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1.
A 3-year microplot study was conducted to characterize the interaction between Meloidogyne arenaria race 1 (MA1) and M. hapla (MH), as affected by the five peanut genotypes: Florigiant, NC 7, NC 6, NC Ac 18416, and NC Ac 18016. The interactive effects on infection (total parasitic forms per root unit) and reproduction potentials of each nematode species and crop damage were determined. As a single population, MA1 had greater infection capacity and caused more crop damage than did MH, but both species had similar reproduction potentials. In mixed infestations, MA1 was more competitive than MH, as reflected by incidence of infection. Infection and reproduction potentials, and crop-damage capabilities of the mixed populations were similar to those of MA1 alone. All peanut genotypes were susceptible to infection by both nematodes. NC 6 was less susceptible to damage by MA1 and the mixed populations than other genotypes. A nematode treatment x genotype interaction was detected for root infection and crop damage, but not for population density or reproduction. With high preplant nematode levels (Pi), the populations reached their peak by midseason, whereas those with low Pi peaked after midseason. Crop damage in the second and third years was correlated with Pi level. 相似文献
2.
Riccardo E. Marioni Lars Penke Gail Davies Jennifer E. Huffman Caroline Hayward Ian J. Deary 《Proceedings. Biological sciences / The Royal Society》2014,281(1781)
Human cognitive ability shows consistent, positive associations with fitness components across the life-course. Underlying genetic variation should therefore be depleted by selection, which is not observed. Genetic variation in general cognitive ability (intelligence) could be maintained by a mutation–selection balance, with rare variants contributing to its genetic architecture. This study examines the association between the total number of rare stop-gain/loss, splice and missense exonic variants and cognitive ability in childhood and old age in the same individuals. Exome array data were obtained in the Lothian Birth Cohorts of 1921 and 1936 (combined N = 1596). General cognitive ability was assessed at age 11 years and in late life (79 and 70 years, respectively) and was modelled against the total number of stop-gain/loss, splice, and missense exonic variants, with minor allele frequency less than or equal to 0.01, using linear regression adjusted for age and sex. In both cohorts and in both the childhood and late-life models, there were no significant associations between rare variant burden in the exome and cognitive ability that survived correction for multiple testing. Contrary to our a priori hypothesis, we observed no evidence for an association between the total number of rare exonic variants and either childhood cognitive ability or late-life cognitive ability. 相似文献
3.
Robert A. Krebs 《Journal of Insect Behavior》1991,4(2):221-233
Variation in copulation duration of Drosophila mojavensisstrains was influenced by both sexes. Males maintained predominant control, as copulation duration of pairs from different strains was more similar to that of the strain from which the male was derived, but female origin also contributed significantly to the duration of copulation. Variation among strains was controlled by genes acting additively in both sexes. The size of both males and females also affected copulation duration. Small males copulated longer on average than large males, while males paired with large females copulated longer than those paired with small females. The importance of copulation duration to fitness was tested by correlation analyses with male size, female size, female remating latency, and number of eggs laid prior to female remating. Longer copulations stimulated earlier oviposition, possibly by increasing accessory gland secretions that are passed by males during copulation. 相似文献
4.
B. F. J. Manly 《Biometrical journal. Biometrische Zeitschrift》1981,23(3):267-281
The situation is considered where the multivariate distribution of certain variables X1, X2, …, Xp is changing with time in a population because natural selection related to the X's is taking place. It is assumed that random samples taken from the population at times t1, t2, …, ts are available and it is desirable to estimate the fitness function wt(x1, x2,…,xp) which shows how the number of individuals with Xi = xi, i = 1, 2, …, p at time t is related to the number of individuals with the same X values at time zero. Tests for population changes are discussed and indices of the selection on the population dispersion and the population mean are proposed. The situation with a multivariate normal distribution is considered as a special case. A maximum likelihood method that can be applied with any form of population distribution is proposed for estimating wt. The methods discussed in the paper are illustrated with data on four dimensions of male Egyptian skulls covering a time span from about 4500 B.C. to about 300 A.D. In this case there seems to have been very little selection on the population dispersion but considerable selection on means. 相似文献
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Kristjan Zobel 《Evolutionary ecology》2008,22(3):487-492
Although sexuality is considered evolutionarily progressive, clonality is very common in plants and the prevailing means of
reproduction in several community types. I discuss what could be the forces that have influenced the selection among sexual
versus non-sexual reproduction at community level. I propose that, among others, the probability of self-competition must
have been one of the key factors. The probability of meeting one’s own genes for wasteful competition is higher in communities
where clonality prevails (and relatively high mean intra-species relatedness is expected), and higher in communities with
low species diversity. On the other hand, lower diversity indicates a higher average fitness of species since the (finite)
total pool of resources is distributed among fewer population with high density. I show, using four community types with contrasting
diversity and clonality that community fitness (average fitness in the assemblage of species) can be expressed as the product
of two variables––anti-diversity and degree of sexuality. 相似文献
7.
Erin L. Landguth Brenna R. Forester Andrew J. Eckert Andrew J. Shirk Mitra Menon Amy Whipple Casey C. Day Samuel A. Cushman 《Molecular ecology resources》2020,20(2):605-615
We implemented multilocus selection in a spatially‐explicit, individual‐based framework that enables multivariate environmental gradients to drive selection in many loci as a new module for the landscape genetics programs, CDPOP and CDMetaPOP. Our module simulates multilocus selection using a linear additive model, providing a flexible platform to evaluate a wide range of genotype‐environment associations. Importantly, the module allows simulation of selection in any number of loci under the influence of any number of environmental variables. We validated the module with individual‐based selection simulations under Wright‐Fisher assumptions. We then evaluated results for simulations under a simple landscape selection model. Next, we simulated individual‐based multilocus selection across a complex selection landscape with three loci linked to three different environmental variables. Finally, we demonstrated how the program can be used to simulate multilocus selection under varying selection strengths across different levels of gene flow in a landscape genetics framework. This new module provides a valuable addition to the study of landscape genetics, allowing for explicit evaluation of the contributions and interactions between gene flow and selection‐driven processes across complex, multivariate environmental and landscape conditions. 相似文献
8.
Suitability of woodlice prey for generalist and specialist spider predators: a comparative study 下载免费PDF全文
1. Predators select a prey according to its energetic and nutritional composition. Generalist predators avoid, whereas specialists often specialise on well‐defended prey. The aim of this study was to find the suitability of woodlice prey for generalist and specialist predators by comparing their handling efficiency. 2. Laboratory experiments were performed in which specialist and generalist predators were reared on monotypic diets comprising one or other of two woodlice species that differ in their defensive strategies: rollers (Armadillidium) and clingers (Porcellio). A control group was reared on a mixture of arthropods (excluding woodlice). Three spider predators were used that differ in their adaptations to deal with woodlice prey: a woodlice specialist, Dysdera crocata; an oligophagous generalist, Pholcus phalangioides, that also captures woodlice; and a euryphagous generalist, Tegenaria domestica, that does not feed on woodlice. The frequency of capture was recorded and various fitness parameters were measured, namely survival, growth rate, and ontogenetic development. 3. It was found that the specialist, D. crocata, performed best on the Porcellio diet, and similarly well on Armadillidium and mixed diets. The two generalists, P. phalangioides and T. domestica, had poor performance on both woodlice diets but performed well on the mixed diet. 4. The results show that woodlice are unsuitable prey for both oligophagous and euryphagous generalist predators. 相似文献
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