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opencc-zeroDec 2011View details →

Data from: Geographical parthenogenesis and population genetic structure in the alpine species Ranunculus kuepferi (Ranunculaceae)

Geographical parthenogenesis describes the enigmatic phenomenon that asexual organisms have larger distribution areas than their sexual relatives, especially in previously glaciated areas. Classical models suggest temporary advantages to asexuality in colonization scenarios because of uniparental reproduction and clonality. We analyzed population genetic structure and self-fertility of the plant species Ranunculus kuepferi on 59 populations from the whole distribution area (European Alps, Apennines and Corsica). Amplified fragment length polymorphisms (AFLPs) and five microsatellite loci revealed individual genotypes for all populations and mostly insignificant differences between diploid sexuals and tetraploid apomicts in all measures of genetic diversity. Low frequencies of private AFLP fragments/simple sequence repeat alleles, and character incompatibility analyses suggest that facultative recombination explains best the unexpectedly high genotypic diversity of apomicts. STRUCTURE analyses using AFLPs revealed a higher number of partitions and a stronger geographical subdivision for diploids than for tetraploids, which contradicts expectations of standard gene flow models, but indicates a reduction of genetic structure in asexuals. Apomictic populations exhibited high admixture near the sexual area, but appeared rather uniform in remote areas. Bagging experiments and analyses of pollen tube growth confirmed self-fertility for pollen-dependent apomicts, but self-sterility for diploid sexuals. Facultative apomixis combines advantages of both modes of reproduction: uniparental reproduction allows for rapid colonization of remote areas, whereas facultative sexuality and polyploidy maintains genetic diversity within apomictic populations. The density dependence of outcrossing limits range expansions of sexual populations.

opencc-zeroDec 2012View details →

Data from: Facultative use of thelytokous parthenogenesis for queen production in the polyandrous ant Cataglyphis cursor

The evolutionary paradox of sex remains one of the major debates in evolutionary biology. The study of species capable of both sexual and asexual reproduction can elucidate factors important in the evolution of sex. One such species is the ant Cataglyphis cursor, where the queen maximises the transmission of her genes by producing new queens (gynes) asexually while simultaneously maintaining a genetically diverse workforce via the sexual production of workers. We show that the queen can also produce gynes sexually, and may do so to offset the costs of asexual reproduction. We genotyped 235 gynes from 18 colonies, and found that half were sexually produced. A few colonies contained both sexually and asexually produced gynes. While workers in this species can also use thelytoky, we found no evidence of worker production of gynes based on genotypes of 471 workers from the six colonies producing sexual gynes. Gynes are thus mainly, and potentially exclusively, produced by the queen. Simulations of gynes inbreeding level following one to ten generations of automictic thelytoky suggest that the queen switches between or combines thelytoky and sex, which may reduce the costs of inbreeding. This is supported by the relatively small size of inbred gynes in one colony, though we found no relationship between the level of inbreeding and immune parameters. Such facultative use of sex and thelytoky by individual queens contrasts with other known forms of parthenogenesis in ants, which are typically characterised by distinct lineages specialising in one strategy or the other.

opencc-zeroDec 2011View details →

Data from: Sex at the margins: parthenogenesis vs. facultative and obligate sex in a Neotropical ant

Geographic parthenogenesis is a distribution pattern, in which parthenogenetic populations tend to live in marginal habitats, at higher latitudes and altitudes and island-like habitats compared with the sexual forms. The facultatively parthenogenetic ant Platythyrea punctata is thought to exhibit this general pattern throughout its wide range in Central America and the Caribbean Islands. Workers of P. punctata from the Caribbean produce diploid female offspring from unfertilized eggs by thelytokous parthenogenesis, and mated females and males are rare. In contrast, workers in one colony from Costa Rica were incapable of thelytoky; instead mated workers produced all female offspring. Because sample sizes were very low in former studies, we here use microsatellite markers and explicit tests of thelytoky to examine the population genetic structure of ancestral and derived populations of P. punctata throughout the Caribbean and Central America. Populations from the Caribbean islands were fully capable of parthenogenesis and population genetic signatures indicate that this is the predominant mode of reproduction, although males are occasionally produced. In contrast, the northernmost population on the mainland (Texas) showed signatures of sexual reproduction and individuals were incapable of reproduction by thelytoky. Contrary to expectations from a geographic parthenogenesis distribution pattern, most parts of the mainland populations were found to be facultatively thelytokous, with population genetic signatures of both sexual and parthenogenetic reproduction.

opencc-zeroDec 2014View details →

Data from: Facultative parthenogenesis in a critically endangered wild vertebrate

Facultative parthenogenesis — the ability of sexually reproducing species to sometimes produce offspring asexually — is known from a wide range of ordinarily sexually reproducing vertebrates in captivity, including some birds, reptiles and sharks 1, 2 and 3. Despite this, free-living parthenogens have never been observed in any of these taxa in the wild, although two free-living snakes were recently discovered each gestating a single parthenogen — one copperhead (Agkistrodon contortrix) and one cottonmouth (Agkistrodon piscivorus). Vertebrate parthenogens are characterized as being of the homogametic sex (e.g., females in sharks, males in birds) and by having elevated homozygosity compared to their mother 1, 2 and 3, which may reduce their viability. Although it is unknown if either of the parthenogenetic snakes would have been carried to term or survived in the wild, facultative parthenogenesis might have adaptive significance. If this is true, it is reasonable to hypothesize that parthenogenesis would be found most often at low population density, when females risk reproductive failure because finding mates is difficult. Here, we document the first examples of viable parthenogens living in a normally sexually reproducing wild vertebrate, the smalltooth sawfish (Pristis pectinata). We also provide a simple approach to screen any microsatellite DNA database for parthenogens, which will enable hypothesis-driven research on the significance of vertebrate parthenogenesis in the wild.

opencc-zeroDec 2016View details →

Data from: The effects of outbreeding on a parasitoid wasp fixed for infection with a parthenogenesis-inducing Wolbachia symbiont

Trichogramma wasps can be rendered asexual by infection with the maternally inherited symbiont Wolbachia. Previous studies indicate the Wolbachia strains infecting Trichogramma wasps are host-specific, inferred by failed horizontal transfer of Wolbachia to novel Trichogramma hosts. Additionally, Trichogramma can become dependent upon their Wolbachia infection for the production of female offspring, leaving them irreversibly asexual, further linking host and symbiont. We hypothesized Wolbachia strains infecting irreversibly asexual, resistant to horizontal transfer Trichogramma would show adaptation to a particular host genetic background. To test this, we mated Wolbachia-dependent females with males from a Wolbachia-naïve population to create heterozygous wasps. We measured sex ratios and fecundity, a proxy for Wolbachia fitness, produced by heterozygous wasps, and by their recombinant offspring. We find a heterozygote advantage, resulting in higher fitness for Wolbachia, as wasps will produce more offspring without any reduction in the proportion of females. While recombinant wasps did not differ in total fecundity after ten days, recombinants produced fewer offspring early on, leading to an increased female-biased sex ratio for the whole brood. Despite the previously identified barriers to horizontal transfer of Wolbachia to and from Trichogramma pretiosum, there were no apparent barriers for Wolbachia to induce parthenogenesis in these non-native backgrounds. This is likely due to the route of infection being introgression rather than horizontal transfer, and possibly the co-evolution of Wolbachia with the mitochondria rather than the nuclear genome. These results help to elucidate the mechanisms by which Wolbachia adapt to hosts and the evolution of host-symbiont phenotypes.

opencc-zeroApr 2022View details →

Parthenogenesis doubles the rate of amino acid substitution in Whiptail mitochondria

Sexual reproduction is ubiquitous in the natural world, suggesting that sex must have extensive benefits to overcome the cost of males compared to asexual reproduction. One hypothesized advantage of sex with strong theoretical support is that sex plays a role in removing deleterious mutations from the genome. Theory predicts that transitions to asexuality should lead to the suppression of recombination and segregation and, in turn, weakened natural selection, allowing for the accumulation of slightly deleterious mutations. We tested this prediction by estimating the dN/dS ratios in asexual vertebrate lineages in the genus Aspidoscelis using whole mitochondrial genomes from seven asexual and five sexual species. We found higher dN/dS ratios in asexual Aspidoscelis species, indicating that asexual whiptails accumulate non-synonymous substitutions due to weaker purifying selection. Additionally, we estimated nucleotide diversity and found that asexuals harbor significantly less diversity. Thus, despite their recent origins, slightly deleterious mutations accumulated rapidly enough in asexual lineages to be detected. We provided empirical evidence to corroborate the connection between asexuality and increased amino acid substitutions in asexual vertebrate lineages.

opencc-zeroAug 2021View details →

Geographic parthenogenesis in the brown alga Scytosiphon lomentaria (Scytosiphonaceae): Sexuals in warm waters and parthenogens in cold waters

Geographic parthenogenesis, a phenomenon where parthenogens and their close sexual relatives inhabit distinct geographic areas, has been considered an interesting topic in evolutionary biology. Reports of geographic parthenogenesis from land and freshwater are numerous, however, this occurrence has been rarely reported from the sea. Brown algae are mostly marine and are thought to include numerous obligate parthenogens; still, little is known about the distribution, origin, and evolution of parthenogens in this group. Here we report a novel pattern of geographic parthenogenesis in the isogamous brown alga Scytosiphon lomentaria. Sex ratio investigation demonstrated that, in Japan, sexual populations grew in the coast along warm ocean currents, whereas female-dominant parthenogenetic populations grew mainly in the coast along a cold ocean current. In the two localities where sexual and parthenogenetic populations were parapatric, parthenogens grew in more wave-exposed areas than sexuals. Population genetic and phylogenetic analyses, including those based on genome-wide single nucleotide polymorphism data, indicated that parthenogens have initially evolved at least twice and subsequent hybridizations between the parthenogens and sexuals have generated multiple new parthenogenetic lineages. The origin of the initial parthenogens is not clear, except that it would not be inter-species hybridization. Interestingly, we found that the production of sex pheromones, which attract male gametes, has been independently lost in the initial two parthenogenetic lineages. This parallel loss of the sexual trait may represent the direct origin of parthenogens, or the regressive evolution of a useless trait under asexuality.

opennotspecifiedOct 2002View details →

FIG. 3. Echinostoma deserticum n in Life cycle of a new African echinostome species reproducing by parthenogenesis

FIG. 3. Echinostoma deserticum n. sp. (A) Cercaria (general morphology); (B) cercaria (lateral view); (C) metacercaria.

opennotspecifiedOct 2002View details →

FIG. 2. Echinostoma deserticum n in Life cycle of a new African echinostome species reproducing by parthenogenesis

FIG. 2. Echinostoma deserticum n. sp. (A) Miracidium (epidermal cells); (B) miracidium (general morphology); (C) sporocyst; (D) attachment zone of the sporocysts; (E) young daughter redia; (F) mature daughter redia containing cercariae embryos.

Figure 6 in Amblypygi parthenogenesis, embryonic and post-embryonic development: a case study with the Amazonian species Charinus guto Giupponi and Miranda, 2016 (Amblypygi: Charinidae)

Figure 6. Graphs showing the correlation between clutch size (number eggs; left) and number of prenymphs (right) against female carapace length for 43 Amblypygi species in four families. Details on the values are listed in Table 3.

Figure 3 in Amblypygi parthenogenesis, embryonic and post-embryonic development: a case study with the Amazonian species Charinus guto Giupponi and Miranda, 2016 (Amblypygi: Charinidae)

Figure 3. Dorsal habitus of Charinus guto Miranda and Giupponi, 2016 (upper); retrolateral view of ovigerous female (bottom). Photos: César Favacho.

Figure 1 in Amblypygi parthenogenesis, embryonic and post-embryonic development: a case study with the Amazonian species Charinus guto Giupponi and Miranda, 2016 (Amblypygi: Charinidae)

Figure 1. Flowchart illustrating the female specimens of Charinus guto Miranda and Giupponi, 2016 used in the study.

Figure 2 in Amblypygi parthenogenesis, embryonic and post-embryonic development: a case study with the Amazonian species Charinus guto Giupponi and Miranda, 2016 (Amblypygi: Charinidae)

Figure 2. Total number of moults per month of Charinus guto Giupponi and Miranda, 2016 in captivity.

opencc-by-4.0Apr 2023View details →

Virgin Birth: A genetic basis for facultative parthenogenesis in Drosophila - genome assemblies

Drosophila mercatorum genome assemblies used in https://doi.org/10.1101/2022.03.13.484157. The wildtype assembly is non-parthenogenic, while the "partho" assembly is parthenogenic. Assembly process is described here: https://github.com/ekg/drosophila.

Fig. 2. Phylogeographical results for Clade D in World Travelers: Parthenogenesis and Ecological Tolerance Enable Multiple Colonization Events by the Widespread Short-Tailed Whipscorpion, Stenochrus portoricensis

Fig. 2. Phylogeographical results for Clade D of the short-tailed whipscorpion, Stenochrus portoricensis Chamberlin, 1922 (Schizomida: Hubbardiidae Cook, 1899). (A, B) Bar plots of results recovered by analyses with BAPS (A) and STRUCTURE (B). (C) Map of North America showing pie charts of individuals with corresponding subclade assignations recovered by analyses with STRUCTURE. (D, E) Median-joining network obtained from Cytochrome c Oxidase Subunit I, COI (D) and Internal Transcribed Spacer, ITS (E): black circles represent median vectors presumed to be unsampled or missing intermediates; hashmarks represent number of mutations between haplotypes; numbers inside circles denote haplotypes; colors denote regions used for ancestral range estimation; circle size proportional to frequencies; dotted line enclosure haplotypes correspond to Subclades 1 and 2 in Fig. 1.

Fig. 1 in World Travelers: Parthenogenesis and Ecological Tolerance Enable Multiple Colonization Events by the Widespread Short-Tailed Whipscorpion, Stenochrus portoricensis

Fig. 1. (A) Phylogenetic relationships of the short-tailed whipscorpion, Stenochrus portoricensis Chamberlin, 1922 (Schizomida: Hubbardiidae Cook, 1899), obtained by analysis of the concatenated data matrix with Maximum Likelihood. Colored areas represent clades recovered in phylogenetic and phylogeographic analyses: Clade A (dark green), Stenochrus longimanus (Rowland, 1971), comb. nov.; Clade B (blue), Stenochrus cavernicolens (Chamberlin and Ivie, 1938), comb. nov.; Clade C (purple), Stenochrus sp.; Clade D (grey), S. portoricensis s. str. Subclades of S. portoricensis recovered with structure analyses: Subclade 1 (red), Subclade 2 (dark blue). (B) Close-up of Clade D. Numbers on branches represent bootstraps and posterior probabilities above 50%; numbers in grey to right of species indicate position matching STRUCTURE analysis order. Inset schizomid: S. portoricensis female from Chichenitza,Yucatán, Mexico.

Fig. 4 in World Travelers: Parthenogenesis and Ecological Tolerance Enable Multiple Colonization Events by the Widespread Short-Tailed Whipscorpion, Stenochrus portoricensis

Fig. 4. Matrix of uncorrected genetic p-distances among samples of the short-tailed whipscorpion, Stenochrus portoricensis Chamberlin, 1922 (Schizomida: Hubbardiidae Cook, 1899), ordered by subclades of Clade D.

Fig. 3 in World Travelers: Parthenogenesis and Ecological Tolerance Enable Multiple Colonization Events by the Widespread Short-Tailed Whipscorpion, Stenochrus portoricensis

Fig. 3. Dated phylogeny and ancestral range estimation of the short-tailed whipscorpion, Stenochrus portoricensis Chamberlin, 1922 (Schizomida: Hubbardiidae Cook, 1899) under DIVALIKE model. Pie charts illustrate probabilities for ancestral range reconstruction at each node; area assignation represented by squares at tips; colors correspond to areas in map of Mexico and the Caribbean (upper left). Blue lines at nodes represent 95% credibility intervals for molecular dating. Inset schizomid: S. portoricensis female from Ocosingo, Chiapas, Mexico.