A review of the endemic Hawaiian Drosophilidae and their host plants

Abstract

The Hawaiian Drosophilidae is one of the best examples of rapid speciation in nature. Nearly 1,000 species of endemic drosophilids have evolved in situ in Hawaii since a single colonist arrived over 25 million years ago. A number of mechanisms, including ecological adaptation, sexual selection, and geographic isolation, have been proposed to explain the evolution of this hyperdiverse group of species. Here, we examine the known ecological associations of 326 species of endemic Hawaiian Drosophilidae in light of the phylogenetic relationships of these species. Our analysis suggests that the long-accepted belief of strict ecological specialization in this group does not hold for all taxa. While many species have a primary host plant family, females will also oviposit on non-preferred host plant taxa. Host shifting is fairly common in some groups, especially the grimshawi and modified mouthparts species groups of Drosophila, and the Scaptomyza subgenus Elmomyza. Associations with types of substrates (bark, leaves, flowers) are more evolutionarily conserved than associations with host plant families. These data not only give us insight into the role ecology has played in the evolution of this large group, but can help in making decisions about the management of rare and endangered host plants and the insects that rely upon them for survival.

Attraction ofCeratitis capitata(Diptera: Tephritidae) and Endemic and Introduced Nontarget Insects to BioLure Bait and Its Individual Components in Hawaii

“…The larval breeding substrate for the majority of the trapped endemic species is decaying leaves of Cheirodendron trigynum (Gaud.) (Araliaceae) (Magnacca et al 2008). Trapping at 57 other endemic forest sites on Hawaii and Maui islands has shown that at least the common species of most of the other endemic groups (haleakalae, picture wings, Nudidrosophila, split tarsus, ciliated tarsus, bristle tarsus, modiÞed mouthparts, and the genus Scaptomyza) are also attracted to BioLure (L.L., unpublished data).…”

“…They were slightly more common at the highest (1,138 m) location (0.031 Ϯ 0.011 SEM per trap per day) than the three other locations (0.012 Ϯ 0.004). The catches mainly consisted of three Drosophila species in the haleakalae group, whose larvae breed on fungus (Magnacca et al 2008), but also included nine species of Scaptomyza trapped in very small numbers (3.4 specimens per species). Most of these endemic species were common in the Maui endemic forest traps (L.L., unpublished data).…”

Phylogenetic and ecological relationships of the Hawaiian Drosophila inferred by mitochondrial DNA analysis

“…Data on substrate type (fungi, leaves, bark or stem, fruit, sap flux) and host plant (fungi, Araliaceae, Campanulaceae, ferns, Nyctagenaceae, Amaranthaceae, Sapindaceae, Fabaceae, Myrsinaceae, Aquifoliaceae and other) were entered based on Magnacca, Foote, and O'Grady (2008). When multiple records existed, we selected those with multiple rearings or multiple offspring.…”

“…While Araliaceae and Campanulaceae are the most commonly used host plant families (Magnacca, Foote, & O'Grady, 2008), switches between host plant families occurs more frequently, with many shifts occurring within a given species group or even species subgroup (Fig. 2B).…”

Diversification and dispersal of the Hawaiian Drosophilidae: The evolution of Scaptomyza

“…For example larvae of some Scaptomyza species are animal predators. Larvae of species in the subgenus Titanochaeta were reared from thomisid spider egg sacs (Hardy, 1965), and some species in the subgenus Elmomyza feed on insects (Magnacca, et al, 2008). The subgenus Scaptomyza is an herbivorous lineage whose larvae are leaf-miners of mustards (Brassicaceae) and other plant families (Hackman, 1959; Wheeler and Takada, 1966; Maca, 1972; Brncic, 1983; Whiteman, et al, 2011), including the genetic reference plant, Arabidopsis thaliana (Chittenden, 1902).…”