Showing papers on "Fluctuating asymmetry published in 2009"
TL;DR: Although the generality of these results remain to be tested among other populations and species, otolith asymmetry may be an important indicator, and potentially a predictor, of larval quality and replenishment success.
Abstract: Fluctuating asymmetry (FA), defined as random deviations from perfect symmetry, has become a popular tool with which to examine the effects of stress during the development of bilaterally symmetrical organisms. Recent studies have suggested that FA in otoliths may serve as an indicator of stress in fish larvae. We examined the relationship between otolith asymmetry and temporal patterns in the occurrence of late-stage larvae to a tropical reef (i.e. replenishment) for the Caribbean lizardfish, Saurida suspicio (family Synodontidae). Late-stage larvae were collected in light traps over a period of 18 consecutive lunar months in the San Blas Archipelago, Panama. Asymmetry within otolith pairs was calculated from 24 variables: area, perimeter, longest and shortest axis of the otolith and 20 shape descriptors (Fourier harmonics). Otolith asymmetry was correlated strongly with fluctuations in lunar light trap catches. Two measured variables, otolith area and one of the 20 shape descriptors, accounted for 60% of the variability in lunar replenishment of S. suspicio. Individuals from small replenishment pulses exhibited higher levels of asymmetry compared to larvae from large pulses. When dry and wet seasons were analysed separately, otolith asymmetry explained a surprising 70 and 97% of the variation, respectively. Although the generality of these results remain to be tested among other populations and species, otolith asymmetry may be an important indicator, and potentially a predictor, of larval quality and replenishment success.
43 citations
TL;DR: Large sample size and experimental design allowed removal of potentially confounding directional asymmetry (DA) and measurement error terms, and significant DA was found in both populations, although the pattern differed between populations.
Abstract: Many authors have proposed that inbreeding destabilizes developmental processes. This destabilization may be reflected by increased fluctuating asymmetry (FA) in inbred compared to relatively outbred populations, but many studies have failed to find such differences. We measured the left and right wings of a large number of individual Drosophila melanogaster from two genetically distinct populations to estimate changes in FA caused by inbreeding. The large sample size and experimental design allowed removal of potentially confounding directional asymmetry (DA) and measurement error terms. Trait means in the two populations were essentially unchanged by inbreeding (less than 0.5% smaller in both populations). Inbred lines showed higher signed FA variances (16 and 38% higher, significantly so in one population) and higher unsigned FA means (3.7 and 13.2%, significantly increased in one population). Significant DA was found in both populations, although the pattern differed between populations. DA did not change due to inbreeding.
33 citations
TL;DR: The observed patterns suggest that specific developmental pathways have a stronger effect on DI than others do, and that the functional importance of symmetry in limbs has resulted in strong selection for symmetry and reduced its sensitivity to stress.
Abstract: Developmental instability (DI), as measured by fluctuating asymmetry (FA), may reflect fitness and facilitate the expression of morphological variation. Insights in the underlying mechanisms and magnitude of DI during early development would increase our understanding of its role in evolutionary biology. We studied associations between FA and congenital abnormalities of different origins and functional systems in deceased human fetuses. Major congenital abnormalities corresponded to severe, often-lethal developmental disorders disrupting normal development from early organogenesis onward, but only moderately increased FA. Lower FA with age also supported the hypothesis that more severe abnormalities, leading to an earlier death, increased DI. Although FA related significantly to measures of fitness or health, we anticipated stronger associations because fetal health problems were detrimental. Furthermore, elevated FA occurred in only 4 of 17 disorders (left—right patterning, limb defects, and problems of ...
27 citations
TL;DR: Results support the second prediction, providing evidence that selection history can shape associations between DI and population‐level genetic variation at neutral markers, which potentially reflect genetic stress.
Abstract: Developmental instability (DI) is the sensitivity of a developing trait to random noise and can be measured by degrees of directionally random asymmetry [fluctuating asymmetry (FA)]. FA has been shown to increase with loss of genetic variation and inbreeding as measures of genetic stress, but associations vary among studies. Directional selection and evolutionary change of traits have been hypothesized to increase the average levels of FA of these traits and to increase the association strength between FA and population-level genetic variation. We test these two hypotheses in three-spined stickleback (Gasterosteus aculeatus L.) populations that recently colonized the freshwater habitat. Some traits, like lateral bone plates, length of the pelvic spine, frontal gill rakers and eye size, evolved in response to selection regimes during colonization. Other traits, like distal gill rakers and number of pelvic fin rays, did not show such phenotypic shifts. Contrary to a priori predictions, average FA did not systematically increase in traits that were under presumed directional selection, and the increases observed in a few traits were likely to be attributable to other factors. However, traits under directional selection did show a weak but significantly stronger negative association between FA and selectively neutral genetic variation at the population level compared with the traits that did not show an evolutionary change during colonization. These results support our second prediction, providing evidence that selection history can shape associations between DI and population-level genetic variation at neutral markers, which potentially reflect genetic stress. We argue that this might explain at least some of the observed heterogeneities in the patterns of asymmetry.
22 citations
TL;DR: It is concluded that there is no evidence of a role for system-wide developmental instability in the etiology of nonsyndromic sagittal craniosynostosis, and localized evidence of asymmetry at the anterior clinoid processes in the sagittal synostosis group suggests an association with the tracts of dura mater that attach there.
Abstract: Objective: To determine whether premature sagittal craniosynostosis is associated with developmental instability in the skull by analyzing fluctuating asymmetry in skull shape. Design: Cranial shape was quantified by collecting coordinate data from landmarks located on three-dimensional reconstructions of preoperative computed tomography (CT) images of 22 children with sagittal craniosynostosis and 22 age-matched controls. A fluctuating asymmetry application of Euclidean distance matrix analysis (EDMA) was used to quantify and compare asymmetry in cranial shape using these landmark data. Results: In contrast to expectations, the sagittal craniosynostosis group did not show a statistically significant increase in the overall level of fluctuating asymmetry relative to the control group. However, we discerned statistically significant localized increases in fluctuating asymmetry in the sagittal craniosynostosis group at pterion and the anterior clinoid processes (α = .05). We also determined a sig...
21 citations
TL;DR: It is suggested that males preferentially use their best side and, hence, that males respond adaptively to temporary changes in signal trait asymmetry.
Abstract: Asymmetries in courtship signals can result from both developmental instability during ontogeny and from temporary or permanent damage following mating, fighting, or interactions with predators. These two types of asymmetries, which can be divided into fluctuating asymmetry (FA) and damage asymmetry (DA), have both been suggested to play an important role in mate choice as potential honest indicators of phenotypic and/or genetic quality, while at the same time, DA may affect ornament asymmetry in a random manner. Interestingly, despite the massive research effort that has been devoted to the study of asymmetry during the past decades, very little is known about how an individual's behaviour relates to asymmetry. Here, we measure and characterise asymmetry in morphological courtship signals in Corynopoma riisei, a fish where males carry elaborate paddle-like appendices on each side of the body that they display in front of females during courtship. Moreover, we investigate whether male courtship display, employing this bilateral morphological trait, reflects trait asymmetry. Finally, we assess whether males respond to phenotypic manipulations of DA with corresponding changes in courtship behaviour. We show that male display behaviour is asymmetric in a manner that reflects asymmetry of their morphological courtship trait and that male display behaviour responds to manipulations of asymmetry of these paddles. Our results thus suggest that males preferentially use their best side and, hence, that males respond adaptively to temporary changes in signal trait asymmetry.
20 citations
TL;DR: The hypothesis that developmental instability is a useful bioindicator of environmental quality is not supported, due to weak correlations between FA and different patterns of two developmental instability measurements.
Abstract: Developmental instability in morphological characters can occur during individual development due to various environmental stresses. Fluctuating asymmetry (FA) is often used as a measurement of developmental instability, but within-environment variation (CV e ) is also considered an indicator of developmental instability. Cabbage aphid (Brevicoryne brassicae) populations were reared on zinc- (Zn) or cadmium- (Cd) contami- nated cabbage and radish plants. Developmental instability indicators were measured and their relations with fitness were explored. Results revealed that cabbage aphids exposed to Cd and Zn displayed considerable developmental instability, particularly fluctuating asymmetry. Differences in developmental instability between the two metals were also detected, as well as differences between the two developmental instability measurements. For almost all measured traits, FA was greater on Cd- and Zn-contaminated compared to non-contaminated host plants. In contrast, CV e of some traits was greater on non-contami- nated host plants, yet for other traits CV e was greater on contaminated host plants. There were also non-significant inverse relationships between FA and fitness of cabbage aphid populations. Due to weak correlations between FA and different patterns of two developmental instability measurements, this study does not support the hypothesis that developmental instability is a useful bioindicator of environmental quality.
17 citations
TL;DR: The usefulness of asymmetry in digits 2 and 4 was explored, finding significant associations between asymmetry measured in hands and face and 2D:4D ratios were detected for asymmetries in digits2 and 4 only.
Abstract: Background: Both asymmetry and the second and fourth digit ratio (2D:4D) relate to various aspects of human life history. Higher asymmetry with extreme 2D:4D ratios have suggested a link between both processes, indicating that early development determines levels of developmental instability. However, most observed associations may be biased because combinations of the digit lengths are used as both dependent and independent variables.Aim: The present study explored the usefulness of asymmetry in digits 2 and 4 to study this association.Subjects and methods: A combination of literature review, a small simulation study, and a study of 2D:4D ratios and asymmetry in a total of 100 young males and females is presented.Results: Using asymmetry in digits 2 and 4 results in bias and increased type I error rates, leading to stronger associations between asymmetry and 2D:4D ratios. In spite of low sample sizes, significant associations between asymmetry measured in hands and face and 2D:4D ratios were detected for ...
17 citations
TL;DR: This is the first study of FA in invertebrates associated with environmental stress from a catastrophic natural disturbance and indicates that FA in this secondary sexual character (male leg tufts) is a more sensitive indicator of putative environmental stress than a non-sexual trait (femur length).
Abstract: Animals subject to environmental stress often exhibit higher levels of developmental instability, frequently measured as Fluctuating Asymmetry (FA), small, random deviations from perfect left-right symmetry in bilaterally symmetrical animals. We used FA measurement as a means of determining the impact of a catastrophic ecosystem disturbance (a major Class F3 tornado) on populations of Schizocosa ocreata, a common forest-dwelling wolf spider. As FA in sexually selected ornamental traits in males has been shown in some (but not all) species studied to be a sensitive indicator of environmental stress, we measured FA of foreleg tufts in male S. ocreata. Spiders from the first post-disturbance generation were collected by pitfall trapping in the spring of 2000, and preserved specimens were photographed and measured using digital imaging. Spiders from disturbed and undisturbed areas within the forest did not differ significantly in body size parameters, although body condition varied significantly bet...
16 citations
TL;DR: The levels of FA of different morphological traits were similar in parental species and their hybrids of different generations in males (except SCTN) and in females (except for WL and W/T ratio).
Abstract: Due to inconsistent results of the empirical studies, the relationship between fluctuating asymmetry (FA, a measure of developmental stability) and interspecific hybridization has been the subject of intense debates. In the present study, we have assessed the impact of interspecific hybridization between 2 sibling species of Drosophila: Drosophila ananassae and Drosophila pallidosa on the levels of FA over 3 generations. Trait size of different morphological traits, namely, sternopleural bristle number, wing length (WL), wing to thorax (W/T) ratio, sex comb tooth number (SCTN), and ovariole number differed significantly among parental species and their hybrids of different generations in both the sexes. However, the levels of FA of different morphological traits were similar in parental species and their hybrids of different generations in males (except SCTN) and in females (except for WL and W/T ratio). These results are interpreted in terms of developmental stability as a function of a balance between the level of heterozygosity and the disruption of coadapted gene complexes.
15 citations
TL;DR: The relation between developmental stability and condition is complex and sex dependent, and both positional FA and bristle loss were greater in males than in females.
Abstract: Developmental stability is widely regarded as a condition-dependent trait, but its relation to genotype and environment, and extent of developmental integration, remain contentious. In Telostylinus angusticollis, the dorsocentral bristles exhibit striking variation in developmental stability, manifested as fluctuating asymmetry (FA) in bristle position (‘positional FA’) and failure to develop some bristles (‘bristle loss’), in natural and laboratory populations. To determine whether this variation reflects condition, I tested for effects of genotype and environment (larval diet quality), and examined covariation with condition-dependent traits. Positional FA was not affected by genotype or environment. However, positional FA covaried negatively with secondary sexual trait expression in males, and with sexual dimorphism in body shape, but covaried positively with body size in females. Bristle loss reflected both genotype and larval diet. Flies reared on poor-quality diet exhibited a similar rate of bristle loss as wild flies. Both positional FA and bristle loss were greater in males. These results suggest that the relation between developmental stability and condition is complex and sex dependent.
TL;DR: The results suggest that environmental radioactivity from the Chernobyl incident did not significantly affect the symmetry of lower permanent molar intercuspal distances in the specific population, even though increased levels of radionuclides have been reported in teeth and other tissues.
TL;DR: There appears to be very little evidence of any link between DI and 2D:4D in this population for limb measurements, which means highly stabilized and functionally important traits such as human limbs may in general show limited increases in asymmetry with prenatal stress.
TL;DR: The presence of a droppings pit is associated with the well-being of hens, and does not contribute to their fear or stress levels, as indicated by the tonic immobility duration and the heterophil:lymphocyte ratio.
TL;DR: It is suggested that many earlier studies may have failed to observe morph differences in quality or fitness because selection by male harassment was weak, and mated female morphs of the damselfly Enallagma cyathigerum clearly differed in one quality estimate and in the authors' measure of fitness.
Abstract: Sex-limited colour polymorphism occurs in several animal taxa and is usually explained in the context of sexual selection. Specifically, for polymorphism restricted to the female sex, multiple phenotypes may have evolved in response to male harassment. Such male harassment is generally considered to entail differential costs to female morphs, which may ultimately result in fitness differences. However, contrary to this prediction, most previous studies do not support that female morphs (andromorphs and heteromorphs) differ in measures of quality and (or) fitness components. In this study, we evaluate quality and fitness differences between mated female morphs of the damselfly Enallagma cyathigerum . We suggest that many earlier studies may have failed to observe morph differences in quality or fitness because selection by male harassment was weak. Here, we selected a study population for which our expectation was that levels of per female capita male harassment were high. Nevertheless, also in this population mated female morphs did not differ in body size or condition (body mass/body length). However, mated female morphs did differ in levels of developmental instability: heteromorphs consistently showed a higher level of fluctuating asymmetry than andromorphs. Also, mated female morphs differed in fecundity: andromorphs had a lower clutch size than heteromorphs. In addition, larger females contained more eggs, but the slope of this relationship was steeper in heteromorphs. In conclusion, mated female morphs of the damselfly E. cyathigerum at our study site clearly differed in one quality estimate (developmental instability) and in our measure of fitness (fecundity).
TL;DR: It is suggested that spot pattern may be less canalized than hind limb development andalyses of hind limb FA may be a useful and non-invasive tool for identifying potentially vulnerable amphibian populations.
Abstract: Measures of fluctuating asymmetry (FA) have been used to assess the significance of stress in amphibian populations. When animals with bilateral body plans are challenged by environmental stressors, departures from bilateral symmetry can emerge during development. The tendency for FA to develop has been linked to greater susceptibility to pathogens in many organisms. In our study, newts (Notophthalmus viridescens) infected with Ichthyophonus-sp. exhibited greater size-corrected FA of the hind limbs than uninfected animals from the same population. Among infected animals, however, the intensity of infection and the extent of hind limb asymmetry were not correlated, suggesting that asymmetry did not arise following infection, but rather that newts having greater FA may have been more susceptible to infection as a result of the same stresses that produced the increase in FA. There was no relationship between dorsal spot pattern FA and infection status or hind limb FA. We suggest that spot pattern may be less canalized than hind limb development. Newts are widely distributed and important components of freshwater communities in eastern North America and, thus, any change in their vitality may affect the composition of those communities. Analyses of hind limb FA may be a useful and non-invasive tool for identifying potentially vulnerable amphibian
TL;DR: Whether stress caused by artificial bidirectional selection for body size has any effect on the levels of FA of different morphological traits in Drosophila ananassae is investigated and the realised heritability was higher in low-line females and high-line males, which suggests an asymmetrical response to selection forBody size.
Abstract: Variation in the subtle differences between the right and left sides of bilateral characters or fluctuating asymmetry (FA) has been considered as an indicator of an organism’s ability to cope with genetic and environmental stresses during development. However, due to inconsistency in the results of empirical studies, the relationship between FA and stress has been the subject of intense debate. In this study, we investigated whether stress caused by artificial bidirectional selection for body size has any effect on the levels of FA of different morphological traits in Drosophila ananassae. The realised heritability (h2) was higher in low-line females and high-line males, which suggests an asymmetrical response to selection for body size. Further, the levels of FA were compared across 10 generations of selection in different selection lines in both sexes for sternopleural bristle number, wing length, wing-to-thorax ratio, sex comb-tooth number and ovariole number. The levels of FA differed significantly among generations and selection lines but did not change markedly with directional selection. However, the levels of FA were higher in the G10 generation (at the end of selection) than G0 (at the start of selection) but lower than the G5 generation in different selection lines, suggesting that the levels of FA are not affected by the inbreeding generated during the course of selection. Also, the levels of FA in the hybrids of high and low lines were significantly lower than the parental selection lines, suggesting that FA is influenced by hybridisation. These results are discussed in the framework of the literature available on FA and its relationship with stress.
TL;DR: Fluctuating asymmetry was not associated with trait size or body mass, although there was significant variation in body mass and toe size among groups, C-chicks being relatively small and A-chick and singletons relatively large.
Abstract: . Fluctuating asymmetry (FA), small random deviation from bilateral symmetry, often increases with stress during development. Common Terns (Sterna hirundo) typically lay two to three eggs that hatch asynchronously. I predicted that C-chicks (last of three) should have greater FA than A- and B-chicks at hatching and that FA should be higher in chicks from smaller clutches, because of differences in parental quality. Tarsus length of newly hatched chicks was measured across three years, and middle toe length was measured in one year. Sample sizes exceeded 100 chicks in two of three years. Variation in tarsus FA with hatching order and clutch size was statistically significant in one year (P < 0.01) and nearly so in another (P < 0.10). No significant differences were present for toe FA. A-chicks from three-egg clutches appeared to have the lowest tarsus FA among categories of chicks in both years, and in one year they were significantly more symmetrical than B- and C-chicks from three-egg clutches. A...
TL;DR: It has been found out in model experiments that damages to genetic structures with chemical toxicants causes chromosomal rearrangements, together with an increase in the fluctuating asymmetry of bilaterally represented characters in leaves, as a result of disturbances in regulatory functions.
Abstract: The influence of environmental xenobiotics leads to an increase in the frequency of gene mutations and chromosomal aberrations, as well as to a higher level of fluctuating asymmetry in Vicia faba, Arabidopsis thaliana, cultivated Ligustrum japonicum Thund., and Olea europea L. used as test systems. These alterations manifest themselves as arbitrary variations in ontogenesis. It has been found out in model experiments that damages to genetic structures with chemical toxicants causes chromosomal rearrangements, together with an increase in the fluctuating asymmetry of bilaterally represented characters in leaves, as a result of disturbances in regulatory functions. Fluctuating asymmetry is an informative and easily available test for quantitative estimation of the level of alterations in regulatory genome function. The parameters of asymmetry in leaves can be used as criteria to reveal the degree of ecological risk to generational and regulatory functions of genetic apparatus.
TL;DR: North American elk do not appear to respond to environmental variation by varying allocation to antler growth, instead they show stronger age-related effects on FA, and there is little support for strong effects of climate or density on FA in length or the number of points.
Abstract: Fluctuating asymmetry (FA) is a measure of the deviation from perfect bilateral symmetry, and has been used across mammals as a reliable indicator of environmental stress during growth and development. Antler size and symmetry can be an indicator of individual fitness and social rank among ungulates such as the North American elk Cervus elaphus. When environmental conditions are favourable, ungulates allocate additional resources to antler development to increase secondary sexual traits and enhance reproduction. We tested whether there was an appreciable change in antler length and the number of points as extreme climatic conditions (e.g. heavy snow and drought) reduced the nutritional condition of elk using 8,690 antler measurements collected at hunter check stations in south-central Montana surrounding the Greater Yellowstone Ecosystem (GYE) during 1982–2006. We also hypothesized that FA in elk antlers would increase at high elk density because of density-dependent competition for food. We developed a p...
01 Jan 2009
TL;DR: Fluctuating asymmetry (FA) represents small deviations from symmetry of a bilaterally symmetrical trait (Ludwig 1932) This variation is non-directional, with a normal distribution of signed right minus left differences whose mean is zero Some researchers, however, suggest that the distribution of these values is generally leptokurtic, i.e., with a more acute peak around the mean and fatter tails than in a normally distributed variable as discussed by the authors.
Abstract: Fluctuating asymmetry (FA) represents small, random deviations from symmetry of a bilaterally symmetrical trait (Ludwig 1932) This variation is non-directional, with a normal distribution of signed right minus left differences whose mean is zero Some researchers, however, suggest that the distribution of these values is generally leptokurtic, ie, with a more acute peak around the mean and fatter tails than in a normally distributed variable (Gangestad & Thornhill 1999) Two other kinds of asymmetry are directional asymmetry (DA), when one side of the body is consistently larger than the other, ie, the mean value of signed right minus left differences differs from zero; and antisymmetry, when the mean value does not differ from zero but the distribution of signed right minus left differences is platykurtic, ie, broad-peaked or even bimodal (Palmer & Strobeck 1986) It is generally accepted that only FA can serve as a measure of developmental instability, reflecting the inability of an individual to control development under genetic and environmental stress (Moller & Swaddle 1997; Leamy 1999; Palmer & Strobeck 1986, 2003)
Dissertation•
01 Jan 2009
TL;DR: Data indicate that triploid forms of O. alpicola are developmentally more stable than diploid and tetraploids forms, which is generally regarded as a measure of developmental stability.
Abstract: This study concerns the contribution of directional asymmetry (DA) and fluctuating asymmetry (FA) as a characterization of variation in six sexual (diploid) and two asexual (triploid and tetraploid) populations of the weevil Otiorhynchus alpicola. It is shown that DA in sexual populations is about 1 % of the mean length of each of the seven bilateral traits and the average contribution of DA to trait variation is even lower in asexual populations (about 0.85 in triploids and 0.65 in tetraploids forms). The average contribution of FA to the total phenotypic variance is about 23 %, 12 % and 19 % in diploid, triploid and tetraploid populations, respectively. Since FA is generally regarded as a measure of developmental stability, our data indicate that triploid forms of O. alpicola are developmentally more stable than diploid and tetraploid forms. The relationship between the level of ploidy and FA is discussed.
01 Jan 2009
TL;DR: The fluctuating asymmetries indexes observed are significantly smaller than those shown in captive stocks of L. vannamei, under high density and endogamy, and suggest an active role of the stabilizing selection in this natural population.
Abstract: Fluctuating asymmetries (FA) are associated to instability in organism development caused by environmental and genetic factors that act during the first stages of ontogenesis. Analysis of bilateral morphometries in commercial Penaeidae stocks has shown a high AF frequency in stocks submitted to several generations in captivity. With the objective of determining a basal level of fluctuating asymmetries found in natural populations of the Litopenaeus genus and determine which segments are most informative in the expression of these asymmetries, 18 parameters were measured obtained from 15 bilateral segments of a sample of 40 specimens of L. schmitti collected along the coast of Rio Grande do Norte state, northeastern Brazil. The analysis indicated the presence of asymmetries in 27.7% of the segments measured, corresponding to segments of the pereiopods. The fluctuating asymmetries indexes observed are significantly smaller than those shown in captive stocks of L. vannamei, under high density and endogamy. Low fluctuating asymmetry indexes suggest an active role of the stabilizing selection in this natural population.
Journal Article•
TL;DR: The behavioural and physiological changes associated with sexual maturity are yet not well understood and behaviours such as increased aggression have been associated with stress in poultry and other animals.
TL;DR: Individuals with more-symmetric wings had a higher immune response as measured by the cellular encapsulation of a surgically-implanted nylon monofilament, but there was no relationship between measures of FA in other organs and immune response, suggesting that this pattern may reflect differing selection pressures.
Abstract: Despite interest in the relationship between fluctuating asymmetry (FA), immune response and ecological factors in insects, little data are available from wild populations. In this study we measured FA and immune response in 370 wild-caught male bush-crickets, Metrioptera roeseli, from 20 experimentally introduced populations in southern-central Sweden. Individuals with more-symmetric wings had a higher immune response as measured by the cellular encapsulation of a surgically-implanted nylon monofilament. However, we found no relationship between measures of FA in other organs (i.e. tibia and maxillary palp) and immune response, suggesting that this pattern may reflect differing selection pressures.
20 May 2009
01 Jan 2009
TL;DR: In this article, the morphological stress experienced by Rana perezi, an anuran endemic to the Iberian Peninsula, in an agricultural landscape with different levels of management impact, by using the fluctuating asymmetry (FA) of its skeleton.
Abstract: This study aimed to determine the morphological stress experienced by Rana perezi, an anuran endemic to the Iberian Peninsula, in an agricultural landscape with different levels of management impact, by using the fluctuating asymmetry (FA) of its skeleton. Tibio-fibula, a highly functional trait, had the lowest FA level, whereas radio-ulna was the most asymmetric. This indicates that traits under directional selection are more prone to reflect stress than the functionally important ones. Metatarsus and radio-ulna were less able to cope with the stress in rice fields than in reservoirs. In ontogeny FA level decreased towards the adult stage suggesting that the mechanism of developmental stability buffered against the stress. In conclusion metatarsal and radio-ulna asymmetry of R. perezi juveniles can be used to assess environmental disturbances in agricultural landscapes.
DOI•
20 Jun 2009TL;DR: In this article, the morphological stress experienced by Rana perezi, an anuran endemic to the Iberian Peninsula, in an agricultural landscape with different levels of management impact, by using the fluctuating asymmetry (FA) of its skeleton.
Abstract: This study aimed to determine the morphological stress experienced by Rana perezi , an anuran endemic to the Iberian Peninsula, in an agricultural landscape with different levels of management impact, by using the fluctuating asymmetry (FA) of its skeleton. Tibio-fibula, a highly functional trait, had the lowest FA level, whereas radio-ulna was the most asymmetric. This indicates that traits under directional selection are more prone to reflect stress than the functionally important ones. Metatarsus and radio-ulna were less able to cope with the stress in rice fields than in reservoirs. In ontogeny FA level decreased towards the adult stage suggesting that the mechanism of developmental stability buffered against the stress. In conclusion metatarsal and radio-ulna asymmetry of R. perezi juveniles can be used to assess environmental disturbances in agricultural landscapes.