Data from: The role of hybridisation in the origin and evolutionary persistence of vertebrate parthenogens: a case study of Darevskia lizards

Obligate parthenogenesis is found in only 0.1% of vertebrate species, is
thought to be relatively short lived and is typically of hybrid origin.
However, neither the evolutionary persistence of asexuality in
vertebrates, nor the conditions that allow the generation of new
parthenogenetic lineages are currently well understood. It has been
proposed that vertebrate parthenogenetic lineages arise from hybridisation
between two divergent taxa within a specific range of phylogenetic
distances (the “Balance Hypothesis”). Moreover, parthenogenetic species
often maintain a certain level of hybridisation with their closest sexual
relatives, potentially generating new polyploid hybrid lineages. Here we
address the role of hybridisation in the origin and evolutionary lifespan
of vertebrate parthenogens. We use a set of microsatellite markers to
characterize the origins of parthenogens in the lizard genus Darevskia to
study the distinctiveness of sexual and asexual taxa currently in
sympatry, and to analyse the evolutionary consequences of interspecific
hybridisation between asexual females and sexual males. We find that
parthenogens result from multiple past hybridisation events between
species from specific lineages over a range of phylogenetic distances.
This suggests that the Balance Hypothesis needs to make allowance for
lineage-specific effects, as envisaged in the “Phylogenetic Constraint
Hypothesis”. Our results show recurrent backcrossing between sexual and
parthenogenetic Darevskia but neither gene flow nor formation of new
asexual lineages is found. We suggest that, along with their demographic
advantage, parthenogens gain additional leverage to outcompete sexuals in
nature when the retention of sexual reproductive machinery allows
backcrossing with their sexual ancestors.