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Females of the American mink Mustela vison Schreber, 1777 were fed on various fractions of comercial PCB. Developmental stability of their progeny was studied. Developmental stability was measured by the value of fluctuating asymmetry, and the frequency of phenodeviants of osteological and dermatoglyphic characters. All these measures proved to be significantly higher in the experimental intoxicated groups than in the control group, thus indicating deterioration of developmental stability from PCB.
A sample of 1037 skulls of otters Lutra lutra (Linnaeus, 1758) from eastern Germany was analysed for inherent dental abnormalities. Deviations from the normal dental pattern were found in 107 individuals. A total of 150 cases were classified in 5 categories of abnormality. In considering variations from the normal number of teeth, supernumerary (polydonty, 1.7%) was more frequent than missing teeth (oligodonty, 0.9%). In most cases, numerical variations were not connected with phylogenetic background. The most frequent variations were displacement of teeth in the tooth row (6.0%) and deviations of the normal shape of teeth (3.3%). Variations of the local position of teeth occurred in 2.6% of cases. None of these deviations showed significant sex-dependent differences. Furthermore, no regional differences in the frequencies of these anomalies were noticed. Another 459 otters (822 cases) had accessory roots at P2, P3, or P4. These characters were considered as non-metrical traits and used to study epigenetic regional differentiation. The Mean Measure of Divergence segregated the Baltic coast from almost all other regions. Preliminary results of analysis of Fluctuating Asymmetry are presented, using these traits to demonstrate the utility of dental deviations for estimating influences on developmental stability. Generally, it can be stated that the dentition of otters is very stable.
We studied temporal changes in the level of phenotypic diversity, measured by the total phenotypic variance for several characters of skull morphology, in two populations of the common shrew Sore:e araneus Linnaeus, 1758. We compared a population from central Siberia having a high-amplitude four-year cycle with a population from southern Finland having noncyclic dynamics. The level of total phenotypic diversity varied significantly among years in both populations, but was correlated neither with density nor with breeding success in either of them. We did, however, find differences between the two populations. When we compared changes in the level of phenotypic diversity with changes in the level of developmental stability, as measured by chance developmental variance (fluctuating asymmetry), the cyclic Siberian population exhibited increased developmental variability in the peak year, which was associated with relatively small proportion of other sources of variation (and genetic variation in particular). In other years, the role of chance variation was less and the proportion of other sources of variance was higher. On the other hand, in the noncyclic Finnish population, oscillations in the level of phenotypic diversity were mainly caused by changes in developmental stability. These results illustrate that not only dynamics of genotype variety, but also the alterations in the level of developmental stability can be of great importance for changes in phenotypic diversity.
Developmental stability analysis was conducted for three strains of laboratory rat Rattus norvegicus Berkenhout, 1769 and their hybrids. Developmental stability was estimated by fluctuating asymmetry of 20 characters of skull morphology. A decrease was revealed in fluctuating asymmetry for the inbred strains and for the hybrids of genetically different strains. There were not any differences in fluctuating asymmetry between the homo- and heterozygotes for the separate locus. This support the hypothesis of the dependence of developmental stability on general genetic coadaptation.
Allozyme variability and fluctuating asymmetry (FA) in skull morphology were used to test the hypothesis of inbreeding in an isolated springbok Antidorcas marsu­pialis fZimmermann, 1780) population from the Chelmsford Nature Reserve, South Africa. Of 39 loci studied in a sample of 30 animals, five displayed allelic polymorphism. Average heterozygosity of 1.8% was not appreciably lower than a value of 2% calculated for 49 animals from a control group from Beniontein Game Farm in the Northern Cape Province, South Africa. Proportion of polymorphic loci and average number of alleles per locus were identical in both populations (10.3% and 1.1). Morphological analysis contradicted the prediction of increased fluctuating asymmetry due to the likelihood of inbreeding in a small, isolated population, with FA almost always higher in the control compared to Chelmsford. Chelmsford animals were however smaller than control animals for seven out of 9 cranial and horn variables analysed (significantly so in four cases), hich could conceivably be explained by environmental influences. It is concluded that loss of genetic diversity is not a problem in the Chelmsford springbok population, although this does not negate the possibility that physical deformities occurring in the population may indeed be genetically induced.
Regular development of morphology is challenged by any environmental influence that draines energy from developing individuals. For half a century biologists have recognized that developmental stability, measured as the capability to regulate development of normal morphological structures, is influenced by genetic variation. This review considers the influence of enzyme polymorphism upon developmental stability. Empirical studies in a wide variety of animals have reported morphological variability and bilateral asymmetry to decrase with the heterozygosity of enzyme polymorphisms. A controversy focuses on the question of whether enzyme polymorphisms directly influence energy budgets and metabolism, or whether the enzymes are neutral markers that either reveal variation in levels of inbreeding or are in linkage disequilibrium with genes directly influencing development. Another controversy focuses on whether the relationships between enzyme heterozygosity and development stability, most commonly reported in poikilotherms, will also be found in homeotherms. These controversies are addressed by considering recent empirical studies of enzyme polymorphism and developmental stability. Kinetic and physiological studies have now established that enzyme polymorphisms can have a major impact upon flux through metabolic pathways and physiological variation. Enzyme heterozygosity is associated with resistance to parasites, which may decrease developmental stability. Enzyme heterozygosity is also related to secondary sexual characters, such as the size and symmetry of horns in white-tailed deer and the size of horns in bighorn sheep. Because symmetry is so important in sexual selection, the development of secondary sexual characters may yield important insights to the relationship between heterozygosity and developmental stability. Many empirical observations are consistent with hypothesis that enzymes have a direct influence on developmental stability. It is not likely that the relationship between heterozygosity and developmental stability will differ substantially between poikilotherms and homeotherms.
We investigated fluctuating asymmetry in 13 traits of the skulls and jaws of historical and contemporary populations of Scandinavian gray wolves (Canis lupus). We hypothesized that there is a higher level of fluctuating asymmetry in the inbred contemporary population than in the historical population. Our analyses did not detect any difference in the level of fluctuating asymmetry as predicted. We propose different explanation for this lack of change in fluctuating asymmetry. It is assumed that a large number of studies have failed to find a positive correlation between the level of genetic stress and developmental instability and have therefore never been published, which hampers a good understanding of fluctuating asymmetry as an indicator of developmental instability. The current study is thus important in this context. The gray wolf population in Scandinavia is characterized by an extreme bottleneck followed by two and a half decades of strong inbreeding, but no associated change in fluctuating asymmetry is detected.
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 and from the 16th to the 21th days, respectively. In the control group, 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 (1-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.
We examined temporal variation in developmental stability measured by fluctuating asymmetry of 10 skull characters in sympatric populations of three shrew species: Sorex araneus Linnaeus, 1758, S. caecutiens Laxmann, 1788 and S. tundrensis Merriam, 1900 from one locality in central Siberia with a high four-year-cycle of small mammals. Simultaneous significant changes in developmental stability have been revealed during a population cycle 1986-1989 for all three, most abundant shrew species in the locality. The highest asymmetry for all these species occurred in the year of maximal density. Similar high asymmetry was found for the separate samples of two other species: S. roboratus Hollister, 1913 and S. isodon Turov, 1924, collected in a peak year 1989 only. The maximal density in 1989 corresponded to the lowest level of breeding success and developmental stability and, vice versa, minimal density in 1986 was accompanied by the highest level of breeding success and developmental stability. These data suggest that overpopulation caused by high density of various small mammals adversely affects an organism's condition. Thus, developmental stability may be used to monitor possible changes in a population even in cases where direct estimation of fitness is difficult.
We examined fluctuating asymmetry of 25 characters of skull morphology (foramina, apertures through the bone for nerves and small blood vessels) to estimate the developmental stability of European bison Bison bonasus (Linnaeus, 1758) (n = 34), cattle (n = 13) and their hybrids (54 hybrids of different generations). Mean number of asymmetrical characters per individual was used as a measure of fluctuating asymmetry. European bison were characterized by a lower developmental stability, compared with cattle. The developmental stability of hybrids was similar to that of cattle and higher than that of European bison. These findings suggest that the genomes of parental forms are similar and that there is no indication of the disruption of genetic coadaptation in their hybrids.
Developmental stability and phenotypic diversity of the bank vole Clethrionomys glareolus Schreber, 1780 were tested in a group of founders collected from natural population in Białowieża National Park (Poland) and in a sample taken from the 20th generation of a laboratory mass-cross strain derived from these founders. Fluctuating asymmetry of 28 skull characters such as the number of foramina were used as a measure of developmental stability. Variance of the foramina on the left and right sides of the skull for the same characters was used as a measure of phenotypic diversity. The data obtained indicate a developmental stability decrease and phenotypic diversity increase as a result of inbreeding during 20 generations in the laboratory.
Fluctuating asymmetry of skull characters, as a measure of developmental stability, wás studied in two seal species: grey seal Halichoerus gry pus (Fabricius, 1791), and ringed seal Pusa hispida Schreber, 1775 from the Baltic Sea. Seals were collected in three different periods of water pollution of the Baltic Sea. We revealed the same temporal dynamics of fluctuating asymmetry level for both species: it proved to be low in "pre-pollution period" (years 1877-1936), high for the "high-pollution period" (1964-1975), and was again low for the "low-pollution period" (1986-1990). These data suggest that changes in the condition of the seal populations in the Baltic Sea revealed by changes in developmental stability are correlated with the dynamics of the pollution level.
Fluctuating asymmetry in 30 bilateral cranial non-metric traits was investigated in three roe deer Capreolus capreolus (Linnaeus, 1758) populations living in different habitats in Poland. For each sample, the mean proportion of asymmetric traits per individual {FAnm) was calculated and used for comparisons among populations. The highest value of FAnm (0.18) was displayed by roe deer belonging to the 'field ecotype', a lower one by roe deer belonging to the 'forest ecotype' (0.14), and the lowest (0.12) in a 'transient' population. In contrast to the 'forest' roe deer and the 'transient' population, a gradual and statistically significant decrease of FANM-values over the last 30 years was recorded in the 'field ecotype'. There the proportion of asymmetric traits was also significantly higher in juveniles than in other age classes. Fluctuating asymmetry in roe deer is discussed with regard to the environmental stress hypothesis and the gradual development of a coadapted gene pool in the 'field ecotype'.
We compared developmental stability and total phenotypic diversity of 25 skull characters in three populations of European bison Bison bonasus (Linnaeus, 1758). Developmental stability was measured by fluctuating asymmetry, which was estimated by the variance of the left-right (1—r) and scaled (l-r)/(l+r) differences between the left (1) and right (r) sides of the skull. Mean number of asymmetrical characters per individual was used as an integrated index of developmental stability. Total phenotypic variability was examined by variance of (1+r) for the same characters. Greater developmental instability and total phenotypic diversity were found in bison from Pszczyna Reserve and Białowieża Primeval Forest, as compared with those from Okskii Reserve. This indicates the gradiial deterioration of developmental stability in the following sequence of the studied populations: Okskii' Reserve, Białowieża Primeval Forest, Pszczyna Reserve. In the Białowieża population, deterioration of developmental stability could be detected, even though commonly used fitness measures showed no response. In the Pszczyna population, more serious developmental stability disturbance was accompanied by decreasead viability, an expression of inbreeding depression. Two samples taken from the Białowieża population at different times showed similar levels of developmental stability, which indicates the reliability of fluctuating asymmetry. These results suggest developmental stability to be an essential characteristic for monitoring populations and especially for revealing the initial response to stress.
This study focused on verifying the fluctuating asymmetry hypothesis in the crustacean Talitrus saltator, which lives in sandy beaches. We analysed three populations, one from an unpolluted Tuscan beach relatively free of tourism, and two from Sicilian beaches, which have been increasingly used for tourism and have been exposed to hydrocarbon/pesticide pollution. Results confirmed the sexual dimorphism in the second antennae flagella, which in the Tuscan population presented directional asymmetry. This population had a significant level of fluctuating asymmetry in the P6 and P3 meri. The results showed the importance of the developmental stage during which environmental mechanical stresses act.
Two contrasting hypotheses on the relationship between dental character variability and biochemical-genetic diversity: (1) "influence of developmental homeostasis" and (2) "genetic-phenetic variation correlation" were tested in brown hare Lepus europaeus Pallas, 1778 populations. Interindividual variability (IV) and fluctuating asymmetry (FA) of 12 non-metrical characters of third lower premolars (P3) as well as allozymic heterozygosity (H) at 13 polymorphic loci was examined in 385 individuals from 19 geographical sampling units (GSU) in Austria. Juveniles and adults were discriminated according to dry eye lens weights. Sex was determined from internal reproductive organs. IV was calculated as the mean standard deviation of the 11 tooth characters in each GSU. GSU-specific FA was calculated as the mean FA of individuals (FAin), where FAin was the percentage of characters found asymmetric in individuals of a GSU. While IV did not show any significant relationship with H at the population level, FA of adults was significantly positively correlated (rs = +0.650, p < 0.05) with H. In juveniles a trend (rs = +0.399, ns) for such a correlation was apparent too. This finding corresponds to the "genetic-phenetic variation correlation hypothesis". Variability of both character systems is high in populations with high genomic variability, because both character systems concordantly portray gene pool diversity. Both IV and FA was significantly lower in juveniles than in adults. Since no ontogenic changes in P3 characters were found, this age-specific difference appears to result from selection against juveniles with low P3 variability (i.e. low genomic diversity). However, H was not lower in juveniles as compared to adults.
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