There is evidence of early speciation through mate preference in guppies. Guppies are located across several isolated streams in Trinidad and male colour patterns differ geographically. Female guppies have no coloration but their preference for these colour patterns also vary across locations. In a mate choice study, female guppies were shown to prefer males with colour patterns that are typical of their home stream. This preference could result in reproductive isolation if two populations came into contact again. There is a similar trend shown in two species of the wood white butterfly, "L. reali" and "L. sinapis." Female "L. sinapis" controls mate choice by engaging only in conspecific mating, while males attempt to mate with either species. This female mate choice has encouraged speciation of the two wood whites.