Genetic diversity is essential to the survival of a species. It's easy enough to maintain if a species reproduces sexually; an egg and a sperm combine genetic material from two creatures into one, ...

Parthenogenetic species are assumed to represent evolutionary dead ends, yet parthenogenesis is common in some groups of invertebrates particularly in those found in relatively constant environments.

Despite the fact that clonal reproduction is a priori expected to be reproductively advantageous (Maynard-Smith, 1978; Bell, 1982), obligate asexual organisms are evolutionarily short lived and have ...

In most vertebrates, males and females are believed to differ in terms of their investment in offspring. Dominance theory suggests that one way individuals of the sex with lower parental investment ...

Flatworms of the species Schmidtea polychroa do it quite differently. First, they are simultaneous hermaphrodites, meaning that every individual worm is both male and female during its entire lifespan ...