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

Hayman, D. L.

doi:10.1071/bt9600058

Cited by 46 publications

(61 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Blake (1944Blake ( , 1969 and Celarier & Harlan (1955) have outlined the distribution of B. bladhii while Hayman (1960) and Evans & Knox (1969) have described that of T. australis (incl. T. triandra).…”

Section: Introductionmentioning

confidence: 97%

Flowering phenology of some native perennial tropical grasses from north‐eastern Australia

Tothill

1977

Australian Journal of Ecology

View full text Add to dashboard Cite

The division of north-eastern Australia into tropical and sub-tropical zones at approximately the latitude of 20 S, as suggested by the flowering phenology o/Heteropogon contortus, ii supported by studies on other perennial grasses of the native pastures. A progressive evolution away from an obligate short-day flowering response which characterizes the tropical forms of Bothriochloa bladhii, perhaps Themeda australis, and the exclusive tropical species Dicanthium tenuiculum, through a quantitative short-day response, as in the more widely distributed B. decipiens var. cloncurrensis, to the day-neutral or opportunistic and largely subtropical species of B. decipiens and D. sericeum, is suggested as a sequence of flowering strategies leading to wider adaptation into the subtropics.There is evidence from here and elsewhere that tropical forms or species of perennial grasses are grosser than their subtropical counterparts and this is coupled with their short-day flowering behaviour. The evidence suggests that B. decipiens and D. sericeum are the evolutionary products of taxa nearer to B. decipiens var. cloncurrensis and D. tenuiculum which exhibit day-length control of flowering.

show abstract

Section: Introductionmentioning

confidence: 97%

Flowering phenology of some native perennial tropical grasses from north‐eastern Australia

Tothill

1977

Australian Journal of Ecology

View full text Add to dashboard Cite

show abstract

“…Polyploidy may also play a role in the success of T. triandra following dispersal, with the species recognised as having numerous populations of different ploidy levels (Birari 1980;Hayman 1960). Ploidy has been associated with the invasive potential of species, through improving the capacity to colonise new environments, via maintaining genetic diversity as new populations establish (te Beest et al 2011).…”

Section: Genome-wide Nuclear Phylogenymentioning

confidence: 99%

The recent and rapid spread of Themeda triandra

et al. 2017

View full text Add to dashboard Cite

Tropical savannas cover over 20% of land surface. They sustain a high diversity of mammalian herbivores and promote frequent fires, both of which are dependent on the underlying grass composition. These habitats are typically dominated by relatively few taxa, and the evolutionary origins of the dominant grass species are largely unknown. Here, we trace the origins of the genus Themeda, which contains a number of widespread grass species dominating tropical savannas. Complete chloroplast genomes were assembled for seven samples and supplemented with chloroplast and nuclear ITS markers for 71 samples representing 18 of the 27 Themeda species. Phylogenetic analysis supports a South Asian origin for both the genus and the widespread dominant T. triandra. This species emerged ~1.5 Ma from a group that had lived in the savannas of Asia for several million years. It migrated to Australia ~1.3 Ma and to mainland Africa ~0.5 Ma, where it rapidly spread in pre-existing savannas and displaced other species. Themeda quadrivalvis, the second most widespread Themeda species, is nested within T. triandra based on whole chloroplast genomes, and may represent a recent evolution of an annual growth form that is otherwise almost indistinguishable from T. triandra. The recent spread and modernday dominance of T. triandra highlight the dynamism of tropical grassy biomes over millennial time-scales that has not been appreciated, with dramatic shifts in species dominance in recent evolutionary times. The ensuing species replacements likely had profound effects on fire and herbivore regimes across tropical savannas.

show abstract

“…In plants, dramatic changes in morphology and physiology resulting from polyploidization often contribute to the obvious habitat differentiation among cytotypes (Hayman, 1960;Dunford, 1984;Senock et al, 1991;Li et al, 1996;Maherali et al, 2009;Ramsey, 2011;Manzaneda et al, 2012). Habitat differentiation increases the species' colonizing ability and amplifies divergence in reproduction, which permits cytotypes to coexist (Lumaret et al, 1987).…”

Section: Introductionmentioning

confidence: 99%

Polyploidy enhances the occupation of heterogeneous environments through hydraulic related trade‐offs inAtriplex canescens(Chenopodiaceae)

et al. 2012

View full text Add to dashboard Cite

SummaryPlant hydraulic characteristics were studied in diploid, tetraploid and hexaploid cytotypes of Atriplex canescens (Chenopodiaceae) to investigate the potential physiological basis underlying the intraspecific habitat differentiation among plants of different ploidy levels.Populations of A. canescens from different habitats of the Chihuahuan Desert (New Mexico, USA) were analyzed using flow cytometry to determine ploidy levels. Traits related to xylem water transport efficiency and safety against drought-induced hydraulic failure were measured in both stems and leaves.At the stem level, cytotypes of higher ploidy showed consistently lower leaf-specific hydraulic conductivity but greater resistance to drought-induced loss of hydraulic conductivity. At the leaf level, comparisons in hydraulics between cytotypes did not show a consistent pattern, but exhibited high plasticity to proximal environmental conditions related to soil water availability.The results suggest that a trade-off between stem hydraulic efficiency and safety across ploidy levels underlies niche differentiation among different cytotypes of A. canescens. Polyploidization may have been facilitated by environmental heterogeneity related to water availability, and variation in water-related physiology found in the present study suggests an important functional basis for the niche differentiation and coexistence of A. canescens cytotypes in desert environments.

show abstract

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

Cited by 46 publications

References 0 publications

Flowering phenology of some native perennial tropical grasses from north‐eastern Australia

Flowering phenology of some native perennial tropical grasses from north‐eastern Australia

The recent and rapid spread of Themeda triandra

Polyploidy enhances the occupation of heterogeneous environments through hydraulic related trade‐offs inAtriplex canescens(Chenopodiaceae)

Contact Info

Product

Resources

About