scholarly journals The effect of different selection intensities on selection response in egg-laying of Tribolium castaneum

1975 ◽  
Vol 25 (1) ◽  
pp. 17-27 ◽  
Author(s):  
R. G. Ruano ◽  
F. Orozco ◽  
C. López-Fanjul
Keyword(s):  
Tribolium Castaneum ◽  
Adult Emergence ◽  
Selection Response ◽  
Fixed Number ◽  
Egg Laying ◽  
Short Term ◽  
Selection Intensities ◽  
Number Of Individuals ◽  
Rate Of Response ◽  
Good Agreement

SUMMARYAn experiment was carried out to test the effect of varying selection intensity on the response to individual selection with a fixed number of individuals scored per generation. The selected trait was egg laying of virgin females of Tribolium castaneum scored from the 7th to the 1 lth day after adult emergence. Five different selected proportions of females were considered (5, 10, 20, 33 and 50%) and each treatment was represented by two replicate lines. Control lines were maintained throughout the experiment. The lines selected at the lowest proportions (5 and 10%) led to the largest initial gains, but the largest final gains were achieved, by the lines where the proportions selected were 10 and 20%, in agreement with theory. Lines where the proportion selected was 50% gave the lowest rate of response over the period considered (32 generations). A good agreement was found between predicted and realized short-term responses to selection. Prediction at later stages of selection deteriorated in the most strongly selected lines mainly due to the levels of inbreeding attained.

scholarly journals RECOMBINATION AND RESPONSE TO SELECTION IN DROSOPHILA MELANOGASTER

Genetics ◽  
1977 ◽  
Vol 85 (1) ◽  
pp. 125-140
Author(s):  
Vinton Thompson
Keyword(s):  
Drosophila Melanogaster ◽  
Selection Response ◽  
Response To Selection ◽  
Short Term ◽  
Chromosome Recombination ◽  
Suppressed Recombination ◽  
Selection For ◽  
Balancer Chromosomes ◽  
Term Response ◽  
Rate Of Response

ABSTRACT Most biologists believe that recombination speeds response to selection for traits determined by polygenic loci. To test this hypothesis, sixteen Drosophila melanogaster populations were selected for positive phototaxis for twenty-one generations. In some populations, balancer chromosomes were used to suppress autosomal recombination, and in others the autosomes were free to recombine. Suppression of recombination had no effect on mean rate of response to selection, though it may have increased variability in the rate of response among replicate lines. Suppressed recombination lines did not shift selection response to the freely recombining × chromosomes, despite fairly large increases in × chromosome recombination. The results suggest that in populations of moderate size, sex does not accelerate short term response to selection.

scholarly journals The effects of population size and selection intensity in selection for a quantitative character in Drosophila: I. Short-term response to selection

1968 ◽  
Vol 12 (3) ◽  
pp. 237-248 ◽  
Author(s):  
R. Frankham ◽  
L. P. Jones ◽  
J. S. F. Barker
Keyword(s):  
Quantitative Character ◽  
Selection Intensity ◽  
Realized Heritability ◽  
Response To Selection ◽  
Short Term ◽  
Population Sizes ◽  
Selection For ◽  
Selection Intensities ◽  
Number Of Individuals ◽  
Term Response

1. The response to selection for increased number of bristles on one abdominal segment was studied over 12 generations using a factorial design of three population sizes (10, 20 and 40 pairs of parents) and five selection intensities (10, 20, 40, 80% and controls).2. The responses on the average agreed well with those expected from the estimated base population heritability, but individual replicates diverged considerably.3. Larger populations tended to give greater response to selection, due mainly to larger realized heritabilities.4. There was no consistent effect of selection intensity on realized heritability.5. For populations with the same number of individuals scored, less intense selection gave greater realized heritabilities.

scholarly journals The Effects of Biotic and Abiotic Factors on the Community Dynamics in a Mountain Subtropical Forest

Forests ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 427
Author(s):  
Tianyang Zhou ◽  
Jiaxin Zhang ◽  
Yunzhi Qin ◽  
Mingxi Jiang ◽  
Xiujuan Qiao
Keyword(s):  
Climate Change ◽  
Ecosystem Services ◽  
Forest Dynamics ◽  
Community Dynamics ◽  
Abiotic Factors ◽  
Subtropical Forest ◽  
Above Ground Biomass ◽  
Short Term ◽  
Forest Ecosystem Services ◽  
Number Of Individuals

From supporting wood production to mitigating climate change, forest ecosystem services are crucial to the well-being of humans. Understanding the mechanisms that drive forest dynamics can help us infer how to maintain forest ecosystem services and how to improve predictions of forest dynamics under climate change. Despite the growing number of studies exploring above ground biomass (AGB) dynamics, questions of dynamics in biodiversity and in number of individuals still remain unclear. Here, we first explored the patterns of community dynamics in different aspects (i.e., AGB, density and biodiversity) based on short-term (five years) data from a 25-ha permanent plot in a subtropical forest in central China. Second, we examined the relationships between community dynamics and biodiversity and functional traits. Third, we identified the key factors affecting different aspects of community dynamics and quantified their relative contributions. We found that in the short term (five years), net above ground biomass change (ΔAGB) and biodiversity increased, while the number of individuals decreased. Resource-conservation traits enhanced the ΔAGB and reduced the loss in individuals, while the resource-acquisition traits had the opposite effect. Furthermore, the community structure contributed the most to ΔAGB; topographic variables and soil nutrients contributed the most to the number of individuals; demographic process contributed the most to biodiversity. Our results indicate that biotic factors mostly affected the community dynamics of ΔAGB and biodiversity, while the number of individuals was mainly shaped by abiotic factors. Our work highlighted that the factors influencing different aspects of community dynamics vary. Therefore, forest management practices should be formulated according to a specific protective purpose.

scholarly journals Selection Response in Finite Populations

Genetics ◽  
1996 ◽  
Vol 144 (4) ◽  
pp. 1961-1974 ◽  
Author(s):  
Ming Wei ◽  
Armando Caballero ◽  
William G Hill
Keyword(s):  
Linkage Disequilibrium ◽  
Inbreeding Depression ◽  
Genetic Variance ◽  
Relative Rate ◽  
Selection Response ◽  
Rate Of Change ◽  
Effective Population ◽  
Short Term ◽  
Model Account

Formulae were derived to predict genetic response under various selection schemes assuming an infinitesimal model. Account was taken of genetic drift, gametic (linkage) disequilibrium (Bulmer effect), inbreeding depression, common environmental variance, and both initial segregating variance within families (σAW02) and mutational (σM2) variance. The cumulative response to selection until generation t(CRt) can be approximated asCRt≈R0[t−β(1−σAW∞2σAW02)t24Ne]−Dt2Ne,where Ne is the effective population size, σAW∞2=NeσM2 is the genetic variance within families at the steady state (or one-half the genic variance, which is unaffected by selection), and D is the inbreeding depression per unit of inbreeding. R  0 is the selection response at generation 0 assuming preselection so that the linkage disequilibrium effect has stabilized. β is the derivative of the logarithm of the asymptotic response with respect to the logarithm of the within-family genetic variance, i.e., their relative rate of change. R  0 is the major determinant of the short term selection response, but σM2, Ne and β are also important for the long term. A selection method of high accuracy using family information gives a small Ne and will lead to a larger response in the short term and a smaller response in the long term, utilizing mutation less efficiently.

scholarly journals EFFECTS OF POPULATION SIZE AND SELECTION INTENSITY ON SHORT-TERM RESPONSE TO SELECTION FOR POSTWEANING GAIN IN MICE

Genetics ◽  
1973 ◽  
Vol 73 (3) ◽  
pp. 513-530
Author(s):  
J P Hanrahan ◽  
E J Eisen ◽  
J E Legates
Keyword(s):  
Population Size ◽  
Selection Response ◽  
Selection Intensity ◽  
Realized Heritability ◽  
Family Selection ◽  
Effective Population ◽  
Population Sizes ◽  
Selection For ◽  
Selection Intensities ◽  
Term Response

ABSTRACT The effects of population size and selection intensity on the mean response was examined after 14 generations of within full-sib family selection for postweaning gain in mice. Population sizes of 1, 2, 4, 8 and 16 pair matings were each evaluated at selection intensities of 100% (control), 50% and 25% in a replicated experiment. Selection response per generation increased as selection intensity increased. Selection response and realized heritability tended to increase with increasing population size. Replicate variability in realized heritability was large at population sizes of 1, 2 and 4 pairs. Genetic drift was implicated as the primary factor causing the reduced response and lowered repeatability at the smaller population sizes. Lines with intended effective population sizes of 62 yielded larger selection responses per unit selection differential than lines with effective population sizes of 30 or less.

scholarly journals Stochastic Models for a Chemostat and Long-Time Behavior

2013 ◽  
Vol 45 (03) ◽  
pp. 822-836 ◽  
Author(s):  
Pierre Collet ◽  
Servet Martínez ◽  
Sylvie Méléard ◽  
Jaime San Martín
Keyword(s):  
Population Size ◽  
Nutrient Concentration ◽  
Bacterial Population ◽  
Fixed Number ◽  
Death Process ◽  
Time Behavior ◽  
Long Time Behavior ◽  
Nutrient Distribution ◽  
Long Time ◽  
Number Of Individuals

We introduce two stochastic chemostat models consisting of a coupled population-nutrient process reflecting the interaction between the nutrient and the bacteria in the chemostat with finite volume. The nutrient concentration evolves continuously but depends on the population size, while the population size is a birth-and-death process with coefficients depending on time through the nutrient concentration. The nutrient is shared by the bacteria and creates a regulation of the bacterial population size. The latter and the fluctuations due to the random births and deaths of individuals make the population go almost surely to extinction. Therefore, we are interested in the long-time behavior of the bacterial population conditioned to nonextinction. We prove the global existence of the process and its almost-sure extinction. The existence of quasistationary distributions is obtained based on a general fixed-point argument. Moreover, we prove the absolute continuity of the nutrient distribution when conditioned to a fixed number of individuals and the smoothness of the corresponding densities.

Characteristics of long-period microtremors and their applicability in exploration of deep sedimentary layers

1994 ◽  
Vol 84 (6) ◽  
pp. 1831-1841 ◽  
Author(s):  
Hiroaki Yamanaka ◽  
Masayuki Takemura ◽  
Hiroshi Ishida ◽  
Masanori Niwa
Keyword(s):  
Rayleigh Waves ◽  
Ground Motions ◽  
Spectral Ratio ◽  
Northwestern Part ◽  
Trial And Error ◽  
Sediment Thickness ◽  
Short Term ◽  
Subsurface Structures ◽  
Long Period ◽  
Good Agreement

Abstract Applicability of long-period microtremors in inferring subsurface structure is examined using measurements of microtremors in the northwestern part of the Kanto Plain in Japan. Short-term continuous measurements of long-period microtremors at both sediment and basement sites were taken. A spectral peak at a period of 4 to 5 sec is stable with time, while peaks at periods less than 2 sec are time variant, suggesting a variation of microtremor sources. However, it was found that the spectral ratio between vertical and horizontal microtremors (ellipticity) at each site is stable with time. Good agreement was found between ellipticities of microtremors at the sediment site and those computed for Rayleigh waves in which the structure of the sediments beneath the site was taken into account. We also found that the ellipticities of Rayleigh waves in earthquake ground motions were consistent with those of the microtremors. These comparisons provide strong evidence that long-period microtremors in the area studied consist mainly of Rayleigh waves. The ellipticity of microtremors was investigated by observing microtremors at temporary observation sites in the Kanto Plain where the sediment thickness varied from 0 to 1 km. The subsurface structures were deduced by trial-and-error fitting of observed ellipticities with theoretical ellipticities that were calculated assuming Rayleigh waves. These results show that ellipticity of long-period microtremors is effective for deducing structure from microtremor data at a single site.

scholarly journals Observations on some biological aspects of Cicadatra persica (Cicadidae: Hemiptera) in apple fruit orchards in Erneh, Syria

2012 ◽  
Vol 44 (3) ◽  
pp. 12 ◽  
Author(s):  
Marah Ahmad Dardar ◽  
Hamzeh Mouhammad Ramadan Belal ◽  
Abedlnabi Mouhammad Basheer
Keyword(s):  
Life Cycle ◽  
Adult Emergence ◽  
Apple Fruit ◽  
Egg Laying ◽  
Egg Development ◽  
Successful Method ◽  
Biological Aspects ◽  
Fruit Orchards

<em>Cicadatra persica</em> Kirkaldy, 1909 (Hemiptera: Cicadidae) is regarded as a potential constraint to the productivity of apple fruit orchards in Erneh (33&deg;21&rsquo;N, 35&deg;52&rsquo;E), near Damascus, Syria. However, no research has been conducted on this pest. This study examined adult emergence, egg laying, and hatching periods. Adults emerged in early June, with an emergence peak in the fourth week of June 2011, and started laying eggs in mid-June. Egg development was approximately 40 days, with the first eggs hatching on 1<sup>st</sup> August 2011 and the final hatch on 17<sup>th</sup> August 2011. The simple and relatively successful method of monitoring egg development reported here may be useful for studying the nymphal ecology and life cycle of this species.

scholarly journals Toxicity and repellency of essential oils to Zabrotes subfasciatus (Boheman) (Coleoptera, Chrysomelidae, Bruchinae) in Phaseolus vulgaris L

2012 ◽  
Vol 42 (3) ◽  
pp. 381-386 ◽  
Author(s):  
Solange Maria de França ◽  
José Vargas de Oliveira ◽  
Alberto Belo Esteves Filho ◽  
Cynara Moura de Oliveira
Keyword(s):  
Phaseolus Vulgaris ◽  
Adult Emergence ◽  
Egg Laying ◽  
Toxicity Tests ◽  
Phaseolus Vulgaris L ◽  
Zabrotes Subfasciatus ◽  
Citrus Medica ◽  
Copaifera Langsdorffii ◽  
Oil Concentration ◽  
Plastic Containers

The effects of tangerine (Phaseolus vulgaris Blanco), lemon (Citrus medica limonum Lush), pear orange (Citrus sinensis L. Osbeck), red copaiba (Copaifera langsdorffii Desf.), rosemary (Baccharis dracunculifolia De Candole), Eucalyptus (Eucalyptus globulus Labillardière and E. citriodora Hook), lemongrass (Cymbopogon citratus Stapf.) and citronella (Cimbopogon nardus Linnaeus) oils at several concentrations on Zabrotes subfasciatus (Boheman) were studied. In toxicity tests, grains of Phaseolus vulgaris L. cv. Rajadinho were impregnated with oils and infested with adults of Z. subfasciatus up to 24 hours old. All tested oils were effective in reducing the viable egg-laying and adult emergence of this pest, in function of the concentrations used, highlighting E. citriodora and E. globulus oils which caused 100% effectiveness from 0.5 mL Kg-1 concentration. In repellency tests, two arenas consisting of plastic containers, connected symmetrically to a central box by two plastic tubes were used. In one of the boxes, untreated beans were placed and on the other ones beans treated with each oil concentration were used. In the central box, five couples of Z. subfasciatus were released. Grains of P. vulgaris treated with oils of E. citriodora, C. citratus and C. oleifera reduced the attraction percentage of Z. subfasciatus adults, while the E. globulus increased this percentage. The percentages of reduced viable eggs ranged from 17.9% (C. medica limonum) to 93.3% (C. nardus), while the reduction on the number of emerged insects was 23.9% and 95.9%, respectively for these same oils.

scholarly journals Species composition and structure of parasites component communities of tugun Coregonus tugun (Pallas, 1814) from the Khatanga and Yenisei Rivers

2019 ◽  
Vol 8 (3) ◽  
pp. 72-80
Author(s):  
Kseniya Viktorovna Polyaeva ◽  
Gennady Nikolaevich Dorovskikh ◽  
Yuliya Konstantinovna Chugunova
Keyword(s):  
Species Composition ◽  
Parasite Community ◽  
Shannon Index ◽  
Egg Laying ◽  
Entire Study ◽  
Generalist Species ◽  
Parasite Communities ◽  
Composition And Structure ◽  
Number Of Individuals ◽  
Species Composition And Structure

Tugun Coregonus tugun (Pallas, 1814) is an endemic of Siberia. Information about the species composition and structure of tugun parasite community on the stage of spawning migration is described in this paper. We carried out ichtioparasitologic studies in the Yenisey and the Khatanga Rivers in 2011-2014. Tugun parasite complex from the Khatanga River remains statistically identical in species composition, number of individuals and biomass and differs from those of the Yeniseis tugun over the entire study period. Apparently two different stocks of tugun were investigated in the Yenisei River. One of them lives in the Yeniseis streambed, the other one lives in the Podkamennaya Tunguska River. The composition of the parasitic fauna of tugun from two rivers is formed by generalist species. Tugun parasites component communities from all material collection stations have high values of the Shannon index and two dominant species (by numbers of parasites and by biomass). We found out that the species biomasses differ significantly on the graphic community structure. The description of tugun parasite communities corresponds to characteristic of a climax community on the stage of destruction except the graphic structure. In the analyzed parasitic communities the processes of egg laying and larval appearance, the death of parasites of previous year generation and infection with this year parasites occur simultaneously. The stages of formation and destruction of the community overlap. The described state of tugun parasites communities has an adaptive value. The load on the host body is reduced which ensures the long-term existence of parasites.

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