Experimental Taxonomy

Gregor, J. W.

doi:10.1111/j.1469-8137.1939.tb07111.x

Cited by 68 publications

(42 citation statements)

References 8 publications

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“…maritima, but retained P. oliganthos as a separate species. Gregor (1939) crossed diploid sea plantains from western and eastern North America with European diploid P. maritima, and obtained good seed set in nearly all crosses. He found that plants from North America and Greenland produced 4 seeds per capsule and were self-compatible, while plants from Europe had 2 seeds per capsule and were self-incompatible.…”

Section: P Maritimamentioning

confidence: 99%

Breeding systems in Plantago

Ross

1970

Heredity

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Section: P Maritimamentioning

confidence: 99%

Breeding systems in Plantago

Ross

1970

Heredity

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“…Nothing is said about hybrid populations and it is not clear whether failure of establishment of hybrids means that individual hybrid plants cannot establish themselves as seedlings and/or grow to maturity or whether hybrid swarms cannot become established. Later (Gregor, 1939), w-e find shorter definitions, as follows: 'The use of the following "specific" terms is advocated : Coenospecies, a population which is incapable of exchanging genes with other populations, even when given the opportunity. Ecospecies, a population with an inherently low capacity for exchanging genes with other populations of its coenospecies.'…”

Section: Terms and Their Definitionsmentioning

confidence: 99%

The Ecotype Concept

Turrill¹

1946

New Phytologist

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In two papers, published in 1922papers, published in , Turesson (1922 introduced the ecotype concept and its importance in the study of the constitution and origin of species was almost immediately recognized. Ecologists and taxonomists alike appreciate the value of combined field observations and controlled cultural experiments. There was some criticism, in part justified, that the field studies of populations and of the conditions of their environment were insufficiently extensive and intensive and that the ecotype concept was based too much on selected individuals and not on the study of whole populations or of sufficiently large random samples of such. Nevertheless, Turesson's researches have opened up new lines of research and full recognition of his great contributions to the study of species problems must be gratefully accorded by anyone familiar with the facts.There is no intention, or need, to give details of the early investigations on ecotypes. A very useful summary is given by Barton-Wright (1932). More recently, Gregor (1944) has published a most valuable summary of much recent research and trends of thought in this subject. The present paper is concerned mainly with two matters: the full significance of changes in definition of terms first used by Turesson in 1922, and the relation between genecology and taxonomy. Gregor (1944) touched on both these problems which were also referred to by the writer in an earlier paper (Turrill, 1938) and more recently in a review (Turrill, 1942). An investigator is unavoidably impressed more by his own experiences, by the examples with which he himself has worked, and by the difficulties he meets, than by those of others, and the value of concepts, terms, definitions, and schemes of classification can only be tested pragmatically. Genecologists have often criticized taxonomists, sometimes not without reason, but sometimes from a misconception of the taxonomist's functions. Taxonomists have too often ignored these criticisms and indeed the whole experimental work of genecologists, though there is increasing improvement in this respect. The present writer again expresses his appreciation of both the methods used and the results obtained in genecological research and is confident that any criticisms he makes will be accepted in the constructive spirit in which they are offered.

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“…Some of these investigations were made in connection with taxonomic studies in order to elucidate the relationships in particular groups of related species (Bocher et al 1955, Rahn 1957, Cartier 1971, 1973, Sopova and Rizova 1975, Zemskova 1977. Other studies were concerned with investigating the cytology of Plantago species in certain floras or phytogeographic regions (Gregor 1939, Runemark 1967, Briggs 1973, Favarger and Vasudevan 1972, Fernandes and Franca 1973.…”

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Chromosomal studies in the Egyptian flora. II. Karyotype studies in the genus Plantaga L.

Badr

El-Kholy

1987

CYTOLOGIA

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The first reliable chromosome counts in species of the genus Plantago L. was made by McCullagh (1934). Later more detailed cytological investigations were carried out on more than half of the species in this genus. Some of these investigations were made in connection with taxonomic studies in order to elucidate the relationships in particular groups of related species (Bocher et al. 1955, Rahn 1957, Cartier 1971, 1973, Sopova and Rizova 1975, Zemskova 1977. Other studies were concerned with investigating the cytology of Plantago species in certain floras or phytogeographic regions (Gregor 1939, Runemark 1967, Briggs 1973, Favarger and Vasudevan 1972, Fernandes and Franca 1973.The cytology of the genus Plantago in Egypt has not been a subject of a study. The chro mosome number of only three species was reported by Badr (1980). The numbers of some other species which grow in Egypt are also known from chromosome counts in plants from near floras particularly that of Europe. The present study is therefore conducted to investigate the cyto logical features in species of the genus Plantago from Egypt. This investigation deals not only with chromosome numbers but also with detailed karyotype features such as chromosome length and centromere position. The impact of karyotype features in the taxonomic relationships of the studied species is also elucidated. Materials and methodsMaterials of 12 samples belonging to 10 different species of Plantago were collected from their natural habitats. The studied species and the localities from which they were collected are given in Table 1. The distribution of localities in the country is illustrated in the map (Fig. 1).Cytological preparations were carried out on root tips obtained from seeds germinated on moist filter paper in petri dishes. Root tips were pretreated with 0.05% colchicine solution for 4 hours and fixed in 3:1 (V/V) ethanol: glacial acetic acid. Squash preparations were made using the Feulgen squash technique and were made permanent by mounting in canada balsam. Cells with good spreading of chromosomes were photographed and prints were enlarged to a magnification of 3000 times. Comparisons of chromosomes of the species studied were made by constructing a karyotype for each species by arranging the chromosomes in homologous pairs in order of their length and arm ratio as measured from the photographic prints. The variation in the chromosome length and arm ratio within the karyotype has been expressed by calculating the standard error (SE) of these parameters.

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Experimental Taxonomy

Cited by 68 publications

References 8 publications

Breeding systems in Plantago

Breeding systems in Plantago

The Ecotype Concept

Chromosomal studies in the Egyptian flora. II. Karyotype studies in the genus Plantaga L.

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