A Quantitative Study of Long-Term Courtship: I. Ethological Isolation Between Sympatric Populations of the Midas Cichlid, Cichlasoma Citrinellum, and the Arrow Cichlid, C. Zaliosum

Abstract

AbstractI. Cichlasoma citrinellum is a cichlid fish found in the Great Lakes and crater lakes of Nicaragua. It is sympatric with C. zaliosum in Lake Apoyo, a Nicaraguan crater lake. C. zaliosum is confined to that lake and is closely related to C. citrinellum; it probably arose from C. citrinellum in Lake Apoyo. C. labiatum is endemic to the Great Lakes and is also closely related to C. citrinellum. All three species have complex reproductive behavior involving a prolonged courtship with pair bondings, followed by a period of joint parental defense and care of the offspring. 2. Fish from sympatric populations of C. citrinellum and C. zaliosum interbred and produced viable F1 offspring in the laboratory, when given no choice except a mate of the opposite species. 3. Given a choice, C. citrinellum and C. zaliosum from both allopatric and sympatric populations formed only homospecific pairs, but the allopatric test was not conclusive. 4. C. labiatum was tested in a mate choice situation with an allopatric population of C. citrinellum and showed incomplete behavioral isolation. 5. Ethological isolating mechanisms are sufficient to explain the maintenance of species isolation between C. citrinellurn and C. zaliosum in a sympatric situation in Lake Apoyo.