scholarly journals Sexual size dimorphism is the most consistent explanation for the body size spectrum of Confuciusornis sanctus

2010 ◽  
Vol 6 (4) ◽  
pp. 531-532 ◽  
Author(s):  
Winfried S. Peters ◽  
Dieter Stefan Peters
Keyword(s):  
Body Size ◽  
Sexual Size Dimorphism ◽  
The Body ◽  
Size Spectrum ◽  
Size Dimorphism

scholarly journals A skeletochronological estimate of age and growth in a large riparian frog from Madagascar (Anura, Mantellidae, Mantidactylus)

Herpetozoa ◽  
2019 ◽  
Vol 32 ◽  
pp. 39-44 ◽  
Author(s):  
Fabio M. Guarino ◽  
Angelica Crottini ◽  
Marcello Mezzasalma ◽  
Jasmin E. Randrianirina ◽  
Franco Andreone
Keyword(s):  
Growth Rate ◽  
Body Size ◽  
Sexual Size Dimorphism ◽  
The Body ◽  
Age And Growth ◽  
Growth Trajectories ◽  
Growth Coefficient ◽  
Size Dimorphism ◽  
Adult Females ◽  
Similar Growth

We characterized the body size (as snout-vent length), age, sexual size dimorphism, and growth rate in a population of one of the larger riparian frog from Madagascar (Mantidactylusgrandidieri) from a rainforest patch close to Vevembe, SE Madagascar. We identified a significant female-biased sexual size dimorphism. Age was estimated using phalangeal skeletochronology and was significantly higher in females than in males. Modal age class turned out to be 4 years in both sexes but a large percentage of adult females (75%) fell in the 5–6 years-old classes, while no male exceeded 4 years. We here report M.grandidieri as a medium-long-lived anuran species. Von Bertalanffy’s model showed similar growth trajectories between the sexes although the growth coefficient in females (k = 0.335) was slightly but not significantly higher than in males (k = 0.329).

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.

Mating pattern, female reproduction and sexual size dimorphism in a narrow-mouthed frog (Microhyla fissipes)

2019 ◽  
Vol 69 (2) ◽  
pp. 247-257
Author(s):  
Guo-Hua Ding ◽  
Yun Tang ◽  
Zhi-Hua Lin ◽  
Xiao-Li Fan ◽  
Li Wei
Keyword(s):  
Body Size ◽  
Sexual Size Dimorphism ◽  
Dry Mass ◽  
Fertilization Rate ◽  
The Body ◽  
Mating Pattern ◽  
Female Reproduction ◽  
Size Dimorphism ◽  
Males And Females ◽  
The Difference

Abstract The difference in body size and/or shape between males and females, called sexual size dimorphism, is widely accepted as the evolutionary consequence of the difference between reproductive roles. To study the mating pattern, female reproduction and sexual size dimorphism in a population of Microhyla fissipes, amplexus pairs were collected, and the snout-vent length of males and females, female reproductive traits and fertilization rate were measured. If the body size of amplexed females is larger than that of amplectant males, this is referred to as a female-larger pair, a phenomenon that was often observed for M. fissipes in this study. Interestingly, snout-vent length of males in male-larger pairs was greater than that in female-larger pairs, however the post-spawning body mass, clutch size, egg dry mass and clutch dry mass did not differ between both types of pairs. Snout-vent length of males was positively related to that of females in each amplexus pair. After accounting for the snout-vent lengths of females, we showed that snout-vent lengths of males in male-larger pairs were greater than those of females in female-larger pairs. The snout-vent length ratio of males and females was not related to fertilization rate in each amplexus pair. The mean fertilization rate was not different between both amplexus pairs. These results suggest that (1) M. fissipes displays female-biased sexual size dimorphism and has two amplexus types with size-assortative mating; (2) the snout-vent length ratio of males and females in each amplexus type was consistent with the inverse of Rensch’s rule, and was driven by the combined effect of sexual selection and fecundity selection; (3) females with a larger body size were preferred by males due to their higher fecundity, while the body size of males was not important for fertilization success.

scholarly journals Emergence ecology and body size dimorphism in Sympetrum fonscolombii and S. meridionale (Odonata: Libellulidae)

2019 ◽  
Vol 29 (1) ◽  
pp. 7-14 ◽  
Author(s):  
Sana Hadjadji ◽  
Hichem Amari ◽  
Nadia Bouiedda ◽  
Amina Guebailia ◽  
Nedjwa Boucenna ◽  
...  
Keyword(s):  
Body Size ◽  
Sex Ratio ◽  
Sexual Size Dimorphism ◽  
Seasonal Pattern ◽  
Biological Significance ◽  
Negative Relationship ◽  
The Body ◽  
Vertical Stratification ◽  
Size Dimorphism ◽  
Abiotic And Biotic Factors

The study of dragonfly emergence provides insights into the understanding of their life history, ecology, and adaptation to abiotic and biotic factors. Here we investigate the emergence ecology and body size of two congeneric dragonflies (Sympetrum fonscolombii Selys, and S. meridionale Selys) in Northeast Algeria, highlighting the seasonal pattern, sex ratio at emergence, sexual size dimorphism (SSD), and vertical stratification. We found that both species, S. fonscolombii in particular, showed quite asynchronous emergence. In both species, and especially in the larger S. meridionale, sex ratio was found to be female-biased, which is in line with the hypothesis of a negative relationship between SSD and sex ratio. There was no seasonal pattern of body size observed in both species. In S. meridionale, SSD with regard to both body and wing sheath length was male-biased, while in S. fonscolombii, it was male-biased with regard to body length and female-biased with regard to wing length. Vertical stratification depended on support height (the higher the support, the higher the height of exuvia fixation) but had a complex relationship with the body size. The biological significance and implications of the vertical stratification-body size relationship are discussed.

scholarly journals Sex-Specific Plasticity Explains Genetic Variation in Sexual Size Dimorphism in Drosophila

2021 ◽  
Author(s):  
Isabelle Vea ◽  
Austin S Wilcox ◽  
W Anthony Frankino ◽  
Alexander W Shingleton
Keyword(s):  
Genetic Variation ◽  
Body Size ◽  
Sexual Size Dimorphism ◽  
Theoretical Models ◽  
The Body ◽  
Condition Dependence ◽  
Male Body ◽  
Developmental Genetic ◽  
Size Dimorphism ◽  
Genetic Mechanisms

The difference in body size between females and males, or sexual size dimorphism (SSD), is almost ubiquitous, and yet we have a remarkably poor understanding of the developmental-genetic mechanisms that generate it. Such an understanding is important if we are to distinguish between the many theoretical models of SSD evolution. One such model is the condition dependence hypothesis, which proposes that the body size of the larger sex is also more environmentally sensitive, a phenomenon called sex-specific plasticity (SSP). Because SSP generates differences in female and male body size, selection on plasticity may underlie the evolution of sexual size dimorphism. To test this hypothesis, however, we need to know the genetic architecture of both SSD and SSP, which is challenging because both are characteristics of populations not individuals. Here, we overcome this challenge by using isogenic lineages of Drosophila to measure both SSD and SSP for a genotype. We demonstrate extensive genetic variation for SSD among genotypes that is tightly correlated with variation in SSP, indicating that the same developmental-genetic mechanisms regulate both phenomena. These data support the condition dependence hypothesis and suggest that the observed SSD is a consequence of selection on the developmental-genetic mechanisms that regulate SSP.

scholarly journals A uni- and multivariate analysis approach to reveal sexual size dimorphism in Iranian populations of Hypera postica (Coleoptera: Curculionidae)

Biologia ◽  
2015 ◽  
Vol 70 (9) ◽  
pp. 1228-1233 ◽  
Author(s):  
Ehsan Sanaei ◽  
Marjan Seiedy ◽  
Farzaneh Momtazi
Keyword(s):  
Body Size ◽  
Sexual Size Dimorphism ◽  
Egg Laying ◽  
Morphological Divergence ◽  
High Fecundity ◽  
Hypera Postica ◽  
Size Dimorphism ◽  
Female Body Size ◽  
Divergence Pattern ◽  
Iranian Populations

Abstract Body size dimorphism between genders is a commonly observed phenomenon in insects, usually manifested in larger female body size. Sexual Size Dimorphism (SSD) varies from species to species, the degree and direction influenced by certain evolutionary pressures. Intraspecific variation in SSD may also occur between populations. The Hypera postica (Gyllenhal, 1813) is a well-known alfalfa plant pest that shows a degree of morphological divergence in its populations. The female alfalfa weevils are very fecund and have a larger body size compared to males. To improve our knowledge on magnitude and direction of SSD in alfalfa weevil, we studied 200 specimens of H. postica from four Iranian populations (Karaj1, Karaj2, Tuyserkan and Jovein). 10 morphological variables from three external anatomic parts (pronotum, elytra and rostrum) and 45 ratio characters were statistically analyzed in order to determine the amount of SSD in Iranian populations. In addition we investigated for morphological divergence pattern in mentioned populations. The results of this study show that a low degree of morphological divergence occurs in Iranian populations. Measured variables indicate that the SSD pattern of H. postica is compatible with the Rensch’s rule, and is related to high fecundity of females and a lack of strong sexual selection. Also it is mentioned that the larger rostrum in females may correspond to its unique role in egg laying.

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