Physical Sciences and Mathematics Commons^™

Evolution In Segregating Genotype Mixtures Of Subterranean Clover, P.G. H. Nichols, P S. Cocks

IGC Proceedings (1997-2023)

A complex segregating mixture of subterranean clover (Trifolium subterraneum L.), was sown in 1978 at Nabawa and Mt Barker, two contrasting sites in Western Australia. Seed harvested from both sites from 1980-1994 was grown out at Shenton Park in 1995, along with seed of the original mixture. Populations diverged markedly for mean days to first flowering (DFF) within three seasons. No further trends in mean DFF occurred in plants derived from the next 14 years, although standard deviation declined significantly in plants from Mt Barker. Between season differences in mean DFF were correlated with estimated growing season length at …

Relationships Among Some Lolium And Festuca Species, G Charmet, F Balfourier, C Ravel

IGC Proceedings (1997-2023)

Molecular markers were used to investigate phylogenetic relationships among the 8 species of ryegrass (Lolium) and 11 species of fescue (Festuca). Nine sequences of non-coding chloroplastic or mitochondrial DNA were amplified through PCR, then digested by 20 restriction enzymes. Restriction sites data were used to draw an UPGMA tree. The main features are: 1) a clear-cut distinction between fine-leaved fescues (subg. Festuca) and broad-leaved fescues (subg. Schedonorus), which include the ryegrasses. 2) among the broad-leaved fescues, meadow fescue and tall fescue are very closely related, which may indicate that they share a common maternal …

Effect Of Stocking Rates On Plant Morphology In The Inner Mongolia Steppe Of China, Shiping Wang, Y. F. Wang, Z. Z. Chen, Bob Patton, Paul Nyren

IGC Proceedings (1997-2023)

During the long period of co-evolution with herbivores, range plants have adapted and developed resistant mechanisms in response to grazing (Briske, 1991). The objective of this experiment was to determine the morphological response of a number of the dominant plant species in the Inner Mongolia steppe of China to stocking rate.

Evolution Of Barred Galaxies In Spinning Dark Matter Halos: High Resolution N-Body Simulations At Dlx, Angela Collier, Isaac Shlosman, Clayton Heller

Commonwealth Computational Summit

Observations show that galaxies are dominated by stellar disks immersed in much more massive, slowly tumbling dark matter (DM) halos. Large fraction of galactic disks, at least 75%, are barred (see Hubble Fork on the right). Stellar bars form either via spontaneous break of axial symmetry or via galaxy interactions.

The formation and evolution of stellar bars is not fully understood. Stellar bar evolution is highly nonlinear and cannot be treated analytically. The main approach to study these disk-halo systems is via numerical simulations, whose goal is to explain why galaxies have such a wide range of morphologies as shown …