Interrelationships Of Species Research Articles

SEGREGATION IN NEW ALLOPOLYPLOIDS OF GOSSYPWM VI. THE EFFECT OF CHROMOSOME ELIMINATION ON SEGREGATION FREQUENCIES

Cytoge~letical studies designed to elucidate species interrelationships and to discern the evolutionary history of the genus GOSSY~~'ZLITT have been in progress in this laboratory for a number of years. These studies have been based pri~llarily on nlultivalent frequencies and segregation of illarlter genes in synthetic allohexaploids of hybrids between the tetraploid New World species and various wild diploid species of Gossypiun~. These amphidiploids exhibited meiotic cl~romosome pairing configurations, such as univalents and multivalents, which can lead to numerical irregularities in chron~osoine distribution, which in turn can result in unbalanced gametes and/or chromosome elimination (Sarvella, 1956; Phillips, 1962 and 1961). Randoill chromosome loss will have a non-' random influence on segregation frequency if one assumes that gametes deficient for a chromosoille are functional. Thus a gamete of the type An for a given iuarker gene becollles -a if the cl~romosome carrying the 4 allele is eliminated. Elimination of an n allele-carrying chromosome from gametes potentially An or nn will not be manifest in testcross progenies. The research reported here was designed to assess the effect of chrornosome loss on segregation frequences by ascertaining the frequency and pattern of variation in chromosome number, both in the direct products of illeiosis (microspores) and in testcross progenies of a series of synthetic allohexaploids. Results and Discussion The hesaploids used in this study were the colchicine doubled triploid hybrids between the New World natural amphidiploids, G. hi?-sz~tz/'/~? L., and G. bnrbade~lse L., and species from the h genome (G. arbo7.e~~~~ L.) and D genome IG. ~.ni1wo7zdii Ulb. and G. gossypioides (Ulb.) Standley1 groups of diploid cotto~ls. Three synthetic allohexaploids, chosen to represent a wide range for both univalent frequency and multivalent frequency, comprised the experimental materials:

The Systematics of the Subfamily Ornithodorinae (Acarina: Argasidae). I. The Genera and Subgenera

The classification of the subfamily is reviewed, and 3 genera are recognized, namely Ornithodoros Koch, Otobius Banks, and Antricola Cooley and Kohls. Approximately two-thirds of the species of Ornithodoros were studied, and 7 subgenera of this genus are recognized: Ornithodoros s.str., Alveonasus Schulze, Pavlovskyella Pospelova-Shtrom ( =Theriodoros Pospelova-Shtrom, n.syn.), ORNAMENTUM (type Ornithodoros coriaceus Koch), Alectorobius Pocock, Reticulinasus Schulze, and SUBPARMATUS (type Ornithodoros viguerasi Cooley and Kohls). The genera and subgenera are described, and the interrelationships of the several species are discussed. It was found possible to assign all but 4 of the known species of Ornithodoros to subgenera.

SOMATIC CHROMOSOMES OF THE INDIAN FIVE STRIPED SQUIRREL FUNAMBULUS PENNANTI WROUGHTON.

The diploid chromosome number of the Indian five striped squirrel <i>{Funambulus pennanti, </i>Wroughton) is 54 with a preponderance of acrocentric chromosomes. On the basis of chromosome number and morphology the interrelationships of the different species of squirrel are discussed.

Chromosome Number and Classification in Hydrophyllaceae

A 20-year investigation of chromosome number in all 18 genera and more than 200 species (perhaps two-thirds of the total) of the plant family Hydrophyllaceae has not resulted in the discovery either of a single base-number for the family or of a primitive genus, and it has not settled the question as to whether or not the famliy is a strictly natural one. Chromosome number has confirmed the general grouping, earlier proposed by various authors on morphological grounds, of such genera asHydrophyllum, Pholistoma, Nemophila, andEllisia (Constance 1939a) ;Eriodictyon, Nama, Lemmonia, andTurricula; andHesperochiron andTricardia. It has also revealed the occurrence of several polyploid series, and has exposed certain trends in morphology, such as reduction in the number of ovules and the specialization of annual habit from perenniality. Within certain genera, especially the large genusPhacelia, chromosome number has been of considerable assistance both in permitting a more natural grouping of species, and in shedding some light on interrelationships of species and species-groups and their probable phylogeny.

Cytogenetic and Evolutionary Studies in Secale. II. Interrelationships of the Wild Species

Cytogenetic and Evolutionary Studies in Secale. II. Interrelationships of the Wild Species

The application of immunological methods to the taxonomy of species within the genus Solanum.

The application of immunological analysis to plant taxonomy has been made practicable by the development of gel-diffusion methods, both by the Elek-Ouchterlony technique and by the more recent immuno-electrophoretic technique of Grabar & Williams. By these means individual proteins in plant extracts may be differentiated and a number of components in the extracts compared individually with those from related species. A modification of these methods has been applied to the investigation of the genus Solanum , with particular reference to the inter-relationships of certain Mexican species of potato with one another and with S. tuberosum , the domestic potato. Antisera were raised in rabbits to crude saps from S. tuberosum and S. ehrenbergii (a Mexican species), using a combination of Freund’s adjuvant technique with courses of intravenous injections. With both antisera well-marked precipitation lines developed against extracts from all the thirty-eight species examined; and by comparison of the direct ‘line-spectra’ and those obtained after cross-absorption of an antiserum, it was possible to divide the species into groups. The results show in their main outline a remarkably close agreement with those obtained from the classical taxonomic methods, and with the general conclusions arrived at from cytological and genetical studies. The value and the limitations of these immunological techniques as applied to taxonomic studies are discussed.

Slide Agglutination as a Presumptive Test in the Laboratory Diagnosis of Candida Albicans

Immunologic methods for the laboratory identification of Candida albicans are not yet in general use. The early work of Benham (1) on the antigenic inter-relationships of the Candida species has remained the most important contribution in this field, while Tsuchiya and his group (2) have recently extended this problem and have charted antigenic “maps” of these organisms. Christie and Morton (3) examined 78 yeast-like organisms isolated from clinical materials and concluded that the slide agglutination test, although not completely accurate, gives much less error in the laboratory diagnosis of C, albicans than other laboratory methods.

Immunological Methods in Plant Taxonomy

THE application of immunological analysis to plant taxonomy has been made practicable by the development of gel-diffusion methods, both by the Elek-Ouchterlony technique1 and by the more recent immuno-electrophoretic technique of Grabar and Williams2. By these means the individual proteins in plant extracts may be differentiated and the extracts compared component by component with those from related species. We have applied a modification of these general methods to the investigation of the genus Solanum, with particular reference to the interrelationships of certain Mexican species of potato, and the comparison of these with S. tuberosum, the domestic potato.

The Ranunculi of the Alaskan Arctic Coastal Plain and the Brooks Range

Until the last five years little has been known of the flora of the Alaskan Arctic 'Coastal Plain, and the writer has seen only one Ranunculus specimen collected in the Brooks Range* prior to 1946. Few of the early collections were made by professional botanists. Nearly all the few specimens are those of members of exploring expeditions not concerned primarily with this fielfd of study, and they record only the existence of species at the few points at whiclh ships stop-nothing of local variability within species. Before 1946 only about twenty collections of Ranunculus were knoNvn from an area the size of California or of New England, New York, and Pennsylvania. These specimens represent only four species, and they give no indication of geographical distribution because nearly all came from Barrow, Wainwright, or Cape Lishburne. Since 1946 half a dozen collectors have visited part of the Alaskan Arctic Coastal Plain or the Brooks Range, particularly the United States Navy Petroleum Reserve No. 4 which covers most of the area. Thirteen species of Ranunculus are known now to occur on the Coastal Plain and/or in the Brooks Range, according to habitat tolerances. Much of the knowledge of inland distribution of species is derived from the collections of Mr. Lloyd A. Spetzman along the north side of the Brooks Range and of the late Mr. Louis B. Jordal at points on the south side of the same range. Dr. Ira L. Wiggins, Director of the Arctic Research Laboratory at Point Barrow and Director of the Natural History Museum of Stanford University, California, and his assistants Mr. Henry J. Thompson and Mr. John H. Thomas of Stanford University have added materially to the knowledge of distribution of plants in the Point Barrow Region as a result of their extended excursions into the tundra along and awav from the immediate coast. Through their kindness, in the summer of 1950 the writer was able to visit various points in the same region and to study more intensively in the field the characters occurring from individual to individual of all the known species of Ranunculus occurring in the Point Barrow Region. These studies were continued in the summer of 1952. The chief fea-tures of this paper are 1) a summary of the known species and their distribution in far northern Alaska as a result of the collections of others and the field studies of the writer and 2) data bearing on the interrelationships of species and their degree of distinctness from each other resulting from field study in the American and European Arctic by the writer. As a result state-

A CYTOLOGICAL STUDY IN THE GRAMINEAE

A CYTOLOGICAL STUDY IN THE GRAMINEAE

SEROLOGICAL REACTIONS AND SPECIES SPECIFICITY OF SOME HELMINTHS

Concepts regarding classification and relationships of organisms have been based chiefly on adult and developmental morphology, but the value of particular structures in determining descent has been variously interpreted by different authors. Accordingly, opinions concerning the phylogenetic status of certain forms have differed. Furthermore, failure to reach agreement as to what constitutes a species has provoked much discussion and controversy. The earlier studies dealing with morphology and development have been supplemented in recent years by the use of serological reactions. Long employed in the diagnosis and control of certain diseases, these reactions have been utilized also to determine species specificity and interrelationships of many organisms. Serological methods have been increasingly stressed in experimental work designed to clarify phylogenetic relationships of parasitic worms and to test taxonomic systems based on morphological characters. Consideration of the several types of serological reactions indicated clearly that the precipitin test is best suited for the determination of species specificity and interrelationships of organisms. This test lends itself admirably to qualitative, quantitative, and objective interpretations, which are necessary and fundamental for the evaluation of serological relationships.

Application of Serologic Technics to General Biologic Research

An increasing number of general biologists are attempting to apply specific serum reactions and related immunologic phenomena to basic nonclinical research. For example, plant juices have been injected parenterally into rabbits and the resulting immune serums (specific precipitins) used as test tube reagents in an attempted determination of the chemical interrelationship of numerous plant species. Animals have been immunized against alien erythrocytes and the resulting specific hemagglutinins used in an attempted confirmation of certain theories of heredity. Specific antilipoidal (complement-deviating) antiserums have been prepared and applied to topographic analyses of adult tissues and growing embryos. The chemical interpretation of serologic data of this type is by no means as obvious as many general biologists have apparently assumed. Most of the routine specific precipitin, agglutinin and complementdeviation technics have been arbitrarily standardized for routine forensic or clinical purposes. Arbitrary dilutions of serum, temperatures and times of reading the end-reaction magnify diagnostically important chemical differences and minimize or eliminate clinically inconclusive heterophile, nonspecific or pseudo reactions and other interfering colloidal phenomena. The minor chemical reactions thus arbitrarily ruled out may be among those of greatest general scientific interest. Routine specific agglutinin reactions, for example, do not suggest that there is a common, highly specialized protein, lipoid or carbohydrate in the meningococcus, the anthrax bacillus and certain nonpathogenic bacteria. These microorganisms are apparently 100 per cent chemically distinct. Nevertheless, a fairly efficient heterophile or reciprocal vaccine can be extracted from any one of these three apparently unrelated bacterial species.1 With routine diagnostic technics little or no cross-reaction is demonstrable between the pneumococcus and certain wild yeasts. Such tests give no hint of the well confirmed fact that oral administration of certain yeast extracts functions as a fairly efficient quasi-specific prophylactic immuniz-

Polyploidy within a Species

THE importance of taking chromosome characters into consideration in the study of genetical problems is becoming increasingly more apparent, particularly in relation to the species problem, and any peculiarity in this respect requires careful attention. The study of large genera and of the occurrence of polyploidy within their limits, as exemplified by Rosa and other genera, has thrown considerable light on the origin and interrelationships of the various species. In investigating Silene and the neighbouring genera from this point of view, the actual base number of chromosomes is itself of considerable interest, since in Saponaria and Dianthus it may be 14 or 15, whereas in Silene, etc., it is invariably 12. So far, however it is these latter genera, Silene, Melandrium, Lychnis, etc., which have chiefly occupied my attention, and it appeared, at first, as if the question of polyploidy scarcely arose at all; even now, after the investigation of more than sixty species, only seven have been found to be other than diploid. Among these, however, one, Silene ciliata, has shown itself of such exceptional interest that it seemed to me worth while directing special attention to it. In the genus Silene, although more than thirty species have been examined, only two show polyploidy: of these S. vallesia is a normal tetraploid, whilst in the case of S. ciliata I have investigated two races, one of which is tetraploid and the other has a haploid count of 96 and is therefore 16-ploid. The plants of this latter race were perfectly normal in chromosome behaviour and fertile. The two races were obtained from different sources and both were quite typical, and this within a species which is somewhat variable.