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Cambios morfológicos y mortalidad en embriones y renacuajos de Agalychnis spurrelli Boulenger (Anura: Hylidae)

Actualidades Biológicas 01/2005; 27:189-202.

ABSTRACT We describe changes in some morphological traits of embryos and tadpoles of the treefrog Agalychnis spurrelli. Also, we made observations about their natural history. Between November 1998 and March 1999, a group of 289 tadpoles were collected, and 26 egg clutches were monitored from a population that breeds around an artificial pool located in Vereda Danubio, región Anchicayá (Valle del Cauca), Colombia. The former 24 stages of embryo development occur in eggs placed in arboreal substrates. After hatching (stage 24) and dropping in water, the gills are reabsorbed, and the growth and development patterns of tadpoles are similar to the showed by tadpoles of anuran species with aquatic oviposition. After 8 days from oviposition, individuals hatched
with a mean body length (BL) of 11.94 mm (n = 3), tadpoles ended metamorphosis with a mean BL of 44.16 mm (n = 4). Most of the embryos´ mortality was due to predation by the snake Leptodeira annulata (< 25% of clutches), while the most of the mortality in tadpoles was due to fishes Astyanax sp. (Pisces: Characidae). Field observations suggest that characteristics of the body water (permanent, large) could affect the growth pattern of tadpoles.

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    ABSTRACT: Throughout 2006 and 2007, at a small swamp in San Francisco del Cabo, northwestern Ecuador, monthly field expeditions were done to monitor a population of the leaf frog Agalychnis spurrelli with the following aims: (1) to determine population size and annual fluctuation; (2) to determine spatial distributional patterns and microhabitat resource partitioning; and (3) to analyze associations with other nocturnal frogs. We employed standardized sampling methods to study the population size, which included capture-recapture analysis using toe clip codes. In northwestern Ecuador, Agalychnis spurrelli presents highly effective population sizes, with local increments in relative density through rainy and breeding seasons, beginning in February. A low recapture rate was obtained and population size was projected between 1400 to 6000 individuals of Agalychnis spurrelli for Laguna del Diablo. Throughout the dry season this particular frog prefers the canopy of higher trees, descending only to low vegetation which occurs around the swamp when the breeding season begins. We obtained low rates in overlap and amplitude functional niche values, demonstrating a high level of specialization in resource partitioning in the habitat. Nine species of nocturnal anurans were identified around this body of water, among which, Hypsiboas rosenbergi and H. pellucens were the most similar species to A. spurrelli in resource use and spatial distribution at the swamp. The snake Leptodeira septentrionalis is its principal predator. Entre los años 2006 y 2007, en un pequeño humedal de la localidad de San Francisco del Cabo al noroccidente de Ecuador, monitoreamos mensualmente una población de la rana arborícola Agalychnis spurrelli. Nuestros objetivos fueron: (1) determinar el tamaño poblacional y las fluctuaciones anuales de la población, (2) evaluar la distribución espacial el hábitat por categoría de edad; y (3) analizar las asociaciones con otras especies de anuros relacionadas con la partición de recursos del sustrato, época reproductiva y sitio de reproducción. Se emplearon métodos estandarizados de muestreo para estudiar la dinámica y tamaño poblacional, los cuales incluían la captura- recaptura, codificados mediante el corte de falanges. La población de Agalychnis spurrelli podría alcanzar altos tamaños poblacionales, con incrementos de su densidad relativa y en su actividad reproductiva durante los períodos de lluvias, que inician desde el mes de Febrero. Se obtuvo una baja tasa de recaptura, con tamaños poblacionales calculados entre 1400 y 6000 individuos adultos para la Laguna del Diablo. Durante los períodos secos, esta especie prefiere los estratos altos del bosque, descendiendo hacia los bordes de la laguna solamente cuando comienzan los períodos de lluvia. Nueve especies de anuros nocturnos fueron identificados en los alrededores de la laguna, de los cuales Hypsiboas rosenbergi y H. pellucens fueron las más similares con A. spurrelli en el uso de recursos del hábitat. La serpiente Leptodeira septentrionalis es su principal depredador. Se reportan valores medianos en la amplitud y solapamiento del nicho, que refleja tendencias generalistas de esta especie en la distribución vertical y uso de sustratos en el humedal.
    Papéis Avulsos de Zoologia (São Paulo) 01/2011; 51(1):1-19. DOI:10.1590/S0031-10492011000100001
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