Data from: Extremely widespread parthenogenesis and a trade-off between alternative forms of reproduction in mayflies (Ephemeroptera)

Studying alternative forms of reproduction in natural populations is of
fundamental importance for understanding the costs and benefits of sex.
Mayflies are one of the few animal groups where sexual reproduction
co-occurs with different types of parthenogenesis, providing ideal
conditions for identifying benefits of sex in natural populations. Here,
we establish a catalogue of all known mayfly species capable of
reproducing by parthenogenesis, as well as species unable to do so.
Overall, 1.8% of the described species reproduce parthenogenetically,
which is an order of magnitude higher than reported in other animal
groups. This frequency even reaches 47.8% if estimates are based on the
number of studied rather than described mayfly species, as reproductive
modes have thus far been studied in only 17 out of 42 families. We find
that sex is a more successful strategy than parthenogenesis (associated
with a higher hatching success of eggs), with a trade-off between the
hatching success of parthenogenetic and sexual eggs. This means that
improving the capacity for parthenogenesis may come at a cost for sexual
reproduction. Such a trade-off can help explain why facultative
parthenogenesis is extremely rare among animals despite its potential to
combine the benefits of sexual and parthenogenetic reproduction. We argue
that parthenogenesis is frequently selected in mayflies in spite of this
probable trade-off because their typically low dispersal ability and short
and fragile adult life may frequently generate situations of mate
limitation in females. Mayflies are currently clearly underappreciated for
understanding the benefits of sex under natural conditions.