scholarly journals DIRECTIONAL versus STABILIZING SELECTION FOR DEVELOPMENTAL TIME IN NATURAL AND LABORATORY POPULATIONS OF FLOUR BEETLES

Genetics ◽  
1975 ◽  
Vol 80 (4) ◽  
pp. 773-783
Author(s):  
Peter S Dawson
Keyword(s):  
Rapid Development ◽  
Natural Populations ◽  
Developmental Time ◽  
The Other ◽  
Stabilizing Selection ◽  
Flour Beetles ◽  
Laboratory Populations ◽  
Fast Development ◽  
Selection For ◽  
Synchronized Cultures

ABSTRACT Artificial selection for fast development is successful in long-established laboratory populations of Tribolium, but not in strains recently derived from natural populations. It is shown that selection against fast development in dense, synchronized cultures operates through cannibalism of early pupae by larvae. Since standard husbandry procedures for laboratory strains involve the periodic creation of dense, synchronized cultures, it is suggested that these populations are subjected to stabilizing selection for intermediate developmental time. Natural populations, on the other hand, are probably subjected to directional selection for rapid development.

scholarly journals Recruitment and the Timing of Reproduction in Lesser Snow Geese (Chen caerulescens caerulescens)

The Auk ◽  
1984 ◽  
Vol 101 (3) ◽  
pp. 451-458 ◽  
Author(s):  
Fred Cooke ◽  
C. Scott Findlay ◽  
Robert F. Rockwell
Keyword(s):  
Reproductive Success ◽  
Natural Populations ◽  
Breeding Population ◽  
Relative Fitness ◽  
Stabilizing Selection ◽  
Chen Caerulescens ◽  
Snow Geese ◽  
Lesser Snow Geese ◽  
Chen Caerulescens Caerulescens ◽  
Selection For

Abstract Recruitment of offspring into a breeding population of Lesser Snow Geese (Chen caerulescens caerulescens) at La Perouse Bay, Manitoba was used as a measure of reproductive success to assess the relative fitness of females who hatched their clutches early, middle, and late in the breeding season. In three of seven seasons investigated, goslings from early-hatching clutches showed significantly greater recruitment rates than their middle- or late-hatching counterparts. No significant differences in recruitment rates were detected in the other four seasons, although early-hatching clutches showed numerically higher recruitment rates in three of these seasons. There is, therefore, some indication of directional selection for early breeding. This conclusion contrasts with that drawn by Cooke and Findlay (1982), who, using fledging success as a measure of reproductive fitness, showed that females whose clutches hatched in the middle period had the highest fitness and concluded that the population was being exposed to stabilizing selection for synchronization. The discrepancy between these results and those presented in this paper indicates that conclusions concerning the action of selection in natural populations depend heavily upon the stage of the life cycle during which reproductive success is estimated. As such, evolutionary biologists must be cautious of relying too heavily on measures taken too early in the life of the organism.

Evidence of local adaptation and stabilizing selection on quantitative traits in populations of the multipurpose American species Acacia aroma (Fabaceae)

2019 ◽  
Vol 191 (1) ◽  
pp. 128-141 ◽  
Author(s):  
Carolina L Pometti ◽  
Cecilia F Bessega ◽  
Ana M Cialdella ◽  
Mauricio Ewens ◽  
Beatriz O Saidman ◽  
...  
Keyword(s):  
Quantitative Traits ◽  
Genetic Basis ◽  
Natural Populations ◽  
Tree Height ◽  
Phenotypic Traits ◽  
Stabilizing Selection ◽  
Trait Variation ◽  
Chaco Region ◽  
Neutral Genetic Variation ◽  
Selection For

Abstract Economically and ecologically important quantitative traits of Acacia aroma are related to life history and the size and shape of fruits and leaves. Substantial variation is observed for these traits in natural populations, suggesting a possible genetic basis that could be useful for selection programmes. Our objective was to detect signals of selection on 12 phenotypic traits in 170 individuals belonging to seven populations of A. aroma in the Chaco Region of Argentina. Phenotypic traits were compared with molecular markers assessed in the same populations. Here, we search for signatures of natural selection by comparing quantitative trait variation to neutral genetic variation through the PST–FST test. We further test for differences among populations for the 12 phenotypic traits, an association of phenotypic variation with environmental variables and geographical distance, and we compare the power of discrimination between the phenotypic and AFLP datasets. The PST–FST test suggested directional selection for tree height and stabilizing selection for the remaining traits. Analyses of variance showed significant differentiation for eight phenotypic traits. These results suggest selecting among provenances as a management strategy to improve tree height (which showed divergent selection), whereas significant genetic gain for the other traits might be obtained by selection within provenances.

scholarly journals Evolution of lower levels of inter-locus sexual conflict in D. melanogaster populations under strong selection for rapid development

2021 ◽  
Author(s):  
Avani Mital ◽  
Manaswini Sarangi ◽  
Snigdhadip Dey ◽  
Amitabh Joshi
Keyword(s):  
Body Size ◽  
Reproductive Isolation ◽  
Sexual Conflict ◽  
Rapid Development ◽  
Female Resistance ◽  
Behavioural Patterns ◽  
Adult Body ◽  
Different Types ◽  
Laboratory Populations ◽  
Selection For

AbstractD. melanogaster laboratory populations subjected to selection for rapid development and early reproduction have been found to have evolved reduced adult body size and lower levels of inter-locus sexual conflict compared to their ancestral controls. We tested the contribution of a smaller body to the evolution of reduced sexual conflict in these populations, since body size differences are known to affect sexual conflict levels in this species. We cultured larvae from the control populations at high density to obtain flies as small as those from the selected populations. The effect of body size reduction on sexual conflict was asymmetric, with smaller body size resulting in reduced male manipulative ability but not female resistance to mating-induced harm. These results were not due to differences in behavioural patterns of smaller flies, such as differences in overall mating exposure of females to different types of males. We hypothesize that evolution for rapid development and the correlated reduction in body size has resulted in lower male manipulative ability, and sexually antagonistic co-evolution has lowered female resistance to such manipulations. These populations have also evolved incipient reproductive isolation from their controls, likely through sexual conflict (reported earlier), and our results support the view that this is an outcome of strong, directional selection for rapid development.

scholarly journals Asymmetrical response to selection for rate of development in Drosophila subobscura

1961 ◽  
Vol 2 (1) ◽  
pp. 70-81 ◽  
Author(s):  
Jean M. Clarke ◽  
J. Maynard Smith ◽  
K. C. Sondhi
Keyword(s):  
Genetic Background ◽  
Rapid Development ◽  
Drosophila Subobscura ◽  
Slow Development ◽  
Large Populations ◽  
Fast Development ◽  
Long Time ◽  
Selection For ◽  
High Level ◽  
Hybrid Foundation

Starting from a geographically hybrid foundation population of Drosophila subobscura, selection for fast and for slow development has been practised without inbreeding on a diet with an unusually high level of protein. Realized heritabilities in the fast and slow lines were + 0·063 ± 0·029 and + 0·186 ± 0·031 respectively. A half-sib analysis of the foundation population and full-sib analyses of the first two and the last two selected generations were carried out. Hybrids between the two lines were approximately intermediate between their parents.Two types of genetic explanation of the asymmetrical response are discussed. The first assumes directional dominance of alleles for fast development. Such an assumption can explain the asymmetrical response, but runs into difficulties in explaining the nature of the genetic variance in the selected populations and the intermediacy of the hybrids between the two lines.A second assumption, which appears to fit the facts better, is that there exists a ‘developmental barrier’ preventing development at a rate appreciably faster than that of the foundation population. In physiological terms this implies that more rapid development requires a more profound modification of the population than could be achieved by a few generations of selection. In genetic terms, it implies epistatic interactions between genes at different loci: gene substitutions at a given locus which increase development rate on a genetic background causing slow development have little or no effect on a genetic background causing rapid development. In other words, there is a law of diminishing returns as more and more alleles for fast development are accumulated in the genotype. It is suggested that genetic situations of this kind may be common in populations which have been exposed to directional selection for a long time in reasonably large populations, either in nature or in domestication.

scholarly journals AN EXPERIMENTAL TEST OF THE RELATIONSHIP BETWEEN GENETIC VARIATION AND ENVIRONMENTAL VARIATION IN TRIBOLIUM FLOUR BEETLES

Genetics ◽  
1986 ◽  
Vol 113 (2) ◽  
pp. 391-404
Author(s):  
Russel A Riddle ◽  
Peter S Dawson ◽  
Dave F Zirkle
Keyword(s):  
Genetic Variation ◽  
Environmental Heterogeneity ◽  
Natural Populations ◽  
Experimental System ◽  
Developmental Time ◽  
Pupal Weight ◽  
Environment Interaction ◽  
Fitness Components ◽  
Flour Beetles ◽  
Experimental Treatments

ABSTRACT The hypothesis that a component of genetic variation for polygenic fitness traits is maintained by environmental heterogeneity was tested using an experimental system involving two species of flour beetles, Tribolium castaneum and T. confusum. Replicated populations of each species from a number of environmental treatments were analyzed for various fitness components following almost 60 generations of natural selection. Environmental differences consisted of flours of cereals commonly invaded by natural populations of these insects.—Tests for adaptation to environments were based on experiments in which populations were reared factorially on each flour, such that population treatment x flour interactions could be detected. Measurements were made of survival, growth rate, larval weight, pupal weight, developmental time, fecundity of individuals at low density and fecundity and cannibalism at high density in both fresh and conditioned media.—Flour differences were found to have significant effects on most traits. Evidence for significant genetic variation and significant genotype x environment interaction was also found. However, no evidence could be found to support the hypothesis that genetic variation was maintained by environmental heterogeneity in food resources. The absence of adaptation to the experimental treatments despite the presence of genetic variation in fitness components suggests that pleiotropy may assume an important role in determining net fitness values of polygenes.

scholarly journals Evolution of dispersal syndrome and its corresponding metabolomic changes

2017 ◽  
Author(s):  
Sudipta Tung ◽  
Abhishek Mishra ◽  
Navdeep Gogna ◽  
Mohammed Aamir Sadiq ◽  
P.M. Shreenidhi ◽  
...  
Keyword(s):  
Climate Change ◽  
Habitat Degradation ◽  
Natural Populations ◽  
Cellular Respiration ◽  
Evolution Of Dispersal ◽  
Selected Lines ◽  
Dispersal Syndrome ◽  
Laboratory Populations ◽  
Selection For ◽  
Dispersal Evolution

AbstractDispersal is one of the strategies for organisms to deal with climate change and habitat degradation. Therefore, investigating the effects of dispersal evolution on natural populations is of considerable interest to ecologists and conservation biologists. Although it is known that dispersal itself can evolve due to selection, the behavioral, life-history and metabolic consequences of dispersal evolution are not well understood. Here we explore these issues by subjecting four outbred laboratory populations of Drosophila melanogaster to selection for increased dispersal. The dispersal-selected populations had similar values of body size, fecundity and longevity as the non-selected lines (controls), but evolved significantly greater locomotor activity, exploratory tendency, and aggression. Untargeted metabolomic fingerprinting through NMR spectroscopy suggested that the selected flies evolved elevated cellular respiration characterized by greater amounts of glucose, AMP and NAD. Concurrent evolution of higher level of Octopamine and other neurotransmitters indicate a possible mechanism for the behavioural changes in the selected lines. We discuss the generalizability of our findings in the context of observations from natural populations. To the best of our knowledge, this is the first report of the evolution of metabolome due to selection for dispersal and its connection to dispersal syndrome evolution.

Pembaharuan Pesantren: Arah dan Implikasi

2018 ◽  
Vol 4 (1) ◽  
pp. 67-84
Author(s):  
Wahyudin Noor
Keyword(s):  
Rapid Development ◽  
The Other ◽  
Learning Methods ◽  
Technology Learning ◽  
Other Hand ◽  
The One ◽  
Traditional Term

Abstract Pesantren are often associated with backwardness and traditionalism in everything: facilities, technology, learning methods, and even the curriculum. For now, it seems like the traditional term for pesantren is no longer relevant enough. The pace of movement in the era of renewal marked by the rapid development of technology has demanded pesantren to make adjustments. However, on the one hand, when viewed from the direction of change, the reform efforts pursued by pesantren are not to erase the old tradition, but merely to add something new so that the old tradition and conditions can be maintained while accepting the presence of a new one. On the other hand, the reform efforts undertaken by pesantren have implications for the fact that the typical values of the pesantren are fading away. Abstrak  Pesantren seringkali diasosiasikan dengan keterbelakangan dan tradisional dalam segala hal: fasilitas, teknologi, metode pembelajaran, dan bahkan kurikulumnya. Untuk saat ini, sepertinya istilah tradisional untuk pesantren, sudah tidak lagi cukup relevan. Laju gerak pembaharuan zaman yang ditandai dengan pesatnya perkembangan teknologi telah menuntut pesantren untuk melakukan penyesuaian diri. Kendatipun demikian, di satu sisi, jika dilihat dari arah perubahan, upaya pembaharuan yang ditempuh pesantren tidaklah untuk menghapus tradisi yang lama, tetapi sekadar menambah dengan sesuatu yang baru sehingga tradisi maupun kondisi yang lama bisa dipertahankan sambil menerima kehadiran yang baru. Di sisi yang lain, upaya pembaharuan yang dilakukan pesantren ternyata berimplikasi pada kenyataan akan semakin pudarnya nilai-nilai khas yang dimiliki oleh pesantren.

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