Cytotaxonomic observations on Villarsia (Menyanthaceae)

1974 ◽  
Vol 22 (3) ◽  
pp. 513 ◽  
Author(s):  
R Ornduff
Keyword(s):  
Indian Ocean ◽  
Distribution Pattern ◽  
South African ◽  
Seed Size ◽  
Ploidy Level ◽  
Climatic Conditions ◽  
Long Distance Dispersal ◽  
Chromosome Counts ◽  
Long Distance ◽  
Australian Species

Chromosome counts for five species of Villarsia indicate that x = 9 for the genus. In Australia one species is diploid, two species are hexaploid, and one species has tetraploid and hexaploid races. The South African V. capensis is tetraploid. Seed size differences in V. reniformis are not correlated with differences in ploidy level. One Australian species and V. capensis are distylous and strongly self-incompatible. Two homostylous species in Australia are self-compatible, but V. albiflora is homostylous and self-incompatible. Villarsia capensis is morphologically variable, but seems closely related to eastern Australian species. The amphi-Indian Ocean distribution pattern exhibited by this genus is an unusual one, and it seems doubtful if it can be accounted for by long-distance dispersal. The present range was perhaps achieved at a time when continental positions and climatic conditions were more favourable for overland migration than they are at present.

A cytotaxonomic survey of the Pteridophyta of Australia

2002 ◽  
Vol 15 (6) ◽  
pp. 839 ◽  
Author(s):  
Mary D. Tindale ◽  
S. K. Roy
Keyword(s):  
Ploidy Level ◽  
New Combination ◽  
Chromosome Counts ◽  
Ploidy Levels ◽  
Australian Species ◽  
Number Of Species ◽  
Lord Howe Island ◽  
Species Complexes ◽  
Living Material ◽  
First Time

A cytotaxonomic survey of the ferns and fern allies of Australia (including Lord Howe Island) is presented. Five-hundred-and-twenty-six chromosome counts of 268 Australian species, subspecies, varieties, variants and hybrids are recorded, only a small number having been previously investigated by other botanists on Australian material. Diploids represent c. 62% of the counts on species and c. 38% on polyploids, the latter ranging principally from triploids to a single decaploid and dodecaploid (but no heptaploids). More than one ploidy level has been reported in 19 taxa (almost 8% of taxa). Counts of 10x for Asplenium aethiopicum and 12x for A.�flabellifolium are the highest definite ploidy levels for the Australian pteridophyte flora. Chromosome counts for 29 families and 89 genera are cited. Only diploids were reported for Osmundaceae and Cyatheaceae, but only polyploids for the Psilotaceae, Vittariaceae and Ophioglossaceae. An analysis is given of the levels of ploidy in 248 taxa, excluding the Lycopodiaceae and Hymenophyllaceae. The percentages of diploids and polyploids in Australian species are compared with those of nearby countries. Many species reported on here have never been cytologically investigated before, while others have not been studied previously on Australian material. The following genera have been examined cytologically for the first time: Coveniella Tindale, n = 41; Paraceterach (F.Muell.) Copel., n = 29; 'Oenotrichia Copel.', 2n = 82 (2x); Revwattsia (Watts) D.L.Jones, 2n = c. 328 (8x); and Pteridoblechnum Hennipman (2n = 54). The phylogeny of the genera is discussed in the light of these findings. Certain families such as the Adiantaceae, Cyatheaceae, Hymenophyllaceae, Lindsaeaceae and Marsileaceae were given special attention by collecting as much living material as possible. A number of species-complexes has been found and further chromosome counts added to intercontinental species complexes. The Döpp-Manton and Braithwaite forms of reproductive apomixis have been reported amongst some genera. Endemism, hybridity and apogamy amongst Australian pteridophytes are discussed, as well as homosporous and heterosporous species. The new combination Phymatosorus membranifolius (R.Br.) Tindale is made.

scholarly journals Phylogeny and Biogeography of Exacum (Gentianaceae): A Disjunctive Distribution in the Indian Ocean Basin Resulted from Long Distance Dispersal and Extensive Radiation

2005 ◽  
Vol 54 (1) ◽  
pp. 21-34 ◽  
Author(s):  
Yong-Ming Yuan ◽  
Sébastien Wohlhauser ◽  
Michael Möller ◽  
Jens Klackenberg ◽  
Martin W. Callmander ◽  
...  
Keyword(s):  
Indian Ocean ◽  
Ocean Basin ◽  
Long Distance Dispersal ◽  
Long Distance ◽  
The Indian Ocean

scholarly journals Annual variation in long-distance dispersal driven by breeding and non-breeding season climatic conditions in a migratory bird

Ecography ◽  
2015 ◽  
Vol 38 (10) ◽  
pp. 1006-1014 ◽  
Author(s):  
Clark S. Rushing ◽  
Michele R. Dudash ◽  
Colin E. Studds ◽  
Peter P. Marra
Keyword(s):  
Breeding Season ◽  
Annual Variation ◽  
Migratory Bird ◽  
Climatic Conditions ◽  
Long Distance Dispersal ◽  
Long Distance

Abiotic pollination: an evolutionary escape for animal-pollinated angiosperms

1991 ◽  
Vol 333 (1267) ◽  
pp. 217-224 ◽  
Keyword(s):  
Sexual Selection ◽  
Climatic Conditions ◽  
Long Distance Dispersal ◽  
Long Distance ◽  
Growing Seasons ◽  
Phylogenetic Profiles ◽  
Abiotic Pollination ◽  
Pollination Systems ◽  
Animal Pollination ◽  
Surprising Fact

Early botanists considered abiotic pollination to be primitive in angiosperms. But we now deduce from studies of palaeoecology and of extant ‘prim itive’ angiosperms that animal pollination was concom itant with the rise of the angiosperms. Recent studies of wind and w ater pollination in angiosperms also show these systems to be highly sophisticated. If entomophily contributed to the rise of the early angiosperms, why should many of their descendants have later evolved abiotic pollination systems? Although entomophily was initially advantageous to the early angiosperms, abiotic pollination systems may be superior in areas of low species diversity, newly colonized habitats, and places with extremely short growing seasons or other adverse climatic conditions. Abiotically pollinated plants are not constrained by the range of animal pollinators, and as a result are spectacularly successful in long-distance dispersal. Abiotic pollination also offers an escape from deleterious sexual selection and from dependency on pollinators that are climatically limited in their distribution in space or time and vulnerable to extinction. Because evolution of abiotic pollination frequently leads to dicliny or dichogamy, it is largely irreversible. This evolutionary irreversibility coupled with lowered rates of extinction and speciation give wind- or water-pollinated taxa unique phylogenetic profiles. As a large quantity of pollen is wasted by anemophilous plants, it is surprising that so many vigorous species of this kind abounding with individuals should still exist in any part of the w orld; for if they had been rendered entomophilous, their pollen would have been transported by the aid of the senses and appetites of insects with incomparably greater safety than by the w ind... It seems at first sight a still more surprising fact that plants, after having been once rendered entomophilous, should ever have again become anemophilous. (Darwin 1876, p. 407)

scholarly journals Back to Gondwanaland: can ancient vicariance explain (some) Indian Ocean disjunct plant distributions?

2015 ◽  
Vol 11 (6) ◽  
pp. 20150086 ◽  
Author(s):  
Michael D. Pirie ◽  
Glenn Litsios ◽  
Dirk U. Bellstedt ◽  
Nicolas Salamin ◽  
Jonathan Kissling
Keyword(s):  
Indian Ocean ◽  
Paradigm Shift ◽  
Indian Subcontinent ◽  
Continental Drift ◽  
Molecular Dating ◽  
Long Distance Dispersal ◽  
Long Distance ◽  
Strong Assumption ◽  
Plant Groups ◽  
Age Constraints

Oceans, or other wide expanses of inhospitable environment, interrupt present day distributions of many plant groups. Using molecular dating techniques, generally incorporating fossil evidence, we can estimate when such distributions originated. Numerous dating analyses have recently precipitated a paradigm shift in the general explanations for the phenomenon, away from older geological causes, such as continental drift, in favour of more recent, long-distance dispersal (LDD). For example, the ‘Gondwanan vicariance’ scenario has been dismissed in various studies of Indian Ocean disjunct distributions. We used the gentian tribe Exaceae to reassess this scenario using molecular dating with minimum (fossil), maximum (geological), secondary (from wider analyses) and hypothesis-driven age constraints. Our results indicate that ancient vicariance cannot be ruled out as an explanation for the early origins of Exaceae across Africa, Madagascar and the Indian subcontinent unless a strong assumption is made about the maximum age of Gentianales. However, both the Gondwanan scenario and the available evidence suggest that there were also several, more recent, intercontinental dispersals during the diversification of the group.

scholarly journals The repeated evolution of large seeds on islands

2014 ◽  
Vol 281 (1786) ◽  
pp. 20140675 ◽  
Author(s):  
Patrick H. Kavanagh ◽  
Kevin C. Burns
Keyword(s):  
Seed Size ◽  
Evolutionary History ◽  
Growth Form ◽  
Plant Traits ◽  
General Tendency ◽  
Long Distance Dispersal ◽  
Long Distance ◽  
Dispersal Mode ◽  
Evolutionary Pathway ◽  
Repeated Evolution

Several plant traits are known to evolve in predictable ways on islands. For example, herbaceous species often evolve to become woody and species frequently evolve larger leaves, regardless of growth form. However, our understanding of how seed sizes might evolve on islands lags far behind other plant traits. Here, we conduct the first test for macroevolutionary patterns of seed size on islands. We tested for differences in seed size between 40 island–mainland taxonomic pairings from four island groups surrounding New Zealand. Seed size data were collected in the field and then augmented by published seed descriptions to produce a more comprehensive dataset. Seed sizes of insular plants were consistently larger than mainland relatives, even after accounting for differences in growth form, dispersal mode and evolutionary history. Selection may favour seed size increases on islands to reduce dispersibility, as long-distance dispersal may result in propagule mortality at sea. Alternatively, larger seeds tend to generate larger seedlings, which are more likely to establish and outcompete neighbours. Our results indicate there is a general tendency for the evolution of large seeds on islands, but the mechanisms responsible for this evolutionary pathway have yet to be fully resolved.

An expanded molecular phylogeny of the southern bluebells (Wahlenbergia, Campanulaceae) from Australia and New Zealand

2012 ◽  
Vol 25 (1) ◽  
pp. 11 ◽  
Author(s):  
Jessica M. Prebble ◽  
Heidi M. Meudt ◽  
Phil J. Garnock-Jones
Keyword(s):  
New Zealand ◽  
Dna Markers ◽  
Long Distance Dispersal ◽  
Long Distance ◽  
Australian Species ◽  
Chloroplast Markers ◽  
Its Regions ◽  
Variable Species ◽  
Low Levels ◽  
Chloroplast Dna Markers

We used nuclear and chloroplast DNA markers to examine relationships and test the current morphology-based taxonomy of several species and subspecies of Australian and New Zealand Wahlenbergia. We sampled nuclear ribosomal ITS regions and the chloroplast regions trnL–F and trnK–psbA from 105 individuals, representing 29 of the 46 species and subspecies currently recognised in New Zealand and Australia. Our phylogeny was incompletely resolved because of low levels of genetic variation in all three markers and some conflict between ITS and chloroplast markers. The New Zealand rhizomatous species appear to have radiated in New Zealand after a single long-distance dispersal event from Australia, but it is unclear to which species in Australia they are most closely related. The New Zealand radicate species do not form a clade; instead they are shown to be very closely related to many Australian radicate species. The four species in the New Zealand lowland radicate W. gracilis complex may all belong to the same morphologically variable species. In contrast, the other New Zealand radicate species, W. vernicosa, is probably a separately evolving lineage, and is not conspecific with the W. gracilis complex, nor the Australian W. littoricola, as previously hypothesised. Two of the New Zealand rhizomatous species, W. albomarginata and W. pygmaea, may be conspecific. By contrast, the morphologically distinctive New Zealand rhizomatous W. cartilaginea, W. matthewsii and W. congesta subsp. haastii each formed monophyletic groups. Samples of two recently described Australian species (W. rupicola and W. telfordii) formed monophyletic groups consistent with their recognition.

Phylogenetic placement and the timing of diversification in Australia’s endemic Vachellia (Caesalpinioideae, Mimosoid Clade, Fabaceae) species

2020 ◽  
Vol 33 (1) ◽  
pp. 103
Author(s):  
D. F. Comben ◽  
G. A. McCulloch ◽  
G. K. Brown ◽  
G. H. Walter
Keyword(s):  
Biological Control ◽  
Molecular Dating ◽  
Long Distance Dispersal ◽  
Monophyletic Clade ◽  
Long Distance ◽  
Australian Species ◽  
Phylogenetic Placement ◽  
Evolutionary Origins ◽  
Species Being ◽  
Relaxed Molecular Clock

The genus Vachellia Wight & Arn. has a pantropical distribution, with species being distributed through Africa, the Americas, Asia and Australia. The relationships among the lineages from Africa and America are well understood, but the phylogenetic placement and evolutionary origins of the Australian species of Vachellia are not known. We, therefore, sequenced four plastid genes from representatives of each of the nine Australian species of Vachellia, and used Bayesian inference to assess the phylogenetic placement of these lineages, and a relaxed molecular clock to assess the timing of diversification. The Australian species of Vachellia form a well-supported monophyletic clade, with molecular-dating analysis suggesting a single dispersal into Australia 6.5 million years ago (95% range 13.9–2.7 million years ago). Diversification of the Australian clade commenced more recently, c. 3.1 million years ago (95% range 9.2–1.2 million years ago), perhaps driven by the increased aridification of Australia at this time. The closest relatives to the Australian Vachellia were not from the Malesian bioregion, suggesting either a long-distance dispersal from Africa, or two separate migrations through Asia. These results not only improve our understanding of the biogeography of Vachellia species, but also have significant implications for the biological control of invasive Vachellia species in Australia.

scholarly journals Climatic conditions for emergence and flight of mountain pine beetle: implications for long-distance dispersal

2017 ◽  
Vol 47 (7) ◽  
pp. 974-984 ◽  
Author(s):  
Huapeng Chen ◽  
Peter L. Jackson
Keyword(s):  
Mountain Pine Beetle ◽  
Forest Canopy ◽  
Meteorological Data ◽  
Climatic Conditions ◽  
Significant Shift ◽  
Long Distance Dispersal ◽  
Long Distance ◽  
Climate Conditions ◽  
Mountain Pine ◽  
Pine Beetle

A significant shift in the mountain pine beetle (Dendroctonus ponderosae Hopkins, 1902) range has been attributed to long-distance dispersal from the observed spatiotemporal patterns of beetle infestations in the recent outbreak in western Canada. However, long-distance dispersal is still the least understood aspect of mountain pine beetle ecology. In particular, the mechanisms responsible for the three major phases of long-distance dispersal, the ascent, transport, and descent, are poorly known. In this study, we used the North American Regional Reanalysis meteorological data (1999–2010) to determine climate conditions under and above the forest canopy during mountain pine beetle emergence and flight at the landscape scale. We found that climate conditions are distinct during emergence and flight. They provide an ideal underlying environment to facilitate the potential long-distance dispersal. Climate conditions are unstable under the forest canopy during emergence, which would help loft beetles above the forest canopy to initiate long-distance dispersal. The first direct evidence from wind directions above the forest canopy suggests that atmospheric transportation of mountain pine beetle in the planetary boundary layer is aided by wind.

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