scholarly journals A Biosystematic Study of Microseris Subgenus Monermos (Compositae: Cichorieae)

2021 ◽  
Author(s):  
◽  
Barry Victor Sneddon
Keyword(s):  
Geographical Variation ◽  
Fruit Set ◽  
Self Incompatibility ◽  
Homologous Chromosomes ◽  
Race 1 ◽  
F2 Generation ◽  
Fertile Hybrids ◽  
Two Populations ◽  
Behavioural Adaptations ◽  
Sterile Hybrids

<p>The taxonomy of Microseris subgenus Monermos (Hook. f.) Chambers (Compositae) is investigated. Two species are recognized, namely M. scapigera (sol. ex A. Cunn.) Sch.-Bip. and M. lanceolata (Walp.) Sch.-Bip., which are confined to New Zealand and Australia respectively. In M. scapigera, taxonomic subdivision was not practicable, the formae of Allan (1961) not being upheld. Microseris lanceolata is subdivided into three groups which are described informally as races. The races are viewed as probable subspecies but need further study before this status can be confirmed. The two species are described and illustrated and details are given for each on typification, synonymy, chromosome number, distribution, ecology and geographical variation. Strong self-incompatibility is prevalent in both M. scapigera and M. lanceolata. The only exceptions in the populations examined were in M. scapigera, in which two populations were only moderately self incompatible, and another was substantially self-compatible. The last population appeared to have morphological and behavioural adaptations to promote autogamy. Artificial hybridizations were made within and between the two species. Microseris scapigera and M. lanceolata were freely or poorly intercrossable according to the populations used, and formed semi-fertile or sterile hybrids. Semi-fertile hybrids were virtually blocked from forming a F2 generation (fruit set was very low and no fruits germinated) but they cold be backcrossed. Fertility in BC1 hybrids was mostly higher than in the F1, but was not restored to normal. Microseris scapigera and M. lanceolata race 1 appear to have largely homologous chromosomes. Attempts to cross the species of subgenus Monermos with M. borealis (subgenus Apargidium) were unsuccessful</p>

scholarly journals A Biosystematic Study of Microseris Subgenus Monermos (Compositae: Cichorieae)

2021 ◽  
Author(s):  
◽  
Barry Victor Sneddon
Keyword(s):  
Geographical Variation ◽  
Fruit Set ◽  
Self Incompatibility ◽  
Homologous Chromosomes ◽  
Race 1 ◽  
F2 Generation ◽  
Fertile Hybrids ◽  
Two Populations ◽  
Behavioural Adaptations ◽  
Sterile Hybrids

<p>The taxonomy of Microseris subgenus Monermos (Hook. f.) Chambers (Compositae) is investigated. Two species are recognized, namely M. scapigera (sol. ex A. Cunn.) Sch.-Bip. and M. lanceolata (Walp.) Sch.-Bip., which are confined to New Zealand and Australia respectively. In M. scapigera, taxonomic subdivision was not practicable, the formae of Allan (1961) not being upheld. Microseris lanceolata is subdivided into three groups which are described informally as races. The races are viewed as probable subspecies but need further study before this status can be confirmed. The two species are described and illustrated and details are given for each on typification, synonymy, chromosome number, distribution, ecology and geographical variation. Strong self-incompatibility is prevalent in both M. scapigera and M. lanceolata. The only exceptions in the populations examined were in M. scapigera, in which two populations were only moderately self incompatible, and another was substantially self-compatible. The last population appeared to have morphological and behavioural adaptations to promote autogamy. Artificial hybridizations were made within and between the two species. Microseris scapigera and M. lanceolata were freely or poorly intercrossable according to the populations used, and formed semi-fertile or sterile hybrids. Semi-fertile hybrids were virtually blocked from forming a F2 generation (fruit set was very low and no fruits germinated) but they cold be backcrossed. Fertility in BC1 hybrids was mostly higher than in the F1, but was not restored to normal. Microseris scapigera and M. lanceolata race 1 appear to have largely homologous chromosomes. Attempts to cross the species of subgenus Monermos with M. borealis (subgenus Apargidium) were unsuccessful</p>

scholarly journals Do s genes or deleterious recessives control late-acting self-incompatibility in Handroanthus heptaphyllus (Bignoniaceae)? A diallel study with four full sib progeny arrays

2021 ◽  
Author(s):  
Marta B Bianchi ◽  
Thomas R Meagher ◽  
Peter E Gibbs
Keyword(s):  
Genetic Control ◽  
Inbreeding Depression ◽  
Fruit Set ◽  
Genetic Model ◽  
Pollen Tubes ◽  
Self Incompatibility ◽  
Significant Difference ◽  
Partial Embryo ◽  
Ovule Penetration ◽  
S Genes

Abstract Background and Aims Genetically controlled self-incompatibility (SI) mechanisms constrain selfing and thus have contributed to the evolutionary diversity of flowering plants. In homomorphic gametophytic SI (GSI) and homomorphic sporophytic SI (SSI), genetic control is usually by a single multi-allelic locus S. Both GSI and SSI prevent self pollen tubes reaching the ovary and so are pre-zygotic in action. In contrast, in taxa with late-acting self-incompatibility (LSI), rejection is often post-zygotic, since self-pollen tubes grow to the ovary where fertilization may occur prior to floral abscission. Alternatively, lack of self fruit set could be due to early-acting inbreeding depression (EID). The aim of our study was to investigate mechanisms underlying lack of selfed fruit set in Handroanthus heptaphyllus in order to assess the likelihood of LSI versus EID. Methods We employed four full sib diallels to study the genetic control of LSI in Handroanthus heptaphyllus using a precociously flowering variant. We also used fluorescence microscopy to study the incidence of ovule penetration by pollen tubes in pistils that abscised following pollination or initiated fruits. Key Results All diallels showed reciprocally cross-incompatible full-sibs (RCI), reciprocally cross compatible full-sibs (RCC), and non-reciprocally compatible full-sibs (NRC) in almost equal proportions. There was no significant difference between the incidence of ovule penetrations in abscised pistils following self- and cross-incompatible pollinations, but those in successful cross pollinations were around twofold greater. Conclusions A genetic model postulating a single S locus with four s alleles, one of which, in the maternal parent, is dominant to the other three, will produce RCI, RCC and NRC situations each at 33 %, consistent with our diallel results. We favour this simple genetic control over an early-acting inbreeding depression (EID) explanation since none of our pollinations, successful or unsuccessful, resulted in partial embryo development, as would be expected under a whole genome EID effect.

scholarly journals Geographic variation in the morphology of the sand-dwelling lizard Nothobachia ablephara (Squamata: Gymnophthalmidae)

2019 ◽  
Vol 18 (2) ◽  
pp. 195-207
Author(s):  
Carolina Nisa Ramiro ◽  
Renato Sousa Recoder ◽  
Miguel Trefaut Rodrigues
Keyword(s):  
Geographic Variation ◽  
Morphological Traits ◽  
Geographical Variation ◽  
Multivariate Analyses ◽  
Molecular Study ◽  
Northeastern Brazil ◽  
Sexually Dimorphic ◽  
Morphometric Variation ◽  
The One ◽  
Two Populations

Geographic variation in the morphology of the sand-dwelling lizard Nothobachia ablephara (Squamata: Gymnophthalmidae). Nothobachia ablephara is a small microteiid lizard with an elongated body and reduced limbs; it occurs in isolated dune felds in the state of Bahia (Xique-Xique and Alagoado) and small sandy patches in northeastern Brazil. A previous molecular study found a marked mtDNA divergence between populations of N. ablephara from Alagoado and Xique-Xique dunes, suggesting that the two populations diverged from one another between 3 and 4 million years ago. Given this isolation, it is interesting to explore whether morphological traits of the lizards refect the reported genetic divergence of the populations. Scale counts of the sexes and the populations differ signifcantly, but there is considerable overlap of values. Univariate and multivariate analyses revealed signifcant morphometric variation between sexes and populations; however, this is mostly explained by size differences. Females are larger than males in all characters that are sexually dimorphic, and individuals from Xique-Xique are larger than those from Alagoado in all characters that vary geographically. The sample from Alagoado has more sexually dimorphic characters than the one from Xique-Xique. Although N. ablephara displays some geographical variation, the two populations could not be unequivocally distinguished by scale counts and morphometric data.

scholarly journals Downregulated expression of S2-RNase attenuates self-incompatibility in “Guiyou No. 1” pummelo

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Jianbing Hu ◽  
Qiang Xu ◽  
Chenchen Liu ◽  
Binghao Liu ◽  
Chongling Deng ◽  
...  
Keyword(s):  
Genetic Basis ◽  
Fruit Set ◽  
Spontaneous Mutation ◽  
Practical Significance ◽  
Spontaneous Mutant ◽  
Self Incompatibility ◽  
Yield And Quality ◽  
Citrus Maxima ◽  
Self Compatibility

AbstractSelf-incompatibility (SI) substantially restricts the yield and quality of citrus. Therefore, breeding and analyzing self-compatible germplasm is of great theoretical and practical significance for citrus. Here, we focus on the mechanism of a self-compatibility mutation in ‘Guiyou No. 1’ pummelo (Citrus maxima), which is a spontaneous mutant of ‘Shatian’ pummelo (Citrus maxima, self-incompatibility). The rate of fruit set and the growth of pollen tubes in the pistil confirmed that a spontaneous mutation in the pistil is responsible for the self-compatibility of ‘Guiyou No. 1’. Segregation ratios of the S genotype in F1 progeny, expression analysis, and western blotting validated that the reduced levels of S2-RNase mRNA contribute to the loss of SI in ‘Guiyou No. 1’. Furthermore, we report a phased assembly of the ‘Guiyou No. 1’ pummelo genome and obtained two complete and well-annotated S haplotypes. Coupled with an analysis of SV variations, methylation levels, and gene expression, we identified a candidate gene (CgHB40), that may influence the regulation of the S2-RNase promoter. Our data provide evidence that a mutation that affects the pistil led to the loss of SI in ‘Guiyou No. 1’ by influencing a poorly understood mechanism that affects transcriptional regulation. This work significantly advances our understanding of the genetic basis of the SI system in citrus and provides information on the regulation of S-RNase genes.

scholarly journals Parthenogenesis as a Solution to Hybrid Sterility: The Mechanistic Basis of Meiotic Distortions in Clonal and Sterile Hybrids

Genetics ◽  
2020 ◽  
Vol 215 (4) ◽  
pp. 975-987 ◽  
Author(s):  
Dmitrij Dedukh ◽  
Zuzana Majtánová ◽  
Anatolie Marta ◽  
Martin Pšenička ◽  
Jan Kotusz ◽  
...  
Keyword(s):  
Gene Flow ◽  
Molecular Mechanisms ◽  
Hybrid Sterility ◽  
Triploid Hybrid ◽  
Interspecific Gene Flow ◽  
Homologous Chromosomes ◽  
Specific Manner ◽  
Bivalent Formation ◽  
Mechanistic Basis ◽  
Sterile Hybrids

Hybrid sterility is a hallmark of speciation, but the underlying molecular mechanisms remain poorly understood. Here, we report that speciation may regularly proceed through a stage at which gene flow is completely interrupted, but hybrid sterility occurs only in male hybrids whereas female hybrids reproduce asexually. We analyzed gametogenic pathways in hybrids between the fish species Cobitis elongatoides and C. taenia, and revealed that male hybrids were sterile owing to extensive asynapsis and crossover reduction among heterospecific chromosomal pairs in their gametes, which was subsequently followed by apoptosis. We found that polyploidization allowed pairing between homologous chromosomes and therefore partially rescued the bivalent formation and crossover rates in triploid hybrid males. However, it was not sufficient to overcome sterility. In contrast, both diploid and triploid hybrid females exhibited premeiotic genome endoreplication, thereby ensuring proper bivalent formation between identical chromosomal copies. This endoreplication ultimately restored female fertility but it simultaneously resulted in the obligate production of clonal gametes, preventing any interspecific gene flow. In conclusion, we demonstrate that the emergence of asexuality can remedy hybrid sterility in a sex-specific manner and contributes to the speciation process.

scholarly journals Intra-Specific Venom Variation in the Australian Coastal Taipan Oxyuranus scutellatus

Toxins ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 485 ◽  
Author(s):  
Theo Tasoulis ◽  
Anjana Silva ◽  
Punnam Chander Veerati ◽  
Mark Baker ◽  
Wayne C. Hodgson ◽  
...  
Keyword(s):  
Sexual Dimorphism ◽  
Snake Venom ◽  
Geographical Variation ◽  
East Coast ◽  
Population Variation ◽  
The Other ◽  
North East ◽  
The North ◽  
Specific Variation ◽  
Two Populations

Intra-specific venom variation has the potential to provide important insights into the evolution of snake venom, but remains a relatively neglected aspect of snake venom studies. We investigated the venom from 13 individual coastal taipans Oxyuranus scutellatus from four localities on the north-east coast of Australia, spanning a distance of 2000 km. The intra-specific variation in taipan venom was considerably less than the inter-specific variation between it and the other Australian elapids to which it was compared. The electrophoretic venom profile of O. scutellatus was visually different to six other genera of Australian elapids, but not to its congener inland taipan O. microlepidotus. There was minimal geographical variation in taipan venom, as the intra-population variation exceeded the inter-population variation for enzymatic activity, procoagulant activity, and the abundance of neurotoxins. The pre-synaptic neurotoxin (taipoxin) was more abundant than the post-synaptic neurotoxins (3FTx), with a median of 11.0% (interquartile range (IQR): 9.7% to 18.3%; range: 6.7% to 23.6%) vs. a median of 3.4% (IQR: 0.4% to 6.7%; range: 0% to 8.1%). Three taipan individuals almost completely lacked post-synaptic neurotoxins, which was not associated with geography and occurred within two populations. We found no evidence of sexual dimorphism in taipan venom. Our study provides a basis for evaluating the significance of intra-specific venom variation within a phylogenetic context by comparing it to the inter-specific and inter-generic variation. The considerable intra-population variation we observed supports the use of several unpooled individuals from each population when making inter-specific comparisons.

scholarly journals Female mate preference explains countergradient variation in the sexual coloration of guppies ( Poecilia reticulata )

2011 ◽  
Vol 279 (1734) ◽  
pp. 1684-1690 ◽  
Author(s):  
Kerry A. Deere ◽  
Gregory F. Grether ◽  
Aida Sun ◽  
Janet S. Sinsheimer
Keyword(s):  
Geographical Variation ◽  
Poecilia Reticulata ◽  
Direct Evidence ◽  
Carotenoid Content ◽  
Pigment Ratio ◽  
Male Attractiveness ◽  
Countergradient Variation ◽  
Sexual Coloration ◽  
Two Populations ◽  
Orange Spot

We tested the hypothesis that mate choice is responsible for countergradient variation in the sexual coloration of Trinidadian guppies ( Poecilia reticulata ). The nature of the countergradient pattern is that geographical variation in the carotenoid content of the orange spots of males is counterbalanced by genetic variation in drosopterin production, resulting in a relatively uniform pigment ratio. A female hue preference could produce this pattern, because hue is the axis of colour variation most directly affected by the pigment ratio. To test this hypothesis, we crossed two populations differing in drosopterin production and produced an F 2 generation with variable drosopterin levels. When the carotenoid content of the orange spots was held constant, female guppies preferred males with intermediate drosopterin levels. This shows that females do not simply prefer males with greater orange spot pigment content; instead, the ratio of the pigments also affects male attractiveness. To our knowledge, this is the first direct evidence for a hypothesized agent of countergradient sexual selection.

scholarly journals Reproductive Biology of a Medicinal Orchid Satyarium Nepalense (Orchidaceae) in the Nepalese Himalayas

2020 ◽  
pp. 15-18
Author(s):  
Babu Ram Paudel ◽  
Brihaspati Poudel
Keyword(s):  
Natural History ◽  
Spatial Variation ◽  
Reproductive Biology ◽  
Important Implication ◽  
Fruit Set ◽  
Medicinal Uses ◽  
Floral Visitors ◽  
Medicinal Orchid ◽  
Two Populations ◽  
Very High

Satyrium nepalense is a terrestrial medicinal orchid of the Himalayas. Although, the ecology and medicinal uses of this orchid is well known, little is known about its reproductive mechanism. In this study, we explored the natural history and reproductive biology of S. nepalense and tested their potential spatial variation. We observed the floral visitors and natural fruit set of S. nepalense at its two populations. We found that, despite the presence of outcrossing features, this orchid did not receive any diurnal floral visitors. The natural fruit set was very high (>90.0%) at both the sites, suggesting the possibility of autonomous selfing. This finding may have important implication for the further study to explore how autonomous selfing evolves in a member of the predominately outcrossing genus. Moreover, the finding of this study provides important insight to develop efficient protocol for its conservation.

scholarly journals IDENTIFIKASI FENOMENA SELF-INCOMPATIBILITY PADA Hibiscus rosa-sinensis L.

2021 ◽  
Vol 3 (2) ◽  
pp. 41-49
Author(s):  
Dias Idha Pramesti
Keyword(s):  
Embryo Development ◽  
Fruit Development ◽  
Fruit Set ◽  
Descriptive Analysis ◽  
The Self ◽  
Self Incompatibility ◽  
Globular Embryo ◽  
Hibiscus Rosa Sinensis ◽  
Artificial Pollination

Hybridization is one way to produce Hibiscus rosa-sinensis L. which have various shape and colour of flowers. However, this is hampered by the possibility of self-incompatibility in Hibiscus rosa-sinensis L. To identify self-incompatibility in Hibiscus rosa-sinensis L. the simplest methods are used by observing the morphology and anatomy of fruit development, followed by a descriptive analysis of the data that has been obtained. The analysis results on crossing artificial pollination to 103 flowers of single pink Hibiscus rosa-sinensis L. show that the fruits survive until day 7 after pollination. Furthermore, the data show that there is no fruit, seed, and embryo development. Indeed the fruit turns yellow and finally shed. But the self artificial pollination shows that 35 seeds develop from 96 pollinations. The longer seed, which 13 days after pollination, grew up. The globular embryo could find on 3 DAP (day after pollination) fruit set, and the 9 DAP fruit set shows the development of heart shape. The result suggests that the phenomenon of self-incompatibility on Hibiscus rosa sinensis L. predicts as postzygotic self-incompatibility.

Sign in / Sign up

Export Citation Format

Share Document