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Physiological adaptation and genetic composition in the littoral dog-whelk, Nucella lapillus (L.)

Morgans, Deborah; (1996) Physiological adaptation and genetic composition in the littoral dog-whelk, Nucella lapillus (L.). Doctoral thesis (Ph.D), UCL (University College London). Green open access

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Between Peartree Point and Prawle Point, a distance of ca. 5km along the south Devon coast, Nucella lapillus exhibits coincident variation in genetic composition and phenotype, which has been proposed to covary with an environmental gradient. In this study, laboratory and shore experiments have investigated the physiological consequences of genetic and phenotypic variation. Sample sites were at Peartree Point and Prawle Point and allelic variation at six polymorphic loci confirmed differences in allele frequencies at two clinal loci, Lap-2 and Mdh-1. Shell shape, life history characteristics and growth rates varied between sites. Juveniles reared, from Prawle Point had lower growth rates than at Peartree Point and variation in tissue growth rate exhibited a direct association with Lap-2 or Pep-1 genotypes in the laboratory. Shore juveniles also demonstrated variation in shell growth, feeding rates and growth efficiency among Lap-2, Pep-1 and Mdh-1 genotypes. The hierarchy of growth differences among genotypes was in agreement to the observed 'population' differences and site-specific allele frequencies; genotypes common in Prawle Point samples had lower growth rates, which coincided with reduced feeding rates and growth efficiency. Measured temperature, humidity and desiccation rate varied across the dine and may therefore be important environmental pressures influencing prey abundance and foraging behaviour. Wave intensity was similar between sites. Food availability and temperature have been varied in the laboratory. Juveniles reared from Peartree Point (low temperature, high humidity and potentially higher food availability site) showed a greater reduction in growth with decreasing food rations and tended to exhibit a more costly physiology when starved. Growth differences between sites were reduced at higher temperatures, but indicated that feeding rates were higher for Peartree Point juveniles. Similar differences in foraging behaviour were also suggested under a simulated tidal regime. Interpretation of the results have been discussed in view of the concordance of genetic, phenotypic and environmental variation, and the establishment of a site-specific physiology along this region of coast.

Type: Thesis (Doctoral)
Qualification: Ph.D
Title: Physiological adaptation and genetic composition in the littoral dog-whelk, Nucella lapillus (L.)
Open access status: An open access version is available from UCL Discovery
Language: English
Additional information: Thesis digitised by ProQuest.
Keywords: Biological sciences; Whelks
URI: https://discovery.ucl.ac.uk/id/eprint/10099997
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