At coitus, human sperm are deposited into the anterior vagina, where, to avoid vaginal acid
and immune responses, they quickly contact cervical mucus and enter the cervix. Cervical …

Molecular studies of speciation in birds over the last three decades have been dominated by
a focus on the geography, ecology, and timing of speciation, a tradition traceable to Mayr's …

Referential models based on extant African apes have dominated reconstructions of early
human evolution since Darwin's time. These models visualize fundamental human …

Several elements of the Ardipithecus ramidus foot are preserved, primarily in the ARA-VP-
6/500 partial skeleton. The foot has a widely abducent hallux, which was not propulsive …

Sexual reproduction is a fundamental biological process common among eukaryotes.
Because of the significance of reproductive proteins to fitness, the diversity and rapid …

Sexual reproduction requires coordinated contributions from both sexes to proceed
efficiently. However, the reproductive strategies that the sexes adopt often have the potential …

Postcopulatory sperm competition is a key aspect of sexual selection and is believed to drive
the rapid evolution of both reproductive physiology and reproduction-related genes,,,. It is …

Publisher Summary The mechanisms of sexual reproduction are expected to be complex
and evolutionarily dynamic in internally fertilizing species, where numerous biochemical …

Seminal fluid proteins show striking effects on reproduction, involving manipulation of
female behavior and physiology, mechanisms of sperm competition, and pathogen defense …

Proteins in the seminal fluid of animals with internal fertilization effect numerous responses
in mated females that impact both male and female fertility. Among these proteins is the …