In this respect, it may be significant that parthenogenetic H. binoei have evolved greater aerobic endurance at low temperature when compared with their sexual relatives [44].
In most cases, obligate parthenogens are of similar size, or even larger than their closest sexual relatives – the latter can usually be attributed to polyploidy [26].
Several studies suggest that, in passively dispersed aquatic invertebrates, parthenogens are indeed better and faster colonizers than their sexual relatives [17], [20], [36], [37].
The evolutionary relationships of the parthenogens and their closest Central Asian sexual relatives were reconstructed using A. sinica and A. franciscana as outgroups.
Sequences from A. sinica (DQ119650) and A. franciscana Kellogg, 1906 (DQ119645), the closest sexual relatives to sexual Central Asian species [16], [26], were used as outgroups in our phylogenetic analyses.
Although, under experimental conditions, diploid parthenogenetic Artemia are able to colonize habitats already occupied by the sexual sympatric A. salina and to displace them [41], [42], the ecological relationships between diploid A. parthenogenetica and their sexual relatives are poorly known.
In addition, one undescribed sexual Artemia population from Kazakhstan (Artemia Research Center code - ARC 1039, unknown locality) was analysed to increase the sampling of potential closest sexual relatives of A. parthenogenetica.
Parthenogenetic organisms tend to have broadly distributed genetic lineages, wider geographic distributions than their sexual relatives, and a propensity to occur in marginal areas (see [1] and references therein).
This represents a similar pattern to the so-called 'geographic parthenogenesis' (i.e. distinct geographic distribution of parthenogenetic organisms and their sexual relatives; [38]) reported for other parthenogenetic species.
