Chromosome Numbers in Characeae from the South Pacific
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This study of a total of 18 collections represents the first sampling of chromosome numbers in the charophytes from New Caledonia, Fiji, and Samoa. Chromosome counts were obtained for the first time for material of Lamprothamnium (Chara) succinctum, and the count supports the transfer to the genus Lamprothamnium. Chromosome counts consistent earlier reports are those of 14 for the dioecious taxa included in Chara corallina (Chara australis, Protochara australis, Chara fulgens) by Wood, and 18 for Nitella acuminata. Not in accord some earlier reportS are the counts of 18 for Nitella hyalina, 18 for Nitella pseudoflabellata (including N. mathuata), 18 for Nitella furcata, and 28 for Chara fibrosa. The presence of somatic pairing of chromosomes is noted in Chara fibrosa, and the extent and importance of polyploidy in the charophytes is recalled. THE EXTENSIVE COLLECTIONS of charophytes made by Dr. R. D. Wood during the course of an expedition ranging from Australia to New Zealand and islands of the South Pacific in 196061 will form an important basis for studies on the Characeae of these regions. As already reported (Wood, 1962b) the collections include plant specimens gathered and preserved especially for cytological examination. These the writer was privileged to receive, together the accompanying field notes and identifications which follow the revision of the group by Wood (1962a). This paper, the first in a series to record the chromosome numbers and related cytological findings in the Wood collections, is concerned the plants from New Caledonia, Fiji, and Samoa, and is concurrent detailed taxonomic treatments of these plants by Wood (1963, 1965). Although the present paper is complementary in nature no attempt has been made to support all the taxonomic conclusions in Wood's revision of the Characeae. PLANT MATERIALS AND METHODS For the cytological studies, fertile plants growing tips bearing young stages of gametangial development were selected and fixed in the field. In dioecious species only the male plants are required for the young antheridia used in making chromosome counts. Fixation freshly prepared acetic-alcohol was done in the usual manner. The specimens were then transferred to 70% ethanol and shipped in sealed vials by airmail to Louisville, where they were stored under refrigeration. Chromosome counts were made from mitoses found in squashed preparations of filaments dissected from the antheridia and stained aceto-orcein. Usually a series of preparations were needed before a count could be determined certainty. Drawings were made with the aid of-a'camera lucida. Four vials of specimens were received from New Caledonia, 12 from Fiji, and 1 from Samoa, each of which yielded chromosome counts. All these specimens and the permanent slides of chromosome preparations made from them are in the Herbarium of the University of Louisville; other parts of these collections are deposited elsewhere (Wood, 1962b). The collection data listed below include the notes supplied by Dr. Wood as to dates, localities, ecology, and collecting numbers. The cytology collection numbers (CYT) were included the notes and on the cork stoppers of the 1 This study was supported in part by the National Science Foundation. Manuscript received August 29, 1963. 2 Department of Biology, University of Louisville, Louisville, Kentucky.Keywords:
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Chromosome numbers were determined for five species of Nitella and five species of Chara representing 27 naturally occurring populations. Chromosome counts were as follows: Nitella mirabilis, n=6; N. flexilis, n=12; N. acuminata, n=18; N. axillaris, n=18; N. oligospira, n=18; Chara braunji, n=14; C. contraria, n=42; C. globularis, n = 28; C. foliosa, n = 14; and C. haitensis, n = 42. Relationships among these and similar forms reported from elsewhere in North America are discussed. INTRODUCTION Several authors have reported dhromosome numbers for species of Characeae in North America (Hotchkiss, 1958, 1963; Tindall and Sawa, 1964; Griffin and Proctor, 1964; Tindall et al., 1965; Sawa, 1965, 1966; Tindall, 1966, 1967, 1970; Proctor, 1970, 1971a, 1971b; Proctor and Wiman, 1971; Proctor et at., 1971; Grant and Proctor, 1972). Reports of chromosome numbersfor species of Characeae occurring in other countries are reviewed by Guerlesquin (1966) and Corillion and Guerlesquin (1972). The importance of polyploidy, intraspecific barriers to gene flow, minor ecological differences and geographical distribution in relation to speciation in the Characeae are stressed in several of the above reports. These studies have shown that knowledge of chromosome number is quite useful in resolving taxonomic problems and in clarifying distribution patterns for some species complexes. The present study was carried out to determine relationships between species occurring in southern Illinois and those previously reported from elsewhere in North America. Previous work on the taxonomy of the Characeae of Illinois was reviewed by Stotler (1968). MATERIALS AND METHODS Twenty-seven naturally occurring populations of Characeae in southern Illinois were examined. These populations represented five species of Nitella and five species of Chara. All collections consisted of cvtological sDecimens and voucher specimens. Cytological material for Nitella flexilis was obtained from culture of the field collection. Cytological material was fixed in an absolute ethanol-glacial acetic acid (i3: 1) solution for '24 h. Following fixation, cytological specimens were stored in 70% ethanol at 5 C until examined. Antheridial filaments were dissected from immature antheridia and were squashed and stained with aceto-carmine. No attempt was made to standardize the fixing and staining procedure for determining chromosome morL Current address: School of Medicine, Southern Illinois University, Carbondale 62901.
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AbstractChara is an interesting genus from cytologicalview has been extensively worked out inEurope and North America, but there is a few reportson Asian Charophytes. Chromosome numberwere determined for 10 species of Charafrom 33 populations. Chromosome counts wereas follows: C. connivens, n=14, C. contraria, n=28; C. crassicaulis, n=21; Chara gymnophyllavar. gymnophylla, n=14; Chara gymnophyllavar. rohlenae, n=14; C. kirghisorum, n=14; C.kohrangiana, n=21, C. socotrensioides, n=14;C. tomentosa, n=14; Chara vulgaris var. longibracteata,n=28 and Chara vulgaris var. vulgaris,n=28. Authors made cytological studiesof Iranian charophytes in twelve taxa which 10taxa are new for Iran and five taxa are new forscience.
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The chromosome numbers of 31 species of Angiospermae collected in S. Brazil were determined. Of these species 5 were studied before, the other numbers are new, 11 are first counts for genera and one even for a family. Some notes on the cytology and morphology are added.
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:Over the course of a 25 year ecological and taxonomic study, the chromosomes of Australian charophytes (family Characeae) were examined and enumerated. The usual number for members of Chara was n = 14 (for dioecious species) or n = 28 (for monoecious species); although Chara braunii has always been recorded as having n = 14 despite being monoecious. Species in sections Agardhia and Grovesia often had higher ploidy levels [n = 3 × 14 (42), n = 4 × 14 (56)]. The usual number for Australian members of Nitella was n = 9 (for dioecous species) and n = 18, 24 or 27 for monoecious species. Nitella stuartii was an exception, having n =15 in the specimens studied here. The usual number for monoecious members of Lamprothamnium was n = 28; although, monoecious Lamprothamnium inflatum consistently had n = 14 (populations from Western Australia, Kangaroo Island and South Australia). Chromosome numbers were different for each species of Tolypella examined (n = 11 to 36). There was a high degree of polyploidy within Characeae, and there was evidence that even the lowest numbers of chromosomes represented polyploids (3n for Nitella and 2n for Chara). Polyploidy and consequent doubling or tripling of enzymatic capacity (via potential multiple isozymes) is likely to have a role in the morphological variability and biochemical flexibility of charophytes. Information about the number and appearance of chromosomes (karyotypes) can be used in systematic studies to determine relatedness of taxa and to understand some of the evolutionary processes operating at the population or species level.
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SUMMARYThe present communication deals with a discussion on the significance of chromosome numbers in Charophyta. After presenting a brief review of the various views held on the basic chromosome numbers in the taxa of Chara, Nitella and Tolypella, the role of polyploidy in the evolution of Charophyta and the possible ways in which polyploid taxa might have originated in nature have been considered. On the basis of present evidences aneuploids seem to show restricted geographical distribution as compared to euploids. Maximum degree of polyploidy has been found to be prevalent in Chara zeylanica within the tribe Chareae and Nitella tenuissima and Nitella furcata within the tribe Nitelleae. Significance of polyploidy in relation to sex, taxonomy, external form, chromosome length, pH, and altitude has also been discussed with some specific examples.
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B eaman , J. H. (Michigan State U., East Lansing), D. C. D. D e J ong , and W. P. S toutamire . Chromosome studies in the alpine and subalpine floras of Mexico and Guatemala. Amer. Jour. Bot. 49(1): 41–50. Illus. 1962.—Chromosome counts of 101 collections representing 69 species in 42 genera and 22 families have been obtained. Counts are reported for the first time in 59 species and 2 genera ( Oreobroma and Villadia ). Counts establishing new basic numbers were found in Draba, Lithospermum , and possibly in Arenaria. Where pertinent, the chromosomal data are related to previous taxonomic or chromosomal investigations. Chromosome numbers are now known in nearly half of the species in the alpine flora of Mexico.
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