Data from: Behavioral isolation due to cascade reinforcement in Lucania killifish

Reinforcement occurs when behavioral isolation is strengthened between
species due to selection against hybridization in sympatry. Mate
preferences and their target traits may change in sympatry as a
consequence of reinforcement. This can potentially generate further
behavioral isolation within species if sympatric populations evolve
extreme preferences or traits that cause them to reject individuals from
foreign populations as mates or be rejected as mates. This process is
known as cascade reinforcement. We measured behavioral isolation between
sympatric and allopatric populations of Lucania killifish to determine
whether isolation evolves due to reinforcement between species and whether
reinforcement affects preferences within species, consistent with the
cascade reinforcement hypothesis. We measured mate preferences in both
sexes between species (Lucania parva vs. Lucania goodei) and within
species (among populations of L. parva). Between species, both male and
female preferences for conspecifics were highest in sympatric populations.
Within species, L. parva females from sympatric populations preferred
their own native males over foreign males. Allopatric L. parva females and
all L. parva males showed no preferences within species. Within species,
behavioral isolation showed no association with ecological variables, such
as salinity. Thus, reinforcement is a primary factor generating behavioral
isolation in Lucania killifish, creating strong preferences in both sexes
among species and leading to cascade reinforcement of female mate
preference within species.