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).

Age and growth of the red-belied lizard, Darevskia parvula

2016 ◽  
Vol 66 (1) ◽  
pp. 81-95 ◽  
Author(s):  
Ufuk Bülbül ◽  
Muammer Kurnaz ◽  
Ali İhsan Eroğlu ◽  
Halime Koç ◽  
Bilal Kutrup
Keyword(s):  
Growth Rate ◽  
Sexual Size Dimorphism ◽  
Climatic Factors ◽  
High Elevation ◽  
Older Age ◽  
Age And Growth ◽  
Growth Coefficient ◽  
Size Dimorphism ◽  
Lower Elevation ◽  
Two Populations

In the present study, we investigated potential effects of some environmental climatic factors on life-history traits of twoDarevskia parvulapopulations located at different elevation sites and evaluated age, body size, SSD and growth rate results in these lizards. The age at maturity and longevity were found to be similar in both populations. Males of the highland population had significantly larger snout-vent length and older age than those of the lowland population. Although the mean ages of females were not significantly different between the two populations, the highland population had significantly larger snout-vent length than the lowland population. Considering all individuals (both males and females), we found that specimens from the population in the higher-elevation site had significantly larger snout-vent length and older age than those of the lower-elevation site. A low level of male-biased sexual size dimorphism was observed in both populations. The growth coefficient was lower in the high-elevation site than the lower elevation site. Growth rates were not significantly different between the populations. Our preliminary results indicate that although our studied populations were located at different elevation sites and had distinct climate, longevity, age at sexual maturity and growth rate results were similar. This may be a reason of the lower male-biased sexual size dimorphism in both populations.

scholarly journals Ontogenetic mechanisms underlying sexual size dimorphism in Urodele amphibians: An across-species approach

2013 ◽  
Vol 59 (1) ◽  
pp. 142-150 ◽  
Author(s):  
Lixia Zhang ◽  
Xin Lu
Keyword(s):  
Growth Rate ◽  
Body Size ◽  
Evolutionary Biology ◽  
Sexual Size Dimorphism ◽  
Demographic Data ◽  
High Growth ◽  
Annual Growth Rate ◽  
Size Dimorphism ◽  
Ontogenetic Trajectory ◽  
Delayed Maturation

Abstract Why do two sexes of the same species differ in body size holds a long-standing question of evolutionary biology. While many across-species comparisons have focused on ultimate causes behind sexual size dimorphism (SSD), only have a few been directed toward elucidating its ontogenetic basis. Urodeles are an amphibian group in which the direction and degree of SSD vary greatly among species. Using demographic data yielded by skeletochronology for 33 urodele species, the current study reveals a positive across-species correlation between SSD and the sex difference in mean age of adult animals, and the latter increases with the corresponding difference in age at maturity; annual growth rate does not differ between the sexes. We conclude that extended longevities in one sex, which is mediated by delayed maturation, would allow it to grow for longer and get larger, with growth rate making a weak contribution to body size. The sex-specific divergence in ontogenetic trajectory might be explained by potentially high growth costs of reproduction to females in association with stronger fecundity selection, and to males that are expected to experience stronger sexual selection.

Growth, maturity, and sexual dimorphism in the wood turtle, Clemmys insculpta

1990 ◽  
Vol 68 (4) ◽  
pp. 672-677 ◽  
Author(s):  
Jeffrey E. Lovich ◽  
Carl H. Ernst ◽  
John F. McBreen
Keyword(s):  
Body Size ◽  
Sexual Dimorphism ◽  
Carapace Length ◽  
Sexual Size Dimorphism ◽  
Von Bertalanffy ◽  
Size Dimorphism ◽  
Adult Females ◽  
Body Sizes ◽  
Von Bertalanffy Growth Model ◽  
Wood Turtle

Growth in the wood turtle (Clemmys insculpta) is described using the von Bertalanffy growth model and nonlinear regression. Growth in both sexes is similar until about 160 mm plastron length. Males grew at a faster rate after this size. Males appear to mature at a larger size and later age than females, although age-specific body size is highly variable. Sexual size dimorphism, in carapace length, is pronounced, with males attaining mean body sizes significantly larger (1.07–1.10 times) than those of adult females. Plastron length is an inappropriate measure of sexual size dimorphism because of the development of plastral concavity in males. Females tend to predominate in samples, possibly owing to differential maturity of the sexes. The direction of sexual size dimorphism may be maintained by intrasexual competition among males for access to females. Data for several adults captured at intervals of from 9 to 20 years support the concept of indeterminate growth.

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.

Sexual size dimorphism in relation to age and growth based on skeletochronological analysis in a Tibetan frog

2009 ◽  
Vol 30 (3) ◽  
pp. 351-359 ◽  
Author(s):  
Xin Lu ◽  
Xiaoyan Ma
Keyword(s):  
Growth Rate ◽  
Cross Sections ◽  
Sexual Difference ◽  
Sexual Size Dimorphism ◽  
Population Level ◽  
Age And Growth ◽  
Size Difference ◽  
Size Dimorphism ◽  
Asymptotic Size ◽  
Central Tibet

AbstractThe number of lines of arrested growth (LAGs) in diaphyseal cross-sections of phalanges or femora was used to assess individual age and growth of 612 Nanorana parkeri, including 363 males, 143 females, 70 juveniles, and 36 tadpoles, in a population from central Tibet, China. The oldest immature frogs had an age of 6 years; both the youngest sexually mature males and females were 3 years old. However, the majority of individuals bred for the first time at 5 years in males and 6 years in females. Females had greater average age (6.27 years) and lifespan (11 years) than males (5.72 and 10 years). At the population level, females, on average, were significantly larger in body length (40.3 mm) than males (37.0 mm). However, the significant size difference only occurred when both sexes were over 6 years old, at which most frogs attained maturity. Growth curve and growth rate estimated for each sex based on a von Bertalanffy model showed that females had a larger asymptotic size (54.2 mm) but smaller growth coefficient k (0.16) than males (40.0 mm, 0.37), and that females had greater growth rate than males in all age classes, except at metamorphosis. According to these results, we concluded that the sexual difference of growth between pre- and post-maturation periods contributed to the age-specific sexual size dimorphism of N. parkeri.

Sexual size dimorphism in steppe tortoises (Testudo horsfieldi): growth, maturity, and individual variation

2001 ◽  
Vol 79 (8) ◽  
pp. 1433-1441 ◽  
Author(s):  
Frédéric Lagarde ◽  
Xavier Bonnet ◽  
Brian T Henen ◽  
Johanna Corbin ◽  
Ken A Nagy ◽  
...  
Keyword(s):  
Growth Rate ◽  
Individual Variation ◽  
Sexual Difference ◽  
Sexual Size Dimorphism ◽  
Age And Growth ◽  
Size At Maturity ◽  
Size Dimorphism ◽  
Size Dependent ◽  
Complex Interactions ◽  
Size At Birth

Age and size at maturity are determined through complex interactions among size at birth, growth rate, maturation, and survival. We studied sexual size dimorphism and growth rate and maturation patterns in a long-lived organism, the steppe tortoise (Testudo horsfieldi), using the scute lamina number and width as age and growth measures. There was no sexual difference in the juvenile growth rate, but females matured later and hence were larger at maturity than males. We also observed considerable inter-individual variation in age and size at maturity. In both sexes, precocious animals grew faster during the juvenile phase but matured at a smaller body size than did tardy animals. Consequently, maturity did not seem size-dependent per se but rather was determined by growth rate. The strong variation between and within the sexes in age and size at maturity suggest that different growth trajectories and maturation schedules depend upon sex and individual responses to resource availability.

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.

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