DOI: 10.5061/dryad.j3tx95xd7
title: Split sex ratio due to maternal condition

description: In females of haplodiploid animals, female production requires
 fertilisation, whereas male production does not. Therefore, haplodiploid
 species can display extraordinary sex ratios. Constrained sex allocation
 occurs when a female cannot produce daughters. This can be due to
 virginity but may also occur after mating due to insemination failure,
 selfish genetic elements or physiological constraints. Here, we
 investigated the mechanism underlying constrained sex allocation
 in Pezothrips kellyanus. In this species some mated females
 produce highly female-biased broods, yet, for unknown reasons, others
 produce extremely male-biased broods. Using crossing experiments
 controlled for maternally inherited endosymbionts we confirmed that
 constrained females were successfully inseminated. Furthermore,
 male-biased offspring production was not paternally inherited, ruling out
 paternal sex ratio elements previously identified as sex ratio distorters
 in some parasitoid wasps. Next, we excluded mating time and paternal
 fitness effects (male size) on sex allocation. However, we found that
 constrained sex allocation only occurred in small females producing
 smaller eggs than large females producing larger eggs and female-biased
 broods. Consequently, the bimodal sex allocation pattern correlates with
 maternal condition, and may have arisen (adaptively or non-adaptively) in
 association with an egg size-mediated fertilization mechanism recently
 detected in some haplodiploids, with egg size positively affecting
 fertilization success. 
description: The data set describes the post-mating constrained sex allocation
 in Kelly’s citrus thrips, <i>Pezothrips
 kellyanus </i>(Thysanoptera: Thripidae). It demonstrates the results
 of three separate crossing experiments: experiment 1) analysis of mating
 effectiveness by dissection of spermathecae of mated females; experiment
 2) test for the presence of a paternal sex ratio (PSR) element by
 assessing the sex ratio patterns in two successive generations, as well as
 the data for mating time and male size (forewing length) measurements; and
 experiment 3) analysis of effect of maternal fitness [female body size
 (forewing length) and size of eggs ovipositioned before mating] on sex
 ratio after mating. Mother types are categorised according to their mating
 status and their offspring sex ratio: virgins [V], constrained mated
 females producing male-biased broods (M-broods) [M(♂)] and unconstrained
 mated females, producing female biased broods (F-broods) [M(♀)]. The brood
 types of mated females are categorized as F and M denoting female-biased
 and male-biased brood types, respectively. According to the data,
 all <i>P.</i><i>kellyanus </i>mated females were
 successfully inseminated irrespective of their brood-types produced
 (experiment 1 – spreadsheet 1). M-brood production is not paternally
 inheritable: the prevalence of M-brood production was not different
 between matings that involved males produced by virgin and unconstrained
 mothers (experiment 2 – spreadsheets 2 and 3). Moreover, brood-type was
 not affected by mating duration and male size (experiment 2 – spreadsheets
 4 and 5). Finally, the data reveals mother size and egg size (maternal
 effects) influence brood-type: smaller females (producing smaller eggs in
 virginity) are more likely to produce M-broods after mating. These results
 indicate that the constrained sex allocation in <i>P.
 kellyanus</i>is due to the maternal condition and the resource
 investment towards egg size.