for proposing and testing hypotheses about the ecology and evolution of hydropsychid caddisflies.

Plasticity in sexual size dimorphism and Rensch’s rule in Mediterranean blennies (Blenniidae)

2008 ◽  
Vol 86 (10) ◽  
pp. 1173-1178 ◽  
Author(s):  
W. Lengkeek ◽  
K. Didderen ◽  
I. M. Côté ◽  
E. M. van der Zee ◽  
R. C. Snoek ◽  
...  
Keyword(s):  
Genetic Variation ◽  
Sexual Size Dimorphism ◽  
Fine Scale ◽  
Evolutionary Patterns ◽  
Rensch’S Rule ◽  
Size Dimorphism ◽  
Rensch's Rule ◽  
Close Proximity ◽  
Species Comparisons ◽  
Aidablennius Sphynx

Comparative analyses of sexual size dimorphism (SSD) across species have led to the discovery of Rensch’s rule. This rule states that SSD increases with body size when males are the largest sex, but decreases with increasing size when females are larger. Within-species comparisons of SSD in fish are rare, yet these may be a valuable tool to investigate evolutionary patterns on a fine scale. This study compares SSD among closely related populations of three species of Mediterranean blennies (Blenniidae): Microlipophrys canevae (Vinciguerra, 1880), Parablennius incognitus (Bath 1968), and Aidablennius sphynx (Valenciennes, 1836). SSD varied more among populations than among species and Rensch’s rule was confirmed within two species. It is not likely that the variation among populations in SSD mirrors genetic variation, as many of the populations were in close proximity of one another, with a high potential for genetic exchange. This study complements larger scale analyses of other taxa and demonstrates the fine scale on which evolutionary processes responsible for Rensch’s rule may be operating.

scholarly journals Sexual selection explains Rensch's rule of size dimorphism in shorebirds

2004 ◽  
Vol 101 (33) ◽  
pp. 12224-12227 ◽  
Author(s):  
T. Szekely ◽  
R. P. Freckleton ◽  
J. D. Reynolds
Keyword(s):  
Sexual Selection ◽  
Rensch’S Rule ◽  
Size Dimorphism ◽  
Rensch's Rule

scholarly journals Sexual selection explains Rensch's rule of allometry for sexual size dimorphism

2007 ◽  
Vol 274 (1628) ◽  
pp. 2971-2979 ◽  
Author(s):  
James Dale ◽  
Peter O Dunn ◽  
Jordi Figuerola ◽  
Terje Lislevand ◽  
Tamás Székely ◽  
...  
Keyword(s):  
Sexual Selection ◽  
Sexual Size Dimorphism ◽  
Bird Species ◽  
Confounding Factors ◽  
Allometric Relationship ◽  
Rensch’S Rule ◽  
Size Dimorphism ◽  
Rensch's Rule ◽  
Clear Solution ◽  
General Explanation

In 1950, Rensch first described that in groups of related species, sexual size dimorphism is more pronounced in larger species. This widespread and fundamental allometric relationship is now commonly referred to as ‘Rensch's rule’. However, despite numerous recent studies, we still do not have a general explanation for this allometry. Here we report that patterns of allometry in over 5300 bird species demonstrate that Rensch's rule is driven by a correlated evolutionary change in females to directional sexual selection on males. First, in detailed multivariate analysis, the strength of sexual selection was, by far, the strongest predictor of allometry. This was found to be the case even after controlling for numerous potential confounding factors, such as overall size, degree of ornamentation, phylogenetic history and the range and degree of size dimorphism. Second, in groups where sexual selection is stronger in females, allometry consistently goes in the opposite direction to Rensch's rule. Taken together, these results provide the first clear solution to the long-standing evolutionary problem of allometry for sexual size dimorphism: sexual selection causes size dimorphism to correlate with species size.

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