Buscar
Mostrando ítems 31-40 de 154
Sexual selection towards a protamine expression ratio optimum in two rodent groups?
(Wiley Blackwell Publishing, Inc, 2021-08)
Post-copulatory sexual selection is thought to influence the evolution of genes involved in reproduction. However, the detection of straightforward effects has been proven difficult due to the complexity and diversity of ...
Seminal fluid and spermatophore production in a western Atlantic invasive swimming crab, Charybdis hellerii, reveals a different pattern to Portunoidea
(2022-01-01)
The male reproductive system in Portunoidea is voluminous in order to produce the sperm plug, avoiding sperm competition. The portunid crab, Charybdis hellerii, is a successful invasive species, and this study describes ...
Redescription and first record in South America of Neogriphoneura timida Curran (Diptera, Lauxaniidae)
(2017-01-01)
The genus Neogriphoneura Malloch, 1924 is currently composed of 11 species with New World distribution. Neogriphoneura timida Curran, 1942 is recorded for the first time in South America, with occurrences in Brazil, Colombia ...
Successive matings produce opposite patterns on ejaculate volume and spermatozoa number in an ancient arthropod model with indirect sperm transfer
(National Research Council Canada-NRC Research Press, 2019-01-15)
The production of spermatophore and ejaculate is energetically expensive for males. High mating rates may accelerate sperm depletion and progressively decrease the size of the ejaculates. Sperm competition can shape ...
Ejaculate allocation in Brachyura: What do males of Metacarcinus edwardsii respond to?
(2018)
In polygynous species, the sperm economy hypothesis predicts that males can adjust the amount of their ejaculate during copulation in response to (1) individual traits of females according to potential female fecundity, ...
First record of a macroraptorial sperm whale (Cetacea, physeteroidea) from the miocene of Argentina
(Sociedade Brasileira de Paleontologia, 2018-09)
Raptorial sperm whales of the genus Livyatan were described from the Miocene of Peru and Chile. Revision of paleontological collections resulted in the finding of isolated teeth belonging to aff. Livyatan sp. coming from ...
Spermatogenesis chronology in Achroia grisella Fabricius (Lepidoptera, Pyralidae) comparing eupyrene and apyrene spermiogenesis
(Brill Academic Publishers, 2014)
An effective sperm competition avoidance strategy in crabs drives genetic monogamy despite evidence of polyandry
(2016)
For polyandrous species where females have sperm storage structures, males develop several strategies to avoid sperm competition and thus to maximize the number of eggs fertilized. On the other hand, females may receive ...