scholarly journals Genetic variation in foraging traits among inbred lines of a predatory mite

Heredity ◽  
2002 ◽  
Vol 89 (5) ◽  
pp. 371-379 ◽  
Author(s):  
F Jia ◽  
D C Margolies ◽  
J E Boyer ◽  
R E Charlton
Keyword(s):  
Genetic Variation ◽  
Inbred Lines ◽  
Predatory Mite

scholarly journals Sex-Linked and Maternal Effects in the Diallel Cross

1966 ◽  
Vol 19 (6) ◽  
pp. 1061 ◽  
Author(s):  
EJ Eisen ◽  
BB Bohren ◽  
HE Mckean
Keyword(s):  
Genetic Variation ◽  
Maternal Effects ◽  
Sex Chromosomes ◽  
Statistical Models ◽  
Diallel Cross ◽  
Inbred Lines ◽  
Diallel Crosses ◽  
Combining Abilities

The diallel cross has been used frequently in plant experiments to partition the genetic variation into general and specific combining abilities of inbred lines. The statistical models developed for analysis of diallel crosses in plants have been used in a number of studies of diallel crosses in mammals and poultry, without due consideration to the presence and effect of the sex chromosomes.

Utilization of heterosis in poultry

1958 ◽  
Vol 9 (4) ◽  
pp. 599 ◽  
Author(s):  
FHW Morley
Keyword(s):  
Body Weight ◽  
Genetic Variation ◽  
Genetic Variability ◽  
Sex Chromosome ◽  
Inbred Lines ◽  
White Leghorn ◽  
Egg Weight ◽  
Additive Genetic Variation ◽  
White Leghorns ◽  
Recessive Genes

Records were analysed of 500-day production, egg weight, 11-week and mature body weight, sex maturity, and broodiness of the crossbred progeny of inbred lines of Australorps mated to White Leghorns, and inbred lines of White Leghorns mated to Australorps. Clear differences between lines of both breeds mere found in most characters, indicating the presence of potentially useful amounts of additive genetic variation. Non-additive genetic variation was also found to be present in varying degrees in different characters. Because of the difficulties of developing and maintaining inbred stocks of poultry, and the importance of sex-linked characteristics in some commercial environments, a scheme is proposed which may enable heterosis to be exploited without the use of inbred material. The basis of this scheme is the combination of the White Leghorn sex chromosome, with varying proportions of Australorp and White Leghorn autosomes, in a new breed. Assuming that the heterosis observed in the F1 is due to elimination of certain biochemical blocks determined by recessive genes, the formation of the new breed should enable the methods of closed flock breeding to be used in material at a higher level of production, and likely to contain more genetic variability, than either parent breed.

scholarly journals Genetic variation of dietary restriction and the effects of nutrient-free water and amino acid supplements on lifespan and fecundity of Drosophila

2011 ◽  
Vol 93 (4) ◽  
pp. 265-273 ◽  
Author(s):  
KENNETH B. DICK ◽  
CHELSEA R. ROSS ◽  
LEV Y. YAMPOLSKY
Keyword(s):  
Amino Acids ◽  
Genetic Variation ◽  
Dietary Restriction ◽  
Free Water ◽  
Water Source ◽  
Essential Amino Acids ◽  
Inbred Lines ◽  
Life History Variation ◽  
Trade Off ◽  
Specific Mortality

SummaryWe measure genetic variation in lifespan and fecundity at two food levels in 34 core lines of the Drosophila Genetic Reference Panel collection. Lines were significantly different from each other in lifespan and fecundity at both restricted and full food. There was a strong food-by-line interaction for the slope of age-specific mortality, fecundity and proportion of fertilized eggs, indicating the presence of genetic variation for the strength of the dietary restriction effect, likely to represent standing genetic variation in a natural population from which the lines used have originated. No trade-off between fecundity and lifespan manifested in life-history variation among inbred lines. Our data partially corroborate the recent proposition that availability of nutrient-free water eliminates the apparent dietary restriction at least in some conditions. Although flies on full food with water added had lifespan slightly higher than those without a water source, it was still significantly lower than that in flies on restricted food, with no indication of interaction. We fully corroborate the recently discovered effect of addition of essential amino acids to the medium: addition of 1·5 mM methionine to restricted food significantly increased fecundity without a measurable decrease in lifespan; addition of each of 10 essential amino acids increased fecundity and decreased females lifespan to the levels observed on full food, again with no evidence of line-by-food interactions. We propose a mechanistic hypothesis explaining the observed data, based on the assumption that food consumption by flies is adjusted according to flies’ saturation in water and methionine.

scholarly journals The effects of X-rays on quantitative characters

1964 ◽  
Vol 5 (3) ◽  
pp. 410-422 ◽  
Author(s):  
G. A. Clayton ◽  
Alan Robertson
Keyword(s):  
Genetic Variation ◽  
Population Size ◽  
Effective Population Size ◽  
Artificial Selection ◽  
Inbred Lines ◽  
X Rays ◽  
Effective Population ◽  
Outbred Population ◽  
Culture Bottle ◽  
Quantitative Characters

1. The rate of production by X-rays of new genetic variation in two quantitative characters in Drosophila melanogaster (sternital and sternopleural bristles) has been investigated, using ‘plateaued’ populations which had reached the limit under artificial selection and, for sternital bristles only, populations which had been made genetically invariant by inbreeding. The genetic variation was always measured by the response of the population to selection. The X-rays dose given in any generation was always 1800 r. to adults.2. Seven plateaued lines had eight cycles of alternate irradiation and selection, each with its non-irradiated control. All the responses were small but in three lines they were significantly greater after irradiation.3. Selection was applied to three different inbred lines, genetically marked to detect contamination, after varying periods of irradiation. At the same time, the inbred lines and lines derived from them which had been mass mated in bottles were selected. The irradiated populations showed a greater response. The new genetic variance produced by the irradiation was approximately 10−5 units/r. The estimate of the dose required to introduce new variation equal to that in a standard outbred population was 500,000 r.4. The effective population size was an important factor in the interpretation of some of these results on the long-term effects of radiation. By observing the variation between replicate lines in the frequency of a gene with a visible effect under these culture conditions (i.e. in a single culture bottle) the effective population size was estimated at sixty. Outbred populations kept under these conditions for many generations showed a reduction of genetic variability in agreement with this value.5. To investigate the possibility that the deleterious genes produced by irradiation would interfere with the response to artificial selection, a standard outbred population was irradiated and selected. In spite of the observed high frequency of recessive lethals produced, the response to selection was very similar to that of the standard population.

Corolla Tube Length and Nectar Height of Fl Red Clover Plants (Trifolium pratense) and Their Seed Yield Following Honey-Bee Pollination

1968 ◽  
Vol 70 (1) ◽  
pp. 5-10 ◽  
Author(s):  
D. A. Bond ◽  
J. L. Fyfe
Keyword(s):  
Genetic Variation ◽  
Seed Yield ◽  
Honey Bees ◽  
Trifolium Pratense ◽  
Red Clover ◽  
Corolla Tube ◽  
Inbred Lines ◽  
Tube Length ◽  
Bee Pollination ◽  
Continental Origin

SummaryCrosses between nine inbred lines of diploid doublecut red clover were measured for corolla tube length and nectar height, caged with honey-bees, and observations made on the number of bee visits and seed yield. There was evidence of additive genetic variation in nectar height, corolla tube length, bee visits and seed yield. The possibilities for improvement in these characters by selection are discussed. Attention is drawn to a remarkable discriminating behaviour of honey-bees, in that they could apparently recognize plants which had only one parent in common. A cage with a strong colony of honey-bees produced more than twice as much seed as a cage with a weak colony, and plants near to hives gave significantly more seed than plants distant from hives. Plants of English origin tended to have higher and more accessible nectar, more bee visits and greater seed yield than plants of continental origin.

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