Seasonal cycles in testicular activity in the frog, Rana perezi

Delgado, M.J.; Gutiérrez, Patrícia; Alonso‐Bedate, M.

doi:10.1016/0016-6480(89)90049-x

Cited by 50 publications

(24 citation statements)

References 21 publications

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“…Um aspecto importante a ser salientado é que as variações climáticas não interferem no comprimento e peso dos testículos de D. minutus como também constatado para Pelophylax perezi (Seoane, 1885) (DELGADO et al 1989). Além disso, em D. minutus não existe variação da área e diâmetro dos lóculos seminíferos nas mesmas condições.…”

Section: Discussionunclassified

Morfometria testicular durante o ciclo reprodutivo de Dendropsophus minutus (Peters) (Anura, Hylidae)

Santos

Oliveira

2007

Rev. Bras. Zool.

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Este estudo descreve o ciclo reprodutivo de machos de Dendropsophus minutus (Peters, 1872) com base na análise da morfometria testicular e a correlação com parâmetros climáticos. Cinqüenta indivíduos foram coletados em São José do Rio Preto, São Paulo. Após as análises macroscópicas, os testículos foram encaminhados à rotina histológica, fixados com Bouin e incluídos em historesina. Cortes de 2 µm foram corados com azul de toluidina 1% e observados ao microscópio. Testículos de D. minutus são órgãos pequenos (comprimento 1,90 ± 0,13 mm), esbranquiçados, com forma oval e encontrados na cavidade abdominal. Estão localizados na extremidade cranial dos rins e apresentam assimetria quanto a sua posição. Estatisticamente não há variação intra-individual no comprimento e no peso dos testículos, bem como na área e diâmetro dos lóculos seminíferos. Quanto à histologia testicular, foi possível identificar ao longo do ano nos lóculos seminíferos, todos os tipos celulares da linhagem espermatogênica, caracterizando uma gametogênese contínua, corroborada por fatores ecológicos e comportamentais. Informações sobre a morfometria testicular e ciclo reprodutivo tem importante valor biológico para anuros de regiões neotropicais.

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Section: Discussionunclassified

Morfometria testicular durante o ciclo reprodutivo de Dendropsophus minutus (Peters) (Anura, Hylidae)

Santos

Oliveira

2007

Rev. Bras. Zool.

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“…Relative testis size in frogs is known to fluctuate seasonally (Lofts 1964;Delgado et al 1989;SassoCerri et al 2004;Othman et al 2011), and at least in birds, seasonal variation in sperm morphology has been reported (Lüpold et al 2012;Cramer et al 2013). Yet, these reported fluctuations (for testis mass across the entire year; also see Othman et al 2011 for F. limnocharis) are much smaller than the between-population differences we observed, with all samples collected within the first half of each breeding season.…”

Section: Sample Collectionmentioning

confidence: 94%

Altitude underlies variation in the mating system, somatic condition, and investment in reproductive traits in male Asian grass frogs (Fejervarya limnocharis)

Jin

Yang

Liao

et al. 2016

Behav Ecol Sociobiol

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There is substantial comparative and growing experimental evidence that the competition for fertilization among sperm from different males can drive variation in male reproductive investments. However, less is known about the extent of natural variation in these investments relative to environmental variables affecting resource availability and mating system dynamics, which would allow insights into the mechanisms shaping reproductive allocation. Here, we studied interpopulation variation in male investments in testis size and sperm length across 25 populations of the Asian grass frog Fejervarya limnocharis along a 1550-km latitudinal and 1403-m altitudinal transect in China. We found relative testis mass and sperm length, male somatic condition, and the male/female sex ratio to increase with elevation but not latitude or longitude. Our results suggest that environmental variation may underlie local adaptations to reproductive investments among natural populations, mediated by differences in the availability of both resources and sexual partners (including the resulting male-male competition). These findings contrast with previous predictions that increasing latitude and/or elevation should lead to declining reproductive investments in male anurans due to shortening breeding seasons, declining resource availability, and lowering (rather than increasing) male/female sex ratios. We discuss these species differences in the context of differential resource allocation strategies, breeding ecology, and patterns of male-male competition. These differences show the need for future work on reproductive investments in anurans beyond the few model systems and for potential extension of the theoretical framework to species with different mating systems and strategies. Significance statementDespite a broad theoretical framework of how environmental parameters can shape mating systems and these, in turn, drive the evolution of reproductive traits, there is limited empirical evidence from natural populations. We examined differences in the size of testes and sperm between males between natural populations along latitudinal and altitudinal transects. We found that at high elevation, males were relatively heavier and had longer sperm and disproportionately large testes, and the sex ratio was more male-biased. These interpopulation differences may reflect local adaptations to variation in the resource availability and temporal patterns of female availability, which affects the breeding synchrony, sperm demand, and male-male competition for mates and paternity. However, our results differ from previous studies of frogs, possibly due to different breeding ecology, which highlights the need for further work and potential extension of theoretical predictions to non-model anurans.

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“…These seasonal changes of testicular testosterone seem to be under the controls of pituitary gonadotropin and environmental factors such as temperature or photoperiod (for review, see Paniagua, 1990). Although the seasonal fluctuation of testicular testosterone was known to reflect the number of interstitial cells, the fluctuation did not reflect directly the spermatogenic activity (Pierantoni et al, 1984a,b;Delgado et al, 1989;Itoh et al, 1990).…”

Section: Testicular Cycle and Testosteronementioning

confidence: 97%

“…Thus, spermatogenic patterns of male frogs well coincide with oocyte growth and spawning of female frogs. The seasonal fluctuation of testosterone levels has been well described in several amphibians such as R. catesbeiana (Licht et al, 1983), R. esculenta (Pierantoni et al, 1984a), Ambystoma tigrium (Norris et al, 1985), R. perezi (Delgado et al, 1989), and Bufo japonicus (Itoh et al, 1990). As observed in other vertebrates, synthesis of testosterone is presumed to be controlled by the hypothalamuspituitary-gonadal axis in Rana.…”

mentioning

confidence: 94%

Testicular cycles in the Korean frogs: Annual spermatogenic patterns, seasonal changes in the steroidogenic competence, and responsiveness to gonadotropinsin vitro

Kang

Kim

et al. 1997

Korean Journal of Biological Sciences

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Seasonal cycles in testicular activity in the frog, Rana perezi

Cited by 50 publications

References 21 publications

Morfometria testicular durante o ciclo reprodutivo de Dendropsophus minutus (Peters) (Anura, Hylidae)

Morfometria testicular durante o ciclo reprodutivo de Dendropsophus minutus (Peters) (Anura, Hylidae)

Altitude underlies variation in the mating system, somatic condition, and investment in reproductive traits in male Asian grass frogs (Fejervarya limnocharis)

Testicular cycles in the Korean frogs: Annual spermatogenic patterns, seasonal changes in the steroidogenic competence, and responsiveness to gonadotropinsin vitro

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