Showing papers in "Heredity in 1972"
TL;DR: An alternative approach for dividing genotype-environment interaction into components, one corresponding to each genotype, is proposed, and the optimum properties are discussed, which are then extended to take into account a covariate.
Abstract: The usual regression approach to explaining genotype-environment interaction is considered, using a non-additive model, and the statistical validity of the analysis is discussed. An alternative approach for dividing genotype-environment interaction into components, one corresponding to each genotype, is proposed, and the optimum properties are discussed. The alternative approach is then extended to take into account a covariate. The relationship of the new approach to the regression approach is discussed, and a numerical example is given
908 citations
TL;DR: The following is a study of selection operating in the form of predation on the unusual characteristics of the Black stickleback.
Abstract: THE study of biological variation in terms of the organism's adaptation to its environment is a most revealing approach to understanding diversity. This is exemplified in the classical studies of the ecological genetics of the snail, Cepea nemoralis and various lepidopterans reviewed by Ford (1964) and Sheppard (1969). Such studies of natural selection in the wild have greatly contributed to our knowledge of such phenomena as adaptation, selective agents and their modes of action, intensity of natural selection, and maintenance of polymorphism, to name only a few. Most of this work has dealt with invertebrates. In the Queen Charlotte Islands, Canada, several populations of a vertebrate, the threespine stickleback, Gasterosteus aculeatus L., have diverged markedly from the typical G. aculeatus in respect to their morphology, ecology, and sometimes behaviour, much of the variation appears to be correlated with the presence or absence of predators. In Mayer Lake (latitude 53° 40'N, longitude 132° 02'W) individuals of one of these divergent populations are termed \"Black\" sticklebacks and are characterised by their large size, relatively long pelvic spines, average of seven lateral plates per side, and frequent absence of red pigmentation on the throat of sexually mature males. Black sticklebacks are parapatric with the typical, unkeeled, partially-plated form termed leiurus by European workers. Leiurus individuals are smaller than Black sticklebacks, have relatively short pelvic spines, an average of five lateral plates per side, and sexually mature males usually have red pigmentation on the throat. Various aspects of the ecology, life-history, and morphology of the two populations are discussed by Moodie (in press). The following is a study of selection operating in the form of predation on the unusual characteristics of the Black stickleback. Black sticklebacks, together with prickly sculpin, Cottus asper Richardson; cutthroat trout, Salmo clarki Richardson; dolly varden char, Salvelinus malma (Walbaum); and coho salmon, Oncorhynchus kisutch (Walbaum), are found in the lake proper. Leiurus occurs only in the inlet streams of the lake, where all other fish species are absent (Moodie, unpubl.).
276 citations
TL;DR: Induced polyploidy in plaice ( Pleuronectes platessa) and its hybrid with the flounder ( Platichthys flesus) is studied.
Abstract: Induced polyploidy in plaice ( Pleuronectes platessa ) and its hybrid with the flounder ( Platichthys flesus )
141 citations
TL;DR: This paper considers the two regression methods and their interrelationship from a different point of view and shows that there is a bias in the estimates of the coefficients of regression on the environmental mean when they are derived by the usual method.
Abstract: WHEN the performance of a set of genotypes is compared over a number of environments it is frequently found that genotypic effects are not fixed, but that they vary between environments. In biometrical investigations the problem then arises of how to characterise genotypic effects. A number of authors (e.g. Yates and Cochran, 1938; Finlay and Wilkinson, 1963; Eberhart and Russell, 1966; Perkins and Jinks, 1968a, b) have shown that in many such cases the performance of an individual genotype can be expressed as a linear function of the environmental index (the additive environmental effect). The slope of this regression, a dimensionless quantity, is a measure of the sensitivity of the genotype to the totality of environmental factors. Where the regressions are found to account for a substantial part of the genotype environment interaction variance, this empirical approach to the problem of interactions has proved to have considerable value. An identical technique has been used by Mandel (1959) and Mandel and Lashof (1959) to compare the result of tests at several laboratories on a number of materials, and the theoretical aspects of the statistical analysis have been discussed in a series of papers by Mandel (1961, 1969, 1970, 1971) and Mandel and McCrackin (1963). There has not, to our knowledge, been any reference to this work by biologists, nor as Mather (1971) has pointed out, any discussion of the underlying reasons why the regression technique works for plant material, although various authors have either denied that any such a priori reason exists (Wright, 1971), or have attributed the success of the method to the linearising nature of the transformation (Knight, 1970). In contrast to the empirical methods mentioned above, the classical approach of plant physiologists to the problem of genotypic performance has been by multifactorial experiments and growth analysis. This approach has led to the formulation of various regression models which relate plant performance to environmental variables, and more recently to computer simulation models of the same relationship (e.g. de Wit and Brouwer, 1968). Freeman and Perkins (1971) have suggested on statistical grounds that it may be better to use this approach to analyse genotype-environment interactions, by regression on environmental variables, rather than to use regression on the environmental mean. This paper considers the two regression methods and their interrelationship from a different point of view. First we show that there is a bias in the estimates of the coefficients of regression on the environmental mean when they are derived by the usual method. After considering the relations of this approach to various other techniques, we turn to the interpretation of the values of the coefficients of regression and of the deviations from the regressions on the environmental mean. It will be shown that it is possible to account for their values in terms of the coefficients of an \"underlying\" regression model. Finally a
112 citations
TL;DR: Heterozygous diploid line obtained by coichicine treatment of haploid.
Abstract: Spring R 239/2/10 Inbred from Rigo2; homozygous for G' R.D. 495 HDL from Rigo; partially male-sterile R 238/1 Inbred from NiIla2 R.D. 15 HDL from Nilla; partially male-sterile R.D. 6 HDL from Target4 Bronowski Seed multiplication Station, Poland5 1 Homozygous diploid line obtained by coichicine treatment of haploid. From Swedish Seed Association, Svalof, Sweden. Incompletely dominant allele for glossy leaves and stems. From Professor B. R. Stefansson, University of Manitoba, Canada. From Dr R. K. Downey, Department of Agriculture, Saskatoon, Canada.
86 citations
TL;DR: The role of slugs and snails in the maintenance of the cyanogenesis polymorphisms of Lotus corniculatus and Trifolium repens is studied.
Abstract: The role of slugs and snails in the maintenance of the cyanogenesis polymorphisms of Lotus corniculatus and Trifolium repens
81 citations
TL;DR: The response of cyanogenic and acyanogenic phenotypes of Trifolium repens to soil moisture supply is studied.
Abstract: The response of cyanogenic and acyanogenic phenotypes of Trifolium repens to soil moisture supply
65 citations
TL;DR: The somatic stability of these chromosomes was examined in different chromosome types and in various branches and organs of the same individuals and the behaviour of the supernumeraries was traced in meiosis and in the development of the male gametophyte.
Abstract: Aegilops speltoides (= Triticum speltoides) is a wild diploid (2n = 14) wheat growing in the East Mediterranean Basin. It is also the supposed donor of the second genome to tetraploid wheats (Triticum turgidurrt group). Recently several populations of this wild wheat were found to contain supernumerary chromosomes (in Israel, see Simchen et at., 1971, and in southern Turkey, Zohary, unpublished). This paper deals with the stability and mode of transmission of the accessory chromosomes in Ae. speltoides. The somatic stability of these chromosomes was examined in different chromosome types and in various branches and organs of the same individuals. In representative plants (with B chromosomes ranging from one to six) the behaviour of the supernumeraries was traced in meiosis and in the development of the male gametophyte. Such plants were also used in a crossing programme aimed at the elucidation of the mode of transmission of these chromosomes.
56 citations
TL;DR: The results of the study are used to predict possible evolutionary outcomes of natural selection among genotypes that differ in the sex balance of their outcrossing phase of mutant and wild-type forms.
Abstract: DETERMINATIONS of the reproductive mode in higher hermaphrodite plants are usually based on observations of seed parent performance. While a seif-fertilising plant makes equal male and female gamete contributions to the next generation, so that male gamete contributions can be extrapolated from data on functional embryo sacs, this situation need not hold in outcrossing plants. Here the 1 1 ratio between male and female gametes obtains only at the level of the population and individuals or gentoypes in the breeding entity can function more largely as male than as female parents, or vice versa, at each other's expense. In partially self-fertilising plants this inequality can affect the outcrossing rate and in the present study such an effect is traced in the partially selfing California annual legume, Lupinus nanus Dougi. (ex. Benth.). The sporophytic outcrossing rate is usually measured in progeny tests by the frequency with which functional female gametes unite with male gametes produced by different sporophytes. For the purposes of the present study this rate is termed the female outcrossing rate. For the frequency with which functional male gametes unite with female gametes from a different sporophyte a separate estimator is derived and termed the male outcrossing rate. Environmental and genetic influences on rates of outcrossing in partial selfers have been demonstrated in numerous investigations (see e.g. Stevens and Finkner, 1953; Harding and Tucker, 1964; Vasek, 1967). In Lupinus nanus it seemed plausible that outcrossing would be affected by flower colour and pattern. Evidence on visual responses in honey bees (Daumer, 1956; Menzel, 1967) and bumble bees (Manning, 1956) suggested that the lupine mutant genotypes pink and spotless (Harding and Mankinen, 1967; Horovitz, 1969) were likely to attract pollinating insects less efliciently and, therefore, outcross at lower rates than a blue-flowered wild-type form. Our purpose was to verify such outcrossing differences and relate them separately to male and female outcrossing phases of mutant and wild-type forms. The results of the study are used to predict possible evolutionary outcomes of natural selection among genotypes that differ in the sex balance of their outcrossing phase.
55 citations
TL;DR: It is argued that, in an outbreeding species, the widespread occurrence of heterozygous advantage is very much to be expected and may well provide a sufficient though, of course, not necessarily the only reason for the frequent occurrence of enzyme polymorphisms.
Abstract: THE development of methods for resolving variant proteins by electrophoresis in starch or polyacrylamide gels has led to the recognition, in populations of a wide variety of organisms, of polymorphisms with respect to a high proportion of the enzymes amenable to study. Much of the information available has been reviewed by Manwell and Baker (1970). According to one school of thought such widespread polymorphism can be accounted for by the occurrence of mutations of neutral survival value (Kimura and Ohta, 1971), though the likelihood of many mutations being truly neutral is still disputed (Clark, 1970; Richmond, 1970). Alternative selectionist interpretations of the phenomenon can invoke frequencydependent selection, periodic or disruptive selection (different genotypes selected for at different times or in different places in a variable environment) or heterozygous advantage. The idea of the rather general superiority of heterozygotes is one which has long had a considerable following, but a plausible rationalisation of such an effect has been lacking and belief in it has often seemed to rest more on faith than on reason. It is the purpose of this communication to argue that, in an outbreeding species, the widespread occurrence of heterozygous advantage is very much to be expected and may well provide a sufficient though, of course, not necessarily the only reason for the frequent occurrence of enzyme polymorphisms. In considering the effects of heterozygosity, the classical notions of dominance and recessiveness may have conditioned our thinking unduly. While the common existence of incomplete dominance is universally recognised, there is still a widespread feeling that it is, if not exceptional, still far from being the rule. This feeling has some justification at the level of morphology, but when enzyme phenotypes are considered, intermediacy of heterozygotes is almost universal. In cases of alleles determining normal versus low or zero amounts of a specific enzyme one almost always finds intermediate enzyme levels in diploid heterozygotes or haploid fungal heterokaryons. Alleles determining qualitatively (e.g. electrophoretically) distinct varieties of an enzyme can, furthermore, frequently be shown to interact in heterozygotes or heterokaryons to form hybrid oligomeric enzyme forms with intermediate properties. Admittedly, this lack of dominance at the biochemical level is often not manifest at the level of morphology; organisms have complex homoeostatic controls which tend to minimise any overt disruption of normal metabolism or development by moderate variations in enzyme activities. Nevertheless, it would be unwarranted to conclude that the underlying biochemical variations are without significance for fitness. Different genotypes may achieve a superficially standard phenotype but still differ markedly in the extent to which their metabolism was
50 citations
TL;DR: The principal component analysis of genotype-environmental interactions and physical measures of the environment shows clear relationships between genotype and environment and the values of these values are related to health and disease.
Abstract: The principal component analysis of genotype-environmental interactions and physical measures of the environment
TL;DR: The gene sine controls the incubation period of all strains of scrapie agent which have so far been isolated in mice, but the effect of this gene on scrapie incubation is confined to extraneural injections.
Abstract: ONLY one gene has previously been found to have a major effect on the pathogenesis of scrapie in mice: the gene sine controls the incubation period of all strains of scrapie agent which have so far been isolated in mice (Dickinson and Meikle, 1971). The two known alleles of sine, s7 and p7, apparently act on some early phase of agent replication in each tissue (Dickinson and Fraser, 1969; Dickinson, Meikie and Fraser, 1969) and in consequence the effect of the gene on incubation period is seen following either intraneural or extraneural routes of injection (Dickinson and Meikle, 1969). With intraperitoneal injection the incubation period is longer than with intracerebral injection. In the latter case, replication of injected agent which persists in the brain evidently leads to the death of the recipient even though much of the inoculum passes to organs of the reticulo-endothelial system where replication can be shown to take place (Fraser and Dickinson, 1970; Hunter, Kimberlin and Millson, 1972): with intracerebral injection it is reasonable to infer that the two alleles of sine determine variation in the incubation period entirely because of their effect within nervous tissues. However, following intraperitoneal injection the genetical control of the longer incubation period is almost certainly due to the composite effect of sine in organs of the reticulo-endothelial system, such as the spleen, together with its subsequent effect in nervous tissue. The gene Dli (dominant hemimelia) is almost always lethal in the homozygous combination, while in heterozygotes the spleen is absent and various degrees of hind limb abnormalities occur (Searle, 1964). The effect of this gene on scrapie incubation is confined to extraneural injections as will be seen from the results which are presented in this paper.
TL;DR: The influence of soil moisture on the frequency of cyanogenic plants in populations of Trifolium repens and Lotus corniculatus is studied.
Abstract: The influence of soil moisture on the frequency of cyanogenic plants in populations of Trifolium repens and Lotus corniculatus
TL;DR: Genetical and maternal determinants of the activity and preening behaviour of Drosophila melanogaster reared in different environments are studied.
Abstract: Genetical and maternal determinants of the activity and preening behaviour of Drosophila melanogaster reared in different environments
TL;DR: The theoretical basis of such predictions follows directly from the treatment of continuously varying characters of Mather and Jinks (1971), and the experimental observations required to make the predictions are relatively undemanding.
Abstract: ALTHOUGH the prediction of the expected response to selection from estimates of environmental and genetical parameters obtained from the base population has attracted considerable theoretical and practical attention, there have been no corresponding developments in predicting the properties of the extreme phenotypes that are expected to emerge since the initial step was taken by Mather (1949). Nevertheless, such predictions would have at least the same practical and theoretical interest. For the simplest case, where the base population is the F2 of a cross between two pure breeding lines and the genes are independent in their action and in their segregation, i.e. no epistasis and no linkage, the theoretical basis of such predictions follows directly from the treatment of continuously varying characters of Mather and Jinks (1971). And, as we shall see, the experimental observations required to make the predictions are relatively undemanding. Following Mather and Jinks (1971), we can define the means of any pair of pure breeding lines around their joint mean, m, as
TL;DR: Extrachromosomal elements in a super-suppression system of yeast II are studied to find out how these elements affect the ability of yeast to secrete nonvolatile substances such as polypeptide A and polymethine.
Abstract: Extrachromosomal elements in a super-suppression system of yeast II. Relations with other extrachromosomal elements
TL;DR: This work constitutes the first attempt at analysing in Chiamydomonas the fine structure of a gene in relation to the enzymatic properties of the protein controlled by this gene, the gene controlling the formation of argininosuccinate lyase.
Abstract: ALTHOUGH the green alga Chiamydomonas reinhardi may now be considered as a classical material in both genetical and biochemical research, very little work has been devoted to the study of genetic complementation. This failure may be explained by the fact that in this alga the diploid state is normally restricted to the zygote which, under the proper conditions, immediately undergoes meiosis. In 1967, however, Ebersold demonstrated that immature zygotes of Chiamydomonas reinhardi could occasionally divide mitotically to give rise to stable diploid vegetative cells. By crossing different auxotrophs in various combinations, this author succeeded in selecting on minimal medium several diploid strains, each of them heterozygous for two mutant genes. That these strains were really diploids carrying both mutations was supported by strong cytological and genetical arguments. This method has been applied to test whether complementation occurred between closely linked flagellar mutants (paralysed flagella pf18): no interallelic complementation was found in that system (Starling, 1969). In the course of our experiments on the isolation and characterisation of argininerequiring mutants of Chiamydomonas reinhardi, we found that among the 15 newly isolated mutants, seven were lacking the same enzyme arginino. succinate lyase like the arg-7 mutant previously isolated by Giliham (1965). This enzyme catalyses the splitting of argininosuccinate to arginine and fumarate and seems to play a key role in the regulation of arginine metabolism in Chiamydomonas (Strijkert and Sussenbach, 1969). Argininosuccinate lyase has been purified from beef liver: it was shown to have a molecular weight of 202,000 and to be formed of at least two subunits (Havir et al, 1965). This paper deals with the study of the gene controlling the formation of argininosuccinate lyase. Allelic complementation was shown to occur between certain pairs of mutants lacking this enzyme. Convincing evidence for diploidy has been gained from cytological, genetical and biochemical studies. The properties of the enzyme present in stable diploids displaying complementation were investigated in comparison with the properties of the wild-type enzyme. This work constitutes, to our knowledge, the first attempt at analysing in Chiamydomonas the fine structure of a gene in relation to the enzymatic properties of the protein controlled by this gene.
TL;DR: Competitive interaction between two S alleles in a sporophytically-controlled incompatibility system is studied to demonstrate the role of competitive interaction in determining incompatibility status.
Abstract: Competitive interaction between two S alleles in a sporophytically-controlled incompatibility system
TL;DR: Fripp and Caten as mentioned in this paper used the mean yield in each environment of the particular set of genotypes under investigation, calculated from the actual data being analysed for its genotype-environmental interactions.
Abstract: ALTHOUGH the importance of genotype-environmental interactions has long been recognised, it is only in the last decade that it has been possible to describe and predict this component of an individual's phenotype. This success followed the recognition that the phenotypic character under study itself provides a quantitative assessment of an environment (Yates and Cochran, 1938), and the finding that phenotype was often linearly related to such environmental values (Finlay and Wilkinson, 1963; Perkins and Jinks, 1968). The various regression approaches that have been used have been described and compared in a previous paper (Fripp and Caten, 1971). Inmost previous studies (e.g. Finlay and Wilkinson, 1963; Eberhart and Russell, 1966; Perkins and Jinks, 1968; Breese, 1969) the environmental values used were the mean yield in each environment of the particular set of genotypes under investigation, calculated from the actual data being analysed for its genotype-environmental interactions. This use as independent variable of values which are not independent of the phenotypic variable regressed on to them, has been criticised by Freeman and Perkins (1971). The regression technique can still be used to study genotypeenvironmental interactions provided the environmental values used are independent of the data being analysed. Freeman and Perkins (1971) list and discuss a number of ways in which independent environmental values might be obtained and describe a biometrical-genetical model and a regression analysis (approach 3 in Fripp and Caten, 1971) appropriate to such values. The many possible methods of assessing the environments may be grouped into four major categories:
TL;DR: Height and length of maturity differences, some pest and disease resistances, and some leaf and panicle characters tend to belong to this category.
Abstract: TRADITIONAL methods of breeding improved varieties of mainly selfpollinating
crops have been very successful. Success has been greatest when
characters controlled by relatively few genetic factors have been the main
objects of selection. Height and length of maturity differences, some pest
and disease resistances, and some leaf and panicle characters tend to belong
to this category. Even in an out-pollinating crop such as maize, initial yield
increase may be due largely to major characters, as in Harrison's Kenya
hybrid H-611 (Eberhart et at, 1967), where a short cob with many rows
crossed to a long..
TL;DR: Use of genotype-environmental interaction analysis in the study of natural populations of Aspergillus nidulans and its role in food spoilage and infectious disease is studied.
Abstract: Use of genotype-environmental interaction analysis in the study of natural populations of Aspergillus nidulans
TL;DR: The work described in this paper was undertaken in an attempt to elucidate some of the properties of the nuclear phenotype during meiosis with a view to throwing light on a possible visible cytological basis to the strong linkage.
Abstract: The colour and banding polymorphism entails at least five and possibly six linked loci (Cook, 1967; Cain, Sheppard and King, 1968), and the data from the breeding programmes (Lamotte, 1954; Cain and Sheppard, 1957; Cain, King and Sheppard, 1960; Cain, Sheppard and King bc cit.; Cook bc. cit.) show that the linkage is very tight with usually little or no apparent recombination. Cepaea is thus frequently stated to possess a supergene (e.g. Ford, 1964). Very little is known of the cytology of Cepaea beyond the fact that the haploid chromosome number is 22 (Perrot, 1938) and that one metacentric chromosome is much larger than any of the others. The work described in this paper was undertaken in an attempt to elucidate some of the properties of the nuclear phenotype during meiosis with a view to throwing light on a possible visible cytological basis to the strong linkage.
TL;DR: The analysis and interpretation of differences between reciprocal crosses of Nicotian rustica varieties shows clear differences in the behaviour of the different varieties towards each other.
Abstract: The analysis and interpretation of differences between reciprocal crosses of Nicotian rustica varieties
TL;DR: This paper analyses the relationship between sex ratio and maximum seed production in plants where pollen distribution is independent of plant density.
Abstract: THE selective consequences and effects of population sex ratios have been reviewed by Edwards (1962) and additionally discussed by Jam (1963) and MacArthur (1965). A closely related topic is how changes in the sex ratio influence seed production. Recently Mulcahy (1967) demonstrated the importance of sex ratios and their effect on seed production in an insectpollinated plant species and found that maximum seed production occurs when the proportion of staminate plants is less than one-half. Presumably the effect of sex ratios on seed production holds true for wind-pollinated plant species as well. It should, however, be considered that wind pollination differs from insect pollination in that in general pollen distribution of entomophilous plants changes as plant density changes, while with anemophilous plants the pollen distribution apparently remains constant (Levin and Kerster, 1969). This paper analyses the relationship between sex ratio and maximum seed production in plants where pollen distribution is independent of plant density. Most wind-pollinated plants have uniovulate ovaries, or produce but one seed per ovary. Thus, as a simplification, one functional ovule per ovary is assumed.
TL;DR: Variation in wild populations of Papaver dubium V. is studied to study the application of factor analysis to the study of variation.
Abstract: Variation in wild populations of Papaver dubium V. The application of factor analysis to the study of variation
TL;DR: It is proposed to use the term polymorphism for cases where characters are controlled by genes which show variation within populations, although, strictly speaking, metrical characters are excluded from the definition of polymorphism given by Ford (e.g. Ford, 1964).
Abstract: 1w earlier papers in this series (Lawrence, 1965, 1969, 1972), it was demonstrated that natural populations of Papaver dubium showed genetic variation within populations for the characters flowering time, stigmatic ray number and final height. A fourth character, capsule number, did not exhibit such intra-population variation. Since these characters were chosen entirely for ease of measurement, without any prior knowledge of their population genetics, the results would suggest that genetic variation within populations is common in this species. Accordingly, it was decided to conduct a wider survey of characters, in order to obtain a more quantitative check on the proportion of characters which might show such variation. Ten new characters reflecting the general morphology and rate of growth of the plant were chosen for study. Where appropriate, these characters were measured at different stages of development. In view of the large number of measurements, some of which were time-consuming, it was decided to measure only a restricted number of plants (72) and grow the plants throughout in the glasshouse. However, subsequently, plants having the same parentage as those raised in the glasshouse were grown under experimental field conditions and some of the characters remeasured. A comparison between results obtained under these two regimes would give information about genotype-environmental interaction. A well-known difficulty found in working with metrical characters is that of inferring the performance of a genotype under one set of conditions (e.g. the natural habitat) from the performance under quite different conditions (e.g. the experimental field. Thus, it is easiest to work with characters showing little genotype-environmental interaction. Our results should give some evidence on this. We propose to use the term polymorphism for cases where characters are controlled by genes which show variation within populations, although, strictly speaking, metrical characters are excluded from the definition of polymorphism given by Ford (e.g. Ford, 1964). It seems best at the present stage to assume that variation within populations for major genes and for genes controlling metrical characters are different aspects of the same phenomenon, and hence to use the same term for both. However, given that we have demonstrated that a number of characters (n, say) are showin such variation, it does not necessarily follow that there are n separate polymorphisms to be accounted for, since several characters may represent pleiotropic effects of one set of genes. By calculating correlations between
TL;DR: The results of Paroda and Hayes (1971) confirmed previous findings, that the character was quantitatively inherited and that both additive and dominance components were present.
Abstract: REVIEWS of the published studies on time to heading in barley have been compiled by Smith (1951) and Nilan (1964). Early genetic studies were generally limited to single or a small number of crosses and the results indicated variously that the character was simply or polygenically determined and that dominance was present in varying degrees. Later studies, using more sophisticated statistical techniques, have also led to the conclusion that the character is quantitatively inherited and that it is partially governed by dominant genes or gene groups. Johnson and Paul (1958) analysed data from the F1, F2 and F3 generations of seven crosses between spring barley varieties of different maturity periods and concluded that additive alleles at two loci were operative in the inheritance of earliness. These authors rejected the biometrical technique of analysis proposed by Mather (1949) in favour of Mendelian analysis. Eunus (1964) reanalysed the data from five of the seven crosses by biometrical techniques and concluded that two to five effective factors were operating. He also detected overdominance in three of the five crosses. Aksel and Johnson (1961) studied \"sowing-to-heading period\" in 10-parent (sixrowed and two-rowed varieties) and 6-parent (six-rowed varieties) diallels at F2. Biometrical analyses described by Hayman (1 954b) were used and the 6-parent crosses were also analysed by a single array technique (Jinks, 1956). They found that dominance acted in the direction of short sowing-toheading period and that the two-rowed varieties fell in the most recessive group. Of the six-rowed varieties, O.A.C. 21 was one of those showing an excess of recessive genes. The results of Paroda and Hayes (1971) confirmed previous findings, that the character was quantitatively inherited and that both additive and dominance components were present. They found a considerable shift in the position of relative dominance of different arrays in different environments and stressed the need to carry out genetic studies in environments similar to those in which the information is to be applied. The results to be described here were obtained for two seasons from a 13-parent diallel in which parents, F1 and F1 were grown in the same experiment.
TL;DR: A survey of the distribution of the various rnorphs of Arianta arbustorum found that this species appears to have only two phenotypes for colour: brown and yellow (or to be more precise, albino, for the character is one of absence of shell pigment rather than presence of yellow as in Cepaea spp).
Abstract: ECOLOGICAL genetics is concerned with accounting for the amount of genetic diversity in natural populations of animals and plants. Problems arise in conjunction with field studies over the selection of genetically controlled characters for examination. For example, gross morphological characters such as wing structure or eye colour of Drosophila species are attractive because of their relative ease of assay. However, they are frequently at such a selective disadvantage that they are more or less absent outside the population cage. This makes them impracticable for field work. There has been a considerable interest in the selective forces acting upon the visibly detectable varieties (morphs) of land snails. Visual selection for crypsis by predators has been shown to be of importance in controlling the relative frequencies of the various phenotypes of Cepaea nemoralis (Cain and Sheppard, 1950; Currey, Arnold and Carter, 1964), C. hortensis (Clarke, 1962), Cochlicella acuta (Dr G. A. Lewis, personal communication), Hygromia striolata (B. C. Clarke et al., personal communication), and Arianta arbustorum (Parkin, 1971), among others. Of these, the first two have attracted most attention, partly because of their conspicuous and remarkable polymorphisms. In C. nemoralis for example, at least 10 loci are known to control characters manifest in the colour and banding of the shell (Cain, Sheppard and King, 1968). This variation makes the detection of selective forces other than those directly associated with crypsis difficult (see for example Cain and Currey, 1963a, b; Goodhart, 1963; also Clarke, 1962; Carter, 1967; Clarke, 1969). Simpler variation will result in less interaction between the various polymorphisms, and should ease the detection of consistencies in the natural distribution of the genes in nature. It was with this in mind that a survey of the distribution of the various rnorphs of Arianta arbustorum was initiated. This species appears to have only two phenotypes for colour: brown and yellow (or to be more precise, albino, for the character is one of absence of shell pigment rather than presence of yellow as in Cepaea spp). Arianta has three alleles for banding (Cook and King, 1966), but two of these cannot be reliably distinguished in natural populations. They are therefore combined as \"banded \", the third allele being for the unbanded condition. Brown and banded are dominant to yellow and unbanded respectively, and the two loci are closely linked (r < I per cent.; Cook and King, 1966), so they effectively form a supergene.
TL;DR: Variation in wild populations of Papaver Dubium III and the genetics of stigmatic ray number, height and capsule number are studied.
Abstract: Variation in wild populations of Papaver Dubium III. The genetics of stigmatic ray number, height and capsule number
TL;DR: This study had several aims, including to establish whether multivariate techniques are effective in the definition of selection criteria in plant breeding and whether this effectiveness has still to be proved.
Abstract: MULTIVARIATE methods have been used widely, though perhaps not always wisely, for investigating genetical variation for complex characters. Studies have been published in plant genetics (e.g. Tukey, 1951; Murty, Arunachalam and Jam, 1970), in behaviour genetics (e.g. Bock and Vandenberg, 1968; Hegman and Defies, 1970; Royce, Carran and Howarth, 1970) and in animal genetics (Bailey, 1956). Multivariate techniques have also been recognised as potentially effective in the definition of selection criteria in plant breeding (Rao, 1953; Whitehouse, 1969) though this effectiveness has still to be proved. This study had several aims: