Egg-laying site, fecundity and degree of sexual size dimorphism in frogs

Abstract Female fecundity is an important selective force leading to female-biased sexual size dimorphism (SSD) in frogs. Because anurans exhibit diverse reproductive modes, we investigated whether variation in SSD and fecundity are related with oviposition site. We asked whether arboreal breeding species show pronounced female-biased SSD and if, paradoxically, females have lower fecundity because of the costs of carrying oocytes and amplectant males. Conversely, we tested whether species that deposit eggs in concealed sites show less pronounced SSD, because females do not carry males and space limitation may reduce female size and fecundity. Our results showed that, in general, males were approximately 20% smaller than females. However, for species with hidden oviposition sites, males and females exhibited more similar body sizes and arboreal hylids showed more pronounced female-biased SSD. Overall, fecundity was higher in aquatic breeders, as expected, but in hylids, fecundity was smaller in arboreal breeders, which suggests that arboreality may impose restrictions on fecundity. By analysing SSD in a broader and more specific lineage (Hylidae), we found that reproductive microhabitat may also influence female size and fecundity, playing an important role in the evolution of SSD in frogs at different evolutionary scales.

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

Biologia ◽

10.1515/biolog-2015-0137 ◽

2015 ◽

Vol 70 (9) ◽

pp. 1228-1233 ◽

Cited By ~ 3

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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Bigger Males, Bigger Females? Pigeons’ Sexual Size Dimorphism

Annual Research & Review in Biology ◽

10.9734/arrb/2020/v35i1030286 ◽

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.

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

Herpetological Journal ◽

10.33256/32.1.2733 ◽

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.

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Sexual Size Dimorphism and Survival of Male and Female Blackbirds (Icteridae)

The Auk ◽

10.1093/auk/98.3.457 ◽

1981 ◽

Vol 98 (3) ◽

pp. 457-465 ◽

Cited By ~ 15

Author(s):

William A. Searcy ◽

Ken Yasukawa

Keyword(s):

Sexual Size Dimorphism ◽

Relative Survival ◽

Female Size ◽

Male Size ◽

Size Dimorphism ◽

Large Size ◽

Survival Selection ◽

Female Survival ◽

Positive Correlations ◽

Dimorphic Species

Abstract In a between-species comparison of icterids, male survival decreases relative to female survival as the degree of sexual size dimorphism increases. This result is consistent with the hypothesis that male size is limited by survival selection in icterids; the degree of size dimorphism is known to correlate with the degree of polygyny in icterids, however, so the decreased relative survival of males in dimorphic species may be caused by some correlate of polygyny other than large size. Survival estimates based on records of recovery of dead birds show positive correlations between male size and male survival and between female size and female survival, but survival estimates based on recaptures of live birds fail to show such relationships.

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Sexual size dimorphism in the viviparous caecilian amphibian Geotrypetes seraphini seraphini (Gymnophiona: Dermophiidae) including an updated overview of sexual dimorphism in caecilian amphibians

Amphibia-Reptilia ◽

10.1163/15685381-00003057 ◽

2016 ◽

Vol 37 (3) ◽

pp. 291-299 ◽

Cited By ~ 1

Author(s):

Markus Maerker ◽

Sandy Reinhard ◽

Peter Pogoda ◽

Alexander Kupfer

Keyword(s):

Sexual Dimorphism ◽

Body Length ◽

Sexual Size Dimorphism ◽

Molecular Ecology ◽

Female Size ◽

Sexually Dimorphic ◽

Size Dimorphism ◽

Mating System Evolution ◽

Accurate Comparison ◽

Widespread Phenomenon

Sexual size dimorphism (SSD) describing intersexual size differences of a given taxon is a widespread phenomenon in the animal kingdom. SSD plays a significant role in understanding life history and mating system evolution. The snakelike morphology of limbless caecilian amphibians lacking obvious secondary sexual characters (in contrast to frogs and salamanders) impedes an accurate comparison between sexes.Here, the phylogenetically derived teresomatan and viviparous caecilianGeotrypetes seraphini seraphiniwas analysed for patterns of sexual dimorphism. In terms of body size females were the larger sex, but when body length was adjusted male-biased intersexual differences in cloacal shape appeared. The larger female size is likely explained by fecundity selection as clutch size was positively correlated to female body length. Unexpectedly a cryptic, ontogeny related variation of the nuchal collars was found. An overview of SSD in caecilians including data for 27 species of nine out of ten existing families revealed a quite high number of taxa showing sexually dimorphic head size dimensions exclusively present among phylogenetically derived teresomatan caecilians. Still further research including insights into the behavioural ecology and molecular ecology of mating systems is warranted to better understand the evolution of sexual size dimorphism of caecilian amphibians.

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Interpopulational variation in sexual dimorphism, reproductive output, and parasitism of Liophis miliaris (Colubridae) in the Atlantic forest of Brazil

Amphibia-Reptilia ◽

10.1163/156853806776052128 ◽

2006 ◽

Vol 27 (1) ◽

pp. 37-46 ◽

Cited By ~ 11

Author(s):

Lígia Pizzatto ◽

Otavio Marques

Keyword(s):

Body Size ◽

Sexual Dimorphism ◽

Atlantic Forest ◽

Reproductive Output ◽

Sexual Size Dimorphism ◽

The Other ◽

Female Body Size ◽

Body Sizes ◽

Northern Atlantic ◽

Males And Females

AbstractSexual maturity, sexual dimorphism, reproductive output, and parasitism of the colubrid snake Liophis miliaris were compared among populations inhabiting four regions of Brazil: (1) northern coastal Atlantic forest, (2) southern coastal Atlantic forest, (3) northern inland Atlantic forest (4) southern inland Atlantic forest. Females delayed maturity and attained larger body sizes than males in all regions. Males and females from northern Atlantic forest were smaller and attained maturity with a smaller body size than males of other regions. The sexual size dimorphism index ranged from 0.19 to 0.23 and was lowest in the northern Atlantic forest. There was no sexual dimorphism in head length in any of the populations studied. Clutch size was similar in all populations and increased with maternal body size. The reproductive frequency was lower in the northern coastal Atlantic forest and in contrast to the other regions, tended to increase with female body size. The nematoda Ophidiascaris sp. and cystacanths of Oligacanthorynchus spira (Acanthocephala) occurred equally in both sexes. Fewer snakes from the northern coastal Atlantic forest were infested by parasites compared to the other regions and parasitism apparently did not influence reproduction.

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Climate change and sexual size dimorphism in an Arctic spider

Biology Letters ◽

10.1098/rsbl.2009.0169 ◽

2009 ◽

Vol 5 (4) ◽

pp. 542-544 ◽

Cited By ~ 40

Author(s):

Toke Thomas Høye ◽

Jörg U. Hammel ◽

Thomas Fuchs ◽

Søren Toft

Keyword(s):

Climate Change ◽

Sexual Size Dimorphism ◽

Carapace Width ◽

Wolf Spider ◽

High Arctic ◽

Relative Fitness ◽

Size Dimorphism ◽

Adult Body ◽

Body Sizes ◽

Female Responses

Climate change is advancing the onset of the growing season and this is happening at a particularly fast rate in the High Arctic. However, in most species the relative fitness implications for males and females remain elusive. Here, we present data on 10 successive cohorts of the wolf spider Pardosa glacialis from Zackenberg in High-Arctic, northeast Greenland. We found marked inter-annual variation in adult body size (carapace width) and this variation was greater in females than in males. Earlier snowmelt during both years of its biennial maturation resulted in larger adult body sizes and a skew towards positive sexual size dimorphism (females bigger than males). These results illustrate the pervasive influence of climate on key life-history traits and indicate that male and female responses to climate should be investigated separately whenever possible.

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Size-Dependent Selective Mechanisms on Males and Females and the Evolution of Sexual Size Dimorphism in Frogs

The American Naturalist ◽

10.1086/678455 ◽

2014 ◽

Vol 184 (6) ◽

pp. 727-740 ◽

Cited By ~ 33

Author(s):

Renato C. Nali ◽

Kelly R. Zamudio ◽

Célio F. B. Haddad ◽

Cynthia P. A. Prado

Keyword(s):

Sexual Size Dimorphism ◽

Size Dimorphism ◽

Size Dependent ◽

Males And Females

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Egg size, prey size, and sexual size dimorphism in digger wasps (Hymenoptera: Sphecidae)

Canadian Journal of Zoology ◽

10.1139/z85-323 ◽

1985 ◽

Vol 63 (9) ◽

pp. 2187-2193 ◽

Cited By ~ 41

Author(s):

Kevin M. O'Neill

Keyword(s):

Body Size ◽

Selection Pressure ◽

Sexual Size Dimorphism ◽

Species Selection ◽

Male Size ◽

Size Dimorphism ◽

Female Body Size ◽

Mean Size ◽

Males And Females ◽

Apparent Association

Female digger wasps invest substantially in each of their offspring, laying relatively few, large eggs and providing the young with the insect prey on which they depend for food. In a study of six species in the genera Philanthus, Bembecinus, and Bembix, it was found that within each species, there is a positive correlation between female body size and both the size of their ovarial eggs and the size of the prey they provision. In five of the six species, females were larger than males on average. It is suggested that the apparent association between body size and certain aspects of parental investment by females may provide the directional selection pressure that results in the evolution of sexual size dimorphism in digger wasps. In one species, males and females have the same mean size, probably because, in this species, selection pressure on male size is similar to that on females.

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Size- and sex-specific predation on dung flies by amphibian and arthropod predators – size match matters

10.1101/631549 ◽

2019 ◽

Author(s):

Wolf U. Blanckenhorn ◽

Gabriele Cozzi ◽

Gregory Jäggli ◽

Juan Pablo Busso

Keyword(s):

Body Size ◽

Sexual Size Dimorphism ◽

Rana Temporaria ◽

Large Body ◽

Mechanistic Study ◽

Mating Activity ◽

Size Dimorphism ◽

Arthropod Predators ◽

Body Sizes ◽

Predation Rates

Because predator-prey interactions in nature are multifarious, linking phenomenological predation rates to the underlying behavioural or ecological mechanisms is challenging. Size- and sex-specific predation has been implicated as a major selective force keeping animals small, affecting the evolution of body size and sexual size dimorphism. We experimentally assessed predation by various amphibian (frogs and toads) and arthropod predators (bugs, flies, spiders) on three species of dung flies with similar ecology but contrasting body sizes, sexual size dimorphism and coloration. Predators were offered a size range of flies in single- or mixed-sex groups. As expected based on optimal foraging theory, some anurans (e.g. Bufo bufo) selected larger prey, thus selecting against large body size of the flies, while others (Bombina variagata and Rana esculenta) showed no such pattern. Small juvenile Rana temporaria metamorphs, in contrast, preferred small flies, as did all arthropod predators, a pattern that can be explained by larger prey being better at escaping. The more mobile males were not eaten more frequently or faster than the cryptic females, even when conspicuously colored. Predation rates on flies in mixed groups permitting mating activity were not higher, contrary to expectation, nor was predation generally sex-specific. We conclude that the size-selectivity of predators, and hence the viability selection pattern exerted on their prey, depends foremost on the relative body sizes of the two in a continuous fashion. Sex-specific predation by single predators appears to contribute little to sexual dimorphism. Therefore, the mechanistic study of predation requires integration of both the predator’s and the prey’s perspectives, and phenomenological field studies of predation remain indispensable.

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