The symbiotic nest association of yellowfin shiners,Notropis lutipinnis,and bluehead chubs,Nocomis leptocephalus

Synopsis Yellowfin shiners spawn in nests constructed by male bluehead chubs. To determine whether yellowfin shiners are obligatory symbionts of bluehead chubs, different densities of shiners were isolated from chubs and presented with artificial nests in stream enclosures. Yellowfin shiners failed to reproduce in the absence of bluehead chubs, indicating that the symbiosis is obligatory for the shiners. Bluehead chubs tended nests by moving stones, which kept the nests free of silt. Nest tending lasted for the same amount of time that embryos and larvae of both species were found in the nests. Yellowfin shiners benefit from a protective nest and parental care given by the chub. Eggs, embryos and larvae of both species may benefit from reduced predation due to a dilution effect. These observations suggest that this nest association is an obligatory, mutualistic symbiosis.