scholarly journals Nature, Nurture, and Noise: Developmental Instability, Fluctuating Asymmetry, and the Causes of Phenotypic Variation

Symmetry ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1204
Author(s):  
John H. Graham

Phenotypic variation arises from genetic and environmental variation, as well as random aspects of development. The genetic (nature) and environmental (nurture) components of this variation have been appreciated since at least 1900. The random developmental component (noise) has taken longer for quantitative geneticists to appreciate. Here, I sketch the historical development of the concepts of random developmental noise and developmental instability, and its quantification via fluctuating asymmetry. The unsung pioneers in this story are Hugo DeVries (fluctuating variation, 1909), C. H. Danforth (random variation between monozygotic twins, 1919), and Sewall Wright (random developmental variation in piebald guinea pigs, 1920). The first pioneering study of fluctuating asymmetry, by Sumner and Huestis in 1921, is seldom mentioned, possibly because it failed to connect the observed random asymmetry with random developmental variation. This early work was then synthesized by Boris Astaurov in 1930 and Wilhelm Ludwig in 1932, and then popularized by Drosophila geneticists beginning with Kenneth Mather in 1953. Population phenogeneticists are still trying to understand the origins and behavior of random developmental variation. Some of the developmental noise represents true stochastic behavior of molecules and cells, while some represents deterministic chaos, nonlinear feedback, and symmetry breaking.

1997 ◽  
Vol 75 (6) ◽  
pp. 919-928 ◽  
Author(s):  
Kjartan Østbye ◽  
Sigurd A. Øxnevad ◽  
Leif Asbjørn Vøllestad

Fluctuating asymmetry is defined as random deviation from perfect bilateral symmetry resulting from environmental or genetic disturbances (termed developmental noise) during early embryonic development. Developmental instability is defined as the inability of an organism to follow the a priori defined growth trajectory that results in perfect bilateral symmetry, owing to insufficient buffering of the disruptive effects of developmental noise during development. Fluctuating asymmetry has been proposed for use as a measure of developmental instability. In this study we tested whether fluctuating asymmetry can be an early indication of acidification stress. Samples were taken from 10 perch (Perca fluviatilis) populations exposed to varying pH levels and aluminium concentrations. We scored 13 bilateral meristic and morphometric characters to assess fluctuating asymmetry. The level of fluctuating asymmetry in the mandibular pores and one index summarizing three of the meristic characters were significantly correlated with the acidification level. When the lakes were split into two groups, "acidified" and "control," each consisting of five lakes, the same pattern emerged. The variance of fluctuating asymmetry estimates was larger in the acidified lakes than in the control lakes. These findings imply that perch in acidic environments experience developmental perturbations during early embryogenesis, resulting in deviating bilateral morphology. The variation in fluctuating asymmetry among lakes was at the same level as previously found among age groups within one acidified lake. Based on these findings, the use of fluctuating asymmetry as a management tool to evaluate the viability of fish populations in acidified waters is of limited value unless a more comprehensive approach is used.


Symmetry ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 9
Author(s):  
John H. Graham

Best practices in studies of developmental instability, as measured by fluctuating asymmetry, have developed over the past 60 years. Unfortunately, they are haphazardly applied in many of the papers submitted for review. Most often, research designs suffer from lack of randomization, inadequate replication, poor attention to size scaling, lack of attention to measurement error, and unrecognized mixtures of additive and multiplicative errors. Here, I summarize a set of best practices, especially in studies that examine the effects of environmental stress on fluctuating asymmetry.


Zoomorphology ◽  
2021 ◽  
Author(s):  
Stephan Scholz ◽  
Torben Göpel ◽  
Stefan Richter ◽  
Christian S. Wirkner

AbstractIn this study, the hemolymph vascular system (HVS) in two cambarid crayfishes, i.e. the Marbled Crayfish, Procambarus virginalis Lyko, 2017 and the Spiny Cheek Crayfish, Faxonius limosus (Rafinesque, 1817), is investigated in regard of areas of non-genetic phenotypic variation. Despite their genetic identity, specimens of P. virginalis show variability in certain features of the HVS. Thus, we describe varying branching patterns, sporadic anastomoses, and different symmetry states in the vascular system of the marbled crayfish. We visualize our findings by application of classical and modern morphological methods, e.g. injection of casting resin, micro-computed tomography and scanning electron microscopy. By comparing our findings for P. virginalis to the vasculature in sexually reproducing crayfishes, i.e. F. limosus and Astacus astacus, we discuss phenotypic variation of the HVS in arthropods in general. We conclude that constant features of the HVS are hereditary, whereas varying states identified by study of the clonal P. virginalis must be caused by non-genetic factors and, that congruent variations in sexually reproducing F. limosus and A. astacus are likely also non-genetic phenotypic variations. Both common causal factors for non-genetic phenotypic variation, i.e., phenotypic plasticity and stochastic developmental variation are discussed along our findings regarding the vascular systems. Further aspects, such as the significance of non-genetic phenotypic variation for phylogenetic interpretations are discussed.


2019 ◽  
Vol 15 (4) ◽  
pp. e1006943 ◽  
Author(s):  
Maria Kiskowski ◽  
Tilmann Glimm ◽  
Nickolas Moreno ◽  
Tony Gamble ◽  
Ylenia Chiari

Biologia ◽  
2010 ◽  
Vol 65 (1) ◽  
Author(s):  
Mátyás Bellaagh ◽  
Eszter Lazányi ◽  
Zoltán Korsós

AbstractThe Fluctuating Asymmetry (FA) is a special type of asymmetry in the populations of bilaterally symmetrical creatures. The FA gives us numerical data on the developmental instability of the populations and refers to potential genetical and environmental stressors affecting the populations. Here we give the first data on the FA of the protected Caspian whipsnake (Hierophis caspius) from Hungary. The FA indices of the biggest population from Villány Mts were compared to the FA indices of two differently stressed Dice snake (Natrix tessellata) populations [stressed (Mád) and seminatural (Lake Balaton)]. Based on the values of the multiple and the simple indices derived from sublabial scales, we can say that the status quo of the highly protected Caspian whipsnake population does not represent significant deviation from the near-natural dice snake population from the Lake Balaton.


2018 ◽  
Vol 24 (2) ◽  
pp. 183-192 ◽  
Author(s):  
Carlo Polidori ◽  
Agustín Pastor ◽  
Alberto Jorge ◽  
José Pertusa

AbstractPolistespaper wasps can be used to monitor trace metal contaminants, but the effects of pollution on the health of these insects are still unknown. We evaluated, in a south-eastern area of Spain, whether workers ofPolistes dominulacollected at urban and rural sites differ in health of midgut tissue and in fluctuating asymmetry, an estimate of developmental noise. We found that wasps collected at the urban sites had abundant lead (Pb)-containing spherites, which were less visible in wasps from the rural sites. Evident ultrastructural alterations in the epithelium of the midgut of the wasps collected at the urban sites included broken and disorganized microvilli, a high amount and density of heterochromatin in the nucleus of epithelial cells, cytoplasmic vacuolization and mitochondrial disruptions. Altogether, these findings suggest a negative effect on the transmembrane transport and a less efficient transcription. On the contrary, a healthy epithelium was observed in wasps from the rural sites. These differences may be preliminarily linked with levels of lead pollution, given that wasps from urban sites had double the Pb concentrations of wasps from rural sites. Level of fluctuating asymmetry was unrelated to wasp origin, thus suggesting no link between developmental noise and Pb-driven pollution.


Symmetry ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 1376 ◽  
Author(s):  
Vladimir M. Zakharov ◽  
Elena G. Shadrina ◽  
Ilya E. Trofimov

Developmental noise—which level may vary within a certain backlash allowed by natural selection—is a reflection of the state of a developing system or developmental stability. Phenotypic variations inside the genetically determined norm observed in case of fluctuating asymmetry provide a unique opportunity for evaluating this form of ontogenetic variability. Low levels of developmental noise for the biologic system under study is observed under certain conditions, while its increase acts as a measure of stress. The concordance of changes in developmental stability with changes in other parameters of developmental homeostasis indicates the significance of fluctuating asymmetry estimates. All this determines the future prospects of the study of fluctuating asymmetry not only for developmental biology, but also for population biology. The study of developmental stability may act as the basis of an approach of population developmental biology to assess the nature of the phenotypic diversity and the state of natural populations under various impacts and during evolutionary transformations.


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