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Summary1 Maximum attainable height varies greatly between tree species in tropical rain forests and covaries with demographic and allometric traits. We examined these relationships in 27 abundant tree species in a mixed dipterocarp forest. These species were monitored over 3 years in two 1-ha plots in western Borneo. A 95-percentile upper height limit was used to represent maximum height, to avoid sample size differences among populations. 2 Average growth rate in trunk diameter was regressed against trunk diameter using a maximum likelihood model and assuming that growth rates were exponentially distributed around the average. Estimated average growth rate at small trunk diameters (up to 11 cm) was independent of maximum height among the 27 species, while the degree of growth reduction at larger diameters was larger for species with smaller maximum height. 3 The recruitment rate efficiency of saplings was negatively correlated with maximum height, regardless of the measure used to assess species abundance. In particular, sapling recruitment per unit basal area declined greatly with increasing maximum height, consistent with model predictions of the traits required for the stable coexistence of species at different heights within the canopy. 4 Allometric analyses showed that understorey species had shorter heights at the same trunk diameter, and deeper crowns at the same tree height, than canopy species. Therefore, understorey species showed adaptive morphology to deep shade. 5 The regressed size-dependent pattern of average growth rate and an assumption that the population was in a steady state readily explained the observed trunk diameter distributions for 21 species among 27 examined. These species, for which the projected size distribution hardly changed when the natural increase or decrease of the population was set at γ = ± 0.005 year − 1 , had mortality rates of more than four times the value of γ .

A molecular-marker linkage map has been constructed for perennial ryegrass (Lolium perenne L.) using a one-way pseudo-testcross population based on the mating of a multiple heterozygous individual with a doubled haploid genotype. RFLP, AFLP, isoenzyme, and EST data from four collaborating laboratories within the International Lolium Genome Initiative were combined to produce an integrated genetic map containing 240 loci covering 811 cM on seven linkage groups. The map contained 124 codominant markers, of which 109 were heterologous anchor RFLP probes from wheat, barley, oat, and rice, allowing comparative relationships between perennial ryegrass and other Poaceae species to be inferred. The genetic maps of perennial ryegrass and the Triticeae cereals are highly conserved in terms of synteny and colinearity. This observation was supported by the general agreement of the syntenic relationships between perennial ryegrass, oat, and rice and those between the Triticeae and these species. A lower level of synteny and colinearity was observed between perennial ryegrass and oat compared with the Triticeae, despite the closer taxonomic affinity between these species. It is proposed that the linkage groups of perennial ryegrass be numbered in accordance with these syntenic relationships, to correspond to the homoeologous groups of the Triticeae cereals.Key words: Lolium perenne, genetic linkage map, RFLP, AFLP, conserved synteny.Résumé : Une carte génétique composée de marqueurs moléculaires a été produite pour l'ivraie vivace (Lolium perenne L.) à l'aide d'une population issue d'un pseudo-testcross unidirectionnel. Les parents étaient, d'une part, un individu multiple hétérozygote et, d'autre part, un génotype haploïde doublé. Des données pour des marqueurs RFLP, AFLP, isoenzymatiques ainsi que des EST ont été contribuées par quatre laboratoires faisant partie du « International Lolium Genome Initiative (ILGI) ». Ces données ont été combinées pour produire une carte génétique intégrée comprenant 240 locus, formant sept groupes de liaison et s'étendant sur 811 cM. La carte compte 124 marqueurs codominants dont 169 sont des sondes-repères RFLP hétérologues provenant du blé, de l'orge, de l'avoine ou du riz. Ces sondes permettent d'examiner les relations entre l'ivraie vivace et d'autres espèces de graminées. Les cartes génétiques de l'ivraie vivace et des céréales de la tribu des hordées sont très conservées en termes de synténie et de colinéarité. Cette conclusion s'appuie sur une concordance générale au niveau des relations de synténie entre l'ivraie vivace, l'avoine et le riz ainsi qu'entre les hordées et ces espèces. Un plus faible niveau de synténie et de colinéarité a été observé entre l'ivraie vivace et l'avoine par rapport aux hordées, malgré la proximité taxinomique entre ces espèces. Il est suggéré que les groupes de liaison chez l'ivraie vivace soient numérotés en fonction des relations de synténie de façon à correspondre aux groupes d'homéologues chez les céréales.

Population structure of Msi was driven by patterns of warming since the LGM, and secondarily by geographical barriers. This study will facilitate germplasm conservation, association analyses and identification of potential heterotic groups for the improvement of Miscanthus as a bioenergy crop.