Symbiont-Driven Male Mating Success in the Neotropical Drosophila paulistorum Superspecies.

Microbial symbionts are ubiquitous associates of living organisms but their role in mediating reproductive isolation (RI) remains controversial. We addressed this knowledge gap by employing the Drosophila paulistorum-Wolbachia model system. Semispecies in the D.

Infectious speciation revisited: impact of symbiont-depletion on female fitness and mating behavior of Drosophila paulistorum.

The neotropical Drosophila paulistorum superspecies, consisting of at least six geographically overlapping but reproductively isolated semispecies, has been the object of extensive research since at least 1955, when it was initially trapped mid-evolution in flagrant statu nascendi. In this classic system females express strong premating isolation patterns against mates belonging to any other semispecies, and yet uncharacterized microbial reproductive tract symbionts were described triggering hybrid inviability and male sterility. Based on theoretical models and limited experimental data, prime candidates fostering symbiont-driven speciation in arthropods are intracellular bacteria belonging to the genus Wolbachia.

Male-specific cuticular compounds of the six Drosophila paulistorum semispecies: structural identification and mating effect.

We have identified cuticular pheromones that sustain the integrity of the six Drosophila paulistorum semispecies. Hexane extracts of male and female cuticles were separated on a silica gel column and analyzed using gas chromatography/mass spectrometry. Both sexes of each of the six semispecies have the same fifteen major cuticular components, all hydrocarbons ranging from C31 to C37.

Human handedness and scalp hair whorl direction: no evidence for a common cause.

A much wider variation in many physical and cognitive behaviours exists among left-handers than among right-handers, which is evidence for more than one aetiology of left-handedness. Despite these findings some researchers are still attempting to link left-handedness to a single cause, most recently genetic determination, by pairing left-handedness with a presumed genetically based characteristic. One of these characteristics is scalp hair whorl, which may be clockwise, counter-clockwise (purportedly associated with left-handedness), or a reversal whorl (rare).

On the other hand.

This paper presents a brief overview of the past and current state of handedness research illustrating some of the controversies. It emphasizes two aspects: the lack of agreement on the behavior that indicates to which hand-use group (left or right) an individual belongs, and the reasons for preferring one hand rather than the other for various manual activities.

Developmental isolation and subsequent adult behavior of Drosophila paulistorum. VI. Quantitative variation in cuticular hydrocarbons.

Our previous studies have demonstrated that long-term chemical contact with heterospecifics during development minimized unproductive heterospecific matings among the six Drosophila paulistorum semispecies. When socially isolated from conspecifics, discrimination significantly decreased so that more ultimately unproductive heterospecific matings occurred. Such results suggest that learning and social experiences play roles in mate recognition, using chemical information.