Aphally versus euphally in self-fertile hermaphrodite snails from the species Bulinus truncatus (Pulmonata: Planorbidae)
Article Abstract:
Bulinus truncatus snails are hermaphroditic but there are some individuals which lack the copulatory organ. This implies that Bulinus may be a partial selfer and that aphallic individuals may be more fit than those with the copulatory organ. This is because the energy expended to maintaining male accessory glands and organs can be otherwise utilized for reproduction. The increased relative fitness of aphallic Bulinus truncatus over the euphallic phenotype is investigated by studying laboratory populations of each phenotype. Results show that aphallic individuals produce 20% more eggs and have increased fitness.
Publication Name: The American Naturalist
Subject: Earth sciences
ISSN: 0003-0147
Year: 1992
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Variance of lifetime reproductive success: estimation based on demographic data
Article Abstract:
Comparison of variances of lifetime reproductive success isparticularly difficult because the parameter is ill-defined and will be valid only if complete life cycles are employed in the estimate of the parameter. Techniques using demographic data can be employed in the approximation of variance of lifetime reproductive success. These methods assume that selection is absent and that reproductive effort and life span covariance is negligible. Applications of the technique and a confidence interval estimation method are presented.
Publication Name: The American Naturalist
Subject: Earth sciences
ISSN: 0003-0147
Year: 1993
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The limits of reproductive output: offspring size versus number in the sand lizard (lacerta agilis)
Article Abstract:
A natural population of sand lizards at Asketunnan, Sweden is examined to determine the factors that affect the trade-off between offspring size and clutch size in said population. Variations in prey availability were made by conducting a separate field study and laboratory study. Results reveal the existence of a trade-off between clutch sizes and offspring sizes in both studies.
Publication Name: The American Naturalist
Subject: Earth sciences
ISSN: 0003-0147
Year: 1997
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