Anomalous apetaly: localized character displacement in Ranunculus eschscholtzii

1979 ◽  
Vol 57 (20) ◽  
pp. 2097-2106 ◽  
Author(s):  
F. J. F. Fisher ◽  
A. Warner ◽  
E. M. Reimer
Keyword(s):  
Normal Form ◽  
Hybrid Sterility ◽  
Diploid Species ◽  
Character Displacement ◽  
Reproductive Barriers ◽  
Cascade Mountains ◽  
Rare Variation ◽  
High Rainfall ◽  
Pollen Vectors

Apetaly is usually a rare variation in populations of the widespread hexaploid alpine Ranunculus eschscholtzii Schlecht. In certain high rainfall sections of the western Cascade Mountains of Washington, where populations of the hexaploid have been found in mixed association with those of a diploid relative, R. suksdorfii (elsewhere ecologically well separated though sympatric), the apetalous condition almost completely replaces the normal form. Any petal-bearing flowers of the hexaploid attract the flying pollen vectors (mainly syrphids) which also visit the overwhelmingly more numerous diploid species. Any resulting hybrids between the two species are sterile. Apetalous flowers are avoided by the syrphid pollinators. These flowers, nevertheless, regularly produce full sets of viable fruits. This may be attributed to the regular foraging visits of large terrestrial ants. The apetalous condition of R. eschscholtzii appears to have replaced the normal form in the high rainfall areas because only it can continue to reproduce and maintain the species in the presence of R. suksdorfii and the syrphid pollinators. This regional intensification of reproductive barriers between species already genetically isolated by their difference in ploidy, and between which hybrids have zero fitness, is interpreted as a case of character displacement involving both competition for a resource (pollinators) and hybrid sterility.

scholarly journals Patterns of reproductive isolation in a haplodiploid mite, Amphitetranychus viennensis: prezygotic isolation, hybrid inviability and hybrid sterility

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Yukie Sato ◽  
Satoshi Fujiwara ◽  
Martijn Egas ◽  
Tomoko Matsuda ◽  
Tetsuo Gotoh
Keyword(s):  
Reproductive Isolation ◽  
Genetic Distance ◽  
Spider Mite ◽  
Hybrid Sterility ◽  
Fertilization Rate ◽  
Spider Mites ◽  
Reproductive Barriers ◽  
Hybrid Female ◽  
Hybrid Inviability ◽  
Prezygotic Isolation

Abstract Background Evolution of reproductive isolation is an important process, generating biodiversity and driving speciation. To better understand this process, it is necessary to investigate factors underlying reproductive isolation through various approaches but also in various taxa. Previous studies, mainly focusing on diploid animals, supported the prevalent view that reproductive barriers evolve gradually as a by-product of genetic changes accumulated by natural selection by showing a positive relationship between the degree of reproductive isolation and genetic distance. Haplodiploid animals are expected to generate additional insight into speciation, but few studies investigated the prevalent view in haplodiploid animals. In this study, we investigate whether the relationship also holds in a haplodiploid spider mite, Amphitetranychus viennensis (Zacher). Results We sampled seven populations of the mite in the Palaearctic region, measured their genetic distance (mtDNA) and carried out cross experiments with all combinations. We analyzed how lack of fertilization rate (as measure of prezygotic isolation) as well as hybrid inviability and hybrid sterility (as measures of postzygotic isolation) varies with genetic distance. We found that the degree of reproductive isolation varies among cross combinations, and that all three measures of reproductive isolation have a positive relationship with genetic distance. Based on the mtDNA marker, lack of fertilization rate, hybrid female inviability and hybrid female sterility were estimated to be nearly complete (99.0–99.9% barrier) at genetic distances of 0.475–0.657, 0.150–0.209 and 0.145–0.210, respectively. Besides, we found asymmetries in reproductive isolation. Conclusions The prevalent view on the evolution of reproductive barriers is supported in the haplodiploid spider mite we studied here. According to the estimated minimum genetic distance for total reproductive isolation in parent population crosses in this study and previous work, a genetic distance of 0.15–0.21 in mtDNA (COI) appears required for speciation in spider mites. Variations and asymmetries in the degree of reproductive isolation highlight the importance of reinforcement of prezygotic reproductive isolation through incompatibility and the importance of cytonuclear interactions for reproductive isolation in haplodiploid spider mites.

scholarly journals When acting as a reproductive barrier for sympatric speciation, hybrid sterility can only be primary

2019 ◽  
Vol 128 (4) ◽  
pp. 779-788 ◽  
Author(s):  
Donald R Forsdyke
Keyword(s):  
Hybrid Sterility ◽  
Sympatric Speciation ◽  
The Other ◽  
Reproductive Barriers ◽  
Evolutionary Time ◽  
Hybrid Inviability ◽  
Prezygotic Isolation ◽  
Microscopic Scale ◽  
A New Species

Abstract Animal gametes unite to form a zygote that develops into an adult with gonads that, in turn, produce gametes. Interruption of this germinal cycle by prezygotic or postzygotic reproductive barriers can result in two cycles, each with the potential to evolve into a new species. When the speciation process is complete, members of each species are fully reproductively isolated from those of the other. During speciation a primary barrier may be supported and eventually superceded by a later-appearing secondary barrier. For those holding certain cases of prezygotic isolation to be primary (e.g. elephant cannot copulate with mouse), the onus is to show that they had not been preceded over evolutionary time by periods of postzygotic hybrid inviability (genically determined) or sterility (genically or chromosomally determined). Likewise, the onus is upon those holding cases of hybrid inviability to be primary (e.g. Dobzhansky–Muller epistatic incompatibilities) to show that they had not been preceded by periods, however brief, of hybrid sterility. The latter, when acting as a sympatric barrier causing reproductive isolation, can only be primary. In many cases, hybrid sterility may result from incompatibilities between parental chromosomes that attempt to pair during meiosis in the gonad of their offspring (Winge-Crowther-Bateson incompatibilities). While such incompatibilities have long been observed on a microscopic scale, there is growing evidence for a role of dispersed finer DNA sequence differences (i.e. in base k-mers).

scholarly journals Patterns of reproductive isolation in a haplodiploid mite, Amphitetranychus viennensis: prezygotic isolation, hybrid inviability and hybrid sterility

2021 ◽  
Author(s):  
Yukie Sato ◽  
Satoshi Fujiwara ◽  
Martijn Egas ◽  
Tomoko Matsuda ◽  
Tetsuo Gotoh
Keyword(s):  
Reproductive Isolation ◽  
Genetic Distance ◽  
Spider Mite ◽  
Hybrid Sterility ◽  
Fertilization Rate ◽  
Spider Mites ◽  
Reproductive Barriers ◽  
Hybrid Female ◽  
Hybrid Inviability ◽  
Prezygotic Isolation

Abstract Background Evolution of reproductive isolation is an important process, generating biodiversity and driving speciation. To better understand this process, it is necessary to investigate factors underlying reproductive isolation through various approaches but also in various taxa. Previous studies, mainly focusing on diploid animals, supported the prevalent view that reproductive barriers evolve gradually as a by-product of genetic changes accumulated by natural selection by showing a positive relationship between the degree of reproductive isolation and genetic distance. Haplodiploid animals are expected to generate additional insight into speciation, but few studies investigated the prevalent view in haplodiploid animals. In this study, we investigate whether the relationship also holds in a haplodiploid spider mite, Amphitetranychus viennensis (Zacher). Results We sampled seven populations of the mite in the Palaearctic region, measured their genetic distance (mtDNA) and carried out cross experiments with all combinations. We analyzed how lack of fertilization rate (as measure of prezygotic isolation) as well as hybrid inviability and hybrid sterility (as measures of postzygotic isolation) varies with genetic distance. We found that the degree of reproductive isolation varies among cross combinations, and that all three measures of reproductive isolation have a positive relationship with genetic distance. Based on the mtDNA marker, lack of fertilization rate, hybrid female inviability and hybrid female sterility were estimated to be nearly complete (99.0–99.9% barrier) at genetic distances of 0.475–0.657, 0.150–0.209 and 0.138–0.204, respectively. Conclusions The prevalent view on the evolution of reproductive barriers is supported in the haplodiploid spider mite we studied here. According to the estimated minimum genetic distance for total reproductive isolation in parent population crosses in this and previous studies, a genetic distance of 0.152–0.210 in mtDNA (COI) appears required for speciation in spider mites. Due to a lack of hybrid males, we could not address Haldane’s rule, which can be extended to haplodiploids, even though we focused on a young diverging group of spider mites. Our results highlight the importance of cytonuclear interactions for reproductive isolation in haplodiploid spider mites.

scholarly journals Cytoplasmic-nuclear incompatibility between wild-isolates of Caenorhabditis nouraguensis

2016 ◽  
Author(s):  
Piero Lamelza ◽  
Michael Ailion
Keyword(s):  
Genetic Basis ◽  
Hybrid Sterility ◽  
Reproductive Barrier ◽  
Reproductive Barriers ◽  
Cytoplasmic Factor ◽  
Hybrid Inviability ◽  
Hybrid Incompatibility ◽  
Endosymbiotic Bacteria ◽  
Nuclear Locus ◽  
Shed Light

ABSTRACTHow species arise is a fundamental question in biology. Species can be defined as populations of interbreeding individuals that are reproductively isolated from other such populations. Therefore, understanding how reproductive barriers evolve between populations is essential for understanding the process of speciation. Hybrid incompatibility (e.g. hybrid sterility and lethality) is a common and strong reproductive barrier in nature, but few studies have molecularly identified its genetic basis. Here we report a lethal incompatibility between two wild-isolates of the nematode Caenorhabditis nouraguensis. Hybrid inviability results from the incompatibility between a maternally inherited cytoplasmic factor from each strain and a recessive nuclear locus from the other. We have excluded the possibility that maternally inherited endosymbiotic bacteria cause the incompatibility by treating both strains with tetracycline and show that hybrid death is unaffected. Furthermore, cytoplasmic-nuclear incompatibility commonly occurs between other wild-isolates, indicating that this is a significant reproductive barrier within C. nouraguensis. We hypothesize that the maternally inherited cytoplasmic factor is the mitochondrial genome and that mitochondrial dysfunction underlies hybrid death. This system has the potential to shed light on the dynamics of divergent mitochondrial-nuclear coevolution and its role in promoting speciation.

Diverse Variation of Reproductive Barriers in Three Intraspecific Rice Crosses

Genetics ◽  
2002 ◽  
Vol 160 (1) ◽  
pp. 313-322
Author(s):  
Yoshiaki Harushima ◽  
Masahiro Nakagahra ◽  
Masahiro Yano ◽  
Takuji Sasaki ◽  
Nori Kurata
Keyword(s):  
Dna Markers ◽  
Hybrid Sterility ◽  
Rapid Evolution ◽  
Allele Frequencies ◽  
Reproductive Barriers ◽  
Entire Genome ◽  
Mendelian Segregation ◽  
Asian Rice ◽  
Segregation Ratios ◽  
Hybrid Weakness

Abstract Reproductive barriers are thought to play an important role in the processes of speciation and differentiation. Asian rice cultivars, Oryza sativa, can be classified into two main types, Japonica and Indica, on the basis of several characteristics. The fertility of Japonica-Indica hybrids differs from one cross to another. Many genes involved in reproductive barriers (hybrid sterility, hybrid weakness, and gametophytic competition genes) have been reported in different Japonica-Indica crosses. To clarify the state of Japonica-Indica differentiation, all reproductive barriers causing deviation from Mendelian segregation ratios in F2 populations were mapped and compared among three different Japonica-Indica crosses: Nipponbare/Kasalath (NK), Fl1084/Dao Ren Qiao (FD), and Fl1007/Kinandang puti (FK). Mapping of reproductive barriers was performed by regression analysis of allele frequencies of DNA markers covering the entire genome. Allele frequencies were explained by 33 reproductive barriers (15 gametophytic and 18 zygotic) in NK, 32 barriers (15 gametophytic and 17 zygotic) in FD, and 37 barriers (19 gametophytic and 18 zygotic) in FK. The number of reproductive barriers in the three crosses was similar; however, most of the barriers were mapped at different loci. Therefore, these reproductive barriers formed after Japonica-Indica differentiation. Considering the high genetic similarity within Japonica and Indica cultivars, the differences in the reproductive barriers of each cross were unexpectedly numerous. The reproductive barriers of Japonica-Indica hybrids likely evolved more rapidly than other genetic elements. One possible force responsible for such rapid evolution of the barriers may have been the domestication of rice.

scholarly journals Specificity in pollination and consequences for postmating reproductive isolation in deceptive Mediterranean orchids

2008 ◽  
Vol 363 (1506) ◽  
pp. 3037-3046 ◽  
Author(s):  
Salvatore Cozzolino ◽  
Giovanni Scopece
Keyword(s):  
Reproductive Isolation ◽  
Hybrid Sterility ◽  
Species Differentiation ◽  
Hybrid Zones ◽  
Reproductive Barriers ◽  
Premating Isolation ◽  
Group A ◽  
Rate Of Emergence ◽  
Pollination Strategy ◽  
Evolutionary Consequences

The type of reproductive isolation prevalent in the initial stages of species divergence can affect the nature and rate of emergence of additional reproductive barriers that subsequently strengthen isolation between species. Different groups of Mediterranean deceptive orchids are characterized by different levels of pollinator specificity. Whereas food-deceptive orchid species show weak pollinator specificity, the sexually deceptive Ophrys species display a more specialized pollination strategy. Comparative analyses reveal that orchids with high pollinator specificity mostly rely on premating reproductive barriers and have very little postmating isolation. In this group, a shift to a novel pollinator achieved by modifying the odour bouquet may represent the main isolation mechanism involved in speciation. By contrast, orchids with weak premating isolation, such as generalized food-deceptive orchids, show strong evidence for intrinsic postmating reproductive barriers, particularly for late-acting postzygotic barriers such as hybrid sterility. In such species, chromosomal differences may have played a key role in species isolation, although strong postmating–prezygotic isolation has also evolved in these orchids. Molecular analyses of hybrid zones indicate that the types and strength of reproductive barriers in deceptive orchids with contrasting premating isolation mechanisms directly affect the rate and evolutionary consequences of hybridization and the nature of species differentiation.

scholarly journals Restoring fertility in yeast hybrids: Breeding and quantitative genetics of beneficial traits

2021 ◽  
Vol 118 (38) ◽  
pp. e2101242118
Author(s):  
Samina Naseeb ◽  
Federico Visinoni ◽  
Yue Hu ◽  
Alex J. Hinks Roberts ◽  
Agnieszka Maslowska ◽  
...  
Keyword(s):  
Genetic Analysis ◽  
Parental Species ◽  
Hybrid Sterility ◽  
Diploid Species ◽  
Hybrid Vigor ◽  
The Road ◽  
High Sugar Concentration ◽  
Interspecies Hybrids ◽  
Beneficial Traits ◽  
Species Specific

Hybrids between species can harbor a combination of beneficial traits from each parent and may exhibit hybrid vigor, more readily adapting to new harsher environments. Interspecies hybrids are also sterile and therefore an evolutionary dead end unless fertility is restored, usually via auto-polyploidisation events. In the Saccharomyces genus, hybrids are readily found in nature and in industrial settings, where they have adapted to severe fermentative conditions. Due to their hybrid sterility, the development of new commercial yeast strains has so far been primarily conducted via selection methods rather than via further breeding. In this study, we overcame infertility by creating tetraploid intermediates of Saccharomyces interspecies hybrids to allow continuous multigenerational breeding. We incorporated nuclear and mitochondrial genetic diversity within each parental species, allowing for quantitative genetic analysis of traits exhibited by the hybrids and for nuclear–mitochondrial interactions to be assessed. Using pooled F12 generation segregants of different hybrids with extreme phenotype distributions, we identified quantitative trait loci (QTLs) for tolerance to high and low temperatures, high sugar concentration, high ethanol concentration, and acetic acid levels. We identified QTLs that are species specific, that are shared between species, as well as hybrid specific, in which the variants do not exhibit phenotypic differences in the original parental species. Moreover, we could distinguish between mitochondria-type–dependent and –independent traits. This study tackles the complexity of the genetic interactions and traits in hybrid species, bringing hybrids into the realm of full genetic analysis of diploid species, and paves the road for the biotechnological exploitation of yeast biodiversity.

HYBRID STERILITY AS A REPRODUCTIVE BARRIER ISOLATING THE TWO SUBSPECIES OF AEGILOPS GENICOLATA ROTH (GRAMINEAE)

1999 ◽  
Vol 47 (2) ◽  
pp. 89-95 ◽  
Author(s):  
Shoji Ohta
Keyword(s):  
Hybrid Sterility ◽  
Chromosomal Rearrangements ◽  
Reproductive Barrier ◽  
Reproductive Barriers ◽  
Polyploid Species ◽  
Negative Interaction ◽  
Aegilops Geniculata ◽  
Chromosome Differentiation ◽  
Infraspecific Taxa ◽  
Mother Cells

To detect possible reproductive barriers isolating the two subspecies of Aegilops geniculata, ssp. gibberosa was crossed with ssp. geniculata. The two subspecies differ significantly in shape of spikes, spikelet density on spikes, and number of awns on empty glumes. The F hybrids were intermediate in morphology and almost completely sterile. A chromatid bridge with a fragment was observed at first anaphase (AI) of meiosis in some pollen mother cells (PMCs) of the F1 hybrids. Though multivalents were formed at first metaphase (MI) in all the PMCs of the F1 hybrids, the frequency was not higher than that in the intra-subspecific hybrids of ssp. geniculata. These results suggest that the intraspecific sterility is not caused by a gross chromosome differentiation. The hybrid sterility, which is an effective reproductive barrier isolating the two subspecies, might be caused by negative interaction(s) between genes of the two subspecies, or by small chromosomal rearrangements not detectable from chromosome pairing configuration at MI. It is strongly proposed that the delineation of species and infraspecific taxa in the polyploid species of the genus Aegilops is worthy of reassessment from a biosystematic viewpoint.

scholarly journals Wolbachia and host intrinsic reproductive barriers contribute additively to post-mating isolation in spider mites

2020 ◽  
Author(s):  
Miguel Alfredo Cruz ◽  
Sara Magalhaes ◽  
Elio Sucena ◽  
Flore Zele
Keyword(s):  
Reproductive Isolation ◽  
Spider Mite ◽  
Cytoplasmic Incompatibility ◽  
Hybrid Sterility ◽  
Spider Mites ◽  
Reproductive Barriers ◽  
Hybrid Breakdown ◽  
F1 Hybrid ◽  
Hybrid Production ◽  
Relative Contribution

Wolbachia are widespread maternally-inherited bacteria suggested to play a role in arthropod host speciation through induction of cytoplasmic incompatibility, but this hypothesis remains controversial. Most studies addressing Wolbachia-induced incompatibilities concern closely-related populations, which are intrinsically compatible. Here, we used three populations of two genetically differentiated colour forms of the haplodiploid spider mite Tetranychus urticae to dissect the interaction between Wolbachia-induced and host-associated incompatibilities, and to assess their relative contribution to post-mating isolation. We found that these two sources of incompatibility act through different mechanisms in an additive fashion. Host-associated incompatibility contributes 1.5 times more than Wolbachia-induced incompatibility in reducing hybrid production, the former through an overproduction of haploid sons at the expense of diploid daugters (ca. 75% decrease) and the latter by increasing the embryonic mortality of daughters (by ca. 49%). Furthermore, regardless of cross direction, we observed near-complete F1 hybrid sterility and complete F2 hybrid breakdown between populations of the two forms, but that Wolbachia did not contribute to this outcome. This study identifies the mechanistic independence and additive nature of host-intrinsic and Wolbachia-induced sources of isolation. It suggests that Wolbachia could drive reproductive isolation in this system, thereby potentially affecting host differentiation and distribution in the field.

scholarly journals Restoring fertility in yeast hybrids: breeding and quantitative genetics of beneficial traits

2021 ◽  
Author(s):  
S. Naseeb ◽  
F. Visinoni ◽  
Y. Hu ◽  
A. J. Hinks Roberts ◽  
A. Maslowska ◽  
...  
Keyword(s):  
Genetic Analysis ◽  
Parental Species ◽  
Hybrid Sterility ◽  
Diploid Species ◽  
Hybrid Vigour ◽  
The Road ◽  
High Sugar Concentration ◽  
Beneficial Traits ◽  
Species Specific ◽  
Species Hybrids

AbstractHybrids species can harbour a combination of beneficial traits from each parent and may exhibit hybrid vigour, more readily adapting to new harsher environments. Inter-species hybrids are also sterile and therefore an evolutionary dead-end unless fertility is restored, usually via auto-polyploidisation events. In the Saccharomyces genus, hybrids are readily found in nature and in industrial settings, where they have adapted to severe fermentative conditions. Due to their hybrid sterility, the development of new commercial yeast strains has so far been primarily conducted via selection methods rather than breeding. In this study, we overcame infertility by creating tetraploid intermediates of Saccharomyces inter-species hybrids, to allow continuous multigenerational breeding. We incorporated nuclear and mitochondrial genetic diversity within each parental species, allowing for quantitative genetic analysis of traits exhibited by the hybrids, and for nuclear-mitochondrial interactions to be assessed. Using pooled F12 generation segregants of different hybrids with extreme phenotype distributions, we identified QTLs for tolerance to high and low temperatures, high sugar concentration, high ethanol concentration, and acetic acid levels. We identified QTLs that are species specific, that are shared between species, as well as hybrid specific, where the variants do not exhibit phenotypic differences in the original parental species. Moreover, we could distinguish between mitochondria-type dependent and independent traits. This study tackles the complexity of the genetic interactions and traits in hybrid species, bringing hybrids into the realm of full genetic analysis of diploid species, and paves the road for the biotechnological exploitation of yeast biodiversity.

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