Two Homogametic Genotypes – One Crayfish: On the Consequences of Intersexuality

Abstract

Summary In the Australian redclaw crayfish, Cherax quadricarinatus (WZ/ZZ system), intersexuals, although exhibiting both male and female gonopores, are functional males bearing a female genotype (WZ males). Therefore, the occurrence of the unusual homogametic WW females in nature is plausible. We developed W/Z genomic sex markers and used them to investigate the genotypic structure of experimental and native C. quadricarinatus populations in Australia. We discovered, for the first time, the natural occurrence of WW females in crustacean populations. By modeling population dynamics, we found that intersexuals contribute to the growth rate of crayfish populations in the short term. Given the vastly fragmented C. quadricarinatus habitat, which is characterized by drought-flood cycles, we speculate that intersexuals contribute to the fitness of this species since they lead to occasional increment in the population growth rate which potentially supports crayfish population restoration and establishment under extinction threats or colonization events.

Identification of sex linked molecular markers in Indonesian giant freshwater prawn Macrobrachium rosenbergii

“…The sex chromosome of female giant freshwater prawn is heterogametic (Justo et al, 1991), with the chromosome code was WZ (Malecha et al, 1992). Furthermore, some of the previous studies has confirmed that there are other species with sex chromosome of WZ/ ZZ, i.e., crayfish and white shrimp (Guo et al, 2019;Levy et al, 2020). Levy et al (2020) stated that the chromosome system of WZ/ ZZ is commonly found in macruran decapoda crustacea (crayfish and lobster).…”

“…Furthermore, some of the previous studies has confirmed that there are other species with sex chromosome of WZ/ ZZ, i.e., crayfish and white shrimp (Guo et al, 2019;Levy et al, 2020). Levy et al (2020) stated that the chromosome system of WZ/ ZZ is commonly found in macruran decapoda crustacea (crayfish and lobster). However, until now, there is no identification report about sex chromosome mating of giant freshwater prawn from karyotyping process.…”

Protandric Transcriptomes to Uncover Parts of the Crustacean Sex-Differentiation Puzzle

“…To find the sequence of the IAG mRNA in H. inermis (Hi-IAG), we aligned the IAG sequence from P. platyceros [Pnp-IAG; GenBank accession number: KX619617.1 (Levy et al, 2020a)] to the H. inermis body transcriptome generated in this study. From the IAG sequences that are available for dozens of decapod species, with different reproductive strategies and from various clades within the Crustacea (Levy and Sagi, 2020), Pnp-IAG was chosen for alignment due to the similar protandric nature of P. platyceros and H. inermis and their close evolutionary relationship (Wolfe et al, 2019;Levy et al, 2020c). After finding the Hi-IAG mRNA transcript in the body transcriptome of H. inermis, the predicted structure of the protein was inferred from its deduced amino acid sequence.…”

“…Important examples of sexual plasticity may be found among the crustaceans (Pandian, 2016), an ancient highly diverse group of animals in which a variety of reproductive strategies are represented, including gonochorism (separate sexes) (Juchault, 1999), intersexuality (combination of male and female features within a gonochoristic species) (Goldschmidt, 1938;Reinboth, 1975;Sagi et al, 1996;Abdel-Moneim et al, 2015;Levy et al, 2020c), asexual reproduction (e.g., parthenogenesis) (Scholtz et al, 2003;Martin et al, 2007), and different types of hermaphroditism (Levy et al, 2018;Benvenuto and Weeks, 2020). The last of these strategies constitutes a means of reproduction in which a particular individual bears both ovarian and testicular tissues [ovotestis (Hoffman, 1972;Stentiford, 2012)] and produces gametes of both sexes (Benvenuto and Weeks, 2020).…”

“…To obtain insight into the function of these novel genes, we also performed a comparative in silico analysis with P. platyceros, taking advantage of RNA libraries of specific tissues previously obtained over the life cycle of P. platyceros (Levy et al, 2020a). P. platyceros is particularly suitable for such an analysis for two reasons: (i) taxonomically, the two species, H. inermis and P. platyceros, belong to families -Pandalidae and Hippolytidae, respectively (Martin et al, 2009) -that are closely related within the infraorder Caridea (Christoffersen, 1990;Wolfe et al, 2019;Levy et al, 2020c), and (ii) technically, the RNA for the H. inermis libraries was extracted from the entire body of the animal (due to its small size that prevented dissection of specific tissues), while the RNA for constructing P. platyceros libraries was obtained by dissecting out specific tissues (Levy et al, 2020a). Therefore, our working hypothesis for the in silico analysis part of this study was that a search for homologs to the newly discovered H. inermis genes in transcriptomic libraries of P. platyceros (and other decapod crustaceans) might reveal the function of those genes in a more general context that includes a wider range of crustaceans.…”