Multiple stressors lead to complex responses in reproductive behaviors in an African cichlid

Exposure to multiple environmental stressors is a common occurrence that
can affect organisms in predictable or unpredictable ways. Hypoxia and
turbidity in aquatic environments are two stressors that can affect
reproductive behaviors by altering energy availability and the visual
environment, respectively. Here we examine the relative effects of
population and the rearing environment (oxygen concentration and
turbidity) on reproductive behaviors. We reared cichlid fish (the Egyptian
mouthbrooder, Pseudocrenilabrus multicolor) from two populations (a swamp
and river) until sexual maturity, in a full factorial design
(hypoxic/normoxic x clear/turbid) and then quantified male competitive and
courtship behaviors and female preference under their respective rearing
conditions. Overall, we found that the rearing environment was more
important than population for determining behavior, indicating there were
few heritable differences in reproductive behavior between the two
populations. Unexpectedly, males in the hypoxic rearing treatment
performed more competitive and courtship behaviors. Under turbid
conditions males performed fewer competitive and courtship behaviors. We
predicted that females would prefer males from their own population.
However, under the hypoxic and turbid combination females from both
populations preferred males from the other population. Our results suggest
that reproductive behaviors are affected by interactions between male
traits, female preference, and environmental conditions.