Size matters: To livebearer fish, big fins are a big deal

Biologists studied the evolution of 40 molly and Limia species, and concluded dorsal fin displays arose first for males to compete with other males, only later being used in courtship displays to females. These changes in fin function went hand in hand with enlargement of the male dorsal fin. The fins reached extreme sizes in a few species and appear to be associated with rapid evolution, especially in mollies.

from Latest Science News -- ScienceDaily http://bit.ly/2QW1xpe