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.

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.

Resilience of floodplain ecosystems in a semi-arid environment

2010 ◽  
Vol 32 (3) ◽  
pp. 305 ◽  
Author(s):  
Matthew J. Colloff ◽  
Darren S. Baldwin
Keyword(s):  
Stable State ◽  
Arid Environment ◽  
Ecosystem Functions ◽  
Arid Environments ◽  
Ecosystem Resilience ◽  
Floodplain Ecosystems ◽  
Murray Darling Basin ◽  
Single State ◽  
Floods And Droughts ◽  
Semi Arid

Implicit to loss of ecosystem resilience is that systems can shift from one stable state to another as a result of disturbance. We present a conceptual model of ecosystem resilience of floodplains and wetlands in semi-arid environments like those of the Murray–Darling Basin. The model is based on a single state characterised by fluctuating wet and dry phases driven by episodic floods and droughts. It might appear that such a single state is inherently unstable, but stability, and the measure of resilience, is conferred by the capacity of floodplains and wetlands to undergo drought and yet return to a functioning wet phase following inundation as well as to undergo flooding and return to the dry phase following flood recession. Floodplains and wetlands are driven by strong, periodic abiotic disturbances and their ecosystem functions and biogeochemical processes are highly rate-limited, spatiotemporally variable and driven by relatively species-poor assemblages of plants and animals adapted to withstand drought and flooding. Extreme drying due to climatic change and over-allocation of water resources represents the primary mechanism via which resilience is lost.

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.

scholarly journals A hydrological framework for persistent river pools in semi-arid environments

2020 ◽  
Author(s):  
Sarah A. Bourke ◽  
Margaret Shanafield ◽  
Paul Hedley ◽  
Shawan Dogramaci
Keyword(s):  
Western Australia ◽  
Groundwater Discharge ◽  
Geological Mapping ◽  
Diagnostic Tools ◽  
Arid Environments ◽  
Hydrogeological Characteristics ◽  
Through Flow ◽  
Bedrock Aquifers ◽  
North Western ◽  
Semi Arid

Abstract. Persistent surface water pools along non-perennial rivers represent an important water resource for the plants, animals, and humans that inhabit semi-arid regions. While ecological studies of these features are not uncommon, these are rarely accompanied by a rigorous examination of the hydrological and hydrogeological characteristics that create or support the pools. Here we present an overarching framework for understanding the hydrology of persistent pools based on data from 22 pools in the Hamersley Basin in Western Australia. Three dominant mechanisms that control the occurrence of persistent pools have been identified; perched pools, through flow pools and groundwater discharge pools. Groundwater discharge pools are further categorized into those that are present because of a geological contact or barrier, and those that are controlled by topography. A suite of diagnostic tools (including geological mapping, hydraulic data and hydrochemical surveys) is generally required to identify the mechanism supporting persistent pools. Perched pools are sensitive to climate variability but their persistence is largely independent of groundwater withdrawals. Water fluxes to pools from alluvial and bedrock aquifers can vary seasonally and resolving these inputs is generally non-trivial. The susceptibility of through-flow and groundwater discharge pools to climate variations and groundwater withdrawals depends on the mechanism of pool persistence and the spatial distribution of stressors relative to the pool. Although this framework was developed in the context of north-western Australia, this framework can also be applied to pools and springs found along non-perennial rivers around the world.

scholarly journals Evidence for convergent evolution among phylogenetically distant rare species of Tetratheca (Elaeocarpaceae, formerly Tremandraceae) from Western Australia

2007 ◽  
Vol 20 (2) ◽  
pp. 126 ◽  
Author(s):  
Ryonen Butcher ◽  
Margaret Byrne ◽  
Darren M. Crayn
Keyword(s):  
Western Australia ◽  
Rare Species ◽  
Cladistic Analysis ◽  
Geographic Area ◽  
Arid Environments ◽  
High Conservation ◽  
Superficial Similarity ◽  
Evolutionary Lineages ◽  
Semi Arid

Morphological and molecular investigations of taxon relationships among rare species of Tetratheca Sm. occurring near Koolyanobbing, Western Australia, have confirmed the distinctness of T. aphylla F.Muell., T. harperi F.Muell. and T. paynterae Alford and identified three new rare taxa from collections affiliated with T. aphylla and T. paynterae. The recognition of these taxa at specific and sub-specific ranks is based on their different degrees of morphological and molecular divergence, combined with geographic disjunction. Cladistic analysis of nrDNA internal transcribed spacer and cpDNA trnL-trnF sequences from a range of Tetratheca species from Western Australia and the eastern states indicates that T. aphylla, T. harperi and T. paynterae belong to three separate evolutionary lineages and that the endemism displayed among these taxa to small, disjunct ranges within the same geographic area, is a result of in situ speciation due to historical fragmentation. These results exemplify the extremely high conservation value of the Yilgarn banded ironstone ranges. The superficial similarity among the study taxa in having a ‘leafless’ habit can be seen to be adaptive convergence in response to the marginal and semi-arid environments in which they occur, and this character is highly homoplastic within the genus.

scholarly journals Long Term Hydrodynamic Effects in a Semi-Arid Mediterranean Multilayer Aquifer: Campo de Cartagena in South-Eastern Spain

Water ◽  
2018 ◽  
Vol 10 (10) ◽  
pp. 1320 ◽  
Author(s):  
Juan Domingo-Pinillos ◽  
Javier Senent-Aparicio ◽  
José García-Aróstegui ◽  
Paul Baudron
Keyword(s):  
Arid Environment ◽  
Anthropogenic Activity ◽  
Arid Environments ◽  
Aquifer System ◽  
Intensive Exploitation ◽  
The Mediterranean ◽  
Hydrodynamic Effects ◽  
Flow Transfer ◽  
Semi Arid ◽  
Campo De Cartagena

The Mediterranean basin contains many semi-arid environments where aquifers are subject to intensive exploitation, generally to meet irrigation demands. The Campo de Cartagena aquifer is a clear example from such a semi-arid environment, and its hydrodynamic effects have aroused great scientific interest. The main objective of this study is to evaluate the hydrodynamic effects that have occurred in the last century of anthropogenic activity in this aquifer system. This aquifer is subject to intensive exploitation and shows clear deficits in times of drought, with recharge by irrigation playing an important role. This study’s methodology includes groundwater modelling to reconstruct the transient evolution of the aquifer system during the last century, to generate water balances and to illustrate how the evolution of irrigation has, in many ways, changed the aquifer’s groundwater flow pattern. The results delineate the hydraulic communication of the aquifer stratums through specific geological structures, as well as the flow transfer from the Quaternary layer to the Mar Menor and the Mediterranean Sea. The reconstruction of the entire system’s temporal evolution shows a fragile water balance that is supported by surface-water contributions.

Prolonged isolation and persistence of a common endemic on granite outcrops in both mesic and semi-arid environments in south-western Australia

2014 ◽  
Vol 41 (11) ◽  
pp. 2032-2044 ◽  
Author(s):  
Sarah-Louise Tapper ◽  
Margaret Byrne ◽  
Colin J. Yates ◽  
Gunnar Keppel ◽  
Stephen D. Hopper ◽  
...  
Keyword(s):  
Western Australia ◽  
Arid Environments ◽  
Granite Outcrops ◽  
Semi Arid

scholarly journals Break-crop effects on wheat production across soils and seasons in a semi-arid environment

2015 ◽  
Vol 66 (6) ◽  
pp. 566 ◽  
Author(s):  
T. M. McBeath ◽  
V. V. S. R. Gupta ◽  
R. S. Llewellyn ◽  
C. W. Davoren ◽  
A. M. Whitbread
Keyword(s):  
Field Experiments ◽  
Primary Source ◽  
Arid Environment ◽  
Soil Types ◽  
Cereal Crops ◽  
Arid Environments ◽  
Beneficial Effects ◽  
Cereal Production ◽  
High Level ◽  
Semi Arid

In low-rainfall environments, a high frequency of cereal crops has been favoured for optimising productivity and risk. However, cereals at high intensity often lead to declining water-use efficiency and increasing inputs to cope with emergent nutritional, disease and weed problems. The value of including breaks in the cropping sequence can involve a high level of uncertainty in low-rainfall areas where non-cereal crops are more risky and profitability is largely determined by the subsequent benefit to cereal productivity. In this study, we aimed to improve understanding of the magnitude and primary source of break benefits such as nutrition, water and disease management in a low-rainfall environment where a high level of within-field soil variability can also contribute to uncertainty about the value of breaks. In on-farm field experiments near Karoonda in the South Australian Mallee, breaks were grown in 2009 or 2010 on four distinct soil types across a dune–swale catena. The effect of these breaks on subsequent cereal production was measured for up to 3 years. In addition, the effect of breaks on nutrition and water available, along with disease infection in subsequent cereal crops, was explored and actual yields were compared with nitrogen and water-limited potential yields. Consistent cumulative benefits to subsequent cereal crops of at least 1 t ha–1 after 3 years accrue from breaks grown on the different soil types. The inclusion of breaks had beneficial effects on the cycling and supply of nutrients along with some short-term impacts on infection by Rhizoctonia solani AG8 in subsequent cereals, whereas there were no conclusive effects of breaks on the supply of water to subsequent crops. This study suggests that the inclusion of both legume and brassica breaks is likely to be beneficial to subsequent cereal production where nitrogen is a factor limiting productivity in low-rainfall, semi-arid environments.

Do Australian Sheep Blowflies, Lucilia Cuprina (Diptera: Calliphoridae), Breed in Either Goat or Sheep Carcasses in a Semi-Arid Environment?

1995 ◽  
Vol 17 (2) ◽  
pp. 186 ◽  
Author(s):  
DF Cook ◽  
EC Steiner ◽  
I Watson ◽  
IR Dadour
Keyword(s):  
Life Cycle ◽  
Western Australia ◽  
Abundant Species ◽  
Arid Environment ◽  
Gut Contents ◽  
Australian Sheep ◽  
One Year ◽  
Insect Attack ◽  
Feral Goat ◽  
Semi Arid

Feral goat and sheep carcasses were exposed to insect attack on semi-arid pastoral land each month for one year. The native calliphorids Chrysomya rujifacies and Ch. varipes were by far the most abundant species de.veloping in virtually all carcasses. Sheep blowflies (L. cuprina) were incapable of developing from egg to adult on either feral goat or sheep carcasses during any month. Bush flies (Musca vetustissima) emerged from both feral goat and sheep carcasses from January to May, particularly from the gut contents. Chrysomya species were trapped in all months except June, whereas L. cuprina adults were only trapped from September to December. L. cuprina and Ch. rujifacies adults are very similar in appearance, hence many pastoralists assume that green blowflies on feral goat carcasses are sheep blowflies. However, this study clearly shows that L. cuprina are unable to complete their life cycle on either feral goat or sheep carcasses in the semi-arid environment of Carnarvon, Western Australia.

Genotype by environment interactions for productivity and resistance to gastro-intestinal nematode parasites in Red Maasai and Dorper sheep

2004 ◽  
Vol 79 (3) ◽  
pp. 343-353 ◽  
Author(s):  
R. L. Baker ◽  
J. M. Mugambi ◽  
J. O. Audho ◽  
A. B. Carles ◽  
W. Thorpe
Keyword(s):  
Smallholder Farmers ◽  
Arid Environment ◽  
Productive Efficiency ◽  
Metabolizable Energy ◽  
Arid Environments ◽  
Genotype By Environment ◽  
Nematode Parasites ◽  
Humid Environment ◽  
Dorper Sheep ◽  
Semi Arid

AbstractRed Maasai and Dorper sheep were evaluated for their resistance to gastro-intestinal (GI) nematode parasites (predominantly Haemonchus contortus), productivity and productive efficiency (assessed on a metabolizable energy basis) in experiments undertaken at the Kenyan coast (sub-humid environment) and the Kenya highlands (semi-arid environment). In both ewes and lambs there were few significant genotype by environment (G X E) interactions for either resistance (assessed by faecal egg counts-FEC) or resilience (assessed by blood packed red cell volume-PCV) to GI nematodes. Red Maasai sheep were consistently more resistant (low FEC) and more resilient (high PCV) than Dorper sheep. However, there were significant G X £ interactions for ewe reproductive performance and for ewe and lamb mortality rates and live weights. These interactions were due to very poor performance of the Dorper compared to the Red Maasai in the sub-humid coastal environment and to the much improved performance of the Dorper in the semi-arid environment. When these component traits were combined into estimates of flock productivity and productive efficiency there were highly significant GXE interactions with the Red Maasai sheep being considerably more efficient than Dorper sheep in the sub-humid environment, while in the semi-arid environment there was a negligible breed difference in productive efficiency. The results are discussed in terms of breeding strategies for smallholder farmers and pastoralists managing sheep in low-input systems in sub-humid and semi-arid environments.

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