Observations of numerous mammals suggest males self‐groom more than females in response to the odours of opposite‐sex conspecifics. Two experiments tested the hypothesis that self‐grooming may be a tactic used by males to attract mates in prairie voles Microtus ochrogaster. In the first experiment, we measured the amounts of time voles self‐groomed during exposure either to male‐scented cotton bedding, female‐scented cotton bedding, or clean cotton bedding. Results from this experiment support the hypothesis and also show that female prairie voles self‐groom in response to odours of males. In addition, male prairie voles groom more in response to male odours than to female odours, suggesting that self‐grooming also serves a role in male–male competition. In the second experiment, male and female voles spent more time investigating scent marks of opposite‐sex conspecifics that recently self‐groomed at a higher rate than those of opposite‐sex conspecifics that self‐groomed at a lower rate. Female, but not male prairie voles, spent more time investigating scent marks of opposite‐sex conspecifics that self‐groomed at a high rate than those of same‐sex conspecifics that self‐groomed at a high rate. For prairie voles, self‐grooming may increase the detection of their scent marks by conspecifics. By self‐grooming, prairie voles may be attempting to attract opposite‐sex conspecifics, and males may also be attempting to deter encounters with male conspecifics.

This study demonstrates that iron chelation interrupts the completion of the fermentative pathway of E. histolytica by removing the metal cofactor indispensable for the structural and functional stability of EhADH2, thus affecting trophozoite survival. We propose that iron-starvation-based strategies could be used to treat amoebiasis.

Horizontal gene transfer (HGT) and common descent interact in space and time. Because events of HGT co-occur with phylogenetic evolution, it is difficult to depict evolutionary patterns graphically. Tree-like representations of life’s diversification are useful, but they ignore the significance of HGT in evolutionary history, particularly of unicellular organisms, ancestors of multicellular life. Here we integrate the reticulated-tree model, ring of life, symbiogenesis whole-organism model, and eliminative pattern pluralism to represent evolution. Using Entamoeba histolytica alcohol dehydrogenase 2 (EhADH2), a bifunctional enzyme in the glycolytic pathway of amoeba, we illustrate how EhADH2 could be the product of both horizontally acquired features from ancestral prokaryotes (i.e. aldehyde dehydrogenase [ALDH] and alcohol dehydrogenase [ADH]), and subsequent functional integration of these enzymes into EhADH2, which is now inherited by amoeba via common descent. Natural selection has driven the evolution of EhADH2 active sites, which require specific amino acids (cysteine 252 in the ALDH domain; histidine 754 in the ADH domain), iron- and NAD+ as cofactors, and the substrates acetyl-CoA for ALDH and acetaldehyde for ADH. Alternative views invoking “common design” (i.e. the non-naturalistic emergence of major taxa independent from ancestry) to explain the interaction between horizontal and vertical evolution are unfounded.

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