Data from: The genetics of egg retention and fertilization success in Drosophila: one step closer to understanding the transition from facultative to obligate viviparity

Oviparous, facultative egg retention enables Drosophila females to
withhold fertilized eggs in their reproductive tracts until circumstances
favor oviposition. The propensity to retain fertilized eggs varies greatly
between species, and is correlated with other reproductive traits, such as
egg size and ovariole number. While previous studies have described the
phenomenon, no study to date has characterized within-species variation or
the genetic basis of the trait. Here, we develop a novel microscope-based
method for measuring egg retention in Drosophila females and determine the
range of phenotypic variation in mated female egg retention in a subset of
91 Drosophila Genetic Reference Panel (DGRP) lines. We inferred the
genetic basis of egg retention using a genome-wide association study
(GWAS). Further, the scoring of more than 95,000 stained, staged eggs
enabled estimates of fertilization success for each line. We found
evidence that ovary- and spermathecae-related genes as well as genes
affecting olfactory behavior, male mating behavior, male-female attraction
and sperm motility may play a crucial role in post-mating physiology.
Based on our findings we also propose potential evolutionary routes
towards obligate viviparity. In particular, we propose that the loss of
fecundity incurred by viviparity could be offset by benefits arising from
enhanced mate discrimination, resource specialization, or modified egg
morphology.