Effect of environmental stress on fluctuating asymmetry in certain morphological traits in Drosophila ananassae: nutrition and larval crowding

2008 ◽  
Vol 86 (5) ◽  
pp. 427-437 ◽  
Author(s):  
C. Vishalakshi ◽  
B. N. Singh
Keyword(s):  
Genetic Variability ◽  
Environmental Stress ◽  
Fluctuating Asymmetry ◽  
Morphological Traits ◽  
Larval Density ◽  
Drosophila Ananassae ◽  
Developmental Stress ◽  
Significant Difference ◽  
Larval Crowding ◽  
Asymmetry Measures

The association of fluctuating asymmetry and phenotypic and genetic variability with environmental stress was investigated using poor nutrition and larval density as stresses on 10 recently collected isofemale lines of Drosophila ananassae Doleschall, 1858. Trait means for different morphological traits were reduced by stress, whereas phenotypic and genetic variability increased. The levels of fluctuating asymmetry and positional fluctuating asymmetry were similar in flies reared on poor and standard media. In constrast, there is a significant difference in both asymmetry measures in the flies reared at different larval densities for all traits. However, when asymmetry values across all traits were combined into a single index, composite fluctuating asymmetry, significant differences were found in males and females reared at different larval densities but not under nutritional stress. Moreover, composite fluctuating asymmetry is higher in males than in females, suggesting that males are more vulnerable to developmental stress. The results suggest that trait means are more sensitive to stress than fluctuating-symmetry measures and that the effect of stress is trait- and sex-specific. Generalizations based on the use of fluctuating asymmetry as an indicator of environmental stress in D. ananassae should therefore be used with caution.

Fluctuating asymmetry in certain morphological traits in laboratory populations of Drosophila ananassae

Genome ◽  
2006 ◽  
Vol 49 (7) ◽  
pp. 777-785 ◽  
Author(s):  
C Vishalakshi ◽  
B N Singh
Keyword(s):  
Fluctuating Asymmetry ◽  
Morphological Traits ◽  
Composite Index ◽  
Developmental Instability ◽  
Drosophila Ananassae ◽  
Developmental Stress ◽  
Phenotypic Quality ◽  
Laboratory Populations ◽  
Males And Females ◽  
Sexual Traits

Fluctuating asymmetry (FA, subtle random deviations from perfect bilateral symmetry) is often used as a measure of developmental instability (DI), which results from perturbations in developmental pathways caused by genetic or environmental stressors. During the present study, we estimated FA in 5 morphological traits, viz. wing length (WL), wing to thorax ratio (W:T), sternopleural bristle number (SBN), sex-comb tooth number (SCTN), and ovariole number (ON) in 18 laboratory populations of Drosophila ananassae. FA levels of measured traits differed significantly among populations except for SBN (in males and females) and W:T ratio (in females). Positional fluctuating asymmetry (PFA), a sensitive measure of DI, also varied significantly among the populations for SBN in females and SCTN in males. Interestingly, both males and females were similar for nonsexual traits. However, when FA across all traits (sexual and nonsexual) was combined into a single composite index (CFA), significant differences were found for both populations and sexes. Males showed higher CFA values than females, suggesting that males are more prone to developmental perturbations. The magnitude of FA differed significantly among traits, being lowest for nonsexual traits (SBN, WL, W:T ratio) and highest for sexual traits (SCTN and ON). The trait size of sexual traits (SCTN and ON) was positively correlated with their asymmetry. The possible reasons for variation in FA both among traits and among populations, and the usefulness of FA as an indicator of developmental stress and phenotypic quality in D. ananassae are discussed.Key words: fluctuating asymmetry, developmental instability, morphological traits, laboratory populations, D. ananassae.

PROFILING OF GUAVA GENOTYPES GROWN IN VIDARBHA CONDITIONS ON THE BASIS OF MORPHOLOGICAL TRAITS

2017 ◽  
Vol 23 (1) ◽  
Author(s):  
R.A. PATIL ◽  
S.G. BHARAD ◽  
S.N. SAWANT
Keyword(s):  
Genetic Diversity ◽  
Genetic Variability ◽  
Morphological Traits ◽  
Considerable Extent ◽  
Fruit Traits ◽  
Breeding Programmes ◽  
Tree Leaf ◽  
Qualitative Characteristics ◽  
Intrapopulation Diversity

Assessment of genetic diversity in the available germplasm is the prerequisite for development of improved genotypes through planned breeding programmes. In the view of this Forty-eight genotypes of seedling origin guava along with 1 check (L-49/Sardar) collected and conserved at germplasm block, Main Garden, Department of Horticulture, Dr. P. D. A. University, Akola were evaluated for genetic variability and diversity based on the qualitative characteristics. The genotypes were evaluated for sixteen morphological traitsviz. tree, leaf, floral and fruit traits. Results Show considerable extent of variability amongst the 49 genotypes in each traits. A sizeable amount of intrapopulation diversity recorded can be used to identify diverse parents which can be utilized in hybridization programmes.

scholarly journals Fluctuating Asymmetry and Developmental Instability, a Guide to Best Practice

Symmetry ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 9
Author(s):  
John H. Graham
Keyword(s):  
Measurement Error ◽  
Best Practices ◽  
Environmental Stress ◽  
Fluctuating Asymmetry ◽  
Best Practice ◽  
Developmental Instability ◽  
The Past ◽  
Size Scaling ◽  
Research Designs

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.

scholarly journals First evaluation of coral recruitment in Madagascar

2021 ◽  
Vol 20 (1) ◽  
pp. 47-62
Author(s):  
Gildas G.B. Todinanahary ◽  
Nomeniarivelo Hasintantely ◽  
Igor Eeckhaut ◽  
Thierry Lavitra
Keyword(s):  
Larval Density ◽  
Average Density ◽  
Recruitment Rate ◽  
Seasonal Distribution ◽  
Coral Recruitment ◽  
Significant Difference ◽  
Southwest Region ◽  
The Mean ◽  
First Time ◽  
Very High

The distribution of larvae and recruitment of scleractinians in the southwest region of Madagascar were evaluated for the first time between October 2013 and September 2014 at 3 sites. The presence of coral larvae (planulae) was monitored through weekly sampling using a plankton net and the recruitment rate evaluated by monthly sampling of the newly settled corals (<1 year stage) on recruitment tiles and by a monitoring of the recruitment of juveniles (1< Juveniles < 2 years) using the quadrat method. Planulae were present in the plankton for 9 months during the survey. The recorded mean annual density of planula varied from 0.43 ± 0.41 larvae m-3 to 3.23 ± 5.72 larvae m-3 depending on site, with a peak in larval density towards the end of November and the beginning of December. The variability in the occurrence of planula is very high and implied that the density observed in the year does not present a significant difference between the sites (pKW=0.33). The average density of total recruits was 620.13 ± 621.30 recruits m-2, 40.28 ± 50.97 recruits m-2 and 36.34 ± 33.82 recruits m-2, respectively at the sites of Nosy Tafara, Grande Vasque and Rose Garden. Seasonal distribution of coral recruitment was different between the sites. The mean annual density of newly settled recruits (< 1 month stage) was significantly higher at Nosy Tafara with 94.91±101.08 recruits m-2 compared to Grande Vasque and Rose Garden with 18.75±34.32 recruits m-2 and 11.57±18.47 recruits m-2 (pKW<0.001), respectively. The highest density of newly settled recruits was observed between October to December. Higher density of recruits was also observed in March at Nosy Tafara and in May at all three sites. Results of juvenile monitoring showed high rates (> 10 juveniles m-2) compared to other regions and the threshold, but it revealed high mortality among recruits. Coral recruitment in the southwest region of Madagascar was found to be high and could result in increased resilience of the coral reef assemblages.

Food stress, fluctuating asymmetry and reproductive performance in the gryllid crickets Gryllus bimaculatus and Gryllodes sigillatus

Behaviour ◽  
2004 ◽  
Vol 141 (2) ◽  
pp. 219-232 ◽  
Author(s):  
Samantha Mallard ◽  
C.J. Barnard
Keyword(s):  
Reproductive Performance ◽  
Fluctuating Asymmetry ◽  
Developmental Stress ◽  
Gryllus Bimaculatus ◽  
Food Treatment ◽  
General Hypothesis ◽  
Food Stress ◽  
Effect Of Food ◽  
Gryllodes Sigillatus ◽  
Measures Of Performance

AbstractWhile associations between sexual selection, developmental stress and fluctuating asymmetry (FA) remain controversial, this does not necessarily undermine the more general hypothesis that FA reflects developmental instability and functional competence. This applies as much to reproductive processes as to any other. If this is the case, however, we should expect FA and measures of performance to covary under conditions of developmental stress. Using an established association between morphometric FA and reproductive performance in the gryllid crickets Gryllus bimaculatus and Gryllodes sigillatus, we looked at the effect of food stress on covariation between FA and measures of performance (vigour of locomotion and interaction, mating speed, sperm transfer, egg production and offspring weight). The results showed a clear effect of food treatment in males and females of both species, with composite measures reflecting greater FA and reduced performance being greatest when crickets were reared on impoverished food. Inspection of independent means suggested FA may have been most influenced by a relaxation of food stress under high quality feeding conditions, while reproductive performance was more susceptible to the reduction in food quality under low quality conditions.

GENETIC VARIABILITY AND INTERRELATIONSHIP AMONG MORPHOLOGICAL TRAITS IN AFRICAN PEAR FRUIT (DACRYODES EDULIS (G.DON) H.J. LAM) ACCESSIONS

2020 ◽  
Vol 19 (1) ◽  
pp. 46-59
Author(s):  
V. I. ALAJE ◽  
C. O. ALAKE
Keyword(s):  
Genetic Variability ◽  
Total Variation ◽  
Morphological Traits ◽  
Biomass Accumulation ◽  
Leaf Length ◽  
Root Weight ◽  
Pear Fruit ◽  
Leaf Weight ◽  
Dacryodes Edulis ◽  
African Pear

African pear fruit (Dacryodes edulis) is a highly sought for multipurpose agroforestry tree species that has the potential for both local and international trades, Nigeria is among the leading producer of the fruit, but its pattern and extent of its genetic variability is currently unknown. Hence, a study was carried out to determine the pattern and extent of genetic variability and interrelationships among 13 morphological traits of African pear fruit accessions. The experiment was laid in a Completely Randomized Design in 5 replications. Data collected on number of leaf production, leaf length,  leaf breadth,  leaf length/breadth ratio,  internode distances, plant height, collar diameter, fresh leaf weight, fresh stem weight, fresh root weight, dry leaf weight, dry stem weight, dry root weight and  biomass accumulation were subjected to Analysis of Variance. Treatment means were separated using Duncan’s Multiple Range Test at 5% probability level. Results showed significant (p<0.05) differences among the D. edulis genotypes for most of the traits evaluated  indicated variation in the performance of the genotypes and  pattern of clustering indicated that there was no association between eco-geographical distribution of genotypes and genetic diversity. PCA revealed that fourteen axes accounted for 100% of the variations observed while the first five axes contributed 73.23% of the total variation observed. The first axis accounted for 25.61% of the total variation while the second and third accounted for 15.43 and 15.01%, respectively. The fourth axis contributed 9.82% of the total variation while the fifth axis contributed 7.36% of the total variation. Significant phenotypic and genotypic correlations were observed between most of the plant characters evaluated and biomass accumulation  which is an indication that the phenotypic association will be a good index for the genotypic association.  

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