Data from: Reproductive transitions and sperm utilisation in a facultatively parthenogenetic stick insect

Facultative parthenogenesis enables females to switch from asexual
(parthenogenetic) to sexual reproduction after mating, but the process of
fertilisation is poorly understood in such animals. In particular, it is
not known whether switching reproductive modes requires changes in the
eggs themselves, delaying the transition from laying unfertilised to
fertilised eggs. Likewise, very little is known about patterns of sperm
precedence in facultatively parthenogenetic females that mate with
multiple males. In this study, we manipulated reproductive mode in females
of the facultatively parthenogenetic stick insect Megacrania batesii. We
used offspring sex ratio, fertilisation rate, and paternity analysis to
investigate how females descended from distinct natural populations switch
between reproductive modes and utilise sperm from different males. In the
switch treatment group, females were first allowed to lay unfertilised
eggs, and then paired with a male. In the non-switch treatment group,
females were instead paired successively with two different males. We
collected eggs laid over two successive 10-day periods after male
introduction (switch treatment) or substitution (non-switch treatment). We
found little difference between the treatment groups in fertilisation rate
or in the number of sons produced during the first and second 10-day
egg-collection. We also observed similar reproductive performance between
switch and non-switch treatment groups, but females’ population of origin
influenced fertilisation rate and offspring sex ratio. In the non-switch
group, we found near-equal fertilisation rates by the first and second
male. Our results show that M. batesii females can quickly switch from
producing parthenogenetic to fertilised eggs, suggesting that this
transition does not require production of distinct types of eggs. Our
results also show that M. batesii females can rapidly utilise sperm from a
new mate, and exhibit near-complete sperm mixing which suggests that
paternity may be evenly distributed in this species.