Abstract:

In this study we analysed the body size, age structure, age at maturity, longevity and growth pattern of Argenteohyla siemersi pederseni in north-eastern Argentina using skeletochronological methods. Body size was sexually dimorphic; females were significantly larger and heavier than males, regardless of age. As A. s. pederseni is an explosive breeder with only one reproductive episode per year, we assumed that each Line of Arrested Growth (LAG) observed was equivalent to one period of decreasing growth, LAGs reflecting a direct estimation of individual age. The minimum number of LAGs counted was two for males and three for females, but there was no sexual difference in longevity. The von Bertalanffy's growth coefficients (K) were higher in males than in females for both size and body mass. Females had a lower growth rate than males, took longer to reach the minimum maturation size, and were older and larger at reproduction.

Author affiliation: Cajade, Rodrigo. Universidad Nacional del Nordeste. Facultad de Ciencias Exactas Naturales y Agrimensura. Departamento de Biología. Laboratorio de Herpetología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

Author affiliation: Marangoni, Federico. Universidad Nacional de Misiones. Facultad de Ciencias Exactas, Químicas y Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

Author affiliation: Gangenova, Elena. Universidad Nacional de Misiones. Facultad de Ciencias Exactas, Químicas y Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

Abstract:

We studied size, age and growth in Chacophrys pierottii, a fossorial amphibian inhabiting the arid region of Gran Chaco, in Northern Argentina. We provide the first detailed demographic data for this cryptic species using skeletochronology. We observed a female-biased sexual size dimorphism, but no differences in age parameters between the two sexes. C. pierottii has a short life span of up to five years, both males and females reaching sexual maturity after one year. Our results suggest that the rapid growth to maturity, followed by a relatively short reproductive lifespan, is a response to the constraints posed by arid environments. The life-history parameters in the studied population of C. pierottii are in line with the observed patterns of other anurans inhabiting xeric habitats. Our study provides conservation managers with the basic data required for the accurate assessment of the species status and the adoption of proper conservation strategies.

Author affiliation: Marangoni, Federico. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste; Argentina. Universidad Nacional del Nordeste; Argentina

Author affiliation: Stănescu, Florina. Universitatea Ovidius Din Constanta; Rumania

Author affiliation: Courtis, Azul Celeste. Universidad Nacional del Nordeste; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste; Argentina

Author affiliation: Piñeiro, Jose Miguel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste; Argentina. Fundación Amado Bonpland; Argentina. Universidad Nacional del Nordeste; Argentina

Author affiliation: Ingaramo, María del Rosario. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste; Argentina. Universidad Nacional del Nordeste; Argentina

Author affiliation: Cajade, Rodrigo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste; Argentina. Universidad Nacional del Nordeste; Argentina. Fundación Amado Bonpland; Argentina

Author affiliation: Cogălniceanu, Dan. Universitatea Ovidius Din Constanta; Rumania

Abstract:

We explored age-related parameters and growth patterns in a population of Dermatonotus muelleri inhabiting the Arid Chaco, at the southern limit of the species' distribution range using skeletochronology. In addition, we studied sexual size dimorphism and female reproductive investment. Males and females attained sexual maturity at a similar age (2 years) and both had a low reproductive lifespan (3 years). Females were significantly larger than males and had a higher reproductive investment compared to other anurans. The growth rate coefficient (k) was similar in males (1.14) and females (1.07), indicating that the sexual size dimorphism in this species is caused by differentiated growth before sexual maturity. Overall, we suggest that the short reproductive lifespan justifies the high reproductive investment in the studied population.

Author affiliation: Stǎnescu, Florina. Ovidius University; Rumania

Author affiliation: Marangoni, Federico. Universidad Nacional del Nordeste. Facultad de Ciencias Exactas, Naturales y Agrimensura. Departamento de Biología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

Author affiliation: Reinko, Ivana Noelia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Posadas | Universidad Nacional de Misiones. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Posadas; Argentina

Author affiliation: Cogalniceanu, Dan. Ovidius University; Rumania

Abstract:

In the toad Bufo calamita, among-population variation of size follows roughly a converse Bergmann cline, but populations exist that do not fit this pattern. We propose that latitudinal body size variation is a byproduct of adaptive covariation among the life-history traits juvenile growth rate, longevity and lifetime fecundity. We choose five populations (two in Andalusia, two in Catalonia and one in Rhineland-Palatinate) representing a variation of adult size from 39 mm to 95 mm snout-vent length, a latitudinal gradient from 37 to 50° and an altitudinal gradient from sea level to 420 m. Skeletochronology was used to estimate the age-related life-history traits of 313 toads and their lifetime pattern of growth. At southern latitudes, toads matured and reproduced earlier than those at northern latitudes, but had a reduced potential reproductive lifespan due to lower longevity. Age-adjusted adult size depended mainly on the size achieved between metamorphosis and first hibernation or aestivation, which in turn was influenced by local factors. We propose that first-year size corresponds to the duration of the aboveground activity period, temperature during the activity period and the type of shelter sites and hibernacula available in the habitat. After attaining sexual maturity, the growth rates did not differ among populations. Interactions of multiple environmental factors during the first year of life determine age at maturity, adult size and size variation among populations. Local body size and potential reproductive lifespan covary to optimize lifetime fecundity throughout the geographical range. The presence of a small-sized population in southern Spain does not fit the pattern predicted by a converse Bergmann cline, but is compatible with the hypothesis that body size variation among B. calamita populations may be the evolutionary byproduct of optimized lifetime fecundity.

Author affiliation: Sinsch, U.. Universitat Koblenz; Alemania

Author affiliation: Marangoni, Federico. Universidad Nacional de Misiones; Argentina. Consejo Superior de Investigaciones Científicas. Estación Biológica de Doñana; España. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

Author affiliation: Oromi, N.. Universidad de Lleida; España

Author affiliation: Leskovar, C.. Universitat Koblenz; Alemania

Author affiliation: Sanuy, D.. Consejo Superior de Investigaciones Científicas. Estación Biológica de Doñana; España

Author affiliation: Tejedo, M.. Universidad de Lleida; España