Cytogeography of the genus Eremophila

1971 ◽  
Vol 19 (3) ◽  
pp. 295 ◽  
Author(s):  
BA Barlow
Keyword(s):  
Western Australia ◽  
Frequent Occurrence ◽  
Cell Physiology ◽  
Genetic Isolation ◽  
Ploidy Levels ◽  
Chromosome Races ◽  
Geographical Expansion ◽  
Land Surfaces ◽  
Diploid Populations

Polyploidy is of relatively frequent occurrence in Eremophila (x = 18). In 27 species examined karyologically from four or more localities, 13 were uniformly diploid, one was uniformly tetraploid, and 13 showed infraspecific polyploidy, diploid and/or tetraploid and/or hexaploid races being recorded. In most cases the chromosome races within a species have a pattern of geographical replacement. It is suggested that the formation of polyploid biotypes may lead to geographical expansion into new territory. Polyploidy may be effective in fixing adaptive recombinants near the margins of the diploid area, or may have direct adaptive effects on cell physiology. The ancient land surfaces of Western Australia appear to be a reservoir for relic diploid populations. In a few cases closely related entities which occur sympatrically have been found to be at different ploidy levels in the area of overlap. It is suggested that polyploidy in Eremophila has also facilitated the establishment of genetic isolation between differentiating biotypes.

The distribution and cytology of the chromosome races of Themeda australis in southern Australia

1960 ◽  
Vol 8 (1) ◽  
pp. 58 ◽  
Author(s):  
DL Hayman
Keyword(s):  
Chromosome Number ◽  
Western Australia ◽  
Polyploid Complex ◽  
Clear Pattern ◽  
Cytological Evidence ◽  
Native Flora ◽  
Chromosome Races ◽  
Close Relationship ◽  
Eastern Highlands ◽  
Diploid Populations

Thermeda australis (R.Br.) Stapf is a polyploid complex based on n = 10, and diploid, triploid, tetraploid, pentaploid, and hexaploid individuals have been found. Over 98 per cent. of more than 800 individuals examined were either diploid or tetraploid. Some 300 populations, from localities on the Australian mainland below the Tropic of Capricorn, were characterized by their chromosome number and a very clear pattern of distribution was found. Diploid populations occur exclusively on the Eastern Highlands and slopes in southern Victoria and in Tasmania; elsewhere tetraploid populations occur across to Western Australia. Triploid, pentaploid, and hexaploid plants are found as individuals in populations of another chromosome number. The cytological evidence shows a very close relationship to exist between the constituent genomes of the polyploids. The significance of the distribution of the chromosome races, the effects of polyploidy, and the implications of this pattern for further studies on the native flora are discussed.

Prehistory Down Under: archaeological investigations of submerged Aboriginal sites at Lake Jasper, Western Australia

Antiquity ◽  
1997 ◽  
Vol 71 (271) ◽  
pp. 116-123 ◽  
Author(s):  
Charles Dortch
Keyword(s):  
Western Australia ◽  
Field Studies ◽  
Archaeological Sites ◽  
Continental Margins ◽  
Land Surfaces

Much of Australian prehistory lies under water. Although confined to the continent's extreme southwestern corner, field studies described in this report show that this submerged prehistoric component is very real, with numerous archaeological sites and former land surfaces awaiting investigation on the floors of Australia's lakes, rivers and estuaries, and on its submerged continental margins.

Sex-Ratios in a Gynodioecious Plant Ptilotus obovatus (Gaudich) F-Muell (Amaranthaceae)

1987 ◽  
Vol 35 (6) ◽  
pp. 679 ◽  
Author(s):  
GC Kirby ◽  
BA Barlow ◽  
S Habel
Keyword(s):  
Western Australia ◽  
Sex Ratios ◽  
South Australia ◽  
Low Frequencies ◽  
Ploidy Levels ◽  
High Frequencies ◽  
South Wales ◽  
Perennial Shrub ◽  
Present Distribution ◽  
Tetraploid Cytotypes

Ptilotus obovatus is a gynodioecious perennial shrub with diploid and tetraploid cytotypes and is widespread in arid Australia. This study involved sex ratio counts in colonies of both cytotypes across much of the species range. Samples from diploid colonies had high frequencies of females (>55%) in Western Australia, low frequencies (<41%) in South Australia, and variable frequencies (36-77%) in southwestern Queensland. Tetraploid colonies had the opposite trend with low frequencies of females (<47%) in Western Australia and high frequencies (>54%) in the Northern Territory, South Australia and New South Wales. Ptilotus obovatus appears to be subdivided into at least five biotypes with distinct ploidy levels and sex ratios. We suggest that tetraploidy arose at least twice from diploid ancestors with different sex ratios and that the present distribution of cytotypes may reflect dispersal from refugia after recent arid maxima. The study of the genetics of male sterility in this species was impeded by the remarkably low seed set of plants in glasshouse crosses and in the field.

Wasp-Pollinated Species of Caladenia (Orchidaceae) in South-Western Australia

1983 ◽  
Vol 31 (4) ◽  
pp. 383 ◽  
Author(s):  
WP Stoutamire
Keyword(s):  
Western Australia ◽  
Food Advertising ◽  
Genetic Isolation ◽  
Limited Evidence ◽  
Flight Behaviour ◽  
Wasp Species ◽  
Pollination Mechanisms ◽  
Flower Form

Twelve of the 40 Caladenia species of Western Australia have been observed to attract male wasps (Tiphiidae; subfamily Thynninae) by visual and pheromonal mechanisms. Floral colours are predominantly combinations of green, cream and brown. Labella bear dark maroon tips or dark calli on the upper surface which are visual wasp equivalents. Glandular areas on perianth tips are demonstrated to be sources of sexual attractants in some species. Flower form and position are adjusted to the flight behaviour of the wasps. Each Caladenia species appears to attract and be pollinated by only one wasp species at the orchid site although there is limited evidence of geographic pollinator replacement in some species. Sexually attracting Caladenia species form occasional hybrids with food- advertising species. Divergent pollination mechanisms have not resulted in complete genetic isolation.

Malformación polínica y niveles de ploidía en Ranunculus grex parnassiifolius. Pollen malformation and ploidy levels in Ranunculus grex parnassiifolius

2011 ◽  
Vol 36 ◽  
pp. 145-158 ◽  
Author(s):  
Eduardo Cires ◽  
Candela Cuesta ◽  
María Ángeles Fernández Casado ◽  
María del Carmen Fernández-Carvajal ◽  
José Antonio Fernández Prieto
Keyword(s):  
Iberian Peninsula ◽  
Polyploid Complex ◽  
Ploidy Levels ◽  
Remarkable Result ◽  
Península Ibérica ◽  
Diploid Populations

Español.  Se presenta un estudio sobre la malformación polínica en Ranunculus grex parnassiifolius, un complejo poliploide cuya distribución va desde las montañas del noroeste de la Península Ibérica hasta la mayor parte de los macizos alpinos. El resultado más notable es la baja viabilidad de polen en las poblaciones tetraploides (85,27% de polen no viable) en comparación con las poblaciones diploides (17,72%); y se considera como una prueba de la existencia de procesos reproductivos parcialmente apomícticos.English.  Asurvey of pollen malformation in Ranunculus grex parnassiifolius, a polyploid complex distributed from the northwestern mountains of the Iberian Peninsula to the most alpine massifs, is presented. The most remarkable result is the low viability of pollen in tetraploid populations (85.27% of nonviable pollen) compared to diploid populations(17.72%); and is considered as a proof ofthe existence of partial reproductive apomictic processes.

scholarly journals Ecotypic differentiation of a circumpolar Arctic-alpine species at mid-latitudes: variations in the ploidy level and reproductive system of Vaccinium vitis-idaea

AoB Plants ◽  
2021 ◽  
Author(s):  
Akimi Wakui ◽  
Gaku Kudo
Keyword(s):  
Genetic Diversity ◽  
Ploidy Level ◽  
Leaf Size ◽  
Isolated Populations ◽  
Ploidy Levels ◽  
Ecotypic Differentiation ◽  
Alpine Species ◽  
Self Compatibility ◽  
Circumpolar Arctic ◽  
Diploid Populations

Abstract Although plant species originated from Arctic regions commonly grow in alpine habitats at mid-latitudes, some populations of these species exist also in some specific habitats below the treeline. Local populations at lower elevations may have different origins, ploidy levels, mating systems and/or morphological traits from alpine populations, but comparative studies between alpine and low-elevation populations are scarce. We aimed to reveal the ecological and genetic differentiations between higher and lower populations of Vaccinium vitis-idaea in Hokkaido, northern Japan by comparing 22 populations growing in diverse environments.We analyzed the ploidy level of individual populations using flow-cytometry. Genetic differentiation among populations, and genetic diversity within populations were calculated using microsatellite markers. Fruit and seed production were recorded under natural conditions, and a pollination experiment was conducted to reveal the variations in mating system across populations. Furthermore, we compared shoot growth and leaf characteristics among populations.Most of the low-elevation populations were tetraploid, whereas all but one of the alpine populations were diploid. Tetraploid populations were clearly differentiated from diploid populations. Some tetraploid populations formed huge clonal patches but genetic diversity was higher in tetraploids than diploids. Alpine diploids were self-incompatible and produced more seeds per fruit than tetraploid populations. In contrast, tetraploids showed high self-compatibility. Leaf size and foliar production were greater in tetraploid populations.Our results indicate that the genetic compositions of low-elevation tetraploid populations are different from those of alpine diploid populations. Most populations at lower elevations contained unique ecotypes suited to persistence in isolated situations. Local, low-elevation populations of typical alpine species maintain ecologically and genetically specific characteristics and could be valuable in terms of evolutionary and conservation biology. The present study demonstrates the biological importance of small and isolated populations at the edges of species distribution.

scholarly journals Strategies to breed sterile leucaena for Western Australia

2019 ◽  
Vol 7 (2) ◽  
pp. 80-86
Author(s):  
Daniel Real ◽  
Yong Han ◽  
C. Donovan Bailey ◽  
Saipriyaa Vasan ◽  
Chengdao Li ◽  
...  
Keyword(s):  
Western Australia ◽  
Leucaena Leucocephala ◽  
Gene Editing ◽  
Diploid Species ◽  
Agronomic Performance ◽  
Target Species ◽  
Ploidy Levels ◽  
Flowering Genes ◽  
Keynote Paper ◽  
Main Target

Keynote paper presented at the International Leucaena Conference, 1‒3 November 2018, Brisbane, Queensland, Australia.Strategies to breed sterile leucaena for Western Australia include plant breeding and biotechnology tools to generate sterile lines at both the tetraploid and triploid ploidy levels. For tetraploids, the main target species is the commercial Leucaena leucocephala, that is well known for its potential as a high-quality, productive and persistent forage. Gene editing technologies (CRISPR) will be utilized to edit out flowering genes and develop a non-flowering L. leucocephala. For triploids, the strategy is to cross tetraploid species (L. leucocephala and/or L. diversifolia) with diploid species to generate sterile triploid hybrids. The diploid parents will include species that have good forage attributes such as L. collinsii, L. macrophylla, L. shannonii and L. pulverulenta. Several of these triploid crosses have already been created by the Department of Primary Industries and Regional Development (Perth, Western Australia) and will be evaluated in the Kimberley and Pilbara regions of Western Australia for their agronomic performance and sterility. Vegetative propagation will be required for the tetraploid gene-edited non-flowering L. leucocephala. Triploids can either be vegetatively propagated, once generated, or generated via a seed production nursery.

scholarly journals Icelandic Birch Polyploids—The Case of a Perfect Fit in Genome Size

2010 ◽  
Vol 2010 ◽  
pp. 1-9 ◽  
Author(s):  
K. Anamthawat-Jónsson ◽  
Æ. Th. Thórsson ◽  
E. M. Temsch ◽  
J. Greilhuber
Keyword(s):  
Flow Cytometry ◽  
Genome Size ◽  
Interspecific Hybrids ◽  
Introgressive Hybridization ◽  
Frequent Occurrence ◽  
Ploidy Levels ◽  
Betula Nana ◽  
Dwarf Birch ◽  
Spring Leaf

Two birch species coexist in Iceland, dwarf birch Betula nana and tree birch B. pubescens. Both species are variable morphologically, which has been shown to be due to introgressive hybridization via interspecific hybrids. The aim of this study was to examine if the introgression could be related to genome size. We characterized 42 plants from Bifröst woodland morphologically and cytogenetically. The population consisted of diploid B. nana (38%), tetraploid B. pubescens (55%), and triploid hybrids (7%). Genome size was measured from 12 plants, using Feulgen DNA image densitometry (FDM) on spring leaf buds and flow cytometry (FCM) with dormant winter twigs. The use of winter twigs for FCM is novel. The average 1C-values for diploid, triploid, and tetraploid plants were 448, 666, and 882 Mbp, respectively. Monoploid genome sizes were found to be statistically constant among ploidy levels. This stability is in contrast to the different taxonomic positions of the di- and tetraploids and also contrasts with the frequent occurrence of genome downsizing in polyploids.

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