Quantitative Morphological Characters Research Articles

Genetic distance and heterosis in Indian mustard: developmental isozymes as indicators of genetic relationships

The use of isozymes as indicators of genetic diversity and as markers for the selection of agronomic traits has been proposed in different crop species. The present investigation was conducted to study the use of isozyme-derived genetic distance between parents in predicting the F1 heterosis in Indian mustard. In addition, the interaction of isozyme-based diversity with quantitative trait and pedigree-based diversity measures, and its role in predicting hybrid heterosis has also been examined. Sixteen Indian mustard lines and their 48 crosses (12 × 4, line x tester crossing) were evaluated over two environments for isozyme and quantitative morphological characters. The results from this study suggest that the heterotic response to isozymic changes is more responsive in crosses derived from morphologically and pedigree-wise related parents in comparison to crosses derived from unrelated parents. It was possible to improve heterosis predictions by partitioning the isozyme-based genetic distance into general genetic distance and specific genetic distance and correlating the latter with the specific combining ability of morphological traits. The possible reasons for these observations are discussed.

EVOLUTION, PHYLOGENY, SEXUAL DIMORPHISM AND MATING SYSTEM IN THE GRACKLES (QUISCALUS SPP.: ICTERINAE).

According to theory, two consequences of sexual selection are sexual dimorphism in size and secondary sexual characteristics, due to either intra- or intersexual selection. In this paper I suggest three criteria for the test of an evolutionary hypothesis involving quantitative morphological characters. First, the postulated change must be shown to have occurred in evolutionary time. Second, this change must be positively correlated with a change in the proposed selective agent. Third, given two taxa with different degrees of sexual size dimorphism and different mating system, the possible influence of drift must be rejected. If the hypothesis is not rejected by these three criteria, then we still have no proof of causality, but we can at least be more confident about its plausibility. This is applied to the particular hypothesis that sexual dimorphism in the Boat-tailed and Great-tailed grackles (Quiscalus spp; Icterinae; Aves) is caused by the highly polygynous mating system in these species. In relation to an outgroup, both species have increased disproportionately in male tarsus and tail size, creating an increased sexual dimorphism. This has cooccurred with the evolution of their particular mating system. However, the variance among species in male tarsus size can be accounted for by drift, and need not be a result of selection for increased size. In contrast, the variance among species in male tail size was much larger than expected under a null model of drift, indicating directional selection for long tails. The variance in female tail size was not larger than expected by drift, whereas the variance in female tarsus size was in fact lower than expected by drift, indicating stabilizing selection. The data are consistent with the hypothesis with regard to tail size, but not with regard to body size.

Geographic distribution of variation in quantitative traits in a world lentil collection

In a world lentil collection the distribution of variation amongst accessions from 13 major lentil-producing countries was examined on the basis of nine quantitative morphological characters by discriminant analysis and canonical analysis. Stepwise discriminant analysis revealed major differences between accessions from different countries. Three major regional groups were apparent: 1) a levantine group (Egypt, Jordan, Lebanon and Syria, 2) a more northern group composed of Greece, Iran, Turkey, and USSR, and 3) accessions from India and Ethiopia with strikingly similar quantitative morphological characters. Misclassifications of individuals within groups were frequent. Characters useful in discriminating between accessions from different countries were in descending order of importance: time to maturity, lowest pod height and 100-seed weight. The regional grouping indicates the importance of local adaptation through clusters of associated characters with phenological adaptation to the ecological environment as the major evolutionary force in the species.

A SYSTEMATIC CIRCUMSCRIPTION OF CAREX MITCHELLIANA (CYPERACEAE) WITH REFERENCE TO TAXONOMIC STATUS

Carex mitchelliana M. A. Curtis, first described in 1843, is a cryptic member of the C. crinita Lam. species complex. Although recently attributed varietal status, historically it has been treated as both a species and a variety. In order to determine the taxonomic distinctness of this taxon, data were collected from a variety of sources including: morphology, scanning electron microscopy, chromosome counts, and biogeography. Results from scanning electron microscopy and statistical analyses of morphological data provide the strongest support for recognition of C. mitchelliana. Perigynia of C. mitchelliana are uniformly papillate; the length of the elongate papilla differs significantly among taxa (P < 0.001). Additionally, a variety of qualitative and quantitative morphological characters distinguish this taxon from the others in the complex; these include attributes of the pistillate scale, achene, perigynium, sheathing leaves, and habit. These data support and enhance those results previously reported from allozyme analyses of electrophoretic data. Although the geographical range of extant C. mitchelliana has been reduced, the historic range extends from Massachusetts to northern Florida and eastern Alabama. Chromosome counts, though not divergent from the other taxa in the complex, are presented for the first time for this species (n = 33).

The status of Juncus oronensis (Juncaceae)

Juncus oronensis has been treated as a species, a hybrid of uncertain parentage, or a synonym of J. tenuis. Various qualitative morphological and anatomical features and discriminant analyses using quantitative morphological characters suggest that the type material from Orono, Maine, is a hybrid of J. vaseyi and J. tenuis. The Canadian reports of J. oronensis are based on material referable to J. vaseyi and to a putative hybrid involving J. dudleyi and J. vaseyi.

A CLADISTIC ANALYSIS OF ANGOPHORA CAV. (MYRTACEAE).

Abstract- A cladistie analysis of Angophora Cav. used a data set dominated by quantitative morphological characters. These were coded into multistates using Generalized Gap-Coding, and treated as ordered sequences of stales. The reasons for choosing an ordered over an unordered sequence are discussed. A branch and bound method yielded one minimal-length, unrooted tree. Because of uncertainty in the position of the root, five cladograms were derived from the unrooted tree. The consensus cladogram comprises four main clades. The consensus cladogram was used for a biogeographic study using component analysis, which generated a single statement of relationships for five areas of eastern Australia. An infra-generic classification of Angophora comprising four series corresponding to the four main clades, and two subseries, is presented. The following new names are published: Angophora series i>Floribundinae, series Subvelutininae, series Bakerinae. subseries Costntitac. Angophora leiocarpa: L. Johnson ex G. Leach) K. R. Thiele and P. Y. Ladiges and A.paludosa (G. Leach) K. R. Thiele and P. Y. Ladiges are published as new combinations.

Genetic differentiation in Japanese populations of Drosophila simulans and D. melanogaster. II Morphological variation.

Geographical variation in ten quantitative morphological characters in each sex were studied for seven sympatric populations of D. simulans and D. melanogaster, the former has recently colonized the main islands of Japan. Populations of D, melanogaster showed geographical variation in most of the characters studied (wing size, body weight, thorax length, eye size, ovariole number, and ratio of eye width and wing length). In D. simulans, geographical differentiation was found only in three characters, among which the ovariole number increased with the latitude as was seen in D. melanogaster. Ovariole number was positively correlated with fecundity. Morphological characters appear to be differentiated at various speeds among geographical populations according to their adaptive significance. In both species, Ogasawara population was strikingly different from the other six populations in characters relating body size and eye size. Eye size and ovariole number were highly correlated with body size in D, simulans, but not in D. melanogaster.

Mutational changes of quantitative morphological traits in the convict cichlid ( Cichlasoma nigrofasciatum Guenther) after irradiation of parental spermatogonia and oogonia with different doses of X-rays

10 continuous and 6 discrete variables of body dimensions as well as 16 proportions calculated from them were determined in postirradiation F 1 convict cichlid fish ( Cichlasoma nigrofasciatum) which were derived from spermatogonia and oogonia both exposed to either 0 (controls), 250, 500, 750, 1000, or 2000 R of X-rays. While no interactions with sex or radiation dose were found, clear dosage effects and some sex effects occurred. The highest response for almost all quantitative traits examined as well as for variants of coloration or of vertebral aberrations appeared after 250 R to both parental germ cells. The lowest effectiveness was observed for almost all characters under investigation after 0 and 500 R. Accordingly, the largest difference between the 6 different treatment groups was found between 250 and 500 R, followed by 250 and 0, 250 and 1000, and 250 and 750 R to parental gonia. The present finding on the alterations of quantitative morphological traits completely corresponds to the changes of intraspecific aggressiveness as found for the same individual fish in a previous study thus confirming the complete congruence of the mutational response of quantitative morphological characters with that of behavioral traits to ionizing radiation.

GENETIC COMPONENTS OF MORPHOLOGICAL VARIATION IN SALIX REPENS

SummaryThe presence of statistically significant levels of genetic variation in a series of quantitative morphological characters in a dune population of Salix repens L. was demonstrated by the comparison of half‐sibs grown in the glasshouse from field‐collected seed. Although the plants showed considerable phenotypic differentiation between ridges and slacks in the natural population, only the amount of branching could be shown to be genetically different between plants grown from cuttings from the two environments. Comparison of plants grown from different collections of cuttings showed that these were genetically different for a variety of other morphological characters, although this variation was not correlated with ridge or slack origin. Analysis of the number of collections of this dioecious species containing male or female flowers, or flowers of both sexes, indicates that even within areas 0–5 m in diameter several different clones frequently occur.

Über kausale Zusammenhänge zwischen der Zuchttemperatur, dem Aminosäuren-Pool und einigen quantitativen morphologischen Phänen bei Drosophila melanogaster1,2

In Drosophila melanogaster the level of most of the free amino acids is low when environmental temperature is high and vice-versa. However the amount of glutamic acid decreases with decreasing environmental temperature. We have found that additional feeding of glutamic acid at low environmental temperature causes an increase of most of the free amino acids except glutamic acid itself. Low environmental temperature as well as feeding of glutamic acid causes an increase of quantitative morphological characters such as body size, number of facets and others. Our investigations demonstrate, that a high amino acid level, which in other experiments 20, 21 has promoted synthesis of nucleic acids, may be an important condition for increasing of quantitative morphological characters in Drosophila.

ÉTUDES SUR LE GENRE SOLIDAGO L. : II. LA MISE EN ÉVIDENCE DE LA POLYPLOÏDIE ENDOTAXONIQUE CHEZ S. PURSHII PORTER ET LES TAXA SIMILAIRES

In Solidago Purshii Porter, there are two cytodemes, one diploid (2n = 18) and the other tetraploid (2n = 36), which can be distinguished on the basis of the length of the guard cells of their leaf stomata. The diploid plants possess guard cells which are smaller than those of the tetraploid. These two entities of S. Purshii thus belong to the groups of cytodemes in which there exists a positive correlation between the chromosome numbers and the dimensions of certain quantitative morphological characters, such as the length of the guard cells.In groups in which the variation curves of the characters of the different cytodemes overlap little or not, the geographical distribution of the different cytodemes of the complex may be studied much more easily, rapidly, and comprehensively by measuring the length of the guard cells of herbarium specimens than by making chromosome number determinations. The data presented indicate that when sampling is made under the conditions described in this paper, determinations of the length of two guard cells of stomata of one mid-leaf per individual, made on two individuals per colony, is satisfactory for that purpose, on the average. However, it is recommended, as a safeguard, to increase these figures by a few units, and to make always a few direct chromosome number determinations to check the accuracy of this rapid technique. These direct determinations may also be necessary to know the chromosome numbers of certain extreme individuals of the different cytodemes which have guard cells that differ little in length.