Research in salty ponds shows how one species of pupfish becomes three — in a few cases. More important, it shows why this did not happen in thousands of other locations. Does an impenetrable “death valley” isolate viable species?
A chemical from plastics “looks” like estrogen to the body. If it makes female fish more likely to flirt with males of a different species, could endocrine disruptors cause cross-breeding, and a decline in native fish after invaders enter their rivers?
During Hurricane Charley, ocean fish sing their mating songs louder and longer.