Population Dynamics and Regeneration of a Hybrid Zone Between Eucalyptus risdonii Hook-F and E amygdalina Labill

1986 ◽  
Vol 34 (3) ◽  
pp. 305 ◽  
Author(s):  
BM Potts
Keyword(s):  
Hybrid Zone ◽  
Null Point ◽  
Asymmetric Distribution ◽  
Hybrid Swarm ◽  
Population Response ◽  
Pure Species ◽  
Seed Migration ◽  
Hybrid Swarms ◽  
Population Turnover ◽  
Phenotypic Fitness

Regeneration of a hybrid zone between E. amygdalina and E. risdonii and pure species stands following wildfire is reported, as well as the reproductive and vegetative fitness of parental and hybrid phenotypes. E. risdonii phenotypes dominated the seed rain and seedling cohort and there was clearly a marked fitness differential between E. amygdalina and E. risdonii at their boundary. When the F1 type hybrid is in competition with both parental types it is generally reproductively the least fit, although frequently vegetatively vigorous. Reduced fitness appears to extend to advanced generations as hybrid phenotypes tending.toward either species are, on average, less fit than the corresponding parental type. The pattern of phenotypic fitness suggests that the species' boundary is in disequilibrium and it is argued that E. risdonii is invading the range of E. amygdalina by both pollen and seed migration. There is an asymmetric distribution of F1 type hybrids across the boundary and the hybrid swarm examined is being invaded by E. risdonii genes. It is suggested that hybridization may be associated with natural disequilibrium and, where seed migration is limited, boundary movements may be preceded by a wave of hybridization due partly to pollen swamping of the least fit species. Hybrid swarms may develop but, at the boundary of large stands, are probably transitory. There is a marked inertia in the population response to the prevailing selective regime due to the extremely slow population turnover and limited dispersal potential. This is discussed in the broader context of non-equilibrium models where it is argued that dispersal may be the factor limiting population response to perturbation of a shallow environmental gradient. This is due to large geographical shifts in the position of the null point and would be accentuated in a patchy environment where migration as a front is prevented.

Genetic status of the putative hybrid swarms of mountain dwarf pine and Scots pine in contact zones of their distribution in Slovakia

Biologia ◽  
2015 ◽  
Vol 70 (10) ◽  
Author(s):  
Peter Maňka ◽  
Andrej Kormuťák ◽  
Martin Galgóci ◽  
Dušan Gömöry
Keyword(s):  
Genetic Structure ◽  
Scots Pine ◽  
Molecular Level ◽  
Natural Populations ◽  
Hybrid Origin ◽  
Putative Hybrid ◽  
Hybrid Swarm ◽  
Pure Species ◽  
Hybrid Swarms ◽  
History Of

AbstractGenetic structure of the mountain dwarf pine (Pinus mugo) and Scots pine (P. sylvestris) natural populations along with their 4 putative hybrid swarms in Slovakia were analyzed using 12 enzyme loci. The study aimed in evaluation of postulated hybrid status of the swarms on molecular level. Based on semidiagnostic allele frequencies of the MDH B, MDH C, 6PGDH B, ADH 1 and F-EST loci in their megagametophytes and vegetative buds, the conspicuous genetic differences were detected between P. mugo and P. sylvestris populations. The putative hybrid swarms seem to incline by their genetic structure to P. mugo rather than to P. sylvestris. Obtained results indicate independent developmental history of each of the scored hybrid swarms. The putative hybrid swarm in Sucha Hora was found to be a mixed stand consisting prevailingly of pure-species individuals of P. mugo and P. sylvestris. On the contrary, the putative hybrid swarms in Habovka, Tisovnica and Terchova are supposed to be of hybrid origin.

Analysis of a Hybrid Swarm Between Eucalyptus risdonii Hook. F. And E. amygdalina Labill

1985 ◽  
Vol 33 (5) ◽  
pp. 543 ◽  
Author(s):  
BM Potts ◽  
JB Reid
Keyword(s):  
Phenotypic Diversity ◽  
Flowering Phenology ◽  
Hybrid Swarm ◽  
Hybrid Fitness ◽  
Seedling Vigour ◽  
Pure Species ◽  
Closely Related Species ◽  
Intermediate Phenotypes ◽  
Disjunct Populations ◽  
Tasmanian Endemic

E. risdonii is a rare Tasmanian endemic which occurs as a series of small disjunct populations within a more-or-less continuous population of a closely related species, E. amygdalina. In localized areas (e.g. Risdon, Tasmania), patches of high phenotypic diversity are encountered, with individuals encompassing the complete phenotypic range between these two species. Progeny trials indicate a large heritable component to this variation. Open-pollinated progenies from intermediate mothers exhibit greater variability than those from either pure species, which strongly suggests that these intermediate phenotypes are a result of hybridization. Progenies from pure species mothers near a hybrid swarm are more variable than those from pure stands. There is a greater proportion of seedlings which match the artificially produced F1 in open-pollinated progenies from E. amygdalina than from E. risdonii mothers. In addition, progenies from intermediate mothers show a bias toward E. risdonii types, which implies that they are predominantly outcrossing to E. risdonii. This evidence suggests an asymmetrical flow of genes by pollen migration from E. risdonii into the hybrid swarm and surrounding E. amygdalina. Little difference in seedling vigour or mortality occurred between seedlings from the various parental phenotypes, although differences in seed output per capsule and germination were apparent. The specific identity of E. risdonii and E. amygdalina is usually maintained in parapatry by a range of mechanisms including their specific ecological preference, reduced hybrid fitness and differences in flowering phenology. The reasons for the major zones of hybridization occurring at boundaries on ridge tops as opposed to those on the dry slopes are discussed.

Interrelationships of poplars in a hybrid swarm as studied by gas chromatography – mass spectrometry

1991 ◽  
Vol 69 (1) ◽  
pp. 203-208 ◽  
Author(s):  
W. Greenaway ◽  
S. English ◽  
F. R. Whatley ◽  
S. B. Rood
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Parental Species ◽  
Previous Analysis ◽  
Gas Chromatography Mass Spectrometry ◽  
Hybrid Swarm ◽  
Pure Species ◽  
Populus Angustifolia ◽  
Chromatography Mass Spectrometry ◽  
Hybrid Clones

Analysis of bud exudate by gas chromatography-mass spectrometry (GC–MS) of 14 clones belonging to a natural hybrid swarm involving Populus angustifolia, P. balsamifera, and P. deltoides produced results consistent with those obtained by previous analysis of leaf characteristics. Specimens that had leaves most characteristic of a pure species also produced bud exudate GC–MS profiles which were characteristic of those species. GC–MS profiles of interspecific hybrid clones were intermediate between the parental species. This demonstrates the usefulness of GC–MS analysis of bud exudate as a chemo-taxonomic method for the study of intersecific poplar hybrids and also supports the accuracy of analysis of foliar morphology for taxonomic assessment. Key words: Populus, bud exudate, gas chromatography – mass spectrometry.

scholarly journals Isoenzymatic variability in progeny of Pinus mugo Turra x Pinus sylvestris L. hybrids from Bór na Czerwonem, in experimental culture

2014 ◽  
Vol 69 (2) ◽  
pp. 137-144 ◽  
Author(s):  
Maria A. Bobowicz ◽  
Władysław Danielewicz
Keyword(s):  
Genetic Structure ◽  
Pinus Sylvestris ◽  
Genetic Similarity ◽  
Hybrid Population ◽  
Fixation Index ◽  
Pinus Mugo ◽  
Similarity Coefficients ◽  
Hybrid Swarm ◽  
Pure Species ◽  
Natural Hybrids

The article describes the genetic structure of 12-year old seedlings. They were grown in an experimental culture representing the progeny of natural hybrids of <em>Pinus mugo</em> Turra and <em>Pinus sylvestris</em> L. from the peatbog Bór na Czerwonem. The studies were carried out on seedlings, employing electrophoresis of enzymatic proteins from winter buds. Parallel isoenzymatic analyses were also conducted for trees of <em>P. mugo</em> Turra from Tatra Mountains and for <em>P. sylvestris</em> L. trees from Białowieża in order to determine similarities of the hybrids to the 'pure' species, thought to represent parental forms, and for natural hybrids from Bór na Czerwonem. The obtained electrophoretic patterns made the determination of genetic structure of the population possible, namely of the observed heterozygosity, expected heterozygosity, Wright's fixation index and coefficients of similarity according to Nei and Hedrick. Genetic distances between the populations were also estimated. The variability of 11 enzymatic loci demonstrated the highest level of variability in the population of hybrids. Coefficients of genetic differentiation (GST) and of gene flow, (Nm) suggested a close relationship of the hybrids to <em>P. mugo</em> which may indicate an introgressive type of the hybrid swarm, from which the studied trees originated. The analysis of genetic similarity coefficients, according to Nei and Hedrick, demonstrated also an extensive similarity of the two hybrid groups to <em>P. mugo</em>. However, upon analysis of individual enzymatic loci, some of them highly resembled <em>P. mugo</em> while others were similar to <em>P. sylvestris</em>. The closest genetic similarity was demonstrated for the group of hybrids from the peatbog and the respective of hybrides group from culture. The variable gene expression as well as asymmetric inheritance of isoenzymes provided additional evidence of the introgressive character of the studied trees from the hybrid population.

scholarly journals Admixture mapping reveals loci for carcass mass in red deer x sika hybrids in Kintyre, Scotland

2021 ◽  
Author(s):  
S. Eryn McFarlane ◽  
Josephine M. Pemberton
Keyword(s):  
Cervus Elaphus ◽  
Red Deer ◽  
Cervus Nippon ◽  
Mass Effect ◽  
Admixture Mapping ◽  
Hybrid Swarm ◽  
Pure Species ◽  
Phenotypic Differences ◽  
Genomic Locations ◽  
Term Analysis

AbstractWe deployed admixture mapping on a sample of 386 deer from a hybrid swarm between native red deer (Cervus elaphus) and introduced Japanese sika (Cervus nippon) sampled in Kintyre, Scotland to search for Quantitative Trait Loci (QTL) underpinning phenotypic differences between the species. These two species are highly diverged genetically (Fst between pure species, based on 50K SNPs, = 0.532) and phenotypically: pure red have on average twice the carcass mass of pure sika in our sample (38.7kg vs 19.1 kg). After controlling for sex, age and population genetic structure we found ten autosomal genomic locations with QTL for carcass mass. Effect sizes ranged from 0.191 to 1.839 Kg and as expected, in all cases the allele derived from sika conferred lower carcass mass. The sika population was fixed for all small carcass mass alleles, whereas the red deer population was typically polymorphic. GO term analysis of genes lying in the QTL regions are associated with oxygen transport. Although body mass is a likely target of selection, none of the SNPs marking QTL are introgressing faster or slower than expected in either direction.

scholarly journals Pollen fertility and seed viability of putative hybrid swarms of Pinus sylvestris and Pinus mugo in Slovakia

2019 ◽  
Vol 68 (1) ◽  
pp. 14-21
Author(s):  
Andrej Kormutak ◽  
Martina Brana ◽  
Martin Galgoci ◽  
Peter Manka ◽  
Denisa Sukenikova ◽  
...  
Keyword(s):  
Pinus Sylvestris ◽  
Seed Quality ◽  
Pollen Viability ◽  
Seed Viability ◽  
Germination Percentage ◽  
Tube Length ◽  
Putative Hybrid ◽  
Pure Species ◽  
Contact Zones ◽  
Hybrid Swarms

Abstract Generally acknowledged reduction of the interspecific hybrid fertility was utilized in evaluation of the putative hybrid swarms of Scots pine (Pinus sylvestris L.) and mountain dwarf pine (P. mugo Turra) viability under field conditions. Pollen viability and seed quality of the trees from the four contact zones of P. syl­vestris and P. mugo in Slovakia were compared with the corres­ponding characteristics of the pure populations of these spe­cies from three reference localities. Pollen germination percentage was comparable in contact zones and control populations of the species. Statistically significant differences between the parent and hybrid groups were detected in pollen tube length only. In general, pollen tubes of the pure species populations were longer than those in contact zones. At the cone level, the individuals from contact zones possessed shor­ter cones than the trees of pure species populations P. mugo and P. sylvestris. This was paralleled by a lower number of seeds per cone in contact zones and higher amount of seeds per cone in the P. mugo population. Striking differences between individuals of the contact zones and reference populations were revealed also in germination potentials of their seeds. Significantly higher proportions of germinating seeds was found in the reference populations of P. mugo and P. sylvestris than in their contact zones. Contrary to seed quality parame­ters mentioned above, the fractions of filled but non-germina­ting seeds and amounts of empty seeds were higher in contact zones than in the parental species populations, indicating hig­her frequency occurrence of abortive embryogenesis in the former. The lower fertility characteristics of the individuals from contact zones indicate their hybrid nature.

scholarly journals Unique genetic signatures of local adaptation over space and time for diapause, an ecologically relevant complex trait, in Drosophila melanogaster

PLoS Genetics ◽  
2020 ◽  
Vol 16 (11) ◽  
pp. e1009110
Author(s):  
Priscilla A. Erickson ◽  
Cory A. Weller ◽  
Daniel Y. Song ◽  
Alyssa S. Bangerter ◽  
Paul Schmidt ◽  
...  
Keyword(s):  
Drosophila Melanogaster ◽  
North America ◽  
Evolutionary History ◽  
Genetic Basis ◽  
Genome Wide Association Study ◽  
Complex Trait ◽  
Hybrid Swarm ◽  
Evolutionary Patterns ◽  
Hybrid Swarms ◽  
History Of

Organisms living in seasonally variable environments utilize cues such as light and temperature to induce plastic responses, enabling them to exploit favorable seasons and avoid unfavorable ones. Local adapation can result in variation in seasonal responses, but the genetic basis and evolutionary history of this variation remains elusive. Many insects, including Drosophila melanogaster, are able to undergo an arrest of reproductive development (diapause) in response to unfavorable conditions. In D. melanogaster, the ability to diapause is more common in high latitude populations, where flies endure harsher winters, and in the spring, reflecting differential survivorship of overwintering populations. Using a novel hybrid swarm-based genome wide association study, we examined the genetic basis and evolutionary history of ovarian diapause. We exposed outbred females to different temperatures and day lengths, characterized ovarian development for over 2800 flies, and reconstructed their complete, phased genomes. We found that diapause, scored at two different developmental cutoffs, has modest heritability, and we identified hundreds of SNPs associated with each of the two phenotypes. Alleles associated with one of the diapause phenotypes tend to be more common at higher latitudes, but these alleles do not show predictable seasonal variation. The collective signal of many small-effect, clinally varying SNPs can plausibly explain latitudinal variation in diapause seen in North America. Alleles associated with diapause are segregating in Zambia, suggesting that variation in diapause relies on ancestral polymorphisms, and both pro- and anti-diapause alleles have experienced selection in North America. Finally, we utilized outdoor mesocosms to track diapause under natural conditions. We found that hybrid swarms reared outdoors evolved increased propensity for diapause in late fall, whereas indoor control populations experienced no such change. Our results indicate that diapause is a complex, quantitative trait with different evolutionary patterns across time and space.

scholarly journals Reconstructing explicit mating schemes in poplar hybrids – a case study in the Populus nigra L. – Populus × canadensis Moench complex

2012 ◽  
Vol 61 (1-6) ◽  
pp. 157-167 ◽  
Author(s):  
R. Bialozyt ◽  
G. Rathmacher ◽  
M. Niggemann ◽  
B. Ziegenhagen
Keyword(s):  
First Generation ◽  
Nuclear Genome ◽  
Populus Nigra ◽  
Hybrid Swarm ◽  
Hybrid Swarms ◽  
Hybrid Complex ◽  
F2 Hybrids ◽  
Cost Efficient ◽  
Set Up ◽  
Individual Trees

Abstract In the plant kingdom, a large percentage of taxa are known to interbreed. If these hybrids are fertile, introgressive gene flow may foster the development of hybrid swarms or even promote gene swamping. Our study focuses on the Eurasian black poplar (Populus nigra L.) which may be threatened by hybridization with the cultivated fertile Euramerican hybrid. Using a combination of taxa specific DNA markers from the chloroplast and the nuclear genome we set up a straightforward and cost efficient method for identification of all possible mating scenarios in the hybrid complex of P. nigra and its cultivar Populus × canadensis Moench. Within a mixed population, we analyzed seed collections from individual trees of both taxa as well as juveniles from natural regeneration for proportions of second-generation hybrids (F2 hybrids) and first generation backcrosses. While F2 hybrids were detected in the seeds only, first generation backcrosses occurred in seeds as well as in juveniles. Due to the meiotic segregation of alleles, a certain amount of such progeny may remain undetected. Based on Mendelian rules, we developed a scheme to adjust the observed proportion of hybrid progeny for these undetected cases. Moreover, the scheme can be used to iteratively add loci necessary to detect poplar hybrids beyond the second hybrid and first generation backcrosses. We questioned whether there is a risk of hybrid swarm formation or swamping of the P. nigra gene pool. We discuss the likelihood of such a scenario and draw conclusions for conservation issues while poplar plantations are increasingly appreciated as renewable resources.

scholarly journals Transcriptome-Based SNP Discovery and Validation in the Hybrid Zone of the Neotropical Annual Fish Genus Austrolebias

Genes ◽  
2019 ◽  
Vol 10 (10) ◽  
pp. 789 ◽  
Author(s):  
Graciela García ◽  
Néstor Ríos ◽  
Verónica Gutiérrez ◽  
Sebastián Serra ◽  
Marcelo Loureiro
Keyword(s):  
Hybrid Zone ◽  
Population Genomics ◽  
Snp Markers ◽  
Life Cycles ◽  
Environmental Stochasticity ◽  
Temporary Ponds ◽  
Large Set ◽  
Annual Fish ◽  
Diapausing Eggs ◽  
Hybrid Swarms

The genus Austrolebias (Cyprinodontiformes: Rivulidae) represents a specious group of taxa following annual life cycles in the neotropical ichthyofauna. They live in temporary ponds and each generation must be completed in a few months, depending on environmental stochasticity. Annual fish survive the dry season through diapausing eggs buried in the substrate of these ponds. A hypothesized bimodal hybrid zone between two taxa of the genus, A. charrua and A. reicherti from Dos Patos Merin lagoon system, was recently proposed based on genetics and morphological analyses. However, hundreds of additional nuclear molecular markers should be used to strongly support this hypothesized bimodal pattern. In the present paper, we conducted RNA-seq-based sequencing of the transcriptomes from pools of individuals of A. charrua, A. reicherti and their putative natural hybrids from the previously characterized hybrid zone. As a result, we identified a set of 111,725 SNP (single nucleotide polymorphism) markers, representing presumably fixed allelic differences among the two species. The present study provided the first panel of 106 SNP markers as a single diagnostic multiplex assay and validated their capacity to reconstruct the patterns of the hybrid zone between both taxa. These nuclear markers combined with Cytb gene and morphological analyses detected a population structure in which some groups among the hybrid swarms showed different level of introgression towards one or the other parental species according to their geographic distribution. High-quality transcriptomes and a large set of gene-linked SNPs should greatly facilitate functional and population genomics studies in the hybrid zone of these endangered species.

scholarly journals Admixture mapping reveals loci for carcass mass in red deer x sika hybrids in Kintyre, Scotland

2021 ◽  
Author(s):  
S Eryn McFarlane ◽  
Josephine M Pemberton
Keyword(s):  
Cervus Elaphus ◽  
Red Deer ◽  
Cervus Nippon ◽  
Mass Effect ◽  
Admixture Mapping ◽  
Hybrid Swarm ◽  
Pure Species ◽  
Phenotypic Differences ◽  
Genomic Locations ◽  
Term Analysis

Abstract We deployed admixture mapping on a sample of 386 deer from a hybrid swarm between native red deer (Cervus elaphus) and introduced Japanese sika (Cervus nippon) sampled in Kintyre, Scotland to search for Quantitative Trait Loci (QTL) underpinning phenotypic differences between the species. These two species are highly diverged genetically (Fst between pure species, based on 50K SNPs, = 0.532) and phenotypically: pure red have on average twice the carcass mass of pure sika in our sample (38.7 kg vs 19.1 kg). After controlling for sex, age and population genetic structure we found ten autosomal genomic locations with QTL for carcass mass. Effect sizes ranged from 0.191 to 1.839 Kg and as expected, in all cases the allele derived from sika conferred lower carcass mass. The sika population was fixed for all small carcass mass alleles, whereas the red deer population was typically polymorphic. GO term analysis of genes lying in the QTL regions are associated with oxygen transport. Although body mass is a likely target of selection, none of the SNPs marking QTL are introgressing faster or slower than expected in either direction.

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