In many plants and animal species, asexuals are more common in marginal habitats such as high latitudes or altitudes than their closely related sexual counterparts. Here we propose a new hypothesis to explain this pattern called “geographic parthenogenesis”. In marginal habitats, populations may often exist as metapopulations with high degrees of subdivision and local extinction and recolonizat...

Asexuality frequently evolves in association with hybridity and polyploidy. The phenotypic consequences of this association must be understood before we can fully appreciate the reason for the short-term success, and the long-term failure, of asexual genetic systems. Parthenogenetic forms within the Australian gecko complex Heteronotia binoei are triploid hybrids and overlap geographically with...

BACKGROUND AND AIMS Asexual organisms are more widespread in previously glaciated areas than their sexual relatives ('geographical parthenogenesis'). In plants, this pattern is probably dependent on reproductive isolation and stability of cytotypes within their respective distribution areas. Both partial apomixis and introgressive hybridization potentially destabilize the spatial separation of ...

offshore jacket-type towers are steel structures designed and constructed in marine environments for various purposes such as oil exploration and exploitation units, oceanographic research, and undersea testing. in this paper a newly developed meta-heuristic algorithm, namely cyclical parthenogenesis algorithm (cpa), is utilized for sizing optimization of a jacket-type offshore structure. the a...

Transitions to asexuality have occurred in many animals and plants, yet the biological mechanisms causing such transitions have often remained unclear. Cyclical parthenogens, such as cladocerans, rotifers or aphids often give rise to obligate asexual lineages. In many rotifers, chemical signals that accumulate during population crowding trigger the induction of sexual stages. In this study, I t...

A nomenclature for phallic structures of members of the family Gryllotalpidae is proposed. Genital structures of the main genera of mole crickets are described, discussing the relationships among subfamilies and their generic delimitation. A key is provided for separation of genera based on genitalia structure. Finally, parthenogenesis in genus Gryllotalpella is recorded for the first time.