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When males are larger than females in ecthotherms: Reproductive investment in the eastern spadefoot toad Pelobates syriacus


Cogălniceanu, Dan; Székely, Paul; Székely, Diana; Roşioru, Daniela; Băncilă, Raluca I; Miaud, Claude (2013). When males are larger than females in ecthotherms: Reproductive investment in the eastern spadefoot toad Pelobates syriacus. Copeia, 13(4):699-706.

Abstract

The way animals allocate resources to growth and reproduction is of major importance in understanding life-history trade-offs. Because the investment in reproduction of the two sexes differs, comparing the costs and the reproductive strategies adopted offers an insight into the evolutionary forces that shaped them. In the Eastern Spadefoot Toad, Pelobates syriacus the males are larger than females in body length, but not in body mass. We studied the reproductive effort and output in a population of P. syriacus from the Danube Delta Biosphere Reserve (Romania), during two consecutive years (2010 and 2011). Body mass loss during mating and egg deposition in females averaged 27%, while in males it was 3.9%. Body mass loss in females was proportional with size, with larger females losing more weight than smaller ones. Initial body mass and body mass loss during reproduction were significantly correlated with clutch size, but egg size was not correlated to female size or body mass loss. Year had a significant effect on body size in both sexes, suggesting high plasticity and the effect of local environmental factors on growth and reproduction. Age of adults ranged between 2–12 years and did not differ significantly between sexes. A nonrandom, but not completely assortative, mating was observed, with the age and body size of paired animals slightly positively correlated, indicating an explosive breeder reproductive strategy.

Abstract

The way animals allocate resources to growth and reproduction is of major importance in understanding life-history trade-offs. Because the investment in reproduction of the two sexes differs, comparing the costs and the reproductive strategies adopted offers an insight into the evolutionary forces that shaped them. In the Eastern Spadefoot Toad, Pelobates syriacus the males are larger than females in body length, but not in body mass. We studied the reproductive effort and output in a population of P. syriacus from the Danube Delta Biosphere Reserve (Romania), during two consecutive years (2010 and 2011). Body mass loss during mating and egg deposition in females averaged 27%, while in males it was 3.9%. Body mass loss in females was proportional with size, with larger females losing more weight than smaller ones. Initial body mass and body mass loss during reproduction were significantly correlated with clutch size, but egg size was not correlated to female size or body mass loss. Year had a significant effect on body size in both sexes, suggesting high plasticity and the effect of local environmental factors on growth and reproduction. Age of adults ranged between 2–12 years and did not differ significantly between sexes. A nonrandom, but not completely assortative, mating was observed, with the age and body size of paired animals slightly positively correlated, indicating an explosive breeder reproductive strategy.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Institute of Evolutionary Biology and Environmental Studies
Dewey Decimal Classification:570 Life sciences; biology
590 Animals (Zoology)
Language:English
Date:2013
Deposited On:22 Jan 2014 12:35
Last Modified:05 Apr 2016 17:23
Publisher:American Society of Ichthyologists and Herpetologists
ISSN:0045-8511
Free access at:Publisher DOI. An embargo period may apply.
Publisher DOI:https://doi.org/10.1643/CE-12-053

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