Intercontinental differentiation in Medicago rigidula

1990 ◽  
Vol 68 (12) ◽  
pp. 2607-2613 ◽  
Author(s):  
Ernest Small ◽  
Brenda Brookes ◽  
Eric J. Crawford
Keyword(s):  
Chromosome Number ◽  
North Africa ◽  
Separate Species ◽  
Spine Morphology ◽  
Medicago Rigidula

European and Asian plants assignable to Medicago rigidula (L.) All., as this species is currently interpreted, were found to differ morphologically. Indeed, a combination of morphological, geographical, and interbreeding evidence supports the recognition of the European and Asian plants presently interpreted as M. rigidula as separate species. The best characters for distinguishing plants of the two continents are number of pollen pores (pollen consistently 3-pored in European plants, and consistently 4-pored in Asian plants), number of coils in the pod (averaging 4.5 in European plants, 5.5 in Asian), and fruit spine morphology (usually more hooked and longer in European compared to Asian plants). Plants of North Africa require further study, but the specimens examined were generally closer to European than to Asian plants. The chromosome number of 28 Asian collections, 24 European collections, and 3 African collections was constant, with n = 7.

Adaptation of Medicago rigidula to a cereal–pasture rotation in north-west Syria

1986 ◽  
Vol 107 (1) ◽  
pp. 179-186 ◽  
Author(s):  
A. M. Abd El-Moneim ◽  
P. S. Cocks
Keyword(s):  
North Africa ◽  
Farming System ◽  
Livestock Production ◽  
Grazing Management ◽  
North West ◽  
Selection Programme ◽  
Ley Farming ◽  
Medicago Rigidula ◽  
Subsequent Regeneration

SUMMARYThe ley-farming system (integrated cereal and livestock production in which cerealsrotate with self-regenerating pastures) is considered to be of great potential benefit to north Africa and west Asia. In the colder parts of this region (of which north Syria is typical) its application is limited by poor adaptation of commercial medic cultivars (mainly Medicago truncatula and M. littoralis). An extended selection programme hag identified M. rigidula as adapted to the soils and climate of the region but nothing is known of its adaptation to the ley-farming system itself.An experiment which included 23 selections of M. rigidula and one each of M. rotata and M. noeana was conducted over 3 years during which herbage production, seed yield, and the fate of seeds were observed during the 1st year when pastures were established, the 2nd year when wheat was sown, and the 3rd year when the pasture regenerated. Of the 400–800 kg seed/ha produced in the 1st year an average of 87% remained in the soil in spring of the 3rd year. The weight of seed regenerating in the 3rd year varied from 30 to nearly 170 kg/ha, and herbage production, especially in winter, depended heavily on the number of regenerating seedlings. The most productive regenerating pastures produced nearly 2 t/ha of dried herbage by 1 January, and more than 6 t/ha for the whole growing season.The results showed that there was sufficient residual and newly produced seed at the end of the 3rd year to be sure that subsequent regeneration would result in similar herbage yields in the 5th year, and that the pasture was assured of long-term persistence. The significance of this for livestock production is discussed, and it is concluded that the results should encourage further investigation of grazing management and socioeconomic factors seen as constraints to introducing the ley-farming system to north Syria.

Cytological studies of subterranean clover (Trifolium subterraneum L.)

1952 ◽  
Vol 3 (3) ◽  
pp. 300 ◽  
Author(s):  
JJ Yates ◽  
NH Brittan
Keyword(s):  
Chromosome Number ◽  
Somatic Chromosome ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
The Other ◽  
Vicia Sativa ◽  
Somatic Chromosome Number ◽  
Separate Species ◽  
Apparent Relationship ◽  
Isolated Species

Somatic chromosome number and morphology in certain strains of subterranean clover and in species of several other fairly closely related genera have been observed. Dwalganup, Yarloop, Mt. Barker, Wenigup, Burnerang, and Red Leaf strains have each 16 fairly small chromosomes, the chromosome complexes being similar to one another and to that obtained by Wexelsen (1928) for the species. Palestine and Israel strains have each 12 large chromosomes, bearing no apparent relationship to those of the other strains but being the same in number and of a similar order of size to those found in Vicia sativa. Chromosome number and morphology may explain the failure to obtain intervarietal crosses involving Palestine, but not the low percentage of successful crosses between other strains. It is suggested that perhaps Palestine and Israel may be more correctly classed as strains of a separate species and that, with regard to their origin, Wexelsen's idea of mutational changes in isolated species offers probably the best explanation.

Taxonomy of Rock Wallabies, Petrogale (Marsupialia, Macropodidae) .1. A Revision of the Eastern Petrogale With the Description of 3 New Species

1992 ◽  
Vol 40 (6) ◽  
pp. 605 ◽  
Author(s):  
MDB Eldridge ◽  
RL Close
Keyword(s):  
New Species ◽  
Gene Flow ◽  
Chromosome Number ◽  
Cryptic Species ◽  
Genetic Identity ◽  
Separate Species ◽  
Species Definition ◽  
Chromosome Races ◽  
Primary Means ◽  
Cape York

The taxonomy of Petrogale has been in a state of flux for many years. The eight chromosome races of the eastern Petrogale radiation are currently placed in four species. However, several of these 'species' contain chromosomally unrelated taxa. In this paper a species definition for Petrogale is proposed that allows for some gene flow between species but requires a species to maintain a substantial and distinct genetic identity. When this definition was applied to the eastern Petrogale eight 'good' species were identified. Thus we now consider the eastern Petrogale complex to consist of P. penicillata, P. herberti (formerly P. penicillata herberti), P. inornata, P. assimilis, P. sharmani, sp. nov. (formerly the Mt Claro race), P. mareeba, sp. nov. (formerly the Mareeba race), P. godmani and P. coenensis, sp. nov. (formerly the Cape York race). Several of these taxa are cryptic species and the primary means of identification used was chromosome number and morphology. However, genic data were useful in establishing whether each taxon should be regarded as a separate species.

Taxonomic studies in Avena abyssinica and A. vaviloviana, and some related species

1971 ◽  
Vol 49 (12) ◽  
pp. 2227-2232 ◽  
Author(s):  
Bernard R. Baum
Keyword(s):  
Chromosome Number ◽  
Morphological Markers ◽  
Separate Species ◽  
Good Marker ◽  
The Past ◽  
Cytological Data ◽  
Close Relationship ◽  
The Status ◽  
The Many ◽  
Taxonomic Studies

This paper reports the use of micromorphologic attributes taken from the lodicules, epiblasts, and disarticulating scars for purposes of circumscription of the taxa associated with the names A. abyssinica and A. vaviloviana and their F1 hybrids, and also A. barbata. Furthermore it is shown that the epiblast can serve as a good marker to distinguish between the hexaploid A. byzantina and the tetraploid A. abyssinica, especially for those cases where previously only the chromosome number could have served this purpose. From the micromorphological findings, some cytological data, and plant distributional data, the author decided to regard A. abyssinica, A. barbata, and A. vaviloviana as separate species. The status of these species in previous classifications is compared with that proposed here. The many different classifications used in the past are attributed to the fact that no reliable diagnostic morphological markers were discovered by previous workers. A connection was discovered between A. occidentalis of the Canary Islands and the tetraploid abyssinian oats and a close relationship in this vicarious group is speculated.

Cytological studies on the specific distinctness of the ovine and bovine 'Strains' of the Nematode Haemonchus Contortus (Rudolphi) cobb (NematodaL Trichostrongylidae)

1955 ◽  
Vol 3 (3) ◽  
pp. 312 ◽  
Author(s):  
KC Bremner
Keyword(s):  
Chromosome Number ◽  
Host Specificity ◽  
Haemonchus Contortus ◽  
Distinct Species ◽  
Breeding Experiment ◽  
Separate Species ◽  
X Chromosomes ◽  
Cross Breeding ◽  
Mixed Infestation

The studies reported here follow the conclusions of Roberts, Turner, and McKevett (1954) that the ovine and bovine "strains" of Haemonchus contortus (Rudolphi 1803) Cobb 1898 are distinct species. The cytology of the two forms has been investigated and it was found that the chromosome number for each form was 2n = 11 (B), 12 (@). The autosomes of each form measure 3� in length and, whereas the X-chromosomes of the worms from sheep are similar in size to the autosomes, the X-chromsomes of the worms from cattle attain a size of 8�. Fertile hybrid females were obtained in a cross-breeding experiment and were also seen in a natural, mixed infestation. These, however, appeared in only small numbers and, furthermore, as they were never seen in animals with pure infestations as judged by the type of larva, it seemed evident that some fertility barrier is present. Some discussion is given to the host specificity of the two forms and further evidence is brought forward to support previous conclusions that some degree of host specificity is present. It is concluded that the restricted degree of interbreeding encountered, together with considerations of host specificity, support the claims of Roberts, Turner, and McKevett (1954) that the two forms are separate species.

A preliminary analysis of phylogenetic relationships and biogeography of the dangerously venomous Carpet Vipers, Echis (Squamata, Serpentes, Viperidae) based on mitochondrial DNA sequences

2009 ◽  
Vol 30 (2) ◽  
pp. 273-282 ◽  
Author(s):  
Michael Robinson ◽  
Nicholas Arnold ◽  
Salvador Carranza
Keyword(s):  
Mitochondrial Dna ◽  
North Africa ◽  
Dna Sequences ◽  
Preliminary Analysis ◽  
Climatic Changes ◽  
Species Status ◽  
Separate Species ◽  
Late Pliocene ◽  
The North ◽  
Oman Mountains

AbstractPhylogenetic analysis of 1117 bp of mitochondrial DNA sequences (731 bp of cytochrome b and 386 bp of 16S rRNA) indicate that Echis consists of four main clades: E. ocellatus, and the E. coloratus, E. pyramidum, and E. carinatus groups. In the E. coloratus group, E. coloratus itself shows substantial genetic divergence from E. omanensis, corroborating their separate species status. In the E. pyramidum clade, E. pyramidum from Egypt and E. leucogaster from West Africa are genetically very similar, even though samples are separated by 4000 km. South Arabian populations of the E. pyramidum group are much better differentiated from these and two species may be present, animals from Dhofar, southern Oman probably being referable to E. khosatzkii. In the E. carinatus group, specimens of E. carinatus sochureki and E. multisquamatus are very similar in their DNA. The phylogeny indicates that the split between the main groups of Echis was followed by separation of African and Arabian members of the E. pyramidum group, and of E. coloratus and E. omanensis. The last disjunction probably took place at the lowlands that run southwest of the North Oman mountains, which are likely to have been intermittently covered by marine incursions; they also separate the E. pyramidum and E. carinatus groups and several sister taxa of other reptiles. The E. carinatus group may have spread quite recently from North Oman into its very extensive southwest Asian range, and there appears to have been similar expansion of E. pyramidum (including E. leucogaster) in North Africa. Both these events are likely to be associated with the marked climatic changes of the Pleistocene or late Pliocene. Similar dramatic expansions have also recently occurred in three snake species in Iberia.

Contribution to the caryological study of the African grass Aristida rhiniochloa Hochst., based on specimens from the Southern Hemisphere

Bothalia ◽  
1972 ◽  
Vol 10 (4) ◽  
pp. 555-5564 ◽  
Author(s):  
Pierre Bourreil ◽  
Alain Geslot ◽  
Monique Gorlier ◽  
Bernard De Winter
Keyword(s):  
Chromosome Number ◽  
Southern Hemisphere ◽  
North Africa ◽  
Diploid Number ◽  
Diploid Species ◽  
Basic Number ◽  
Meiotic Behaviour ◽  
African Grass ◽  
Haploid Complement

The chromosome number established for Aristida rhiniochloa Hochst. by the study of material from three localities in the Southern Hemisphere confirms the results obtained on material from North Africa. The haploid complement (n = 11) and the diploid number (2n = 22) of this species conform to the basic number x = 11 typical for the Aristideae. It is shown that the caryotype of this species is sub-symmetrical. Preliminary studies o f material from two localities show that the meiotic behaviour conforms to that found in the diploid species with n bivalents.

Karyotype analysis of medicinal plant Liriope spicata var. prolifera (Liliaceae)

Biologia ◽  
2009 ◽  
Vol 64 (4) ◽  
Author(s):  
Qun Zhou ◽  
Jianqiu Zhou ◽  
Jiachun Chen ◽  
Xiaogang Wang
Keyword(s):  
Chromosome Number ◽  
Medicinal Plant ◽  
Endemic Species ◽  
Secondary Constriction ◽  
Karyotype Analysis ◽  
Basic Chromosome Number ◽  
Separate Species ◽  
Basic Chromosome ◽  
First Time

AbstractKaryotype of Liriope spicata var. prolifera, a Chinese endemic species, was described in detail for the first time. Its proto-variety L. spicata was also investigated for comparison. The basic chromosome number of these two species was x = 18. L. spicata var. prolifera, recorded as triploid 2n = 54, consisted of 30 metacentric chromosomes and 24 submetacentric chromosomes. Only one chromosome of the 11th group had a secondary constriction with a satellite in the short arm. L. Spicata was tetraploid 2n = 72 and consisted of four sets of 6 submetacentric chromosomes and 12 metacentric chromosomes without visible satellites. This paper provides further available data on Liriope chromosomes, and also indicates that L. spicata var. prolifera and L. spicata are probably separate species.

Infra-specific Variations ofSchistosoma haematobium

1971 ◽  
Vol 45 (4) ◽  
pp. 403-413 ◽  
Author(s):  
G. Webbe ◽  
C. James
Keyword(s):  
North Africa ◽  
Schistosoma Haematobium ◽  
Species Group ◽  
Separate Species ◽  
Species Groups ◽  
Different Strains ◽  
Respective Species

The varying susceptibility of local races of bulinid snails to different strains ofSchistosoma haematobiumhas been recorded by many workers including Le Roux, 1954; Cridland, 1955, 1957; McCullough, 1957, 1962; Wright, 1962, 1963; Cowper, 1963; Pitchford, 1965 and Paperna, 1968. The respective species groups of snails referred to are those created by Mandahl-Barth (1958). As a result of his experiments Le Roux (1958) suggested that there are two separate species of parasite, the form transmitted in North Africa by thetruncatesgroup of snails being known asS. haematobiumand that developing in Africa south of the Sahara in theafricanusspecies group asS. capense(Harley, 1864), a view which has been supported by many workers.

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