scholarly journals Life Cycle in Natural Populations of Canna indica L. from Argentina

10.5772/34338 ◽  
2012 ◽  
Author(s):  
Mara de las Mercedes Ciciarelli
Keyword(s):  
Life Cycle ◽  
Natural Populations ◽  
Canna Indica

scholarly journals Evolutionary dynamics of spore killers.

Genetics ◽  
1993 ◽  
Vol 135 (3) ◽  
pp. 923-930 ◽  
Author(s):  
M J Nauta ◽  
R F Hoekstra
Keyword(s):  
Life Cycle ◽  
Segregation Distortion ◽  
Population Genetic ◽  
Field Data ◽  
Evolutionary Dynamics ◽  
Natural Populations ◽  
Additional Advantage ◽  
Genetic Modeling ◽  
Spore Killing ◽  
Ascospore Formation

Abstract Spore killing in ascomycetes is a special form of segregation distortion. When a strain with the Killer genotype is crossed to a Sensitive type, spore killing is expressed by asci with only half the number of ascospores as usual, all surviving ascospores being of the Killer type. Using population genetic modeling, this paper explores conditions for invasion of Spore killers and for polymorphism of Killers, Sensitives and Resistants (which neither kill, nor get killed), as found in natural populations. The models show that a population with only Killers and Sensitives can never be stable. The invasion of Killers and stable polymorphism only occur if Killers have some additional advantage during the process of spore killing. This may be due to the effects of local sib competition or some kind of "heterozygous" advantage in the stage of ascospore formation or in the short diploid stage of the life cycle. This form of segregation distortion appears to be essentially different from other, well-investigated forms, and more field data are needed for a better understanding of spore killing.

Laboratory comparison of the relative success of Biomphalaria glabrata stocks which are susceptible and insusceptible to infection with Schistosoma mansoni

Parasitology ◽  
1983 ◽  
Vol 86 (2) ◽  
pp. 335-344 ◽  
Author(s):  
D. J. Minchella ◽  
P. T. Loverde
Keyword(s):  
Life Cycle ◽  
Natural Selection ◽  
Reproductive Success ◽  
Natural Populations ◽  
Biomphalaria Glabrata ◽  
Selective Advantage ◽  
Controlled Conditions ◽  
Plausible Answer ◽  
Major Objection ◽  
Transmit Disease

SUMMARYA method of interrupting the life-cycle of the human blood fluke Schistosoma by increasing the proportion of genetically insusceptible intermediate host snails in natural populations was first proposed nearly 25 years ago. The method assumes that insusceptible snails will be at a selective advantage over susceptible snails when the schistosome parasite is present, and therefore natural selection will act to increase the proportion of alleles for insusceptibility. A major objection to the proposed technique is ‘If insusceptible snails are at a selective advantage, then why are they not predominant in natural populations that transmit disease?’ One explanation of this paradox is that insusceptibility may be associated with a disadvantageous character or a physiological defect. This study tests this hypothesis by measuring the relative reproductive success of susceptible and insusceptible snails under controlled conditions. Results indicate that insusceptible (unsuitable) snails are negatively affected in the presence of either susceptible snails or schistosome parasites. Furthermore, in the presence of both susceptible snails and schistosome parasites, insusceptible snails are selectively disadvantaged compared to susceptible snails. These results obtained under laboratory-controlled conditions suggest a plausible answer as to why insusceptible snails are not predominant in natural populations that transmit disease.

Vegetative Propagation of Species of Genus Allium L.

1993 ◽  
Vol 27 (7-8) ◽  
pp. 511-517
Author(s):  
Rina Kamenetsky
Keyword(s):  
Life Cycle ◽  
Vegetative Propagation ◽  
Genetic Stability ◽  
Vegetative Reproduction ◽  
Natural Populations ◽  
Morphological Type ◽  
Useful Plants ◽  
Allium Species ◽  
Apical Buds ◽  
Arid Conditions

The genus Allium L. consists of about 500 species in the Northern hemisphere and includes a large number of useful plants. The highly variable underground organs of Allium species - rhizomes and bulbs - have the function of storing food and moisture in severe environmental conditions. Their other very important function - vegetative reproduction and propagation - increases the chances of survival and supports the genetic stability of natural populations. Among about 40 species studied, 5 types of vegetative reproduction and propagation are distinguishable. The formation of apical buds, daughter bulblets, stolons and apomictic bulblets in the inflorescense have been observed. There is possibly some connection between vegetative propagation, morphological type and life cycle. The process of evolution within the genus and the migration of species to arid conditions lead possibly to the appearance in phylogenesis of prevalence of seminal reproduction over vegetative propagation.

MAINTAINING A COLONY OF THE STRIPED FLEA BEETLE, PHYLLOTRETA STRIOLATA (COLEOPTERA: CHRYSOMELIDAE), IN THE GREENHOUSE

1976 ◽  
Vol 108 (1) ◽  
pp. 53-55 ◽  
Author(s):  
L. Burgess ◽  
J. E. Wiens
Keyword(s):  
Life Cycle ◽  
Host Plant ◽  
Flea Beetle ◽  
Natural Populations ◽  
Suitable Host ◽  
Armoracia Rusticana ◽  
Phyllotreta Striolata ◽  
Small Colony

AbstractA small colony of the striped flea beetle, Phyllotreta striolala (F.), has been maintained in a cage in the greenhouse for more than 21/2 years. Horseradish [Armoracia rusticana (Lam) Gaertn., Mey. & Scherb.] was found to be a suitable host plant, and the caged beetle colony has followed a similar life cycle to natural populations in the field.

scholarly journals Life cycle expression of inbreeding depression in Eucalyptus regnans and inter-generational stability of its mixed mating system

2019 ◽  
Vol 124 (1) ◽  
pp. 179-187 ◽  
Author(s):  
A Rod Griffin ◽  
Brad M Potts ◽  
René E Vaillancourt ◽  
J Charles Bell
Keyword(s):  
Life Cycle ◽  
Mating System ◽  
Inbreeding Depression ◽  
Field Experiments ◽  
Natural Populations ◽  
Forest Tree ◽  
Mixed Mating ◽  
Mature Trees ◽  
Mixed Mating System ◽  
Eucalyptus Regnans

Abstract Background and Aims Many plants exhibit a mixed mating system. Published models suggest that this might be an evolutionarily stable rather than a transitional state despite the presence of inbreeding depression, but there is little empirical evidence. Through field experimentation, we studied the role of inbreeding depression in eliminating inbred progeny from the reproductive cohort of the forest tree Eucalyptus regnans, and demonstrate a stable mixed primary mating system over two successive generations. Methods Two field experiments were conducted using seed from natural populations. We sowed open-pollinated seeds to simulate a natural regeneration event and determined isozyme genotypes of dominant and suppressed individuals over 10 years. We also planted a mixture of open-pollinated, outcross and selfed families with common maternal parentage; monitored survival of cross types over 29 years; and determined the percentage of outcrosses in open-pollinated seed from a sample of reproductively mature trees using microsatellite analysis. Key Results Both experiments demonstrated progressive competitive elimination of inbred plants. By 29 years, the reproductive cohort in the planted experiment consisted only of outcrosses which produced seed which averaged 66 % outcrosses, similar to the estimate for the parental natural population (74 %). Conclusions Selective elimination of inbred genotypes during the intense intra-specific competition characteristic of the pre-reproductive phase of the life cycle of E. regnans results in a fully outcrossed reproductive population, in which self-fertility is comparable with that of its parental generation. The mixed mating system may be viewed as an unavoidable consequence of the species’ reproductive ecology, which includes the demonstrated effects of inbreeding depression, rather than a strategy which is actively favoured by natural selection.

scholarly journals Effects of the Ordering of Natural Selection and Population Regulation Mechanisms on Wright-Fisher Models

2016 ◽  
Author(s):  
Zhangyi He ◽  
Mark Beaumont ◽  
Feng Fu
Keyword(s):  
Population Dynamics ◽  
Life Cycle ◽  
Natural Selection ◽  
Population Regulation ◽  
Genetic Research ◽  
Natural Populations ◽  
Gene Migration ◽  
Local Selection ◽  
Fisher Model ◽  
Regulation Mechanisms

AbstractThe Wright-Fisher model and its extensions are of central importance in population genetics, and so far, they have formed the basis of most theoretical and applied population genetic research. In the present work, we explore the effect that the ordering of natural selection and population regulation in the life cycle has on the resulting population dynamics under the Wright-Fisher model, especially for the evolution of one- and two-locus systems. With weak natural selection, the details of how to order natural selection and population regulation in the life cycle do not matter in the Wright-Fisher model and its diffusion approximation. By contrast, we show that when there is strong natural selection and the population is in linkage disequilibrium, there can be appreciable differences in the resulting population dynamics under the Wright-Fisher model, depending on whether natural selection occurs before or after population regulation in the life cycle. We argue that this effect may be of significance in natural populations subject to gene migration and local selection.F.Y. supported in part by EPSRC Grant EP/I028498/1.

Cytological, molecular and life cycle characterization of Anostracospora rigaudi n. g., n. sp. and Enterocytospora artemiae n. g., n. sp., two new microsporidian parasites infecting gut tissues of the brine shrimp Artemia

Parasitology ◽  
2013 ◽  
Vol 140 (9) ◽  
pp. 1168-1185 ◽  
Author(s):  
NICOLAS OLIVIER RODE ◽  
JULIE LANDES ◽  
EVA J. P. LIEVENS ◽  
ELODIE FLAVEN ◽  
ADELINE SEGARD ◽  
...  
Keyword(s):  
Life Cycle ◽  
Intestinal Epithelium ◽  
Natural Populations ◽  
Post Inoculation ◽  
Polar Tube ◽  
Molecular Approaches ◽  
Life Cycle Stages ◽  
Detection And Identification ◽  
Approaches To Study ◽  
Species Specific

SUMMARYTwo new microsporidia, Anostracospora rigaudi n. g., n. sp., and Enterocytospora artemiae n. g., n. sp. infecting the intestinal epithelium of Artemia parthenogenetica Bowen and Sterling, 1978 and Artemia franciscana Kellogg, 1906 in southern France are described. Molecular analyses revealed the two species belong to a clade of microsporidian parasites that preferentially infect the intestinal epithelium of insect and crustacean hosts. These parasites are morphologically distinguishable from other gut microsporidia infecting Artemia. All life cycle stages have isolated nuclei. Fixed spores measure 1·3×0·7 μm with 5–6 polar tube coils for A. rigaudi and 1·2×0·9 μm with 4 polar tube coils for E. artemiae. Transmission of both species is horizontal, most likely through the ingestion of spores released with the faeces of infected hosts. The minute size of these species, together with their intestinal localization, makes their detection and identification difficult. We developed two species-specific molecular markers allowing each type of infection to be detected within 3–6 days post-inoculation. Using these markers, we show that the prevalence of these microsporidia ranges from 20% to 75% in natural populations. Hence, this study illustrates the usefulness of molecular approaches to study prevalent, but cryptic, infections involving microsporidian parasites of gut tissues.

scholarly journals A key role for UV sex chromosomes in the regulation of parthenogenesis in the brown algaEctocarpus

2018 ◽  
Author(s):  
Laure Mignerot ◽  
Komlan Avia ◽  
Remy Luthringer ◽  
Agnieszka P. Lipinska ◽  
Akira F. Peters ◽  
...  
Keyword(s):  
Life Cycle ◽  
Asexual Reproduction ◽  
Sex Chromosome ◽  
Natural Populations ◽  
Life History Evolution ◽  
Life Cycles ◽  
Negative Effects ◽  
Evolutionary Transitions ◽  
Trade Offs ◽  
Sexual And Asexual Reproduction

AbstractAlthough evolutionary transitions from sexual to asexual reproduction are frequent in eukaryotes, the genetic bases of these shifts remain largely elusive. Here, we used classic quantitative trait analysis, combined with genomic and transcriptomic information to dissect the genetic basis of asexual, parthenogenetic reproduction in the brown algaEctocarpus. We found that parthenogenesis is controlled by the sex locus, together with two additional autosomal loci, highlight the key role of the sex chromosome as a major regulator of asexual reproduction. Importantly, we identify several negative effects of parthenogenesis on male fitness, but also different fitness effects between parthenogenesis and life cycle generations, supporting the idea that parthenogenesis may be under both sexual selection and generation/ploidally-antagonistic selection. Overall, our data provide the first empirical illustration, to our knowledge, of a trade-off between the haploid and diploid stages of the life cycle, where distinct parthenogenesis alleles have opposing effects on sexual and asexual reproduction and may contribute to the maintenance of genetic variation. These types of fitness trade-offs have profound evolutionary implications in natural populations and may structure life history evolution in organisms with haploid-diploid life cycles.

Observations on rearing damselflies under laboratory conditions

2003 ◽  
Vol 53 (1) ◽  
pp. 37-45 ◽  
Author(s):  
Hans van Gossum ◽  
Adolfo Cordero Rivera ◽  
Rosana Sánchez
Keyword(s):  
Life Cycle ◽  
Natural Populations ◽  
Low Density ◽  
Entire Life ◽  
Entire Life Cycle ◽  
Laboratory Conditions ◽  
Sufficient Food

AbstractRearing damselflies under laboratory conditions is a promising means of solving a variety of biological questions. Therefore, in order to improve the success of future researchers we felt the need to indicate potential difficulties in carrying out rearing experiments. Laboratory crosses were obtained using virgin animals originating from natural populations in Belgium and Spain. Resulting offspring was maintained, under laboratory conditions, in small aquaria until emergence and in insectaries as adults. Our results show that keeping damselflies during their entire life cycle under artificial conditions can be very difficult. We suggest that future researchers should change water regularly, supply sufficient food, and rear animals at low density or even individually. Furthermore, suggestions are given on type of food, advisable laboratory conditions and female oviposition methodology.

scholarly journals Seaweed reproductive biology: environmental and genetic controls

2017 ◽  
Vol 60 (2) ◽  
Author(s):  
Xiaojie Liu ◽  
Kenny Bogaert ◽  
Aschwin H. Engelen ◽  
Frederik Leliaert ◽  
Michael Y. Roleda ◽  
...  
Keyword(s):  
Life Cycle ◽  
Current Knowledge ◽  
Natural Populations ◽  
Life Cycles ◽  
Research Papers ◽  
Cycle Progression ◽  
Vast Number ◽  
Endogenous Factors ◽  
Trade Offs ◽  
Excellent Control

AbstractKnowledge of life cycle progression and reproduction of seaweeds transcends pure academic interest. Successful and sustainable seaweed exploitation and domestication will indeed require excellent control of the factors controlling growth and reproduction. The relative dominance of the ploidy-phases and their respective morphologies, however, display tremendous diversity. Consequently, the ecological and endogenous factors controlling life cycles are likely to be equally varied. A vast number of research papers addressing theoretical, ecological and physiological aspects of reproduction have been published over the years. Here, we review the current knowledge on reproductive strategies, trade-offs of reproductive effort in natural populations, and the environmental and endogenous factors controlling reproduction. Given that the majority of ecophysiological studies predate the “-omics” era, we examine the extent to which this knowledge of reproduction has been, or can be, applied to further our knowledge of life cycle control in seaweeds.

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