The use of spatial analysis to measure the effect of environmental heterogeneity on genetic variation in Trifolium species from Sardinia

2002 ◽  
Vol 139 (3) ◽  
pp. 283-294 ◽  
Author(s):  
S. J. BENNETT ◽  
N. W. GALWEY
Keyword(s):  
Genetic Variation ◽  
Spatial Analysis ◽  
Western Australia ◽  
Acid Soils ◽  
Morphological Characters ◽  
Alkaline Soils ◽  
Field Station ◽  
Stressful Environment ◽  
Outcrossing Species ◽  
The University

Trifolium species are native to the Mediterranean Basin where they are an important component of permanent pastures. A number of species have become naturalized in Australia and are agriculturally important in annual pastures. To understand the importance of genetic and ecotypic variation in the adaptation of Trifolium species to a new environment, seeds of three predominantly inbreeding and two predominantly outcrossing species of Trifolium were collected from 12 sites in Sardinia in 1998. Detailed ecogeographic information was collected at each site. The progeny were grown at the University of Western Australia Field Station at Shenton Park, Western Australia in 1999, and were scored for 10 morphological characters. Spatial analysis was applied to the data to improve the estimation of accession means, and to investigate the relationship with environmental variables that characterized the sites of collection. The spatially adjusted means were used as the basis for a principal components analysis. Ecogeographical factors at the sites of collection, particularly soil pH, are suggested to be more important than breeding system in determining the extent of genetic variation within the species. The species that showed the greatest genetic variation between accessions were the predominantly inbreeding species T. glomeratum and T. subterraneum, and the predominantly outcrossing species T. nigrescens. It is suggested that the wide genetic variation of these three species is largely due to their being in an ecogeographic environment close to their optimum, and to the possession of a mating system that is neither completely outcrossing nor completely self-fertilizing. The remaining two species, T. tomentosum and T. resupinatum, both occur more frequently on alkaline soils, and it is suggested that for the collected accessions of these two species the acid soils of Sardinia are a stressful environment that does not promote high levels of genetic variation.

Genetic variation between and within two populations of Trifolium glomeratum (cluster clover) in Western Australia

1997 ◽  
Vol 48 (7) ◽  
pp. 969 ◽  
Author(s):  
Sarita Jane Bennett
Keyword(s):  
Cluster Analysis ◽  
Genetic Variation ◽  
Western Australia ◽  
Morphological Characters ◽  
Field Station ◽  
Site Variation ◽  
Components Analysis ◽  
And Cluster Analysis ◽  
The University ◽  
Two Populations

Genetic variation between and within populations of Trifolium glomeratum (cluster clover) was studied using seed collected from 2 sites in Western Australia: Mount Barker in the south and Kwelkan in the wheatbelt. Seed was collected at 64 subplots within each site and the material was grown at the University Field Station at Shenton Park, Perth. Seventeen morphological characters were scored and the results were analysed using analysis of variance, principal components analysis, and cluster analysis. Within-site variation was much greater than had previously been shown, and a considerable amount of between-site variation was present. It is suggested that within-site variation is due to a small amount of heterozygosity, as a result of limited outbreeding, being present in each population. The 2 populations are shown to be distinct from each other, with the population from Mount Barker containing more within-site variation. It is suggested that this is a result of climatic stress influencing and reducing the amount of variation being maintained in the Kwelkan population.

Genetic variation in five populations of strawberry clover (Trifolium fragiferum cv. Palestine) in Western Australia

2005 ◽  
Vol 45 (11) ◽  
pp. 1445 ◽  
Author(s):  
K. S. McDonald ◽  
P. S. Cocks ◽  
M. A. Ewing
Keyword(s):  
Genetic Variation ◽  
Total Variation ◽  
Western Australia ◽  
Principal Components ◽  
Plant Traits ◽  
Population Variation ◽  
Field Station ◽  
The North ◽  
Perennial Legume ◽  
The University

Genetic variation within and among populations of an outcrossing stoloniferous perennial legume, strawberry clover (Trifolium fragiferum L.), was studied using seed collected from 5 different locations in Western Australia. The sites ranged from Badgingarra to the north of the wheatbelt to Karridale in the southwest of the state. Seed was collected randomly at each site and was grown out at the University of Western Australia Field Station at Shenton Park, Perth. Thirteen morphological plant traits were measured and analysed. Results show that within-population variation was extremely high. In contrast, among-population variation was generally low with most characters showing only 8–15% of the total variation. Despite this, all but 1 of the measured plant traits differed among populations. Principal components analysis highlighted the large amount of variation within the populations with the first 3 principal components accounting for only 59% of the total variation. We suggest that the populations have begun to differentiate into ecotypes more suited to those habitats into which they have been sown but that within-population variation remains high due to the outcrossing nature of strawberry clover.

Ecotypic variation between and within two populations of Trifolium tomentosum (woolly clover) from Syria and Western Australia: its success as a colonising species

1999 ◽  
Vol 50 (8) ◽  
pp. 1443 ◽  
Author(s):  
Sarita Jane Bennett
Keyword(s):  
Western Australia ◽  
Function Analysis ◽  
Acid Soils ◽  
Arid Environment ◽  
Arid Environments ◽  
Alkaline Soils ◽  
Field Station ◽  
Ecotypic Variation ◽  
Site Variation ◽  
Semi Arid

Ecotypic variation was studied between and within populations of Trifolium tomentosum (woolly clover) using seed that was collected from 2 semi-arid environments: Tel Hadya, Syria, and Pingrup, Western Australia. The seed was collected from 64 subplots within a 40-m2 grid at each site and the material was grown at the University of Western Australia Field Station at Shenton Park, Perth. Fifteen morphological characters were scored and were analysed using analysis of variance, principal components analysis, and discriminant function analysis. Material from the 2 sites was separated using multivariate analysis, with the seed from Tel Hadya containing more within-site variation. It is suggested that the lack of within-site variation observed at Pingrup is the result of a number of factors: a limited amount of genetic diversity being present in the original introduced material, a preference of T. tomentosum for alkaline soils rather than the acid soils predominantly occurring in Western Australia, the harsh selection pressures present in a semi-arid environment, and a limited time for genotypes to adapt to specific micro-niches within each environment. The results are used to contribute to our understanding of the success of colonising species in semi-arid environments.

Breeding of an early-flowering and drought-tolerant Lotus corniculatus L. variety for the high-rainfall zone of southern Australia

2012 ◽  
Vol 63 (9) ◽  
pp. 848 ◽  
Author(s):  
D. Real ◽  
G. A. Sandral ◽  
M. Rebuffo ◽  
S. J. Hughes ◽  
W. M. Kelman ◽  
...  
Keyword(s):  
Western Australia ◽  
White Clover ◽  
Acid Soils ◽  
Lotus Corniculatus ◽  
Livestock Production ◽  
Perennial Grasses ◽  
Field Station ◽  
High Rainfall ◽  
Plant Nursery ◽  
Perennial Legume

In the high-rainfall zone of Australia (HRZ, >600 mm), most pasture systems are dominated by perennial grasses with low levels of inter-dispersed legume. Numerous authors have shown that a legume content of 20–50% is required to maximise livestock production. Consequently, the legume content of these systems needs to be increased if livestock production is to be improved. Perennial legume options such as lucerne (Medicago sativa) and white clover (Trifolium repens) are limited in their application in this zone due to the sensitivity of lucerne to acid soils (pH(CaCl2) <4.8) and waterlogging and the inability of white clover to survive most of the annual summer droughts. To address this problem, a breeding program was undertaken to develop varieties of Lotus corniculatus (birdsfoot trefoil) suitable for the HRZ of southern Australia. In the first cycle, 365 populations were screened in nurseries to select the best 62 plants from the best populations at Yalanbee and Medina in Western Australia. These selections were then grown as half-sib families in spaced-plant nurseries at Waroona and Yalanbee; in the second cycle, 61 individuals, selected from the the two sites, were hand-crossed to produce 3160 plants from 202 pair-crosses. These were gown in a spaced-plant nursery at the University of Western Australia Field Station in Shenton Park. In the third cycle, three polycross populations (YF, T, and F) were produced from selections within the 3160 second-cycle plants, and two additional plants which survived for 4 years on a non-wetting sand at Yalanbee, including a significant drought year in 2006. These varieties are expected to extend the adaptation of L. corniculatus to drier areas and/or lower latitudes.

Biogeochemical indicators to evaluate pollutant removal efficiency in constructed wetlands

1997 ◽  
Vol 35 (5) ◽  
pp. 1-10 ◽  
Author(s):  
K. R. Reddy ◽  
E. M. D'Angelo
Keyword(s):  
Microbial Biomass ◽  
Removal Efficiency ◽  
Nitrate Removal ◽  
Oxygen Demand ◽  
Acid Soils ◽  
Pollutant Removal ◽  
Alkaline Soils ◽  
Organic C ◽  
Wetland Treatment ◽  
Biogeochemical Indicators

Wetlands support several aerobic and anaerobic biogeochemical processes that regulate removal/retention of pollutants, which has encouraged the intentional use of wetlands for pollutant abatement. The purpose of this paper is to present a brief review of key processes regulating pollutant removal and identify potential indicators that can be measured to evaluate treatment efficiency. Carbon and toxic organic compound removal efficiency can be determined by measuring soil or water oxygen demand, microbial biomass, soil Eh and pH. Similarly, nitrate removal can be predicted by dissolved organic C and microbial biomass. Phosphorus retention can be described by the availability of reactive Fe and Al in acid soils and Ca and Mg in alkaline soils. Relationships between soil processes and indicators are useful tools to transfer mechanistic information between diverse types of wetland treatment systems.

Significant population genetic structure detected for a new and highly restricted species of Atriplex (Chenopodiaceae) from Western Australia, and implications for conservation management

2012 ◽  
Vol 60 (1) ◽  
pp. 32 ◽  
Author(s):  
Laurence J. Clarke ◽  
Duncan I. Jardine ◽  
Margaret Byrne ◽  
Kelly Shepherd ◽  
Andrew J. Lowe
Keyword(s):  
Genetic Variation ◽  
New Species ◽  
Genetic Structure ◽  
Western Australia ◽  
Sequence Data ◽  
Isolation By Distance ◽  
Conservation Strategies ◽  
New Taxon ◽  
Near Surface ◽  
Two Populations

Atriplex sp. Yeelirrie Station (L. Trotter & A. Douglas LCH 25025) is a highly restricted, potentially new species of saltbush, known from only two sites ~30 km apart in central Western Australia. Knowledge of genetic structure within the species is required to inform conservation strategies as both populations occur within a palaeovalley that contains significant near-surface uranium mineralisation. We investigate the structure of genetic variation within populations and subpopulations of this taxon using nuclear microsatellites. Internal transcribed spacer sequence data places this new taxon within a clade of polyploid Atriplex species, and the maximum number of alleles per locus suggests it is hexaploid. The two populations possessed similar levels of genetic diversity, but exhibited a surprising level of genetic differentiation given their proximity. Significant isolation by distance over scales of less than 5 km suggests dispersal is highly restricted. In addition, the proportion of variation between the populations (12%) is similar to that among A. nummularia populations sampled at a continent-wide scale (several thousand kilometres), and only marginally less than that between distinct A. nummularia subspecies. Additional work is required to further clarify the exact taxonomic status of the two populations. We propose management recommendations for this potentially new species in light of its highly structured genetic variation.

Preferential nitrate immobilization in alkaline soils

Soil Research ◽  
1992 ◽  
Vol 30 (5) ◽  
pp. 737 ◽  
Author(s):  
IJ Rochester ◽  
GA Constable ◽  
DA Macleod
Keyword(s):  
Acid Soil ◽  
Nitrification Inhibitor ◽  
Biological Significance ◽  
Nitrate Assimilation ◽  
Acid Soils ◽  
Ammonium Assimilation ◽  
Potassium Nitrate ◽  
Alkaline Soil ◽  
Alkaline Soils ◽  
Nitrate Immobilization

The literature pertaining to N immobilization indicates that ammonium is immobilized in preference to nitrate. Our previous research in an alkaline clay soil has indicated substantial immobilization of nitrate. To verify the preference for immobilization of nitrate or ammonium by the microbial biomass in this and other soil types, the immobilization of ammonium and nitrate from applications of ammonium sulfate and potassium nitrate following the addition of cotton crop stubble was monitored in six soils. The preference for ammonium or nitrate immobilization was highly correlated with each soil's pH, C/N ratio and its nitrification capacity. Nitrate was immobilized in preference to ammonium in neutral and alkaline soils; ammonium was preferentially immobilized in acid soils. No assimilation of nitrate (or nitrification) occurred in the most acid soil. Similarly, little assimilation of ammonium occurred in the most alkaline soil. Two physiological pathways, the nitrate assimilation pathway and the ammonium assimilation pathway, appear to operate concurrently; the dominance of one pathway over the other is indicated by soil pH. The addition of a nitrification inhibitor to an alkaline soil enhanced the immobilization of ammonium. Recovery of 15N confirmed that N was not denitrified, but was biologically immobilized. The immobilization of 1 5 ~ and the apparent immobilization of N were similar in magnitude. The identification of preferential nitrate immobilization has profound biological significance for the cycling of N in alkaline soils.

scholarly journals Obituary

2010 ◽  
Vol 16 (2) ◽  
pp. 83
Author(s):  
Andrew A Burbige
Keyword(s):  
Nature Conservation ◽  
Western Australia ◽  
Emeritus Professor ◽  
Public Figure ◽  
Research Fellow ◽  
Distinguished Career ◽  
The University

Albert Russell Main, Emeritus Professor of Zoology and Senior Honorary Research Fellow at The University of Western Australia, had a most distinguished career as a scientist and public figure and greatly influenced the course of science and nature conservation, particularly in Western Australia.

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