This image shows a Gammarus duebeni celticus pair. Parasites can play an important role in driving cannibalism, according to a new study.

New research shows that courtship rituals evolve very fast in cichlid fish in Lake Malawi. Whenever species evolve to feed at different depths, their courtship evolves as well. In the shallows where the light is good, males build sand castles to attract females. Males of deep-dwelling species dig less elaborate pits and compensate with longer swimming displays. The results are published in the open-access journal Frontiers in Ecology and Evolution.