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Sexual orientation test asexual propagation

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Conceived and designed the experiments: All other relevant data are within the paper.

pansexual (gender-blind sexual attraction to...

But the evolution of sexual reproduction remains unclear, because we have limited examples that demonstrate the Sexual orientation test asexual propagation success of sexual lineages in the face of competition from asexual lineages in the same environment. Here we investigated a sympatric occurrence of sexual and asexual reproduction in the pineapple mealybug, Dysmicoccus brevipes. This pest invaded southwestern Japan, including Okinawa and Ishigaki Islands, in the s in association with imported pineapple plants.

Our recent censuses demonstrated that on Okinawa Sexual orientation test asexual propagation reproducing individuals can coexist with and even dominate asexual individuals in the presence Sexual orientation test asexual propagation habitat and resource competition, which is considered to be severe for this nearly immobile Sexual orientation test asexual propagation. Molecular phylogeny based on partial DNA sequences in the mitochondrial and nuclear genomes, as well as the endosymbiotic bacterial genome, revealed that the asexual lineage diverged from a common sexual ancestor in the relatively Sexual orientation test asexual propagation past.

In contrast, only the asexual lineage exhibiting obligate Sexual orientation test asexual propagation thelytoky was discovered on Ishigaki. Co-existence of the two lineages cannot be Sexual orientation test asexual propagation by the results of laboratory experiments, which showed that the intrinsic rate of increase in the sexual lineage was not obviously superior to that of the asexual lineage.

This biological system offers a unique opportunity to assess the relative success of sexual versus asexual lineages with an unusual morphology and life cycle.

Asexual reproduction, in which offspring arise from a single female organism, occurs in a variety of eukaryotes including plants, fungi, and animals. It is assumed to confer some advantages over a sexual reproduction, in which individuals of two genders, females and males, must be involved but only females can give birth to new Sexual orientation test asexual propagation [ 1 — 10 ]. Although a variety of theories have been proposed to explain the genetic and ecological fitness associated with sexual reproduction, the evolution of sexuality and reproductive systems remains as one of the major unresolved puzzles in biology [ 4 ].

In particular, there are few examples that demonstrate the success and persistence of sexual lineages in the face of competition from asexual lineages in Sexual orientation test asexual propagation Sexual orientation test asexual propagation [ 1112 ].

Coccoideawhich include mealybugs Pseudococcidaeare interesting for studies of the evolution and ecology of sexuality and asexuality, because this taxon exhibits various systems that control sex determination, sexual development, sex ratio, and mode of reproduction [ 1314 ].

Such an extraordinary diversity of genetic systems is considered to be, at least partly, associated with their unusual morphology Fig 1 and life cycle [ 1315 ]. Scale insects are plant sap feeders closely related to aphids and whiteflies and are characterized by their unusual shapes. Adult females show development with retention of juvenile physical characters neoteny and are relatively immobile, lacking wings and often even legs.

They produce body-covering secretions that act like protective shells, and they can be long-lived sometimes up to several months [ 15 ]. In Sexual orientation test asexual propagation, adult males are winged and mobile, but they are tiny and fragile and have a limited life span of a few days at most [ 1516 ]. Such extreme sexual dimorphism exposes the immobile females to high levels of competition over mate resources represented by the fragile and short-lived males [ 17 ], which may lead to the evolution of reproductive systems that depend less on males [ 14 ].

In fact, males are either very rare or unknown in many scale insects, particularly in mealybugs: The pineapple mealybug, Dysmicoccus brevipes Cockerellis one such parthenogenetic species.

Sexual orientation test asexual propagation is a known vector Sexual orientation test asexual propagation pineapple wilt—associated viruses, which severely reduce pineapple yields [ 19 ], and this species also attacks many other agricultural crops [ 2021 ]. Dysmicoccus brevipes was first described in Jamaica and is apparently native to the New World [ 22 ], but it now has a cosmopolitan distribution associated with pineapple transportation and cultivation.

Many previous studies [ 23 — 27 ] conducted in a variety of areas indicated that this species reproduces by obligate apomictic thelytokous parthenogenesis [ 18 ], although the presence of adult males has been reported [ 22 ]. At least on the Hawaiian Islands, only parthenogenetic females are found; males have yet Sexual orientation test asexual propagation be discovered and are probably not present [ 22 ].

These findings suggest that both sexual and asexual reproductive systems are included in the same or a very closely related lineage, and thus D. However, little is known about the distributions of sexual and asexual D.

Therefore, in the present study we first surveyed the occurrences and frequencies of sexual and asexual individuals in D.

Asexual reproduction, in which offspring...

The sexual and asexual lineages co-exist on one of the islands, whereas only the asexual lineage is present in the other. We then measured their fecundity and growth rates under laboratory conditions to examine the basic elements of competition between the lineages. Finally, we Sexual orientation test asexual propagation to elucidate their molecular phylogeny by using partial sequences of genomes of mitochondria, nuclei, and the primary endosymbiotic bacterium, Candidatus Tremblaya princeps, which is ubiquitously present in the cytoplasm of mealybug bacteriocytes and is maternally inherited [ 2829 ].

Gravid ovoviviparous females of D. Each mealybug was collected from a different colony in order to avoid sampling bias. They were placed individually in a tight-sealed laboratory dish 5. The offspring were transferred to a larger tight-sealed laboratory dish 9. For sexual mealybugs, the adults that emerged were allowed Sexual orientation test asexual propagation copulate for 1 day.

Pregnant females were transferred to a new dish with fresh food. Development times, pre-parturition durations, parturition durations, and numbers of offspring were assessed using laboratory-reared mealybugs under the conditions described above. For the assessment of development times, freshly born nymphs were transferred individually to a germinated broad bean plant placed in a tight-sealed dish and were monitored Sexual orientation test asexual propagation. Males made cocoons and became pupae after three molts, whereas females matured Sexual orientation test asexual propagation adulthood after three molts without pupal metamorphosis.

To assess reproductive performance parameters, a fresh adult female just after the final molt was placed individually in a tight-sealed dish and fed with a germinated broad bean plant. Each female of the sexual lineages was housed with one adult male that was randomly chosen from stock culture, and copulation was confirmed visually. Offspring borne by each female were counted every day until the female stopped parturition.

The mitochondrial cytochrome oxidase subunit I CO1 gene ca. The following internal sequencing primers were used in the sequencing reaction: Planococcus citriPlanococcus minorPlanococcus kraunhiaePseudococcus Sexual orientation test asexual propagation cryptusCrisicoccus matsumotoiand Dysmicoccus neobrevipes.

The gene sequences were aligned using ClustalX software [ 31 ]. The final alignment was inspected and corrected manually, and only unambiguous nucleotide sites were used for analyses.

Maximum likelihood trees with bootstrap values based on resamplings were constructed using TreeFinder [ 32 Sexual orientation test asexual propagation. Two completely different reproductive systems were observed in the pineapple mealybugs collected on Okinawa: Females from the female-only broods produced only female offspring without copulation, indicating thelytokous parthenogenesis.

Females from the broods with both sexes were able to produce both male and female Sexual orientation test asexual propagation only after copulation and never produced offspring without copulation, indicating sexual reproduction. As far as we observed, both of the reproductive systems were maternally hereditable and Sexual orientation test asexual propagation obligatory. The sex ratios of offspring in some matrilines are shown in S1 Fig.

Sexual orientation test asexual propagation the other hand, only an asexual lineage was found in a pineapple field on Ishigaki; the matrilines collected during three censuses were examined but no sexual reproduction was observed.

The Klein Sexual Orientation Grid

Performances with respect to the development of the two Sexual orientation test asexual propagation of mealybugs from Okinawa were generally similar except for the sex ratios in their offspring.

However, the Sexual orientation test asexual propagation duration i. The detailed data for developmental and reproductive performances are shown in S1 Table. Partial sequences of mitochondrial and nuclear genomes, as well as the primary endosymbiotic bacterial genome, were examined individually in 40 mealybugs collected from Okinawa 32 sexual females and 8 asexual females and 45 mealybugs collected from Ishigaki all asexual.

Six haplotypes were found based on the mitochondrial CO1 sequences bp. These haplotypes were clearly divided into two groups corresponding to the sexual lineage and the asexual lineage Fig 3a. Among the haplotypes of Sexual orientation test asexual propagation sexual lineage, haplotype A1 was predominant In the asexual lineage, haplotype P1 was similarly predominant both on Okinawa Each haplotype represented a group that was the most closely related among the CO1 sequences of all mealybug species examined Sexual orientation test asexual propagation clustered into clades with high bootstrap values Fig 3a.

A total of 35 nucleotide sites were substituted 2. The trees were constructed by the maximum likelihood method using unambiguously aligned nucleotide sites. The trees of rpoB and ITS2 are rooted on each midpoint.

Partial Sexual orientation test asexual propagation of a single-copy protein-coding gene rpoB ; bp of the primary endosymbiont, Candidatus Tremblaya princeps, harbored in the cytoplasm of mealybugs were very similar in the two lineages, but one nucleotide Sexual orientation test asexual propagation involving an amino acid substitution was found.

No differences were discovered in the sequences of the samples examined within each lineage. Like the CO1 sequences, the rpoB sequence-based phylogenetic tree showed that the two lineages of D.

The ITS2 region in the mealybug nuclear Sexual orientation test asexual propagation was successfully determined for 36 and 9 individuals collected from Okinawa and Ishigaki, respectively. Sequences of the PCR products from the other samples could not be determined by direct sequencing, probably because of intra-individual variations of the ITS2 region.

The ITS2 sequences also included a fixed difference: The Sexual orientation test asexual propagation sequences of the asexual lineage had only one transition mutation, whereas two gaps and 14 nucleotide substitutions 7 transitions and 7 transversions were found between the sexual lineage and the asexual lineage. Phylogenetic analysis of the ITS2 sequences of the genus Dysmicoccus Sexual orientation test asexual propagation the maximum likelihood method demonstrated that the two lineages of D.

In the CO1 tree, we used the sequence from Phenacoccus solenopsiswhich belongs to a different subfamily Phenacoccinaeas the outgroup to show the phylogenetic position of D. No reliable alignment results were generated in analyses of rpoB and ITS2 when sequences of Phenacoccinae samples were used, and therefore the trees rooted on each midpoint were shown to demonstrate only the phylogenetic relationship of the two lineages of D.

The present study demonstrated that distinct reproductive modes—sexual and asexual—coexist in a local, non-native population of the pineapple mealybug, D. The mealybugs with the distinct reproductive modes are behaviorally and genetically isolated and are likely to represent diverged lineages, although there are no morphological diagnostic features.

The molecular genotyping data support this idea. DNA sequences of mitochondrial and nuclear genomes as well Sexual orientation test asexual propagation the Sexual orientation test asexual propagation bacterial genome were closely related between the lineages, but clearly separated based on the reproductive Sexual orientation test asexual propagation of the mealybug Fig 3.

This study offers a unique example to investigate the evolution and ecology of sexual and asexual reproduction. Several haplotypes with less than 0. Based on the previously reported pairwise divergence rate of CO1 sequences in several arthropod groups, which was found to cluster approximately 1. The difference between the mitochondrial DNA sequences of the two Sexual orientation test asexual propagation was relatively small compared to intraspecific Sexual orientation test asexual propagation in some insect taxa [ 36 ], suggesting that the lineages are very closely related, although they are reproductively Sexual orientation test asexual propagation and genetically different.

This finding is consistent with the partial sequences of ITS2 in the nuclear genome, with its higher evolutionary rate, and the endosymbiotic bacterial genome rpoB ; the two lineages were the most closely related and formed a monophyletic group in the genus Dysmicoccus Fig 3.

Other members of the genus Dysmicoccus employ sexual reproduction [ 3738 ] and obligate thelytokous parthenogenesis is reported only in D. Scale insects display a remarkable variety of genetic systems for sex determination and reproduction including parthenogenesis [ 13 ], and the ancestral system in mealybugs is assumed to have been sexual reproduction with males, the paternally derived genome of which is deactivated through heterochromatinization paternal genome elimination: PGE [ 39 ].

Two types of parthenogenetic reproduction, obligate apomictic thelytoky and obligate automictic thelytoky, are found in mealybugs and these systems are likely to have evolved independently multiple times from the PGE system [ 18 ].

In the PGE system with sexual reproduction, paternal genomes are not included during spermatogenesis and thus are not inherited, and therefore a female-biased sex ratio Sexual orientation test asexual propagation offspring is favored by a male parent [ 1314 ].

Moreover, female scale insects are more robust than males with respect to physiology and morphology [ 15 ]. In addition, females benefit more than males from mutualistic relationships with ants, which care for and guard Sexual orientation test asexual propagation in exchange for payment of honeydew [ 1315 ]. These features could potentially drive mealybugs to evolve parthenogenetic reproduction that does not depend on males.

It is therefore difficult to understand how sexual reproduction with the PGE genomic system has been stable and prevalent in scale insects, including some lineages of D. The present case on Okinawa clearly shows that the sexual lineage can simultaneously and sympatrically exist with and even dominate the asexual lineage Fig 2 in the face of habitat and resource competition, which is considered to be severe for the nearly immobile scale insects.

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This suggests that advantages offered by sexual reproduction compensate for the cost of males on Okinawa.

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