Asexuality and species invasion

Founding populations of non-native species typically contain a small subset of their home range populations, exhibiting a reduced subset of their genetic diversity. Many of these non-native species predominantly, or even solely, engage in asexual reproduction, but it is unclear whether asexual reproduction is linked with species invasion. We used a systematic review of peer-reviewed literature to investigate whether species with reproductive polymorphisms are more often asexual in their invaded than native range. We also investigated whether genetic diversity was higher in home than invaded ranges. We found 219 relevant studies, and those showed that asexual reproduction is three times more common in invaded than home ranges, and higher genetic diversity is 20 times more common in home than invaded ranges for these organisms (this difference highest in the more recently introduced species). Hence, asexual reproduction appears associated with species invasion. Whereas asexual reproduction lacks the genetic mixing needed to respond to heterogenous environments and natural enemies, it confers several advantages for small founding populations, including the ability to establish new populations from a single or very few founding members with no requirement for finding a mating partner or pollinator, and asexual species invasion often brings relatively low intraspecific competition (allowing monoculture domination). For non-native species, high phenotypic plasticity and a lack of natural enemies may offset the disadvantages of asexual reproduction, leading to enhanced success for asexual non-native plants and animals.