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  • 1
    Electronic Resource
    Electronic Resource
    Sperm competition in horseshoe crabs (Limulus polyphemus) (1994)
    Springer
    Behavioral ecology and sociobiology 35 (1994), S. 153-160 
    Details
    ISSN: 1432-0762
    Keywords: Horseshoe crabs ; Limulus polyphemus ; Satellite males ; DNA paternity analysis ; Sperm competition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Male horseshoe crabs have two mating tactics. Some males come ashore attached to a female (clasping the posterior margin of the females' carapace with their modified pedipalps) and nest with her on the intertidal portion of the beach during the high tide. Other males come ashore unattached and crowd around nesting couples. Fertilization is external and unattached males that are in contact with a pair, i.e. ‘satellite’ males, release sperm, so the assumption has been that they are fertilizing eggs. We conducted a paternity analysis to determine the proportion of eggs fertilized by attached and satellite males. Pairs with one satellite were observed during nesting on beaches in Florida and Delaware and their eggs were collected and reared to the late trilobite or first instar horseshoe crab stage. DNA was extracted from these offspring and from each adult (female, attached and satellite male) for use in paternity analysis. A Limulus-specific hypervariable microsatellite locus was identified and primers were constructed to amplify this locus via the polymerase chain reaction (PCR). Genotypes of putative parents and offspring were determined by resolving length variants of these PCR products on acrylamide gels. This allowed us to determine parentage of the offspring. We demonstrate that satellite males fertilized 40% of the eggs on average, attached males fertilized 51% and 4% of the eggs that were laid by the female were fathered neither by the attached male nor by the satellite (and 5% could not be determined unambiguously). There is high variability in the success of satellite males, ranging from 0 to 88%. Part of this variability can be explained by the position of the satellite relative to the attached male. We discuss the mechanics of fertilization and the possible advantages for multiple mating in this species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00167954
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Sperm competition in horseshoe crabs (Limulus polyphemus) (1994)
    Springer
    Behavioral ecology and sociobiology 35 (1994), S. 153-160 
    Details
    ISSN: 1432-0762
    Keywords: Key words Horseshoe crabs ; Limulus polyphemus ; Satellite males ; DNA paternity analysis ; Sperm competition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Male horseshoe crabs have two mating tactics. Some males come ashore attached to a female (clasping the posterior margin of the females' carapace with their modified pedipalps) and nest with her on the intertidal portion of the beach during the high tide. Other males come ashore unattached and crowd around nesting couples. Fertilization is external and unattached males that are in contact with a pair, i.e. 'satellite' males, release sperm, so the assumption has been that they are fertilizing eggs. We conducted a paternity analysis to determine the proportion of eggs fertilized by attached and satellite males. Pairs with one satellite were observed during nesting on beaches in Florida and Delaware and their eggs were collected and reared to the late trilobite or first instar horseshoe crab stage. DNA was extracted from these offspring and from each adult (female, attached and satellite male) for use in paternity analysis. A Limulus-specific hypervariable microsatellite locus was identified and primers were constructed to amplify this locus via the polymerase chain reaction (PCR). Genotypes of putative parents and offspring were determined by resolving length variants of these PCR products on acrylamide gels. This allowed us to determine parentage of the offspring. We demonstrate that satellite males fertilized 40% of the eggs on average, attached males fertilized 51% and 4% of the eggs that were laid by the female were fathered neither by the attached male nor by the satellite (and 5% could not be determined unambiguously). There is high variability in the success of satellite males, ranging from 0 to 88%. Part of this variability can be explained by the position of the satellite relative to the attached male. We discuss the mechanics of fertilization and the possible advantages for multiple mating in this species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00167954
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Sex ratios and life-history patterns of a solitary wasp, Trypoxylon (Trypargilum) politum (Hymenoptera : Sphecidae) (1992)
    Springer
    Behavioral ecology and sociobiology 30 (1992), S. 7-27 
    Details
    ISSN: 1432-0762
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Werren and Charnov (1978) and Seger (1983) proposed a model to explain a fairly common pattern of alternating sex ratio biases between generations in partially bivoltine insects. When first-generation males overlap and mate with females of the second generation, then females should bias sex ratios in favor of sons for the first generation and daughters for the second generation. In an intensive, 7-year study at four sites in northern Florida, pipe-organ mud-daubing wasps (Trypoxylon (Trypargilum) politum; Hymenoptera: Sphecidae) were found to have strongly male-biased sex ratios in the first or overwintering generation and 1:1 or female-biased sex ratios in the second or summer generation. These differences were not due to differences in mortality of the two sexes but rather resulted from changing female sex-allocation decisions. In some respects the mud dauber results fit Seger's model well: alternating sex ratios in partially bivoltine populations, first-generation males overlapping second-generation females and perhaps most convincingly, northern, univoltine populations do not have a male bias. Despite this qualitative fit, however, our data do not meet the quantitative predictions of the model. This could result from the fact that some assumptions of the model are not met by the life history of T. politum. Alternative explanations for alternating sex ratios include split sex ratios, seasonal differences in cost ratios, facultative maternal investment rules and facultative overwintering decisions by offspring. Despite the position that sex ratios have achieved in the modern study of evolution, it is clear that accurate, quantitative predictions on sex-allocation patterns demand the same detailed understanding of the biology of the organism that is required for the study of other adaptations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00168590
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
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