ABSTRACT Sex identification at early stages of development is of great interest for studies in evolutionary biology in many animals. Knowing the sex ratio, even more in offspring, allows testing hypotheses related to the cause of sex ratio biases in populations and species. Spiders born with a defined sex, mostly have an X 1 X 2 0 sex chromosome system, but it is not possible to determine their sex phenotypically until the adult or near‐adult stage. The wolf spider Allocosa marindia inhabits the sandy coast of Southern South America and shows sex role reversal. Laboratory and field studies suggest a strong bias in the sex ratio in favour of females in this species. Here, we analysed the 2C nuclear DNA content by flow cytometry in females and males of A. marindia to determine whether the difference between the sexes is enough to identify the sex of the individuals. The average 2C DNA content for females was 4.96 ± 0.036 pg and for males 4.72 ± 0.020 pg. Then, we tested the usefulness of the technique to sex A. marindia frozen spiderlings, in order to be able to decouple the collection time from the processing time. We analysed 59 spiderlings from four known females. Although we found greater variability in frozen samples, the difference in DNA content was enough to determine the sex of 54 frozen spiderlings (43 females and 11 males). Our results show a promising technique for sexing hatchlings of diplodiploid arthropods. In future studies, we will seek to sex spiderlings from a larger number of mothers to understand the causes of female bias in this species.
Bidegaray‐Batista et al. (Wed,) studied this question.
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