Tuyển tập các báo cáo nghiên cứu về sinh học được đăng trên tạp chí sinh học Journal of Biology đề tài: Selection in sympatric populations of Cepaea | 269 Genet. Sei. Evol. 1989 21 269-281 Elsevier INRA Original article Selection in sympatric populations of Cepaea . Mazon1 . Martinez de Pancorbo2 A. Vicario1 . Aguirre1 A. Estomba1 and . Lostao1 1 Universidad del Pais Vasco faculdad de ciencias departamento de biologia y genetica APDO 644 48080 2Universidad del Pais Vasco faculdad de medicina departamento de histologia y biologia 48080 Spain received 16 May 1988 accepted 30 January 1989 Summary - Interspecific competition is often thought to produce evolutionary changes This competition has been studied mainly using subjects whose heritability is not well known. Hence it is preferable to study polymorphic characters whose inheritance is known. Land snails of the genus Cepaea have several advantages for such studies. Ninety-five samples of allopatric and sympatric populations of Cepaea nemoralis and Cepaea hortensis were collected near the southern limit of the aera occupied by Cepaea hortensis. In the area studied Cepaea nemoralis and Cepaea hortensis populations are divided into two zones corresponding to the north and south-facing slopes of the Iberian Mountains. . Changes in phenotype frequencies were observed passing from allopatry to sympatry in both species In the North a decrease in the frequencies of yellow yellow-banded and effectively banded yellow snails was detected in sympatric populations of Cepaea nemoralis and at the same time the frequencies of the banded five-bậnded and effectively banded phenotypes in Cepaea hortensis increased. These changes in phenotype frequencies between allopatric and sympatric populations in one species may depend upon the phenotype frequency of the other. Such frequency dependent selection may interact with other selective forces and with competitive selection. We believe that in southern populations these changes are due to climatic selection in both species. Cepaea - polymorphism - climatic selection - allopatry - sympatry Resume - Selection dans les .
