. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. FIGURE 1. Shell banding dimorphism in Thais (or Nucella) emarginata (Deshayes, 1839). Banding phe- notypes from clutch 80-17-B2-MA (backcross of unbanded Fl female to original banded male parent; actual phenotype frequencies in Table I). The three left-most individuals in each row are predominantly orange, the three right-most, black. All snails in these clutches were raised from egg capsules deposited in the lab; only the three largest individuals of each phenotype combination were photographed. Approximate age of snails =
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. FIGURE 1. Shell banding dimorphism in Thais (or Nucella) emarginata (Deshayes, 1839). Banding phe- notypes from clutch 80-17-B2-MA (backcross of unbanded Fl female to original banded male parent; actual phenotype frequencies in Table I). The three left-most individuals in each row are predominantly orange, the three right-most, black. All snails in these clutches were raised from egg capsules deposited in the lab; only the three largest individuals of each phenotype combination were photographed. Approximate age of snails = 9 mos. Scale bar = 10 mm. dominant allele causing outer shell pigment to be localized in spiral bands, and OBU, a recessive allele resulting in uniformly pigmented shells. Crosses in which one parent was heterozygous at both the banding (OBB/OBU) and the primary outer shell color locus (OCOR/OCBL), while the other parent was homozygous recessive at both loci (OBU/OBU, OCBL/OCBL) revealed that alleles at the banding locus assorted independently from those at the color locus [Group I, Table II; in populations from Barkley Sound the orange, outer shell color allele (OCOR) is usually, but not always dominant to the black allele (OCBL) (Palmer, unpub.)]. Dif- ferential survival of phenotypes was suggested by the results of Table II since unbanded, black offspring (OBU/OBU, OCBL/OCBL) were not only the most frequent in crosses of Group I, where linkage was tested, but also in the crosses of Group II, where no linkage would be detectable since one parent was heterozygous for banding (OBB/OBU), while the other was heterozygous for color (OCOR/OCBL). However, the overall deviation from expected of both groups pooled was not significant (P = , Tooled', Table II). The Fl phenotypes in clutch 82-52-1A (Table I), although consistent with the proposed Mendelian model, reveal the further complexity that the intensity of banding was influenced by other alleles or loci. In this cross, a pre
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
