Phylogenetic Analysis of the \u3ci\u3ecardini\u3c/i\u3e Group of \u3ci\u3eDrosophila\u3c/i\u3e with Respect to Changes in Pigmentation

Phenotypic variability is the engine that drives future diversification with the expectation that polymorphic ancestors give rise to descendants harboring a subset of the ancestral variation. Here we examine evolutionary transitions from polymorphism to monomorphism in a visually striking New World radiation of fruit flies, the Drosophila cardini group. This group is distributed across the Americas and the Caribbean islands and exhibits a wide spectrum of abdominal pigmentation variation. Specifically, the D. dunni subgroup consists of Caribbean island endemics, each of which is monomorphic for its pigmentation pattern, with an interspecific cline of pigmentation across the islands. The D. cardini subgroup consists of American continental species with wide-ranging distributions and intraspecifically variable abdominal pigmentation. We determined the phylogeny of 18 species and subspecies using three nuclear and three mitochondrial regions analyzed with maximum parsimony, maximum likelihood, and Bayesian methods. The topology produced from a combined dataset exhibited high support values at all nodes, and differed from earlier phylogenetic hypotheses based on polytene chromosome inversion patterns and isozyme data. We find that the D. dunni subgroup species, with the exception of D. belladunni, are derived from a single source not of direct South American origin and their dispersal across the islands of the Caribbean does not follow a simple stepping-stone model. Morphological changes in pigmentation across the island species are incongruent with the colonization history of the group indicating that natural selection may have played a role in the determination of this character. Finally, we demonstrate that monomorphic species have arisen independently from polymorphic ancestors two to three times

First record of \u3ci\u3eDrosophila parthenogenetica\u3c/i\u3e and \u3ci\u3eD. neomorpha\u3c/i\u3e, cardini group, Heed, 1962 (Drosophila, Drosophilidae), in Brazil

The cardini group of the Quinaria section of the genus Drosophila is composed of 16 Neotropical species. The two focal species of this report, Drosophila parthenogenetica and D. neomorpha, are included in this group, and are placed in the cardini subgroup with seven other species: D. polymorpha, D. cardinoides, D. cardini, D. neocardini, D. acutilabella, D. bedicheki and D. procardinoides (Heed and Krishnamurthy, 1959; Heed, 1962; Heed and Russell, 1971; Wilder et al., 2003). The group is characterized by medium-sized flies with a shiny thorax (Vilela et al., 2002). Different species of the group display different abdominal pigmentation patterns (Hollocher et al., 2000a, b), different degrees of divergence and population structure (Wilder et al., 2003; Wilder et al., 2004) as well as different abilities to colonize multiple niches (Rhode and Valente, 1986; Machado et al., 2001). We have been investigating the southern Brazilian Drosophilid communities since the 1990’s as a system for understanding the impact of territorial range expansions. In this article, we report the movement of two species of the cardini group, D. parthenogenetica and D. neomorpha, into Brazil and discuss the potential impacts of these range expansions may have on the existing Drosophilid communities