RESUMEN
Molecular tools increasingly reveal cryptic lineages and species that were previously unnoticed by traditional taxonomy. The discovery of cryptic species in sympatry prompts the question of how they coexist in the apparent absence of ecological divergence. However, this assumes first that the molecular taxonomy used to identify cryptic lineages delimits species boundaries accurately. This issue is important, because many diversity studies rely heavily or solely on data from mitochondrial DNA sequences for species delimitation, and several factors may lead to poor identification of species boundaries. We used a multilocus population genetics approach to show that three mtDNA-defined cryptic lineages of the fig wasp Pleistodontes imperialis Saunders, which pollinate Port Jackson figs (Ficus rubiginosa) in north-eastern Australia, represent reproductively isolated species. These species coexist locally, with about 13% of figs (where mating occurs) containing wasps from two or three species. However, there was no evidence for gene flow between them. Confirmed cases of coexisting cryptic species provide excellent opportunities for future studies of the ecological and evolutionary forces shaping both species coexistence and fig/pollinator coevolution.
Asunto(s)
Ficus , Genética de Población , Aislamiento Reproductivo , Simpatría , Avispas/clasificación , Animales , Australia , ADN Mitocondrial/genética , Flujo Génico , Marcadores Genéticos , Genotipo , Hibridación Genética , Repeticiones de Microsatélite , Filogenia , Polinización , Árboles , Avispas/genéticaRESUMEN
In this study of the amino acid nutrition of a marsupial we tested three hypotheses: (a) that brushtail possums eat less when diets contain excesses or deficiencies in essential amino acids, (b) that brushtail possums choose diets that do not contain amino acid excesses, and (c) that amino acid consumption is mediated partly by the 5HT3 receptor. Possums ate less when 0.2-1.0% methionine (wet matter) was added to the diet, but similar concentrations of lysine and threonine had little effect. However, when given a choice, possums always selected the basal ration over one with added lysine, methionine or threonine at concentrations between 0.05% and 0.9%. In contrast to the experiments with excess amino acids, possums did not eat less of a diet almost devoid of an essential amino acid. Instead, the possums ate less when their diets contained synthetic amino acids rather than similar amounts and proportions of amino acids as casein. Contrary to the third hypothesis, the 5HT3 receptor antagonist, ondansetron, did not affect feeding by possums given a diet containing 0.8% methionine, suggesting that post-ingestive feedback, via the 5HT3 receptor, does not regulate amino acid intake when diets contain amino acid excesses.