The extraordinary species richness of freshwater fishes has attracted much research on
mechanisms and modes of speciation. We here review research on speciation in freshwater …

Reinforcement is the process by which selection against hybridization increases
reproductive isolation between taxa. Much research has focused on demonstrating the …

Mate discrimination is a key mechanism restricting gene flow between species. While
studied extensively with respect to female mate choice, mechanisms of male mate choice …

We investigated mechanisms of reproductive isolation in livebearing fishes (genus Poecilia)
inhabiting sulfidic and nonsulfidic habitats in three replicate river drainages. Although sulfide …

Highlights•We examined the mating interactions of eight allopatric Etheostoma species pairs
in the laboratory.•Interspecific differences in male nuptial coloration predicted levels of …

Sexual selection may hinder gene flow across contact zones when hybrid recognition
signals are discriminated against. We tested this hypothesis in a unimodal hybrid zone …

Reinforcement occurs when behavioral isolation is strengthened between species due to
selection against hybridization in sympatry. Mate preferences and their target traits may …

Reinforcement is the process by which prezygotic isolation is strengthened as a response to
selection against hybridization. Most empirical support for reinforcement comes from the …

Adaptation to different environments can directly and indirectly generate reproductive
isolation between species. Bluefin killifish (Lucania goodei) and rainwater killifish (L. parva) …

Highlights•We compared the contribution of males and females to total behavioural
isolation.•Males preferred conspecific females in two sexually dimorphic species of …