Correlated effects of selection for flower size in Raphanus raphanistrum

2007 ◽  
Vol 85 (2) ◽  
pp. 160-166 ◽  
Author(s):  
Kari Lehtilä ◽  
Kristina Holmén Bränn
Keyword(s):  
Plant Traits ◽  
Plant Size ◽  
Flower Size ◽  
Flowering Plant ◽  
Realized Heritability ◽  
Raphanus Raphanistrum ◽  
Trade Offs ◽  
Vegetative Traits ◽  
Two Generations ◽  
Selection For

The evolution of flower size may be constrained by trade-offs between flower size and other plant traits. The aim of this study was to determine how selection on flower size affects both reproductive and vegetative traits. Raphanus raphanistrum L. was used as the study species. Artificial selection for small and large petal size was carried out for two generations. We measured the realized heritability of flower size and recorded flower production, time to flowering, plant size, and seed production in the two selection lines. The realized heritability was h2 = 0.49. Our study, therefore, showed that R. raphanistrum has potential for rapid evolutionary change of floral size. The lines with large flowers produced smaller seeds and started to flower later than the lines with small flowers. There was no trade-off between flower size and flower number, but the lines selected for large flower size had more flowers and a larger plant size than lines selected for small flowers. Estimates of restricted maximum likelihood (REML) analysis of pedigrees also showed that flower size had a positive genetic correlation with start of flowering and plant height.

scholarly journals The leaf economics spectrum’s morning coffee: plant size-dependent changes in leaf traits and reproductive onset in a perennial tree crop

2021 ◽  
Author(s):  
Adam R Martin ◽  
Marney E Isaac
Keyword(s):  
Environmental Conditions ◽  
Plant Traits ◽  
Leaf Traits ◽  
Plant Size ◽  
Leaf Economics Spectrum ◽  
Size Dependent ◽  
Leaf Mass ◽  
Trade Offs ◽  
Reproductive Onset ◽  
Leaf Economics

Abstract Background and Aims Size-dependent changes in plant traits are an important source of intraspecific trait variation. However, there are few studies that have tested if leaf trait co-variation and/or trade-offs follow a within-genotype leaf economics spectrum (LES) related to plant size and reproductive onset. To our knowledge, there are no studies on any plant species that have tested whether or not the shape of a within-genotype LES that describes how traits covary across whole plant sizes, is the same as the shape of a within-genotype LES that represents environmentally driven trait plasticity. Methods We quantified size-dependent variation in eight leaf traits in a single coffee genotype (Coffea arabica var. Caturra) in managed agroecosystems with different environmental conditions (light and fertilization treatments), and evaluated these patterns with respect to reproductive onset. We also evaluated if trait covariation along a within-genotype plant-size LES differed from a within-genotype environmental LES defined with trait data from coffee growing in different environmental conditions. Key Results Leaf economics traits related to resource acquisition – maximum photosynthetic rates (A) and mass-based leaf nitrogen (N) concentrations – declined linearly with plant size. Structural traits – leaf mass, leaf thickness, and leaf mass per unit area (LMA) – and leaf area increased with plant size beyond reproductive onset, then declined in larger plants. Three primary LES traits (mass-based A, leaf N and LMA) covaried across a within-genotype plant-size LES, with plants moving towards the ‘resource-conserving’ end of the LES as they grow larger; in coffee these patterns were nearly identical to a within-genotype environmental LES. Conclusions Our results demonstrate that a plant-size LES exists within a single genotype. Our findings indicate that in managed agroecosystems where resource availability is high the role of reproductive onset in driving within-genotype trait variability, and the strength of covariation and trade-offs among LES traits, are less pronounced compared with plants in natural systems. The consistency in trait covariation in coffee along both plant-size and environmental LES axes indicates strong constraints on leaf form and function that exist within plant genotypes.

Selection for independence of floral and vegetative traits: evidence from correlation patterns in five species

1996 ◽  
Vol 74 (4) ◽  
pp. 642-644 ◽  
Author(s):  
Jeffrey K. Conner ◽  
Andrea Sterling
Keyword(s):  
Natural Selection ◽  
Plant Traits ◽  
Genetic Relationships ◽  
Functional Independence ◽  
Floral Traits ◽  
Evolutionary Time ◽  
Vegetative Traits ◽  
Selection For ◽  
Positive Correlations ◽  
Trait Groups

Underlying developmental and genetic relationships cause positive correlations among the sizes of a variety of plant traits. Selection for functional independence among traits, however, can reduce these correlations over evolutionary time. In 1960, R.L. Berg hypothesized that the sizes of flowers in insect-pollinated plants should be selected to remain constant regardless of the size of vegetative structures, so that flowers match the sizes of their pollinators for effective pollination. This hypothesis of functional independence of floral sizes from the size of the rest of the plant predicts that correlations between floral and vegetative traits should be reduced relative to correlations within trait groups. We measured correlations in five species of insect-pollinated plants, including four Brassicaceae and Phlox divaricata. Our results support the hypothesis. The correlations among floral traits and the correlations among vegetative traits were significantly greater than the correlations across these two groups of traits in all five species. Keywords: phenotypic correlations, natural selection, functional independence, pollination, floral evolution.

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 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.

Positive association between resistance to Bacillus thuringiensis and overwintering survival of cabbage loopers, Trichoplusia ni (Lepidoptera: Noctuidae)

2008 ◽  
Vol 98 (3) ◽  
pp. 317-322 ◽  
Author(s):  
V. Caron ◽  
J.H. Myers
Keyword(s):  
Bacillus Thuringiensis ◽  
Trichoplusia Ni ◽  
Positive Association ◽  
Pest Species ◽  
Development Of Resistance ◽  
Trade Offs ◽  
Major Pest ◽  
Selection For ◽  
Overwintering Survival ◽  
Lepidoptera Noctuidae

AbstractDevelopment of resistance to insecticides has generally been associated with fitness costs that may be magnified under challenging conditions. Lepidopterans which are resistant to the biopesticide Bacillus thuringiensis subsp. kurstaki (Btk) have been shown to have reduced fitness, such as lower survival when subjected to overwintering stress. Recently, resistance to Btk has been found in some populations of Trichoplusia ni Hübner in greenhouses in British Columbia. This situation provides an opportunity to investigate potential trade-offs between overwintering survival and insecticide resistance in a major pest species. Here, we assess the survival and eventual fecundity of Btk resistant and susceptible T. ni pupae exposed to cool temperatures. Contrary to our expectations, resistant T. ni had higher overwintering survival than susceptible individuals. This is the first account of a potential advantage associated with Btk resistance. Resistant and susceptible moths had reduced fecundity and smaller progeny after cold exposure compared to controls, and this may counteract the survival advantage. Nevertheless, it seems unlikely that this is sufficient to select out the resistant phenotype in the presence of strong selection for resistance and in the absence of immigration of susceptible moths. The appearance of resistance without evidence of a trade-off in overwintering survival presents a major challenge to management in production greenhouses.

Selection for resistance to Colletotrichum trifolii in the lucerne cultivars Hunter River and Siro Peruvian

1980 ◽  
Vol 20 (105) ◽  
pp. 447 ◽  
Author(s):  
JAG Irwin ◽  
DL Lloyd ◽  
RA Bray ◽  
PW Langdon
Keyword(s):  
Dry Matter ◽  
Plant Mortality ◽  
River Population ◽  
Colletotrichum Trifolii ◽  
F2 Population ◽  
Two Generations ◽  
Second Year ◽  
Selection For ◽  
Glasshouse Screening ◽  
Made In

Seedlings of lucerne (Medicago sativa) with increased resistance to anthracnose caused by Colletotrichum trifolii, were obtained from cvv. Hunter River and Siro Peruvian by selection through two generations under laboratory conditions. Glasshouse screening of half sib F1 and F2 families confirmed that rapid progress was made in increasing the level of resistance in both populations. In the field, after two years, F1 derivatives had lower percentages of plant mortality and disease indices than their parent cultivars, and F2 derivatives had lower values than their F1 parents. The F2 population of Siro Peruvian, in the second year, yielded 55% and 45% more dry matter than the unselected populations of Siro Peruvian and Hunter River respectively. However, the level of resistance in the field of the Siro Peruvian F2 population was only the equivalent of the unselected Hunter River population, and was inferior to the F1 and F2 populations of Hunter River.

scholarly journals Selective Breeding for Low and High Varroa destructor Growth in Honey Bee (Apis mellifera) Colonies: Initial Results of Two Generations

Insects ◽  
2020 ◽  
Vol 11 (12) ◽  
pp. 864
Author(s):  
Alvaro De la Mora ◽  
Berna Emsen ◽  
Nuria Morfin ◽  
Daniel Borges ◽  
Les Eccles ◽  
...  
Keyword(s):  
Apis Mellifera ◽  
Honey Bee ◽  
Varroa Destructor ◽  
Winter Mortality ◽  
Genotypic Differences ◽  
Two Generations ◽  
Selection For ◽  
Bidirectional Selection ◽  
Future Work ◽  
Initial Results

After two years of bidirectional selection for low and high rates of Varroa destructor population growth (LVG and HVG, respectively) in honey bee (Apis mellifera) colonies in Ontario, Canada, significant differences between the two genotypes were observed. LVG colonies had V. destructor population increases over the summer of 1.7 fold compared to 9.6 fold for HVG colonies by Generation 2. Additionally, HVG colonies had significantly higher mite infestation rates in adult bees compared to LVG colonies for both selected generations. DWV prevalence and levels were significantly higher in HVG colonies than in LVG colonies in Generation 1 but not in Generation 2. Winter mortality rates of Generation 1 colonies were significantly different at 26% and 14% for the HVG and LVG genotypes, respectively. The results of this study thus far indicate that selection for LVG may result in colonies with lower V. destructor infestation rates, lower prevalence, and levels of DWV and higher colony winter survivorship. Future work will focus on determining what mechanisms are responsible for the genotypic differences, estimating genetic parameters, and molecular analyses of the genotypes to identify candidate genes associated with resistance to V. destructor and DWV that could potentially be used for marker-assisted selection.

scholarly journals Can We Agree on What Robots Should be Allowed to Do? An Exercise in Rule Selection for Ethical Care Robots

2019 ◽  
Vol 12 (5) ◽  
pp. 1093-1102
Author(s):  
Dieter Vanderelst ◽  
Jurgen Willems
Keyword(s):  
Cost Effective ◽  
Training Data ◽  
Learning Approaches ◽  
Empirical Survey ◽  
Rule Selection ◽  
Control Rules ◽  
Care Robots ◽  
Trade Offs ◽  
Future Care ◽  
Selection For

AbstractFuture Care Robots (CRs) should be able to balance a patient’s, often conflicting, rights without ongoing supervision. Many of the trade-offs faced by such a robot will require a degree of moral judgment. Some progress has been made on methods to guarantee robots comply with a predefined set of ethical rules. In contrast, methods for selecting these rules are lacking. Approaches departing from existing philosophical frameworks, often do not result in implementable robotic control rules. Machine learning approaches are sensitive to biases in the training data and suffer from opacity. Here, we propose an alternative, empirical, survey-based approach to rule selection. We suggest this approach has several advantages, including transparency and legitimacy. The major challenge for this approach, however, is that a workable solution, or social compromise, has to be found: it must be possible to obtain a consistent and agreed-upon set of rules to govern robotic behavior. In this article, we present an exercise in rule selection for a hypothetical CR to assess the feasibility of our approach. We assume the role of robot developers using a survey to evaluate which robot behavior potential users deem appropriate in a practically relevant setting, i.e., patient non-compliance. We evaluate whether it is possible to find such behaviors through a consensus. Assessing a set of potential robot behaviors, we surveyed the acceptability of robot actions that potentially violate a patient’s autonomy or privacy. Our data support the empirical approach as a promising and cost-effective way to query ethical intuitions, allowing us to select behavior for the hypothetical CR.

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