Meiotic variation in an intergenomic autopolyploid series. I. Chiasma frequency

Genome ◽  
1995 ◽  
Vol 38 (1) ◽  
pp. 122-132 ◽  
Author(s):  
A. J. Wallace ◽  
R. S. Callow
Keyword(s):  
Genome Size ◽  
Chiasma Frequency ◽  
Chromosome Doubling ◽  
Cellular Component ◽  
Absolute Size ◽  
Interspecific Differences ◽  
Threefold Increase ◽  
Multiplicative Effect ◽  
The Absolute ◽  
Diploid Level

Variation in chiasma frequency has been studied in PMCs of diploids and C0 autotetraploids of seven Lathyrus species exhibiting a range of genome size (10.8–19.9 pg DNA/2C). Variation in chiasma frequency showed no relation to changes in genome size, either between species or between disomic sets within nuclei. Mean chiasma frequency of the tetraploids showed a 75% increase over that in the diploids. Half of this increase represents an additive effect of chromosome doubling. Total variance in chiasma frequency of autotetraploids increases by 80% over that in diploids, in line with the square of the multiplicative effect of chromosome doubling. At the diploid level, interspecific differences account for the major component of variance (63.1%). Phenotypic variation in chiasma frequency was apparent in all seven species but represented the smallest component of variance (2.8%). Chromosome doubling results in an eightfold increase in the absolute size of the phenotypic component of variance in chiasma frequency and a threefold increase in that of the cellular component. It has no effect on the absolute size of the interspecific component.Key words: meiosis, chiasma frequency, autopolyploid, Lathyrus.

Nucleotypic influences on chromosome-specific chiasma variation in Crepis capillaris. I. Responses to early colchicine treatment and chromosome doubling

Genome ◽  
1996 ◽  
Vol 39 (6) ◽  
pp. 1078-1085 ◽  
Author(s):  
M. T. Abberton ◽  
R. S. Callow
Keyword(s):  
Key Words ◽  
Chiasma Frequency ◽  
Chromosome Doubling ◽  
Colchicine Treatment ◽  
Seedling Stage ◽  
Published Data ◽  
Crepis Capillaris ◽  
The Mean ◽  
Diploid Level ◽  
Multiplicative Effects

Additive and multiplicative effects of colchicine treatment at the seedling stage and of chromosome doubling on chromosome-specific chiasma frequency at metaphase I have been measured in comparisons between C0 and untreated diploids and between C0 autotetraploids and C0 diploids. Early colchicine treatment increases the frequency of chromosome C univalents to 1.8% but has no similar effect on chromosomes A and D. Colchicine treatment has little net effect on mean chiasma frequency, deducting an average of 0.204 chiasmata per set but otherwise multiplying the mean by a factor of 1.182. These additive and multiplicative effects represent averages of six phenotypes. Chromosome doubling in a tetraploid–diploid chimaera subtracts an average of 0.265 chiasmata per set but otherwise doubles the numbers of chiasmata at the diploid level (× 2.134). Comparison of six diploids and tetraploids reveals modest average additive (+ 1.103) and multiplicative effects (× 1.190). The implications of these findings are discussed in the light of new analyses of previously published data. Key words : chiasmata, Crepis, colchicine, meiosis, polyploidy.

Gravity as a Monocular Cue for Perception of Absolute Distance and/or Absolute Size

Perception ◽  
1992 ◽  
Vol 21 (1) ◽  
pp. 69-76 ◽  
Author(s):  
John S Watson ◽  
Martin S Banks ◽  
Claes von Hofsten ◽  
Constance S Royden
Keyword(s):  
Wave Motion ◽  
Moving Objects ◽  
Formal Analysis ◽  
Free Fall ◽  
Absolute Distance ◽  
Absolute Size ◽  
The Absolute ◽  
Pendulum Wave

When the motion of an object is influenced by gravity (eg free fall, pendulum, wave motion), that influence may provide a cue to computing the absolute distance and/or size of the object. Formal analysis supports the claim that the distance and size of moving objects are generally computable with reference to the gravitational component of motion. Informal evidence from judgments of realism in films is consistent with this gravity-cue hypothesis.

scholarly journals Early and Late Changes in the Distal Forelimb Representation of the Supplementary Motor Area After Injury to Frontal Motor Areas in the Squirrel Monkey

2008 ◽  
Vol 100 (3) ◽  
pp. 1498-1512 ◽  
Author(s):  
Ines Eisner-Janowicz ◽  
Scott Barbay ◽  
Erica Hoover ◽  
Ann M. Stowe ◽  
Shawn B. Frost ◽  
...  
Keyword(s):  
Supplementary Motor Area ◽  
Temporal Dynamics ◽  
Squirrel Monkeys ◽  
Motor Area ◽  
Adaptive Plasticity ◽  
Behavioral Recovery ◽  
Retrieval Task ◽  
Absolute Size ◽  
The Absolute ◽  
Motor Areas

Neuroimaging studies in stroke survivors have suggested that adaptive plasticity occurs following stroke. However, the complex temporal dynamics of neural reorganization after injury make the interpretation of functional imaging studies equivocal. In the present study in adult squirrel monkeys, intracortical microstimulation (ICMS) techniques were used to monitor changes in representational maps of the distal forelimb in the supplementary motor area (SMA) after a unilateral ischemic infarct of primary motor (M1) and premotor distal forelimb representations (DFLs). In each animal, ICMS maps were derived at early (3 wk) and late (13 wk) postinfarct stages. Lesions resulted in severe deficits in motor abilities on a reach and retrieval task. Limited behavioral recovery occurred and plateaued at 3 wk postinfarct. At both early and late postinfarct stages, distal forelimb movements could still be evoked by ICMS in SMA at low current levels. However, the size of the SMA DFL changed after the infarct. In particular, wrist-forearm representations enlarged significantly between early and late stages, attaining a size substantially larger than the preinfarct area. At the late postinfarct stage, the expansion in the SMA DFL area was directly proportional to the absolute size of the lesion. The motor performance scores were positively correlated to the absolute size of the SMA DFL at the late postinfarct stage. Together, these data suggest that, at least in squirrel monkeys, descending output from M1 and dorsal and ventral premotor cortices is not necessary for SMA representations to be maintained and that SMA motor output maps undergo delayed increases in representational area after damage to other motor areas. Finally, the role of SMA in recovery of function after such lesions remains unclear because behavioral recovery appears to precede neurophysiological map changes.

Trends in the population of the Northern Hairy-nosed Wombat Lasiorhinus krefftii in Epping Forest National Park, Central Queensland

1994 ◽  
Vol 1 (2) ◽  
pp. 141 ◽  
Author(s):  
Doug G. Crossman ◽  
Christopher N. Johnsow ◽  
Alan B. Horsup
Keyword(s):  
National Park ◽  
Absolute Size ◽  
Forest Region ◽  
Prolonged Drought ◽  
Males And Females ◽  
The Absolute ◽  
The Stability ◽  
Almost All

The Northern Hairy-nosed Wombat Lasiorhinus krefftii now survives only in Epping Forest National Park, central Queensland. The species was formerly more widespread in the Epping Forest region than at present. Its decline appears to have occurred in three distinct episodes of contraction, two of which were associated with prolonged drought. Indirect monitoring of abundance suggests that the population was stable from 1974 to 1981, when cattle were excluded from the Park, but has increased since 1983. A trapping programme between 1985 and 1989 suggests that the absolute size of the population may be about 70. The population contains approximately equal numbers of males and females; almost all females breed; and a large and apparently increasing proportion of the population consists of young animals. Further increases in density and range within Epping Forest National Park appear possible. Removal of some animals for translocation should be attempted when it is clear that such removals will not jeopardize the stability and vigour of the Epping Forest population.

Size and shape of eggs of Neognathae: effects of developmental mode and phylogeny

2017 ◽  
Vol 95 (5) ◽  
pp. 359-366 ◽  
Author(s):  
I.S. Mytiai ◽  
O.V. Shatkovska ◽  
M. Ghazali
Keyword(s):  
Absolute Size ◽  
Phylogenetic Relatedness ◽  
Developmental Mode ◽  
Size And Shape ◽  
Egg Shape ◽  
Lateral Zone ◽  
Shape Indices ◽  
The Absolute ◽  
Pointed End ◽  
Egg Diameter

We evaluated the variation in absolute size and shape of birds’ eggs and the effects of developmental mode and phylogenetic relatedness on these traits. Eggs were characterized by length, diameter, and three indices of egg shape. Indices of egg shape were calculated as the ratio of radii that described the curvature of pointed end (cloacal zone), blunt end (infundibular zone), and lateral zone to egg diameter. We found that eggs shape was less variable than the absolute size of eggs. Index of the cloacal zone was the most changeable and index of the infundibular zone was very conservative. Size and shape of eggs could be better explained with phylogenetic relatedness than developmental mode.

Fiddler Crabs Use the Visual Horizon to Distinguish Predators from Conspecifics: A Review of the Evidence

1997 ◽  
Vol 77 (1) ◽  
pp. 43-54 ◽  
Author(s):  
John Layne ◽  
Michael Land ◽  
Jochen Zeil
Keyword(s):  
Field Experiments ◽  
Angular Size ◽  
White Background ◽  
Fiddler Crabs ◽  
Absolute Size ◽  
Uca Pugilator ◽  
Glass Dish ◽  
Escape Responses ◽  
The Absolute

Male fiddler crabs, Uca pugilator (Crustacea: Decapoda), respond to conspecifics by claw waving, and to predators by freezing or escape. In field experiments it was found that this distinction was not made on the basis of angular size and speed, nor was shape important. The remaining possibilities were either the absolute size of the stimulus, determined from angular size and distance, or the position of the stimulus relative to the horizon. To distinguish between these, a crab was placed in a glass dish, and moved black stimuli on a white background, at a distance of 22 cm. Stimuli below the crab's horizon hardly ever evoked escape. However, identical stimuli partially or wholly above the crab's horizon produced escape responses whose frequency varied with the angular size of the stimulus. Halving the distance of the stimulus showed that it was angular and not absolute size that determines escape frequency; and experiments with a tilted horizon showed that it is the position of the stimulus relative to the eye equator that is important, rather than the geographical horizon itself. It has been concluded that crabs categorize stimuli as dangerous or otherwise by their position relative to the crabs’ visual horizon.

scholarly journals REPRODUCTIVE BEHAVIOR OF DIPLOID AND ALLOTETRAPLOID AZALEODENDRONS

HortScience ◽  
2006 ◽  
Vol 41 (3) ◽  
pp. 497E-498
Author(s):  
Ryan N. Contreras ◽  
Thomas G. Ranney
Keyword(s):  
Flow Cytometry ◽  
Genome Size ◽  
Reproductive Behavior ◽  
Chromosome Doubling ◽  
Pollen Viability ◽  
Viable Pollen ◽  
Wide Hybrids ◽  
Viable Seeds ◽  
Cold Hardy ◽  
Mitotic Inhibitor

Wide hybridization can potentially lead to the combination of diverse traits, but these hybrids are often sterile as is the case with the inter-subgeneric hybrid Rhododendron `Fragrant Affinity'. Induction of polyploidy can restore chromosome homology and fertility in wide hybrids. In this study we successfully developed an allopolyploid form of R. `Fragrant Affinity' using oryzalin as a mitotic inhibitor and chromosome doubling agent. Approximate genome size (2C), determined using flow cytometry, was 1.6 pg for the diploid and 3.2 pg for the allotetraploid. Pollen viability, determined by staining and germination tests, was 4% and 0%, respectively for the diploid and 68% and 45%, respectively for the allotetraploid. No seeds were produced when the diploid R. `Fragrant Affinity' was crossed with pollen from viable diploid and tetraploid parents. The allotetraploid produced viable seeds and seedlings when crossed with viable pollen from either diploid or tetraploid parents, including self pollination, demonstrating restored fertility. Additional crosses were successfully completed using the allotetraploid as part of an ongoing breeding program to develop new fragrant, cold hardy, evergreen rhododendron.

Comments on the concentration-dependence of the viscosity of solutions of discrete particles in a homogeneous continuum

1979 ◽  
Vol 44 (7) ◽  
pp. 2086-2091
Author(s):  
Josef Kovář ◽  
Miloslav Bohdanecký
Keyword(s):  
Concentration Dependence ◽  
Volume Fraction ◽  
Individual Particle ◽  
Absolute Size ◽  
Mathematical Relation ◽  
The Absolute ◽  
Size Of Particles

It has been demonstrated that, for systems containing discrete particles dispersed in a continuum, the mathematical relation between viscosity and concentration is the same over the whole concentration range, provided that certain conditions are fulfilled; those conditions are: a) concentration is expressed as the volume fraction of the particles in the solution; b) the particles interact only hydrodynamically. This statement is true both for monodisperse solutions, in which the absolute size of particles may vary from one solution to another and for heterodisperse solutions but in the latter case it must be stipulated that all the solutions must contain the same qualitative distribution of shapes and sizes, so that they differ from one another only in the sense that each individual particle is scaled (up or down) relatively to the corresponding particle in another solution by a factor which is constant for all the particles.

scholarly journals Scaling of thermal tolerance with body mass and genome size in ectotherms: a comparison between water- and air-breathers

2019 ◽  
Vol 374 (1778) ◽  
pp. 20190035 ◽  
Author(s):  
Félix P. Leiva ◽  
Piero Calosi ◽  
Wilco C. E. P. Verberk
Keyword(s):  
Genome Size ◽  
Body Mass ◽  
Thermal Tolerance ◽  
Global Climate ◽  
Oxygen Limitation ◽  
Thermal Limits ◽  
Physiological Diversity ◽  
Interspecific Differences ◽  
Extinction Events

Global warming appears to favour smaller-bodied organisms, but whether larger species are also more vulnerable to thermal extremes, as suggested for past mass-extinction events, is still an open question. Here, we tested whether interspecific differences in thermal tolerance (heat and cold) of ectotherm organisms are linked to differences in their body mass and genome size (as a proxy for cell size). Since the vulnerability of larger, aquatic taxa to warming has been attributed to the oxygen limitation hypothesis, we also assessed how body mass and genome size modulate thermal tolerance in species with contrasting breathing modes, habitats and life stages. A database with the upper (CTmax) and lower (CTmin) critical thermal limits and their methodological aspects was assembled comprising more than 500 species of ectotherms. Our results demonstrate that thermal tolerance in ectotherms is dependent on body mass and genome size and these relationships became especially evident in prolonged experimental trials where energy efficiency gains importance. During long-term trials, CTmax was impaired in larger-bodied water-breathers, consistent with a role for oxygen limitation. Variation in CTmin was mostly explained by the combined effects of body mass and genome size and it was enhanced in larger-celled, air-breathing species during long-term trials, consistent with a role for depolarization of cell membranes. Our results also highlight the importance of accounting for phylogeny and exposure duration. Especially when considering long-term trials, the observed effects on thermal limits are more in line with the warming-induced reduction in body mass observed during long-term rearing experiments. This article is part of the theme issue ‘Physiological diversity, biodiversity patterns and global climate change: testing key hypotheses involving temperature and oxygen’.

Granivore seed-size preferences

2011 ◽  
Vol 21 (2) ◽  
pp. 81-83 ◽  
Author(s):  
Troy M. Radtke
Keyword(s):  
Seed Size ◽  
Optimal Foraging ◽  
Optimal Foraging Theory ◽  
Foraging Theory ◽  
Absolute Size ◽  
Herbaceous Communities ◽  
The Absolute ◽  
Size Preference ◽  
As If

AbstractAlthough seed-size preference by granivores is relative to the sizes of seeds offered by researchers, preferences are often inappropriately discussed and interpreted as if they are for absolute seed sizes. Granivores often prefer relatively small seeds in forests and relatively large seeds in herbaceous communities, although the absolute size of preferred seeds in each is often similar. These results are consistent with predictions of optimal foraging theory. Researchers are encouraged to take heed of optimal foraging theory and both relative and absolute seed size when interpreting seed-size preferences.

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