scholarly journals Pigmentation and fitness trade-offs through the lens of artificial selection

2016 ◽  
Vol 12 (10) ◽  
pp. 20160625 ◽  
Author(s):  
Subhash Rajpurohit ◽  
Rani Richardson ◽  
John Dean ◽  
Raul Vazquez ◽  
Grace Wong ◽  
...  
Keyword(s):  
Artificial Selection ◽  
Natural Populations ◽  
Significant Shift ◽  
Melanin Pigmentation ◽  
Fitness Traits ◽  
Trade Offs ◽  
Dark Pigmentation ◽  
Fitness Parameters ◽  
Selection For ◽  
Pigmentation Phenotype

Pigmentation is a classic phenotype that varies widely and adaptively in nature both within and among taxa. Genes underlying pigmentation phenotype are highly pleiotropic, creating the potential for functional trade-offs. However, the basic tenets of this trade-off hypothesis with respect to life-history traits have not been directly addressed. In natural populations of Drosophila melanogaster , the degree of melanin pigmentation covaries with fecundity and several other fitness traits. To examine correlations and potential trade-offs associated with variation in pigmentation, we selected replicate outbred populations for extreme pigmentation phenotypes. Replicate populations responded rapidly to the selection regime and after 100 generations of artificial selection were phenotyped for pigmentation as well as the two basic fitness parameters of fecundity and longevity. Our data demonstrate that selection on pigmentation resulted in a significant shift in both fecundity and longevity profiles. Selection for dark pigmentation resulted in greater fecundity and no pronounced change in longevity, whereas selection for light pigmentation decreased longevity but did not affect fecundity. Our results indicate the pleiotropic nature of alleles underlying pigmentation phenotype and elucidate possible trade-offs between pigmentation and fitness traits that may shape patterns of phenotypic variation in natural populations.

scholarly journals Selection and niche trade-offs in biofilm-forming bacterial communities in experimental microcosms

2020 ◽  
Vol 2 (7A) ◽  
Author(s):  
Robyn Jerdan ◽  
Scott Cameron ◽  
Emily Donaldson ◽  
Andrew Spiers
Keyword(s):  
Biofilm Formation ◽  
Liquid Column ◽  
Significant Shift ◽  
Bet Hedging ◽  
Transfer Experiment ◽  
Serial Transfer ◽  
Fitness Advantage ◽  
Trade Offs ◽  
Selection For ◽  
Cell Densities

Static microcosms are a well-established system used to study the adaptive radiation of Pseudomonas fluorescens SBW25 and the adaptive biofilm-forming mutants known as the Wrinkly Spreaders (WS). We have developed this system to investigate selection within multi-species communities using a soil-wash inoculum dominated by biofilm-competent pseudomonads. Here we present community and isolate-level analyses of one serial-transfer experiment in which replicate populations were selected for over ten transfers and 60 days. Although no significant trends in improving community biofilm characteristics or total microcosm productivity were observed, a significant shift in biofilm-formation and microcosm growth by individual isolates recovered from the initial soil-wash inoculum and final transfers indicated that these communities were subject to selection for growth in these microcosms. Surprisingly, the fitness of the archetypal WS was poor when competing against community samples, and having compared the cell densities in the low-O2 region of liquid column below the biofilm, we suggest that part of the community’s fitness advantage comes from the ability to colonise this under-utilised niche as well as to compete at the A-L interface. Samples from the community biofilms and the low-O2 region were able to re-colonize both niches and many final transfer isolates grew throughout the liquid column as well as forming A-L interface biofilms. This suggests that there is a trade-off between fast growth under highly competitive conditions at the A-L interface and slower growth with less competition in the low-O2 region, with some isolates taking a bet-hedging approach a colonizing both niches in our microcosm system.

scholarly journals Are responses to artificial selection for reproductive fitness characters consistently asymmetrical?

1990 ◽  
Vol 56 (1) ◽  
pp. 35-42 ◽  
Author(s):  
R. Frankham
Keyword(s):  
Artificial Selection ◽  
Random Mating ◽  
Reproductive Fitness ◽  
Animal Breeding ◽  
Directional Selection ◽  
Gene Frequencies ◽  
Directional Dominance ◽  
Fitness Traits ◽  
Selection Experiments ◽  
Selection For

SummaryNon-linear offspring-parent regressions and heritabilities are expected for characters showing genetic asymmetry due to directional dominance and/or asymmetrical gene frequencies. Since reproductive fitness characters exhibit these characteristics, they should show consistently nonlinear heritabilities, with greater heritabilities in the direction of lower fitness. As a consequence, responses to bi-directional selection on fitness traits should be asymmetrical in the same direction. This prediction has been tested by an analysis of published bi-directional selection experiments for reproductive fitness traits. Significant asymmetry (24 of 30 studies) in the predicted direction was found. For studies reporting realized heritabilities, the means were 0·173 and 0·259 for lines selected for higher and lower reproductive fitness, respectively, the high lines being 33% less than the low lines. Asymmetry was evident for studies reporting realized heritabilities and for those with random mating controls of the same size as the selection lines. Consequently, it is argued that the asymmetry results from genetic asymmetries. This asymmetry has important implications in the improvement of reproductive fitness traits in plant and animal breeding.

Age and Size at Maturity

2001 ◽  
Author(s):  
Derek A. Roff
Keyword(s):  
Artificial Selection ◽  
Additive Genetic Variance ◽  
Natural Populations ◽  
The Arctic ◽  
Size At Maturity ◽  
Age At Maturity ◽  
Large Size ◽  
Quantitative Genetic ◽  
Trade Offs ◽  
The Many

Age and size at maturity have been an object of interest to humans since the domestication of animals and plants, for one of the objectives of domestication was to produce an organism that grew fast and matured early at a large size. Selection was also practiced to produce animals that could be used for such purposes as hunting and portaging, and to produce products for pleasure alone, as seen in the many ornamental varieties of dogs, cats, goldfish, pigeons, and plants. All of these instances demonstrate that age and size at maturity are traits that are relatively easily molded by artificial selection and, by extension, natural selection. Historically, artificial selection experiments were concerned not with the evolution of age and size at maturity in natural populations but with the production of economically more valuable plants and animals. Recently, there has been a substantial increase in the quantitative genetic analysis of nondomesticated organisms, which has shown that, with respect to morphological traits such as adult size, there is typically abundant additive genetic variance, with heritabilities averaging approximately 0.4 (reviewed in Roff 1997). Life history traits, such as the age at maturity, show, on average, lower heritabilities (approx. 0.26) but still enough for rapid evolutionary change. Quantitative genetic analyses have shown that age and size at maturity can evolve, but the most significant advances in our understanding of the factors favoring particular age at maturity/body size combinations are due to mathematical models predicated upon the assumption that selection maximizes some fitness measure such as the rate of increase, r. In a paper entitled “Adaptive Significance of Large Size and Long Life of the Chaetognath Sagitta elegans in the Arctic,” McLaren (1966) produced a seminal analysis in which he incorporated all the important elements that have appeared in subsequent analyses of the evolution of age and size at maturity. Specifically, McLaren attempted to take into account the trade-offs produced by increased fecundity being bought at the expense of delayed maturity and increased mortality. In this chapter, I shall primarily consider analyses that have followed in McLaren’s footsteps.

Sex ratio and life history traits at reaching sexual maturity in the dioecious shrub Fuchsia parviflora: field and common garden experiments

2021 ◽  
pp. 1-6
Author(s):  
Jessica S. Ambriz ◽  
Clementina González ◽  
Eduardo Cuevas
Keyword(s):  
Natural Population ◽  
Sexual Maturity ◽  
Sex Ratios ◽  
Natural Populations ◽  
Common Garden ◽  
Common Garden Experiment ◽  
Trade Offs ◽  
Reproductive Biomass ◽  
Common Garden Experiments ◽  
Growth And Reproduction

Abstract Fuchsia parviflora is a dioecious shrub that depends on biotic pollination for reproduction. Previous studies suggest that the male plants produce more flowers, and male-biased sex ratios have been found in some natural populations. To assess whether the biased sex ratios found between genders in natural populations are present at the point at which plants reach sexual maturity, and to identify possible trade-offs between growth and reproduction, we performed a common garden experiment. Finally, to complement the information of the common garden experiment, we estimated the reproductive biomass allocation between genders in one natural population. Sex ratios at reaching sexual maturity in F. parviflora did not differ from 0.5, except in one population, which was the smallest seedling population. We found no differences between genders in terms of the probability of germination or flowering. When flowering began, female plants were taller than males and the tallest plants of both genders required more time to reach sexual maturity. Males produced significantly more flowers than females, and the number of flowers increased with plant height in both genders. Finally, in the natural population studied, the investment in reproductive biomass was seven-fold greater in female plants than in male plants. Our results showed no evidence of possible trade-offs between growth and reproduction. Despite the fact that female plants invest more in reproductive biomass, they were taller than the males after flowering, possibly at the expense of herbivory defence.

scholarly journals Polygenic and single gene responses to selection for resistance to diazinon in Lucilia cuprina.

Genetics ◽  
1992 ◽  
Vol 130 (3) ◽  
pp. 613-620 ◽  
Author(s):  
J A McKenzie ◽  
A G Parker ◽  
J L Yen
Keyword(s):  
Resistant Strain ◽  
Single Gene ◽  
Natural Populations ◽  
Susceptible Strain ◽  
Selection Line ◽  
Base Population ◽  
Gene Response ◽  
Biochemical Profiles ◽  
Resistant Strains ◽  
Selection For

Abstract Following mutagenesis with ethyl methanesulfonate, selection in a susceptible strain with a concentration of the insecticide diazinon (0.0004%, w/v) above that required to kill 100% of the susceptible strain, the LC100 of that strain, resulted in a single gene response. The resultant four mutant resistant strains have equivalent physiological, genetical and biochemical profiles to a diazinon-resistant strain derived from a natural population and homozygous for the Rop-1 allele. Modification of the microsomal esterase E3 is responsible for resistance in each case. The Rop-1 locus maps approximately 4.4 map units proximal to bu on chromosome IV. Selection within the susceptible distribution, at a concentration of diazinon [0.0001% (w/v)] less than the LC100, resulted in a similar phenotypic response irrespective of whether the base population had been mutagenized. The responses were polygenically based, unique to each selection line and independent of Rop-1. The relevance of the results to selection for insecticide resistance in laboratory and natural populations is discussed.

Tales of lizard tails: effects of tail autotomy on subsequent survival and growth of free-ranging hatchling Uta stansburiana

1997 ◽  
Vol 75 (4) ◽  
pp. 542-548 ◽  
Author(s):  
P. H. Niewiarowski ◽  
J. D. Congdon ◽  
A. E. Dunham ◽  
L. J. Vitt ◽  
D. W. Tinkle
Keyword(s):  
Natural Populations ◽  
Reproductive Investment ◽  
Experimental Manipulation ◽  
Costs And Benefits ◽  
Growth And Survival ◽  
Large Sample ◽  
Uta Stansburiana ◽  
Tail Autotomy ◽  
Trade Offs ◽  
Free Ranging

Potential costs and benefits of tail autotomy in lizards have been inferred almost exclusively from experimental study in semi-natural enclosures and from indirect comparative evidence from natural populations. We present complementary evidence of the costs of tail autotomy to the lizard Uta stansburiana from detailed demographic study of a natural population. On initial capture, we broke the tails of a large sample of free-ranging hatchlings (560) and left the tails of another large sample (455) intact, and then followed subsequent hatchling growth and survival over a 3-year period. Surprisingly, in 1 out of the 3 years of study, survival of female hatchlings with broken tails exceeded that of female hatchlings with intact tails. Furthermore, no effects of tail loss on survivorship were detected for male hatchlings. However, in 2 years when recaptures were very frequent (1961, 1962), growth rates of hatchlings with broken tails were significantly slower than those of their counterparts with intact tails. We discuss our results in the broader context of estimating the relative costs and benefits of tail autotomy in natural populations, and suggest that long-term demographic studies will provide the best opportunity to assess realized fitness costs and benefits with minimum bias. We also describe how experimentally induced tail autotomy can be used as a technique to complement experimental manipulation of reproductive investment in the study of life-history trade-offs.

scholarly journals A Genome-Wide Scan for Evidence of Selection in a Maize Population Under Long-Term Artificial Selection for Ear Number

Genetics ◽  
2013 ◽  
Vol 196 (3) ◽  
pp. 829-840 ◽  
Author(s):  
Timothy M. Beissinger ◽  
Candice N. Hirsch ◽  
Brieanne Vaillancourt ◽  
Shweta Deshpande ◽  
Kerrie Barry ◽  
...  
Keyword(s):  
Artificial Selection ◽  
Maize Population ◽  
Genome Wide ◽  
A Genome ◽  
Selection For ◽  
Ear Number ◽  
Genome Wide Scan

The relationship between facial whorl direction and sidedness in ridden horses

2006 ◽  
Vol 35 ◽  
pp. 247-250
Author(s):  
H. Randle ◽  
E. Elworthy
Keyword(s):  
Natural Selection ◽  
Artificial Selection ◽  
Competitive Ability ◽  
Close Association ◽  
Human Behaviour ◽  
Physical Ability ◽  
Facial Hair ◽  
Selection For ◽  
The Relationship ◽  
The Brain

The influence of Natural Selection on the evolution of the horse (Equus callabus) is minimal due to its close association with humans. Instead Artificial Selection is commonly imposed through selection for features such as a ‘breed standard’ or competitive ability. It has long been considered to be useful if indicators of characteristics such as physical ability could be identified. Kidd (1902) suggested that the hair coverings of animals were closely related to their lifestyle, whether they were active or passive. In 1973 Smith and Gong concluded that hair whorl (trichloglyph) pattern and human behaviour is linked since hair patterning is determined at the same time as the brain develops in the foetus. More recently Grandin et al. (1995), Randle (1998) and Lanier et al. (2001) linked features of facial hair whorls to behaviour and production in cattle. Hair whorl features have also been related to temperament in equines (Randle et al., 2003).

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