Related Bisexual Species Research Articles

Genetic Variability and the Potential Range of Darevskia rostombekowi in Transcaucasia

—The results of the analysis of the genetic variability of parthenogenetic Darevskia rostombekowi (Darevsky, 1957) species using four microsatellite-containing loci are presented. Based on 118 records with geographical coordinates of the presence of this species in Transcaucasia, the maps of potential range were created. The analysis of the genetic structure of populations demonstrated that despite the established multiclonality (seven clonal lines in four populations), D. rostombekowi was formed as a result of a single act of hybridization between closely related bisexual species. The predicted distribution of D. rostombekowi using the modelling of potential range revealed new suitable habitats, where the presence of the species has not been reported previously. The results of this study and the absence of multiple acts of hybridization during the formation of these clones may indicate a regression of population size of the species. Consequently, the estimation of the conservation status of this parthenogenetic species seems to be justified.

Parthenogenesis and Sex-Ratio Distorting Bacteria inEmpoasca(Hemiptera: Cicadellidae) Leafhoppers

AbstractEndosymbiotic bacteria can induce parthenogenesis in many haplo-diploid species, but little is known about their role in asexual reproduction in diplodiploids. Bacteria are essential for reproduction in the asexual lineages of springtails and booklice, and possibly some weevils, but whether they are the causative agent of parthenogenesis remains to be proven. This would require comparing unisexual forms and their closely related bisexual species, but such model species are very rare. Empoasca leafhoppers from the Madeira Archipelago provide an excellent case to test whether bacterial infections can cause parthenogenesis. Here we examined the diversity of the sex-distorting bacteria, Wolbachia, Cardinium, Rickettsia, and Arsenophonus, in three apomictic morphotypes (A, B, C) and three bisexual relatives of Empoasca. Wolbachia of group B was present in all unisexual and bisexual species. Rickettsia were the only bacteria restricted to the three unisexual forms, suggesting an association between infection and asexual reproduction. In addition, we found Asaia for the third time in the Cicadellidae, although this may have little to do with the reproductive mode of its host. Adult females of morphotype C reared on plants watered with tetracycline solution did not result in the production of male offspring. To our knowledge, this is the first study to suggest a possible association between bacterial infection and parthenogenesis in apomictic XO/XX diplodiploid bisexual species based on a range of sex ratio-distorting bacteria.

THE EGG OF THE STICK-INSECT BACILLUS ATTICUS CAPRAI NASCETTI & BULLINI: A SCANNING ELECTRON MICROSCOPE STUDY (CHELEUTOPTERA BACILLIDAE)

SUMMARY The morphology of the egg of the stick-insect Bacillus atticus caprai Nascetti & Bullini (Insecta Cheleutoptera Bacillidae), the Italian member of the parthenogenetic B. atticus complex, was observed with the scanning electron microscope (SEM). A structural organization common to all the Cheleutoptera so far investigated at the SEM level is described. Peculiar and diagnostic characters, concerning mainly the sculpturing of the capsule and the morphology of the operculum, were found, which differentiate B. atticus caprai from the other Bacillinae so far studied, B. rossius (Rossi) and Clonopsis gallica (Charp.). A summary of the main differences between the eggs of these three species clearly shows that B. atticus caprai is more related to B. rossius than to C. gallica. A comparison of the egg of B. atticus caprai with those of the other parthenogenetic members of this complex, as well as with the more closely related bisexual species, is expected to clarify both the taxonomic status and the phylog...

Genetic polymorphism and evolution in parthenogenetic animals. X. Solenobia species (Lepidoptera: Psychidae)

The patterns of genetic polymorphism, detected by routine enzyme electrophoresis, have been followed in natural populations of two parthenogenetic species of Solenobia: S. lichenella and S. fennicella. S. lichenella is assumed to be a parthenogenetic derivative of S. furnosella, a bisexual species. Data on another related bisexual species, S. manni, are included. The results do not support the contention that S. lichenella or S. fennicella would be closely related to one another or to S. fumosella or S. manni.

Discriminating males alter sperm production between species

Prezygotic reproductive isolation and its importance in speciation is traditionally approached from the viewpoint of those events that occur before mating. However, recent interest in sperm competition theory has shown that prezygotic isolation can be affected by mechanisms that occur after mating but before fertilization. One neglected aspect of these studies is how the cost of sperm production might play a role in species isolation. We examined differential sperm production in a species whose males are sexually parasitized by a unisexual gynogenetic species. Gynogens are clonal females that require sperm from males of closely related bisexual species to initiate embryogenesis. We tested for differential sperm production by male sailfin mollies (Poecilia latipinna) when they were in the presence of either a heterospecific, gynogenetic female (Poecilia formosa, Amazon molly) or a conspecific female. We found that previously demonstrated male mate choice for conspecific over heterospecific females also is revealed in sperm production. Males from both an allopatric and a sympatric population produce more sperm when in the presence of a conspecific female than when in the presence of a heterospecific female. We suggest that differential sperm production also could play a role in prezygotic reproductive isolation in bisexual species complexes that occur in sympatry.

Clonal Composition of the Parthenogenetic Gecko, Lepidodactylus lugubris, at the Northernmost Extremity of Its Range

The mourning gecko, Lepidodactylus lugubris, is an all-female parthenogenetic species widely distributed in tropical and subtropical regions. We examined clonal diversity of L. lugubris in southern Japan, the northernmost extremity of the species' range. Results indicated that the assemblages of the Ogasawara Islands are composed solely of diploid clone A, which may have originated from artificial transportation after World War II. Assemblages of L. lugubris in the Ryukyu Archipelago were composed solely of triploid clone C. This, along with literature records, suggests that the gecko recently colonized the Ryukyu Archipelago on limited opportunities from limited sources. Samples from the Daito Islands included both diploid and triploid individuals representing one and 11 different clones, respectively. Except for one triploid clone (clone B), these clones were most likely to be endemic to the Daito Islands. Analyses of genotypic pattern suggest that most of the putative endemic triploid clones of the Daito Islands originated from iterative crosses between sympatric diploid clones and males of closely related bisexual species that were most likely extirpated sub- sequently.

POECILIA MEXICANA IS THE RECENT FEMALE PARENT OF THE UNISEXUAL FISH P. FORMOSA.

EvolutionVolume 45, Issue 6 p. 1530-1533 Note and CommentFree Access POECILIA MEXICANA IS THE RECENT FEMALE PARENT OF THE UNISEXUAL FISH P. FORMOSA John C. Avise, John C. Avise Department of Genetics, University of Georgia, Athens, GA, 30602 USASearch for more papers by this authorJoel C. Trexler, Joel C. Trexler Department of Biology, University of Mississippi, University, MS, 38677 USASearch for more papers by this authorJoseph Travis, Joseph Travis Department of Biological Science, Florida State University, Tallahassee, FL, 32306 USASearch for more papers by this authorWilliam S. Nelson, William S. Nelson Department of Genetics, University of Georgia, Athens, GA, 30602 USASearch for more papers by this author John C. Avise, John C. Avise Department of Genetics, University of Georgia, Athens, GA, 30602 USASearch for more papers by this authorJoel C. Trexler, Joel C. Trexler Department of Biology, University of Mississippi, University, MS, 38677 USASearch for more papers by this authorJoseph Travis, Joseph Travis Department of Biological Science, Florida State University, Tallahassee, FL, 32306 USASearch for more papers by this authorWilliam S. Nelson, William S. Nelson Department of Genetics, University of Georgia, Athens, GA, 30602 USASearch for more papers by this author First published: September 1991 https://doi.org/10.1111/j.1558-5646.1991.tb02657.xCitations: 60AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume45, Issue6September 1991Pages 1530-1533 ReferencesRelatedInformation

UNISEXUAL/BISEXUAL BREEDING COMPLEXES IN POECILIIDAE: WHY DO MALES COPULATE WITH UNISEXUAL FEMALES?

Unisexual poeciliid fishes live as sexual parasites in breeding complexes with related bisexual species. Males of the host species copulate with unisexual females as well as with con-specifics, thus maintaining the unisexuals. Copulation with a unisexual offers no selective benefit for a male. A model is proposed that provides an explanation in terms of evolutionary ecology for why males copulate with unisexuals. It assumes that, before copulation, a male attempts to identify a female as conspecific or not but that the correctness of the identification depends on the length of time spent on the identification process. Some cost is involved in the passage of time, so an optimal time spent on identification must exist. Because subordinate males risk being driven away by dominant males, the optimal time is longer for males at the top of the dominance hierarchy than for males at the bottom. Such an optimal strategy gives a male the greatest possible average net benefit from a mating attempt, given his social status; this is a "best of a bad job" strategy.

Nucleoprotein cytochemistry during oogenesis in a unisexual fish, Poecilia formosa.

Cytochemical methods and electron microscopy were used to study changes in the chemical composition of nuclear, nucleolar and perinuclear bodies during the early stages of oocyte development in Poecilia formosa, an apomictic species of fish that produces only female offspring. Prominent accumulations of ribonucleoprotein (RNP) occur in nucleoli and appear on either side of the nuclear envelope during diplotene. In certain planes of section, RNP material seems to be in transit across this interface. En bloc acid extractions or RNAase treatment abolished basophilia and markedly reduced the electron density of both nucleoli and cytoplasmic nucleolar-like bodies. DNA-specific fluorescent probes such as mithramycin failed to reveal nucleolar cores in poeciliid oocytes, although the same procedures showed unequivocal localization of GC-rich DNA cores within multiple nucleoli of diplotene oocytes from Xenopus laevis or the rainbow trout, Salmo gairdneri. Also, cytological hybridization studies, utilizing [3H]rRNA as a probe for nucleolar DNA, failed to show localizations of silver grains above nucleoli in autoradiograms of poeciliid oocytes. Feulgen-stained pachytene oocytes of P. formosa have twice the number of chromosome strands seen in similar stages of oocytes from two, related bisexual species, P. mexicana and P. latipinna. Although the bivalent nature of these chromosomes could not be resolved with the light microscope, configurations resembling, but not identical to, synaptonemal complexes were identified by electron microscopy.

Meiotic mechanisms in a parthenogenetic grasshopper species and its hybrids with related bisexual species

The genetic system of the all-female Australian grasshopper species Warramaba virgo is of a type which is now familiar in parthenogenetic vertebrates (Parker & Selander, 1976, Uzzell, 1970, Uzzell & Darevski, 1975, CueUar 1971), but is very uncommon in parthenogenetic insects. Having originated by hybridization between two bisexual species, lCarramaba virgo reproduces by a form of automictic parthenogenesis in which a premeiotic doubling of the karyotype in the oocyte (from 2n = 15 to 4n = 30 in individuals having the standard karyotype) is followed by a synapsis which is restricted to sister chromosomes. The ensuing meiosis proceeds normally, with 15 chiasmate bivalents, except that there are approximately twice as many bivalents as in related bisexual species (Fig. 2A). The mechanism automatically ensures that all the offspring of a given female are genetically identical to one another and to their mother. No genetic recombination occurs, the chiasmata being without genetic consequences, since they are formed between chromosomes that are molecular copies of one another (White, Cheney & Key, 1963). Although, as mentioned above, this mechanism is now known in parthenogenetic Fu~hes, salamanders and lizards, and also in many earthworms (Omodeo 1952; 1955) it is not known with certainty in other parthenogenetic insects, most of which are either apomictic (lacking meiosis in the oocyte) or if automictic compensate their meiosis by a postmeiotic doubling process of some kind. In the lizards, earthworms etc., which possess what we may call the lCarramaba mechanism, it is not quite certain that synapsis is restricted to sister chromosomes, although this appears probable on general grounds. We do not know how long ago Warramaba virgo arose by hybridization. The fact that it exists in two distinct areas of Australia separated by a gap of 1600 km argues for a respectable antiquity (extinction of populations in the middle of its range probably occurred during the 'great arid' period 6000-3000 y B.P.). On the other hand, the fact that the species which hybridized to give rise to it still exist, with essentially unmodified karyotypes, is evidence against a very remote antiquity. Tentatively, one might suggest that W. virgo arose at least half a million years ago and perhaps even earlier (White 1980). The modem representatives of the species which hybridized to give rise to I4/. virgo are the unnamed

INTERSPECIFIC HYBRIDIZATION AND THE EVOLUTIONARY ORIGIN OF A GYNOGENETIC FISH, POECILIA FORMOSA.

In recent years, largely through the application of allozyme techniques, several unisexual (thelytokous) vertebrates have been shown to be genetically equivalent to F1 hybrids of certain related bisexual species. The causal relationship, however, between interspecific hybridization and the origin of unisexuality has not been elucidated, and the role of hybridization per se is controversial (Cuellar, 1974, 1977, 1978; Cole, 1978; Wright, 1978). The amazon molly, Poeciliaformosa (Girard), an ovoviviparous gynogentic teleost (family Poeciliidae) was the first known unisexual vertebrate (Hubbs and Hubbs, 1932). The discoverers of its unisexuality recognized early that it was probably of hybrid origin, as it was an almost exact morphological intermediate between the sailfin molly (Poecilia latipinna) and the shortfin mollies (which were then regarded as a single species, P. sphenops). Laboratory hybridization of the presumptive parental species, however, produced only bisexual progeny, including fertile males (Hubbs, 1933, 1955, 1961; Meyer, 1938; Hubbs and Hubbs, 1946a, 1946b). Subsequent to those early hybridization experiments, P. sphenops, as it was then recognized, has been shown to be an assemblage of morphologically similar but genetically quite distinct species (Hubbs, 1961; Schultz and Miller, 1971; Miller, 1975; Brett et al., unpubl.). A variety of zoogeographic, morphological (Darnell and Abramoff, 1968), chromosomal (Prehn and Rasch, 1969), and biochemical genetic (Abramoff et al., 1968; Turner et al., 1980) data suggest that the shortfin species involved in the ancestry of P. formosa was P. mexicana, a species restricted to the

Triploidy in the Natural Population of the Psychodine Moth FlyPsychoda ParthenogeneticaTonnoir (Diptera: Psychodidae)

SUMMARYA cytological analysis of the thelytokous species Psychoda parthenogenetica has been made. A 3 n=15 complement and a type of apomictic thelytoky have been found. Apart from the triploidy, the complement of P. parthenogenetica is very similar to the one of P. alternata and P. cinerea. The phylogenetic interrelationships with the related bisexual species P. severini and the origins both of the thelytoky and triploidy have been discussed.

Coexistence in Unisexual‐Bisexual Species Complexes of Poeciliopsis (Pisces: Poeciliidae)

All—female forms of Poeciliopsis rely on males of closely related bisexual species for sperm. The natural habitat of Poeciliopsis in Sonora Mexico, consists of a variety of small ponds connected by intermittent watercourses. Optimal areas, containing mixed female aggregates, are defended by territorial males. Social structure in natural populations very closely resembles that of laboratory experiments, wherein subordinant males show reduced mate discrimination and inseminate unisexuals. An equation relating male density to unisexual inseminations is used in a computer simulation model of a population. A stable equilibrium is inherent in unisexual—bisexual species complexes but the level of equilibrium is affected by the environment. Coexistence does not require niche separation. The simulations predict the percentage of unisexuals pregnant in natural populations and explain their distribution pattern. The strength of the mechanism is demonstrated by a natural population in which the percentage of unisexuals pregnant responded strongly to a modest change in unisexual—bisexual composition.

Cytophotometric evidence for triploidy in hybrids of the gynogenetic fish, Poecilia formosa.

AbstractAmounts of DNA per nucleus were estimated by microphotometry in Feulgen‐stained tissue sections from several species of poeciliid fish and their hybrid offspring. In terms of average nuclear volumes as well as relative DNA levels, the all‐female gynogenetic species P. formosa was indistinguishable from the related bisexual species P. sphenops, confirming the essentially diploid nature of the amazon molly, P. formosa. Although DNA values from the less closely related species P. vittata were about 15% higher than those from P. sphenops, both species showed expected patterns of DNA behavior in several somatic tissues and in developing male sex cells.Somatic nuclei from two types of interspecific hybrids contained more DNA than corresponding types of nuclei from typical maternal P. formosa, the additional amount being equivalent to the haploid DNA value characteristic of the participating paternal species. The results strongly suggest that these hybrids are genetic triploids, probably containing diploid maternal and haploid paternal chromosome contributions. The high incidence of chromosomal stickness, bridging, and fragmentation observed during metaphase I of spermatogenesis, and the occurrence of both “giant” and “micro” spermatids in testis of the hybrid P. formosa X P. vittata may well account for the apparent sterility of amazon molly offspring which show transmission of paternal characteristics.Production of triploid interspecific hybrids in poeciliid fish and corollary implications for interpreting previous tissue transplantation studies are discussed.