ABSTRACT
The green and black poison-dart frog Dendrobates auratus exhibits high intraspecific variation in hue color and pattern throughout its range, making it a very popular species in the pet trade. We analyzed the correspondence between color variation and molecular variation of D. auratus from Costa Rica using RAPD analysis. Twenty-six random primers were analyzed for variation in 99 individuals from seven populations. Color pattern was scored from digital images of the dorsal and ventral views. In general, frogs from the Caribbean coast had significantly more light coloration than black color but cannot be grouped by population based only on hue pattern. Only 3 RAPD primers were found to be polymorphic, representing a total of 16 loci. Most of the molecular variation encountered here occurs within populations, thus making unclear the degree of population structure and differentiation. Further examination of COI mtDNA sequences from our samples also supports these results. Partial Mantel correlations suggested that the pattern of molecular variation is not congruent with the variation in color pattern in this species, an outcome that is discussed in terms of phenotypic evolution. Rev. Biol. Trop. 57 (Suppl. 1): 313-321. Epub 2009 November 30.
La rana venenosa Dendrobates auratus posee una gran variación intraespecífica en tonos y patrones de coloración a lo largo de toda su distribución, lo que la hace una especie muy reconocible entre las especies de dendrobátidos. Analizamos la correspondencia entre variación de coloración y variación molecular de D. auratus de Costa Rica empleando análisis de RAPDs. La variación resultante en veintiséis "primers" aleatorios fue analizada en 93 individuos de siete localidades en Costa Rica. El patrón de coloración fue evaluado de imágenes digitales del dorso y vientre para los mismos individuos. En general, las ranas provenientes de localidades en la costa Caribe tienen significativamente una coloración más clara, con menos proporción de color negro que las de localidades en la vertiente Pacífica, pero no pueden ser agrupadas por localidad basadas simplemente en el patrón de coloración. Solamente tres RAPD "primers" fueron encontrados polimórficos, representando un total de 16 loci. Mucha de la variación molecular encontrada habita dentro de poblaciones, lo que hace difícil determinar el grado de estructura poblacional y diferenciación. La reexaminación posterior de secuencias del gen mitocondrial CO1 también apoya estos resultados. Correlaciones parciales de matrices (test de Mantel) sugieren que el patrón de variación molecular no es congruente con la variación en el patrón de coloración en esta especie, un resultado que es discutido en términos de evolución fenotípica.
Subject(s)
Ranidae/classification , Ecosystem , Costa Rica , Polymorphism, GeneticABSTRACT
Here we describe the immature stages of Acrosternum (Chinavia) ubicum Rolston, and test the effect of the host plant on the size and coloration of the nymphs, by feeding them with developing fruits of Crotalaria incana L., Phaseolus vulgaris L., Glycine max (L.) Merril, Abelmoschus esculentus (L.), and Lycopersicon esculentum Mill. A. ubicum immatures are very similar to those from other neotropical Acrosternum species. The egg coloration varies from ochre to brown; the chorion is reticulated and the micropylar processes are clubbed and white. First to third instars are predominantly dark and the abdomen has a series of creamy to white maculae. Second to fifth instars show red to orange-red maculae on each of the dorso-lateral margins of the pronotum and mesonotum. In the fourth and fifth instars, these maculae are wider, and may also appear on the margins of the jugae, on the pronotum and mesonotum, and in the middle of the mesal and lateral plates of the abdomen. The orange-red coloration of these dorsal maculae seems specific to A. ubicum, but additional studies with other species of the genus are necessary to validate it as a good diagnostic characteristic. Fourth and fifth instars presented light and dark morphs, and their proportion varied according to the type of plant used as food. From the third instar on, the food also affected most of the morphometric parameters measured, i.e., length and width of the body, pronotum and scutelum, and antennal length; only the rostrum length remained unchanged.
Neste trabalho são descritos os estágios imaturos de Acrosternum (Chinavia) ubicum Rolston e é avaliado o efeito do alimento no tamanho e coloração, das ninfas alimentadas com frutos de Crotalaria incana L., Phaseolus vulgaris L., Glycine max (L.) Merril, Abelmoschus esculentus (L.) e Lycopersicon esculentum Mill. Os imaturos de A. ubicum são semelhantes aos das demais espécies neotropicais de Acrosternum. Os ovos apresentam coloração ocre a castanho-parda, cório reticulado e processos micropilares clavados de coloração branca. Do 1° ao 3° ínstar, as ninfas têm coloração do corpo predominantemente escura e abdome com uma série de manchas de coloração creme a branca. A partir do 2° ínstar, apresentam manchas de coloração vermelha a vermelho-alaranjada nas margens dorsais do pronoto e mesonoto. A partir do 4° ínstar, as manchas são mais amplas, podendo também ocorrer nas margens das jugas, na superfície dorsal do pronoto e mesonoto e no centro das placas medianas e laterais do abdome. A coloração vermelho-alaranjada das manchas dorsais é aparentemente específica de A. ubicum, mas é necessário conhecer as ninfas das demais espécies do gênero para verificar se essa característica tem valor diagnóstico. O 4° e o 5° ínstares apresentaram formas escuras e claras, sendo que sua proporção variou de acordo com o tipo de alimento oferecido. A partir do 3° ínstar, o alimento também influenciou praticamente todos os parâmetros morfométricos considerados, isto é, comprimento e largura do corpo, comprimento e largura do pronoto e do escutelo e comprimento das antenas; somente o comprimento do rostro permaneceu inalterado.