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Titolo:
Maternal effects on life-history traits in the Amazonian giant river turtle Podocnemis expansa
Autore:
Valenzuela, N;
Indirizzi:
SUNY Stony Brook, Dept Ecol & Evolut, Stony Brook, NY 11794 USA SUNY StonyBrook Stony Brook NY USA 11794 olut, Stony Brook, NY 11794 USA Fdn Puerto Rastrojo, Santafe de Bogota, DC, Colombia Fdn Puerto Rastrojo Santafe de Bogota DC Colombia e Bogota, DC, Colombia
Titolo Testata:
JOURNAL OF HERPETOLOGY
fascicolo: 3, volume: 35, anno: 2001,
pagine: 368 - 378
SICI:
0022-1511(200109)35:3<368:MEOLTI>2.0.ZU;2-T
Fonte:
ISI
Lingua:
ENG
Soggetto:
CLUTCH-SIZE; BODY-SIZE; EGG-SIZE; INCUBATION-TEMPERATURE; SEX DETERMINATION; PAINTED TURTLES; CHRYSEMYS-PICTA; NATURAL NESTS; REPRODUCTIVE INVESTMENT; CHELYDRA-SERPENTINA;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Agriculture,Biology & Environmental Sciences
Citazioni:
68
Recensione:
Indirizzi per estratti:
Indirizzo: Valenzuela, N Iowa State Univ, Dept Zool & Genet, Ames, IA 50011 USA Iowa State Univ Ames IA USA 50011 Genet, Ames, IA 50011 USA
Citazione:
N. Valenzuela, "Maternal effects on life-history traits in the Amazonian giant river turtle Podocnemis expansa", J HERPETOL, 35(3), 2001, pp. 368-378

Abstract

Energy allocation to eggs and nest site selection by females can affect life-history variables such as offspring size, offspring number, developmental rate, survivorship, growth rate, and performance in oviparous reptiles. Nest site selection can affect offspring phenotype by altering incubation conditions. I present evidence of a positive effect of female size on clutch size, egg mass, and nest depth through the study of trackways left by female river turtles, Podocnemis expansa, on their nesting beaches. Larger females laid larger clutches composed of larger eggs, which were buried deeper than clutches laid by smaller females. The data suggest that P expansa does not conform to optimal propagule size models. Neither egg size nor clutch size reached a plateau as female size increased. Females seem to allocate the extra energy (in absolute terms) gained allometrically with increasing size and age to both number and size of eggs. There was no evidence of a trade-off between egg size and number after removing the effect of female size. Larger eggs produced larger hatchlings that survived better but grew less than individuals of smaller initial size during the first two months of life, under unlimited food conditions. I suggest that fitness of female P expansa increases by producing larger eggs because of the advantage that largerhatchlings have in survival. Deeper nests experience cooler temperatures and tend to produce a higher percentage of males than more superficial nests. Therefore, there is a potential for important effects of nest depth on sex ratios produced by different sized females within the population and possibly by single females throughout their lifetime. Constant temperature in artificial incubation experiments had an effect on the size of individuals at hatching, but differences vanished by the second month of age via the greater growth rate shown by individuals of smaller initial size.

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Documento generato il 21/09/20 alle ore 15:53:12