African cichlids have often undergone rapid adaptive radiation producing closely related species divergent in morphology, behaviour, and ecology, making them excellent subjects for the study of speciation. Alcolapia alcalica (ALC), A. latilabris (LAT), and A. ndalalani (NDL) are morphologically divergent but genetically similar species which coexist sympatrically in the hot, salty springs and lagoons surrounding soda Lake Natron. This study investigates assortative mating using
aquarium mate choice trials, controlling for micro-habitat preference. Trios of males (one per species) were formed and rotated through four tanks, each containing females of one species along with F1 hybrid ALC x LAT. Behavioural observations were recorded and statistically compared to investigate
the influence of the presence of conspecific females. Paternity of offspring was determined using microsatellite DNA obtained from skin swabs of mothers and potential fathers and tissues of offspring. It was found that Alcolapia spp. in soda Lake Natron mate strongly assortatively, while some heterospecific mating was present within. These results indicate the importance of mate choice in the maintenance of sympatric species distinctness.