Skip to content. | Skip to navigation

Personal tools

 

 

 

 
     

 

 

 

 

 

 

 

 

 

 

 

 

You are here: Home / PDFs on demand / Bibliographical References of PDFs on demand / Convergent evolution of shell colour patterns in two Caribbean terrestrial prosobranch snails

Glenn Goodfriend (1983)

Convergent evolution of shell colour patterns in two Caribbean terrestrial prosobranch snails

Journal of Zoology, 201(1):125-133.

Two species of helicinid land snails, the Jamaican endemic Eutrochatella pulchella and the Cuban endemic Viana regina, display a colour pattern of white spots on a greenish background. Microstructural and optical investigations of the shells have revealed that the colour patterns are non-homologous. In E. pulchella the white spots are associated with areas of granular shell structure, in which the crystals have an irregular, peak-like form. In V. regina, there is no structural modification of the shell mineral associated with the spots. Modification of the organic matrix is responsible for the appearance of spotting. In V. regina, the shell pigment is yellow and located in the inner part of the shell. It appears greenish as seen from the outside through the translucent shell. The pigment fluoresces yellow under ultraviolet light. The greenish shell pigment of E. pulchella is non-fluorescent and is uniformly distributed through the shell (except in the white spots). Since the colour patterns are non-homologous, their similarity must have arisen through convergent evolution. The adaptive value of the colour patterns is thus indicated. Both species live exposed on limestone rocks and their colour patterns (at least in the case of E. pulchella) cause them to be very cryptic. Predation by visually oriented predators (perhaps birds) is a probable cause of selection for shell colour pattern. The association of polymorphism with wide habitat breadth and of monomorphism with narrow habitat breadth is proposed. This relationship is seen in the two helicinid species, both of which show little within-population variation as compared with polymorphic snails (e.g. helicids), which occupy a wide range of habitats. The generally monomorphic character of populations of Jamaican snails may be a result of habitat specialization associated with the unusually high species diversity on the island (some 450 species in 11,400 km2). The need for studies on the relationship of shell colour and structure is pointed out.

Year

1875 1876 1877 1878 1879
1880 1881 1882 1883 1884
1885 1886 1887 1888 1889
1890 1891 1892 1893 1894
1895 1896 1897 1898 1899

1900 1901 1902 1903 1904
1905 1906 1907 1908 1909
1910 1911 1912 1913 1914
1915 1916 1917 1918 1919
1920 1921 1922 1923 1924

1925 1926 1927 1928 1929
1930 1931 1932 1933 1934
1935 1936 1937 1938 1939
1940 1941 1942 1943 1944
1945 1946 1947 1948 1949

1950 1951 1952 1953 1954
1955 1956 1957 1958 1959
1960 1961 1962 1963 1964
1965 1966 1967 1968 1969
1970 1971 1972 1973 1974

1975 1976 1977 1978 1979
1980 1981 1982 1983 1984
1985 1986 1987 1988 1989
1990 1991 1992 1993 1994
1995 1996 1997 1998 1999

2000 2001 2002 2003 2004
2005 2006 2007 2008 2009
2010 2011 2012 2013 2014
2015 2016 2017 2018 2019
2020 2021 2022 2023 2024

 
e-ressources

 

PDFs on demand
 

 

 

RBINS private PDFs