File:American malacological bulletin (1987) (17968801380).jpg

Title: American malacological bulletin
Identifier: americanmal4519861987amer (find matches)
Year: 1983 (1980s)
Authors: American Malacological Union
Subjects: Mollusks; Mollusks
Publisher: (Hattiesburg, Miss. ?) : (American Malacological Union)
Contributing Library: Smithsonian Libraries
Digitizing Sponsor: Biodiversity Heritage Library

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116 AMER. MALAC. BULL. 5(1) (1987) These are: 1. a direct relationship between cell calcium and water Ca +2 concentration; 2. regulation of shell CaC03 con- tent at relatively constant levels over a wide range of en- vironmental Ca + 2 concentrations; 3. a relation between shell CaC03 content and trophic conditions (environmental pro- ductivity); and 4. great interpopulation variation, but limited intrapopulation variation in shell CaC03 content reflecting a random geographical distribution of genetic races resulting from founder effects and genetic drift with no obvious adap- tive relationship to biotic or abiotic environmental parameters. Type 1 shell calcium variation is displayed by Lymnaea peregra (MLiller) (Young, 1975; Russell-Hunter ef a/., 1981), Planorbarius corneus (L.) (Young, 1975), Biomphalana pfeif- fen (Krauss) (Harrison ef a/., 1970), B. glabrata (Say) (Thomas ef a/., 1974), Cincinnatia cincinnatiensis (Antony), and a number of sphaeriid and unionid bivalve species (Mackie and Flippance, 1983). Type 2 variation occurs in Physella gyrina (Lea) (Hunter and Lull, 1977). Type 3 shell CaC03 variation occurs in Helisoma anceps (Menke) and Physella integra (Haldeman) (Hunter and Lull, 1977). Type 4 variation has been reported for Stagnicola elodes (Hunter, 1975). A fifth pattern of interpopulation shell variation whereby shell CaC03 con- tent is inversely proportional to ambient water Ca + 2 concen- tration has recently been reported for the sphaeriid bivalves, Sphaerium simile (Say), S. rhomboideum (Say) (Mackie and Flippance, 1983) and S. striatinum (Lamarck) (Burky ef a/., 1979). Among ancylid species, the North American stream limpet, Ferrissia rivularis (Say), is reported to have a type 4 pattern of interpopulation shell CaC03 variation. Shell CaC03 content and organic content (measured in terms of total organic carbon and nitrogen) varied significantly between 10 populations in upstate New York and were neither correlated with each other or with water hardness and dissolved calcium. It was suggested that the synthesis of these two components in this species is under independent genetic controls and that intrapopulation variations in shell CaC03 and organic con- tents resulted primarily from differences in the gene pools 1.9 1.8 x CO \ < T 446
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0.2 0.3 0.4 0.5 0.6 mm AL / 30 DAYS Fig. 7. Allometry of estimated population mean shell aperture width:shell height ratios (AW/SH) with mean annual growth rate in Irish Ancylus fluviatilis populations. The y axis is mean shell AW/SH ratio estimated for a 4.5 mm AL standard individual from least squares linear regres- sion equations relating AW/SH to AL for each population collected. The x axis is growth rate in mm AL per 30 days. The open circles are the estimated mean AL/AW ratio for each population for which collection sites are indicated by the adjacent numbers (see Tables 1 and 2). The vertical bars are standard errors of the means. The solid line represents the best fit of a significant (P < 0.005) log-log least squares linear regression equation relating estimated AW/SH to annual population growth rate (see Table 4 for regression parameters).

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