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A number of species and taxa of Drosophilidae (Diptera) are used as model clades in various fields of biology, but our knowledge on their ecology and co-evolution (e.g. how their populations are regulated and how they interact with host organisms, enemies, and competitors) is still limited. According to studies on their host use, their primary larval resources are fruits, flowers, plant leaves and stems, tree sap, and fungal fruiting bodies, and most species are specialized to one of these resources. Among these species, those exploiting fungal fruiting bodies (i.e. mycophagous species) have been relatively well studied for their ecology, because their resources are commonly found in the field, hence their interactions with enemies and competitors can be assessed rather easily. So far, a review article has been published on their ecology in 1990. Since then, remarkable advances have been achieved on their taxonomy, phylogeny, diversity, and interactions with parasites, parasitoids, and competitors. This article reviews literature mainly published since 1990 to provide a basis for the future study of their ecology and evolution. [ABSTRACT FROM AUTHOR]

Deciphering invasion routes from molecular data is crucial to understanding biological invasions, including identifying bottlenecks in population size and admixture among distinct populations. Here, we unravel the invasion routes of the invasive pest Drosophila suzukii using a multi-locus microsatellite dataset (25 loci on 23 worldwide sampling locations). To do this, we use approximate Bayesian computation (ABC), which has improved the reconstruction of invasion routes, but can be computationally expensive. We use our study to illustrate the use of a new, more efficient, ABC method, ABC random forest (ABC-RF) and compare it to a standard ABC method (ABC-LDA). We find that Japan emerges as the most probable source of the earliest recorded invasion into Hawaii. Southeast China and Hawaii together are the most probable sources of populations in western North America, which then in turn served as sources for those in eastern North America. European populations are genetically more homogeneous than North American populations, and their most probable source is northeast China, with evidence of limited gene flow from the eastern US as well. All introduced populations passed through bottlenecks, and analyses reveal five distinct admixture events. These findings can inform hypotheses concerning how this species evolved between different and independent source and invasive populations. Methodological comparisons indicate that ABC-RF and ABC-LDA show concordant results if ABC-LDA is based on a large number of simulated datasets but that ABC-RF out-performs ABC-LDA when using a comparable and more manageable number of simulated datasets, especially when analyzing complex introduction scenarios.

How species diversity is determined is an old question in community ecology but is not yet well understood. Island biotas offer opportunities to address this issue. Here, the ant fauna was studied in five moderately isolated islands of Japan and compared with those in reference regions on the nearby main islands to assess whether ants' ecological characteristics affect their island colonisation success. Species that were more abundant in the reference regions were more frequently found on the islands, suggesting that ant communities on these islands are likely to have a nested subset structure. Species inhabiting both forests and open lands tended to occur more frequently in the study islands at least than those exclusively inhabiting forests, but this difference was not significant. In addition, nest sites and worker body size did not have significant effects on their occurrence in these islands. These results seem to suggest that the study islands as a whole offer various environments that support a variety of ant species with different ecological characteristics. It is suggested in this study that island size affects the species richness, as has often been reported. [ABSTRACT FROM AUTHOR]

Quercus crispula and Q. dentata (Fagaceae) are dominant members of cool-temperate forests of Japan and are assumed to hybridize in nature. To characterize and discriminate these two species and their hybrids, we carried out multivariate analysis using several morphological traits and principal coordinate analysis using molecular (amplified fragment length polymorphism [AFLP]) data. Further, we examined the composition of Phyllonorycter species (leafmining insects) on individuals from a mixed forest. Morphological traits and Phyllonorycter composition differ enough in these two oak species to be useful for identification of species and hybrids. AFLP data, however, are less informative because the degree of molecular differentiation between the two species is low. Nine out of 105 individuals from a mixed stand had intermediate morphologies according to the multivariate analysis, and eight out of the nine individuals had intermediate Phyllonorycter composition in either one or both of the two study years. These eight individuals were tentatively assigned as hybrids or backcross individuals, and the remaining individual with intermediate morphologies was assigned as Q. dentata according to its Phyllonorycter composition and the AFLP analysis. Key words: AFLP; Fagaceae; hybridization; morphological traits; Phyllonorycter; Quercus crispula; Quercus dentata.

A study to understand how Drosophila elegans discriminates between potential mates has been carried out. Partial sexual isolation has developed between the brown and black morphs, but body coloration is not used as a sexual cue. Sexual isolation and cuticular hydrocarbons are discussed.