scholarly journals Evidence for variations in the morphometric traits between two sibling species of Drosophila: D. ananassae and D. pallidosa

Genetika ◽  
2017 ◽  
Vol 49 (1) ◽  
pp. 1-20 ◽  
Author(s):  
Roshni Singh ◽  
Bashisth Singh
Keyword(s):  
Natural Selection ◽  
Sibling Species ◽  
Wing Length ◽  
Phenotypic Variability ◽  
Strain Differences ◽  
Phenotypic Traits ◽  
Morphometric Traits ◽  
Thorax Length ◽  
Interspecific Variations ◽  
Ovariole Number

Darwinian theory of evolution states that, evolution occurs through the natural selection. Therefore, demonstration of natural selection in nature is the central aim of many evolutionary studies and selection acts primarily at the phenotypic level because it is well known that phenotypic traits are the primary target of natural selection. While keeping this in view, we have studied certain morphometric traits in the sibling species pair, D. ananassae and D. pallidosa to test intra- and interspecific variations. The traits studied are wing length, thorax length, ratio of wing length and thorax length, sternopleural bristle number, ovariole number and sex-comb tooth number. In females of D. ananassae, significant strain differences were found for all the traits except ovariole number. In males, significant strain differences were found for all the traits. On the other hand, in D. pallidosa, significant strain differences were found for all the traits in both, males and females. The values of all the morphometric traits were significantly higher in females of both the species in comparison to males. The values of all the morphometric traits were higher in D. ananassae. However, the phenotypic variability, expressed in terms of coefficient of variation, was higher in D. pallidosa. Except for ratio of wing length and thorax length, CV was higher in the case of females in comparison to males. Size related traits are least variable while bristle numbers and reproductive traits are most variable. Except few, most of the traits are positively correlated with each other in both the species. Intra- and interspecific variations were found with respect to different morphometric traits. Although sibling species have been defined as morphologically identical, our results show that sibling species may show variations in certain morphometric traits and these quantitative differences in the morphometric traits act as discriminant marker between these sibling species in the lack of any qualitative differences.

scholarly journals Genetic latitudinal adaptation of Drosophila melanogaster: new discriminative biometrical traits between European and equatorial African populations

1977 ◽  
Vol 30 (3) ◽  
pp. 247-255 ◽  
Author(s):  
J. David ◽  
C. Bocquet ◽  
M. de Scheemaeker-Louis
Keyword(s):  
Drosophila Melanogaster ◽  
Environmental Conditions ◽  
Wing Length ◽  
Selective Pressure ◽  
Wild Populations ◽  
Thorax Length ◽  
Adult Weight ◽  
Genotype Analysis ◽  
African Populations ◽  
Ovariole Number

SUMMARYFive biometrical traits (thorax length, wing length and width, sternopleural and abdominal chaetae numbers) were measured on 13 equatorial African strains and 30 French strains. In all cases highly significant differences were observed between the two geographic groups. These results are added to previously known variations concerning adult weight and ovariole number. In each place, the genetic particularities of the wild populations seem to be maintained by the selective pressure from environmental conditions, resulting in a homeostatic focusing of the best fitted average genotype. Analysis within each group showed that variations between strains were in most cases poorly or not correlated, so that partial or total genetic independence between the various traits measured seems likely.

Measuring natural selection on multivariate phenotypic traits: a protocol for verifiable and reproducible analyses of natural selection

2019 ◽  
Vol 65 (3-4) ◽  
pp. 130-136 ◽  
Author(s):  
Facundo Xavier Palacio ◽  
Mariano Ordano ◽  
Santiago Benitez-Vieyra
Keyword(s):  
Regression Analysis ◽  
Natural Selection ◽  
Evolutionary Biology ◽  
Specific Model ◽  
Quadratic Model ◽  
Standard Errors ◽  
Phenotypic Traits ◽  
Linear Gradient ◽  
Selection Gradients ◽  
Model Residuals

The use of multiple regression analysis to quantify the regime and strength of natural selection in nature has been an influential approach in evolutionary biology over the last 36 years. However, many studies fail to report the protocol of estimation of selection coefficients (selection gradients) and the specific model assumptions, thus failing to verify and reproduce the estimation of selection coefficients. We present a brief overview of the Lande and Arnold’s approach and a step-by-step R routine to aid researchers to perform a verifiable and reproducible regression analysis of natural selection. The steps involved in the analysis include: (1) assessing collinearity between phenotypic traits, (2) testing normality of model residuals, and (3) testing multivariate normality of phenotypic traits. We also performed a series of simulations to test the effect of non-symmetrical (skewed) phenotypic traits on the estimation of linear selection gradients. These showed that the bias in the linear gradient increased with increased skewness in phenotypic traits for the quadratic model, whereas the linear gradient of a model with only linear terms was nearly independent of trait skewness. If none of the above assumptions are met, selection gradients need to be estimated from two separate equations, whereas standard errors must be computed using other methods (e.g. bootstrapping). We expect that the procedure outlined here and the availability of analytical codes motivate the verifiability and reproducibility of the Lande and Arnold’s approach in the study of microevolution.

Sex-Specific Phenotypic Variability and Social Organization in the Chiribaya of Southern Peru

2010 ◽  
Vol 21 (4) ◽  
pp. 375-397 ◽  
Author(s):  
Kenneth C. Nystrom ◽  
Christine M. Malcom
Keyword(s):  
Social Organization ◽  
Phenotypic Variability ◽  
Explanatory Models ◽  
Phenotypic Traits ◽  
Data Set ◽  
Southern Peru ◽  
Yield Information ◽  
The Two Cultures ◽  
Unique Nature ◽  
Biological Relationship

AbstractAnalyses of skeletal phenotypic traits have the potential to yield information pertaining to social organization, such as kinship and residence patterns. In this research, we examine sex-specific phenotypic variability of craniofacial and mandibular metric traits in eight skeletal samples from four sites (San Gerónimo, Chiribaya Alta, Chiribaya Baja, and El Yaral) attributed to the Chiribaya polity (A.D. 772–1350) and a contemporary Ilo-Tumilaca/Cabuza group (El Algodonal) from southern Peru. Through this data set we investigate various aspects of social organization (e.g., postmarital residence patterns) within the Chiribaya polity. We also examine Chiribaya interactions with the contemporaneous, yet culturally distinct, Tumilaca cultural group. The pattern of between-group bias-corrected estimates of biological distances points toward a more distant biological relationship between the two cultures than has previously been reported. Among the Chiribaya groups considered, determinant ratio analyses indicate that males from two cemeteries (Chiribaya Alta Cemetery 4 and Chiribaya Alta Cemetery 7) were significantly more variable than females, suggesting that males were the more mobile sex. Several explanatory models are considered, including a matrilocal residence pattern and the in-migration of males. We also examine the unique nature of results from within Chiribaya Alta, which support the argument made by previous researchers that this site represents a regional political center.

scholarly journals Clines in body dimensions in populations of Drosophilia subobscura

1964 ◽  
Vol 5 (2) ◽  
pp. 240-256 ◽  
Author(s):  
R. K. Misra ◽  
E. C. R. Reeve
Keyword(s):  
Wing Length ◽  
Head Width ◽  
Mean Annual Temperature ◽  
High Positive Correlation ◽  
Thorax Length ◽  
Five Dimensions ◽  
Positive Correlation ◽  
Length Changes ◽  
Genetic Regression ◽  
Mental Regression

Five dimensions—wing length and width, thorax length, head width and tibia length—have been measured on samples of twelve populations of Drosophila subobscura taken from different parts of the species range, extending from Scotland to Israel. The populations had been started from thirty or more pairs of flies and maintained in the laboratory for eight to eleven generations. They were reared for measurement under standard conditions, so that any differences between them must be of genetic origin. The localities from which the populations came ranged over 25° of latitude and 15° F. in mean annual temperature.The population means of the five dimensions all showed strong positive correlations with latitude and slightly lower negative correlations with mean annual temperature. There is, in consequence, a very uniform cline in the five dimensions, each increasing as we move northwards. This pattern differs from that found for essentially the same dimensions of D. robusta by Stalker & Carson (1947), where all the correlations with latitude are lower and those for head and thorax size are of opposite sign in the two species.A partial correlation analysis and reference to selection experiments suggests that there are two distinct groups of genes involved in these clines: (1) a group of genes causing increase in relative wing and leg size, and responsible for the positive correlation of these dimensions with latitude in both species, and (2) a group of general size genes causing correlated changes in all dimensions, which have been selected in opposite directions in the two species, with the result that head and thorax size increase in subobscura but decrease in robusta as latitude increases. The ratio of wing length to thorax length has a high positive correlation with latitude in both species.Further analysis of the data available on both species brings out the following points:1. In subobscura there is considerable variation between localities remaining for all dimensions when the correlations with latitude are eliminated. This component of variance is much larger in proportion to the within-locality variance in subobscura than in robusta.2. Comparison of the percentage regression coefficients of dimensions on latitude or temperature shows that individual dimensions change more rapidly in proportion to both geographical indices in subobscura, but the ratio of wing to thorax length ?changes more rapidly in robusta.3. The ‘environmental’ regression of dimension on temperature of rearing in the laboratory, measured only for robusta, is very much higher than the corresponding genetic regression between populations on mean annual temperature for all the robusta dimensions and different in sign for head and thorax size. But this environ mental regression is uniformly only about twice as high as the corresponding genetic regression for each character in subobscura. Unexpectedly, the environmental and genetic regressions on temperature of the wing/thorax length ratio are equal in robusta.4. D. subobscura is about 20% smaller in head and thorax size, and 26% less in wing width, than robusta, when both species are reared at 18° C.5. The basic within-culture variances of the five dimensions are 50–100% greater in subobscura than in robusta for all dimensions. Variability in D. melanogaster is about the same as in D. robusta.Some of the possible implications of these results are discussed.

scholarly journals Genetics of morphological differences and hybrid sterility between Drosophila sechellia and its relatives

1991 ◽  
Vol 57 (2) ◽  
pp. 113-122 ◽  
Author(s):  
Jerry A. Coyne ◽  
John Rux ◽  
Jean R. David
Keyword(s):  
Genetic Analysis ◽  
X Chromosome ◽  
Sibling Species ◽  
Male Genitalia ◽  
Hybrid Sterility ◽  
Drosophila Sechellia ◽  
Ovariole Number ◽  
The Difference ◽  
Male Hybrid ◽  
Morphological Differences

SummaryWe conducted classical genetic analysis of the difference in male genitalia and hybrid sterility between the island-dwelling sibling species Drosophila sechellia and D. mauritiana. At least two loci (one on each autosome) are responsible for the genital difference, with the X chromosome having no significant effect. In contrast, male hybrid sterility is caused by at least four gene loci distributed among all major chromosomes, with those on the X chromosome having the largest effect.We also show that the large difference in ovariole number between D. sechellia and its mainland relative D. simulans is due to at least two gene substitutions, one on each major autosome. The X and the left arm of the second chromosome, however, have no significant effect on the character. This implies that the evolution of reduced ovariole number involved relatively few gene substitutions.These results extend previous findings that morphological differences between Drosophila species are caused by genes distributed among all chromosomes, while hybrid sterility and inviability are due primarily to X-linked genes. Because strong X-effects on male sterility have been found in all three pairwise hybridizations among D. simulans, D. sechellia and D. mauritiana, these effects must have evolved at least twice independently.

scholarly journals Morphological Diversity of Muscovy Duck in Humid Zone of Nigeria

2020 ◽  
pp. 39-44
Author(s):  
Muslim K. Ewuola ◽  
M. O. Akinyemi ◽  
W. A. Hassan ◽  
Bello Semiu Folaniyi
Keyword(s):  
Body Length ◽  
Wing Length ◽  
Live Weight ◽  
Phenotypic Correlation ◽  
Muscovy Duck ◽  
Regression Equations ◽  
Plumage Colour ◽  
Morphometric Traits ◽  
Humid Zone ◽  
Relative Prevalence

The study is aimed to assess live weight and some morphometric traits to serve as the basis for documentation and utilization in improvement programme of the locally-adapted ducks. This study observed five phenotypic characteristics and assessed live weight, and seven morphometric traits in 200 adult domestic ducks (105 drakes and 95 ducks) in the humid zone of Nigeria between February and August 2012. The observed characteristics were plumage colour, shank colour, eye colour, incidence and colour of caruncle. The seven morphometric traits included; body length, breast circumference, bill length, neck length, wing length, shank length, and foot length. Data collected were analysed using descriptive statistics, correlation and regression coefficients. Plumage colour was predominantly pied (black/white) with a relative prevalence of 69.0%. Shank colour was mainly yellow with a relative proportion of 62.5%. About 62% of the study ducks were yellow-eyed; the remaining ones had black eyes (38%). One-half (50%) of the study sample had caruncle; the remaining half had no caruncle. Red caruncle was predominant with the relative prevalence of 58.5%. The mean live weights of drakes and ducks were 3.16±0.814 kg and 2.05±0.449 kg, respectively. Coefficients of the phenotypic correlation between live weight and morphometric traits both in ducks and drakes ranged from 0.914 to 0.987 (P<0.01). The correlation coefficients showed that body length had the strongest relationship with live weight followed by wing length (r = 0.987 and 0.984). Regression analysis showed that body length and wing length had the highest coefficients of determination (R2 = 0.974 and 0.969), indicating that they were the best predictors of live weight. Also, the sampled Muscovy ducks showed a substantial level of variation in live weight and some morphometric traits, thereby pointing to probable gainful selection efforts. The regression equations in this study could serve as useful practical tools by livestock farmers, researchers and rural development workers for weight estimation in the field and for selection purposes.

scholarly journals Comprehensive phenotypic and statistical based analysis of foxtail millet (Setaria italic L.) lines for parental line selection

2017 ◽  
Vol 6 (11) ◽  
pp. 1736 ◽  
Author(s):  
Chandra Sekhar Akila ◽  
Palakurthi Ramesh ◽  
Gurulakshmi Kola ◽  
Mallikarjuna Gunti ◽  
Puli Chandra Obul Reddy ◽  
...  
Keyword(s):  
Phenotypic Variability ◽  
Foxtail Millet ◽  
Principal Component ◽  
Breeding Systems ◽  
Phenotypic Traits ◽  
Parental Line ◽  
Panicle Length ◽  
Pure Lines ◽  
Total Seed ◽  
Panicle Weight

Minor millets are the small-grained cereals that belong to family Poaceae, with local importance as a food source but are often called as underutilized plant species.   Foxtail millet is one among  the oldest cultivated small diploid, C4 Panicoid, with short life cycle, and inbreeding nature. The genetic diversity of the foxtail millet is important for breeding systems, geographical distribution studies, assist in conservation of genetic resources for high yielding varietal development in breeding programs, expansion of the genetic base and for identification of genes for various phenotypic traits. Keeping in view of this an attempt has made to develop pure lines from local farmers preserved populations and phenotypically characterize them along with four released cultivars.  A total of eleven farmers varieties and four released cultivars were evaluated for seven quantitative traits in complete random block desing at net house conditions.  The maximum coefficient of variation was observed for panicle exertion, followed by number of tillers/plant and panicle weight. High positive significant correlations was observed for Plant height, panicle length, panicle weight and total seed weight with other traits under study. Panicle exertion exhibit negative correlations with panicle length, panicle weight and no of tillers. The results of principal component analysis (PCA) explains variability of 95.43% in the fifteen genotypes for the traits under study that corresponds to first 4 eigen values with greater than 0.60.  The proportions of the total variance explained by the first 4 principal components (PCs) were 42.98%, 71.02%, 85.43% and 95.43% respectively. Wards method based genetic similarity or dissimilarity clustering based on seven morphological traits among the fifteen foxtail millet genotypes was able to separate and grouped them into 2 major clusters I and II.  The genetic and phenotypic variability present in the foxtail millet genotypes give opportunity for plant breeders for effective selection of specific donor lines for foxtail millet improvement.

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