Approximately 90 vertebrate species are known to exist as unisexual populations, that is, consisting of reproducing females (Lampert & Schartl, 2010). All of these are restricted to fish, amphibian and reptile species (Figure 1). An all-female reproducing population has advantages since every individual can carry young so the population has the potential to grow at a faster rate than bisexual populations, where the male only donates sperm and does not produce offspring. Since this has a distinct advantage it is perhaps unusual that unisexual populations are so rare. However, the main cost of being unisexual is the loss of genetic recombination which occurs in male and female bisexual populations. This is crucial in providing genetic stability, preventing accumulation of mutations and providing opportunities for adapting to a changing environment. Therefore, unisexual species do not occur widely amongst vertebrates. Leer más.