The evolution of sperm

Initially one sees the cilliated vagina and later the received sperm that are anchored in a specialized portion of the female antrum, the sperm-receiving organ Video courtesy of Tim Janicke and Peter Sandner. Permanent link. The organism has no cell wall and the outer body is covered with scales, which is a common feature in primitive green flagellates. English Movie Caption: A short video sequence recorded in the microscope that shows the movements of an individual sperm cell of the free-living flatworm Macrostomum lignano. Cell division enlarges its body size but does not increase its population. In Hirase Sakugoro discovered flagellated sperm in a seed of Ginkgo biloba, then Ikeno Seiichiro found the same phenomenon in Cycas revoluta.

Sperm competition is, quite literally, competition between two or more sperm to reach and fertilize an egg. Continue Reading. Notify me of new comments via email. Instead, Xu had no choice but to catch his own fully endowed rainbow trout on a family trip to a fishpond. Gov't Review. But what about sperm from animals such as frogs, spiders, and mice?

By surviving longer and producing more offspring, these individuals are more likely to pass their beneficial genes onto the next generation. Evolution is the change in the genetics of a population over time. Her research interests include sperm morphology in primates and how hybridization interbreeding and genetic admixture between primate species affects sperm in hybrid individuals. In this case, males not only compete with other males of the same species, but also with males from other species!