Asymmetric Traits Research Articles

Differences in skeletal and ornamental traits between laying hen cannibals, victims and bystanders

We compared the size of skeletal and ornamental traits, and asymmetries in bilateral skeletal traits, between victims of cannibalism, cannibals and bystanders within small groups of caged female White Leghorns at the time of cannibalistic attacks (i.e. injurious pecks resulting in bleeding). We hypothesised that victims of cannibalism have discernible morphological traits that predispose them to cannibalistic attack. We predicted that victims would have smaller skeletal traits (body length, ulna length, metatarsus length and width, toe length), lower body weight, poorer body condition, smaller combs and more asymmetrical bilateral skeletal traits than their flock mates. Contrary to our prediction, victims of cannibalistic attacks to the head/neck area ( N=23) tended to have larger combs than their flock mates (Wilcoxon matched-pairs signed-ranks test, S=59, P=0.037, NS after sequential Bonferroni adjustment). Their cannibals were more asymmetrical than non-cannibalistic bystanders (metatarsus length, S=48, P=0.011 and composite asymmetry, S=62.5, P=0.002, significant after sequential Bonferroni adjustment). In agreement with our prediction, victims of cannibalistic attacks to other body parts ( N=27), including the back, wings, rump, tail, cloaca, abdomen and toes, were more asymmetrical (composite asymmetry, S=78, P=0.022, significant after sequential Bonferroni adjustment) and tended to have lower body weights ( S=79.5, P=0.029, NS after sequential Bonferroni adjustment) than their flock mates. Their cannibals did not differ in skeletal or ornamental traits from the non-participating bystanders. The results suggest that large combs either elicit attacks to the head and neck area or increase vulnerability to injury during such attacks. Attacks to other body parts appear to be directed towards birds with signs of weakness relative to their flock mates. In these attacks, there were no distinguishing features separating cannibals from bystanders, suggesting that the bystanders could all be potential cannibals.

Langzeitselektion bei asymmetrischer Merkmalsverteilung

Abstract. Title of the paper: Long-term selection by asymmetric trait distribution A quantitative trait is assumed to be genetically affected by a polygenic effect and a major effect of a Single dialellic locus. Such a model is called mixed model of inheritance and the identified gene is denoted as quantitative trait locus (QTL). By choosing the part of the QTL-variance, the degree of dominance and the frequency of the favourable allele it is possible to generate distributions with given level of asymmetry characterised by skewness and kurtosis. If the ratio of QTL- and phenotypic variance is small (less than 8%), then genotype-environment interaction can be used in the mixed inheritance model to explain values of skewness and kurtosis estimated with poultry data. The Situation is considered where the environmental variances given for the three QTL-genotypes show a wide ränge. In most of these cases the short- and long-term selection does not effects the high values for skewness and kurtosis over multiple generations. Further the ratio of response to selection and the difference of selection depends on the selection intensity.

Social stress impact on developmental stability of laboratory rat Rattus norvegicus

Developmental stability of the progeny of pregnant female rats Rattus norvegicus Berkenhout, 1769 kept under different conditions was studied. In two experimental groups, females were exposed to social stress by keeping them in crowded cages at different stages of pregnancy, from the 1st to the 15th abd from 16th to the 21th days, respectively. In the control groups, pregnant females were kept under normal conditions. Fluctuating asymmetry of 20 skull characters (number of foramina for small blood vessels and nerves) was used as a measure of developmental stability. Variance of the difference in foramen number between the left and right sides of the skull (l-r) as well as mean number of asymmetrical traits per individual revealed an increase of fluctuating asymmetry in both experimental groups compared with the control group. These results imply the deterioration of developmental stability under impact of social stress.

Reproductive success and symmetry in zebra finches

Fluctuating asymmetries are small, random developmental accidents in morphological traits that would otherwise be described as being bilaterally symmetric. Experimental evidence indicates that in mate choice situations individuals possessing symmetric arbitrary traits or symmetric secondary sexual characters are preferred over those with larger asymmetries. This experiment investigated the effect of symmetric and asymmetric arbitrary traits (arrangements of coloured leg-bands) on reproductive success in captive zebra finches, Taeniopygia guttata. Six groups of six males and six females were separated into six free-flight breeding aviaries. Nestboxes and nesting material were freely available throughout the experiment. Males wore symmetric and asymmetric arrangements of the same coloured leg-bands. Each male wore two orange and two light green bands, two on each leg. There were six possible arrangements of these leg-bands. One male from each of these six leg-band treatments was present in each aviary, along with six females wearing numbered orange bands. Symmetrically banded males produced more offspring that survived past the period of parental care than males in either of the asymmetric treatments; this appeared to be the effect of female choice processes and female-based parental investment and not male intra-sexual dominance. This is the first experiment to indicate that symmetrically manipulated males gain reproductive advantages in controlled laboratory conditions and further supports recent theories indicating the evolutionary importance of symmetry in signalling-trait design.

Superior developmental stability of heterozygotes at enzyme loci in Salmo salar L.

The degree of heterozygosity of five enzymatic loci is related to the degree of fluctuating asymmetry of three bilateral traits in two farm stocks and in two natural populations of Salmo salar. In all cases we verified the existence of an inverse correlation of the degree of heterozygosity with the number of asymmetrical traits per individual as well as with the total magnitude of asymmetry that the individuals present. We also detected the association at the populational levels: a higher average populational heterozygosity implies a lower total magnitude of asymmetry. The phenomenon is general and the possibility that the correlation is due to the direct effect of a particular locus is excluded. The use of fluctuating asymmetry is proposed as an indicator of the loss of heterozygosity in salmon populations.

INHERITANCE OF MERISTIC VARIATION AND THE EVOLUTION OF DEVELOPMENTAL STABILITY IN RAINBOW TROUT

We found relatively high heritabilities in the narrow sense for seven of eight meristic characters in a population of rainbow trout using regression of mean progeny values on mid-parent values. In sharp contrast, there is no statistically significant additive genetic variance controlling developmental stability, as measured by fluctuating asymmetry (h2 = 0.02). However, there is a significant correlation between the average heterozygosity of each family at isozyme loci and the average number of asymmetric traits per individual. We have previously reported a strong correlation between heterozygosity at protein loci and decreased fluctuating asymmetry in this and other salmonid populations. Thus, there is little or no additive, but substantial dominance, genetic variation affecting fluctuating asymmetry. This suggests that there has been directional selection for increased developmental stability.

Observations on the Manner of Clasping the Hands and Folding the Arms

Previous articleNext article No AccessObservations on the Manner of Clasping the Hands and Folding the ArmsAlexander S. WienerAlexander S. Wiener Search for more articles by this author PDFPDF PLUS Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by The American Naturalist Volume 66, Number 705Jul. - Aug., 1932 Published for The American Society of Naturalists Article DOIhttps://doi.org/10.1086/280443 Views: 5Total views on this site Citations: 10Citations are reported from Crossref PDF download Crossref reports the following articles citing this article:Ulrich S. Tran, Ingrid Koller, Ingo W. Nader, Jakob Pietschnig, Anne H. E. Schild, Stefan Stieger, Elisabeth L. Zeilinger, Martin Voracek Lateral preferences for hand clasping and arm folding are associated with handedness in two large-sample latent variable analyses, Laterality: Asymmetries of Body, Brain and Cognition 19, no.55 (Feb 2014): 602–614.https://doi.org/10.1080/1357650X.2014.891607Christine Mohr, Gregor Thut, Theodor Landis, Peter Brugger Arm folding, hand clasping, and Luria's concept of “latent left-handedness”, Laterality: Asymmetries of Body, Brain and Cognition 11, no.11 (Jan 2006): 15–32.https://doi.org/10.1080/13576500500199795Zheng Lianbin, Zheng Qi, Lu Shunhua, Han Zaizhu, Li Shuyuan, Li Yonglan Study on Seven Asymmetric Behavioral Traits in Three Mongolian Groups, Anthropological Science 111, no.22 (Jan 2003): 231–244.https://doi.org/10.1537/ase.111.231M. Reiss The genetics of hand-clasping a review and a familial study, Annals of Human Biology 26, no.11 (Jul 2009): 39–48.https://doi.org/10.1080/030144699282967Michael Reiss, Gilfe Reiss Signs of Latent Handedness in Families, Perceptual and Motor Skills 87, no.33 (Aug 2016): 875–881.https://doi.org/10.2466/pms.1998.87.3.875Vinod Kumar Tandon Functional asymmetry of lower limbs: A study of “Palthi” posture among Khattris of Lucknow, Anthropological Review 53, no.1-21-2 (Dec 1987): 207–210.https://doi.org/10.18778/1898-6773.53.1-2.19I.C. McManus, C.G.N. Mascie-Taylor Hand-clasping and arm-folding: A review and a genetic model, Annals of Human Biology 6, no.66 (Jul 2009): 527–558.https://doi.org/10.1080/03014467900003931John G. Rhoads, Albert Damon Some genetic traits in Solomon Island populations. II. Hand clasping, arm folding, and handedness, American Journal of Physical Anthropology 39, no.22 (Sep 1973): 179–183.https://doi.org/10.1002/ajpa.1330390206G. Forrai, G. Bánkövi Relations of Hand Clasping and Arm Folding to Handedness in Hungarian Children, Acta geneticae medicae et gemellologiae 18, no.22 (Aug 2014): 166–174.https://doi.org/10.1017/S1120962300012154JOSE PONS Hand clasping (Spanish data), Annals of Human Genetics 25, no.22 (Nov 1961): 141–144.https://doi.org/10.1111/j.1469-1809.1961.tb01511.x