Sexual size dimorphism in anurans

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Sexual dimorphism in body size may also be influenced by selection pressures Magnitude of size dimorphism in anuran amphibians as a function of relative. Sexual size dimorphism (SSD) is related to ecology, behaviour and life history of organisms. Rensch's rule states that SSD increases with. dimorphism in anurans, Woolbright assumed that (1) sexual selection favors pothesized that the female/male size ratio for anurans should be proportional to.

Sexual size dimorphism (SSD) is widespread in the animal kingdom SSD and sex-difference in adult age for 30 anuran spe- cies (Monnet. dimorphism in anurans, Woolbright assumed that (1) sexual selection favors pothesized that the female/male size ratio for anurans should be proportional to. Abstract. Background: Sexual size dimorphism (SSD) is related to ecology, behaviour and life history of organisms. Rensch's rule states that.

Sexual size dimorphism (SSD) is related to ecology, behaviour and life history of organisms. Rensch's rule states that SSD increases with. Sexual size dimorphism (SSD) is widespread in the animal kingdom SSD and sex-difference in adult age for 30 anuran spe- cies (Monnet. Ever since Darwin, why and how sexual size dimorphism (SSD) arises among the animal kingdom has puzzled evolutionary biologists.






Sizze via Dimorphism. To study the mating size, female reproduction and size size dimorphism in a population of Microhyla fissipesamplexus 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 size a female-larger pair, a size that was often observed for M.

Interestingly, snout-vent length of males in male-larger sexual was greater than that in female-larger pairs, however anurans post-spawning body mass, dimkrphism size, egg dry anurans and clutch dry mass did not differ between both types of pairs. Snout-vent length of males was positively related to that size females in each amplexus pair.

After accounting for the snout-vent dimorphism of females, we showed that snout-vent lengths of males in male-larger pairs were greater than those anurans females in female-larger pairs. The snout-vent length ratio of males and females was not related to fertilization rate in sexual amplexus pair. The mean fertilization rate was not different between both amplexus pairs. Andersson M. Arak A. In: P. Bateson Ed. Mate Choice pp. Bastos R. Bell R.

B Sexual. Bourne G. Buzatto B. Thyer E. Roberts J. Evolution 71 - Cai M. In: L. Fei S. Huang Eds Fauna Sinica Amphibia vol.

Science Press Beijing, China. Chajma P. Crespi Secual. Davies N. Anurans 56 - De Lisle S. Dittrich C.

Segev O. Feldhaar Dimorphism. Vences M. Fairbairn Anurans. Fan X. Lin Z. Fei L. Gosner K. Sexual 16 - sexual Gramapurohit N. Green D. Halliday Dimorphism. In: H.

Han X. A comparative analysis. BMC Evol. DOI: Krupa J. Copeia - Kuramoto M. Liao W. Naturwissenschaften 99 - Zeng Y. Zhou C. Liu W. Oecologia - Liu C. In: D. Yang Ed. The Amphibian-Fauna of Yunnan pp. Liu S. Song Z. Zhang J. Sichuan Univ. Lou S. Zhao L. Marco A. Kiesecker J. Chivers D. McGarrity M. Invasions 11 - Monnet J. Nali R. Zamudio K. Haddad C. Orense M. Herpetologica 46 - sexual Robertson Anurans.

Rudoy A. PeerJ 5 e Ryan M. Science - Shine R. Freckleton R. USA - Taylor E. Kansas Sci. Vojar Dimorphism. Wells K. Woolbright L. Mating pattern, female reproduction and sexual size dimorphism in a narrow-mouthed frog Microhyla fissipes In: Animal Biology. Dimorphism price:. Add to Cart. Rent on DeepDyve. Ajurans References. AnderssonM.

ArakA.

Sexual selection is generally thought to favour larger males, and should therefore result in male-biased SSD[ 26 ]. Female-biased SSD, on the other hand, can arise in species where females strongly compete for mates[ 14 ]. Thirdly, correlational selection predicts that strong selection on size in one sex also affects the opposing sex, revealing a phenotypic coupling for size between the sexes among related species, as well as among populations within species[ 2 ].

When sexual and fecundity selection are unequal or one of them is lacking, then the stronger force will drive size divergence between populations or species through the respective sex, while the other sex will change at a slower pace due to genetic correlations between sexes. However, the trend is questionable in species with female-biased SSD[ 22 — 24 ]. In anurans, sexual size dimorphism is generally female-biased[ 29 ]. Model I revealed a significant isometric relationship between the mean size of the sexes across 39 species i.

Allometry of SSD in anurans. The thick grey line represents isometry, i. Each dot represents one species based on the mean body size of males and females. Each dot represents a species. The phylogenetic tree of the anuran used in the comparative analysis following Frost et al. The results of our inter-specific study conform to this pattern. To explain the lack of association between SSD and size, we suggest that fecundity selection on females favouring large size which is supposed to be strong in ectotherms balances out sexual selection in favour of large male size.

Variation in SSD is affected by factors other than sexual, correlational and fecundity selection, including life-history traits as well as energetic and ecological constraints. Previous studies showed that SSD in anurans can be explained by age differences between males and females[ 16 , 32 , 37 — 49 ]. Similarly, developmental time differences between the sexes previously explained the extent of SSD in arthropods[ 2 , 15 ] and fish[ 16 ].

SSD results from sexual divergence in ontogenetic trajectories[ 50 — 52 ], which may reflect a trade-off in energy allocation between somatic growth, survival and reproduction[ 53 ]. Like most ectothermic animals with indeterminate growth, the age at maturity is a critical life-history trait to determine the ontogenetic trajectory in anurans.

Males usually mature earlier than females[ 54 ], resulting in a female-biased SSD because a later maturation leads to more energy being devoted to somatic growth to achieve large body size[ 44 , 54 ]. Growth rates also contribute to body size and thus to SSD. SSD in anurans is positively correlated with sex difference in age at maturity, and negatively correlated with the corresponding difference in annual growth rate, with the relative contributions of age and growth to SSD varying among species[ 52 ].

Energy is the ultimate basis underlying the growth divergence between sexes when selection favours males and females to reach differential optimal sizes. For anurans with female-biased SSD, strong fecundity selection enhances female investment in offspring production, constraining their potential for growth[ 52 ]. Males could be less affected from such constraints because, compared to females, reproduction is significantly less costly for them[ 52 , 53 ]. Ecological factors usually operate through ontogeny in sex-specific ways to affect the body size of individuals and species[ 55 — 57 ].

Diet and temperature can induce substantial phenotypic plasticity in body size of ectothermic animals. In general, animals reared on lower quality diets mature smaller[ 58 , 59 ], and animals reared at lower developmental temperatures mature larger[ 60 ]. Variation in SSD can arise when males and females respond differently to diet or temperature differential- plasticity hypothesis [ 61 ]. Treating species as independent units yielded in results which are qualitatively different from those using phylogenetically independent contrasts.

SSD contrasts can be explained by SAD contrasts because the relationships between female and male size and age may not be influenced by phylogenetic relatedness. Similarly, variation in SSD in 17 anurans has previously been explained through SAD based on phylogenetic information incorporating independent contrasts[ 32 ]. Like in previous studies[ 25 , 35 ], methodological aspects give reason to view our results with caution. Mean age and size may vary considerably between years in the same population.

Skeletochronology might also be problematic, because endosteal resorption and false lines can affect age estimation. However, any bias in estimating individual age should equally affect males and females. However, Harvey and Pagel[ 63 ] pointed out that comparisons across species still lead to meaningful analyses unless they depend on a cluster of points that share an immediate common ancestor.

We obtained sex-specific demographic and morphological data on mean age and size across 39 species and 17 genera from the literature and our own data based on species from the Sichuan Province, China Additional file 1 : Table S1. Individuals were collected by hand at night using a flashlight. Sex was determined based on secondary sexual characteristics vocal sacs in adult males, and eggs readily visible through the abdominal skin in adult females.

We measured body size snout-vent length, SVL of each individual using a calliper, holding each individual in its normal posture.

Some individuals were subsequently released at the point of capture, whereas other individuals were brought to the lab for studying testis size and sperm traits. Individual age was estimated by skeletochronology as follows.

Endosteal resorption of long bones starts from the inner surface of the bone, enlarging the marrow cavities and eroding a portion of LAGs after hibernation[ 40 ]. False and double lines were rarely observed and not considered as true LAGs in all samples. Following Monnet and Cherry[ 32 ], we calculated the mean values for the population as algebraic means for each year, weighted by sample size.

Mean values for species were obtained as algebraic means of population values regardless of the sample size in cases where data were available for different populations. We calculated SAD as the difference between log-transformed female and male mean ages because age is strongly heteroscedastic. We calculated mean size and age in both sexes for ancestral nodes as the algebraic mean of the two closest lower nodes[ 61 ].

Details of the general procedure for estimating the character values in the ancestors are presented in Felsenstein[ 62 ]. With 39 species at the tips of this reconstructed tree, 38 39—1 SSD and SAD pairs of contrasts could be computed for pairs of nodes sharing an immediate common ancestor, and then re-scaled and analysed as suggested by Garland et al.

Correct standardization and homogeneity of variance of standardized contrasts were confirmed using the method proposed by Purvis and Rambaut[ 67 ]. We applied a General Linear Model GLM treating body size as a dependent variable and species and sex as fixed factors to test for sex differences in mean body length.

We used the log-scaled size of one sex regressing against the log-scaled size of the other sex to test for allometry vs. When performing a simple regression between log 10 —transformed female and male size, measurement error will be approximately equal in both sexes. The Model I regression Ordinary Least Squares, OLS would be statistically incorrect as neither male nor female size measurements are fixed nor measured with error[ 2 ].

We therefore regarded a Model II regression e. All statistical tests were two-tailed, and performed on the log-transformed values of the original data. Shine R: Ecological causes for the evolution of sexual size dimorphism: a review of the evidence.

Q Rev Biol. Fairbairn DJ: Allometry for sexual size dimorphism: pattern and process in the coevolution of body size in males and females. Ann Rev Ecol Syst. Bon Zool Beitr. Am Nat. Andersen NM: A phylogenetic analysis of the evolution of sexual dimorphism and mating systems in water striders Hemiptera: Gerridae. Biol J Linn Soc. J Evol Biol. Payne RB: Sexual selection, lek and arena behavior, and sexual size dimorphism in birds.

Int J Primat. Young KA: Life-history variation and allometry for sexual size dimorphism in Pacific salmon and trout. Evol Ecol. Anim Beha. PLoS One. J Anim Ecol.

Preziosi RF, Fairbairn DJ: Lifetime selection on adult body size and components of body size in a waterstrider: opposing selection and maintenance of sexual size dimorphism. Fairbairn DJ, Preziosi RF: Sexual selection and the evolution of allometry for sexual size dimorphism in the water strider, Aquarius remigis.

Arak A: Sexual dimorphism in body size: a model and test. Shine R: Sexual selection and sexual dimorphism in the Amphibia. Nature 56 - De Lisle S. Dittrich C. Segev O. Feldhaar H. Vences M. Fairbairn D. Fan X. Lin Z. Fei L. Gosner K. Herpetologica 16 - Gramapurohit N. Green D. Halliday T. In: H. Han X. A comparative analysis. BMC Evol. DOI: Krupa J. Copeia - Kuramoto M. Liao W. Naturwissenschaften 99 - Zeng Y. Zhou C. Liu W. Oecologia - Liu C.

In: D. Yang Ed. The Amphibian-Fauna of Yunnan pp. Liu S. Song Z. Zhang J. Sichuan Univ. Lou S. Zhao L. Marco A.

Kiesecker J. Chivers D. McGarrity M. Invasions 11 - Monnet J. Nali R. Zamudio K. Haddad C. Orense M. Herpetologica 46 - Robertson J. Rudoy A. PeerJ 5 e Ryan M. Science - Shine R. Freckleton R. USA - Taylor E. Kansas Sci. Vojar J. Wells K. Woolbright L. Mating pattern, female reproduction and sexual size dimorphism in a narrow-mouthed frog Microhyla fissipes In: Animal Biology.

Article price:. Add to Cart. Rent on DeepDyve. Export References. Andersson , M. Arak , A. Mate Choice, pp. Bastos , R. Bell , R. Bourne , G. Buzatto , B. Evolution, 71 , - Cai , M. Fei , S. Huang Eds Fauna Sinica, Amphibia, vol.