Peak power, force, and velocity during jump squats in professional rugby players

Training at the optimal load for peak power output (PPO) has been proposed as a method for enhancing power output, although others argue that the force, velocity, and PPO are of interest across the full range of loads. The aim of this study was to examine the influence of load on PPO, peak barbell velocity (BV), and peak vertical ground reaction force (VGRF) during the jump squat (JS) in a group of professional rugby players. Eleven male professional rugby players (age, 26 ± 3 years; height, 1.83 ± 6.12 m; mass, 97.3 ± 11.6 kg) performed loaded JS at loads of 20-100% of 1 repetition maximum (1RM) JS. A force plate and linear position transducer, with a mechanical braking unit, were used to measure PPO, VGRF, and BV. Load had very large significant effects on PPO (p < 0.001, partial η2 = 0.915); peak VGRF (p < 0.001, partial η2 = 0.854); and peak BV (p < 0.001, partial η2 = 0.973). The PPO and peak BV were the highest at 20% 1RM, though PPO was not significantly greater than that at 30% 1RM. The peak VGRF was significantly greater at 1RM than all other loads, with no significant difference between 20 and 60% 1RM. In resistance trained professional rugby players, the optimal load for eliciting PPO during the loaded JS in the range measured occurs at 20% 1RM JS, with decreases in PPO and BV, and increases in VGRF, as the load is increased, although greater PPO likely occurs without any additional load.     

Early evidence of the genus Homo in East Asia

The timing and route of the earliest dispersal from Africa to Eastern Asia are contentious topics in the study of early human evolution because Asian hominin fossil sites with precise age constraints are very limited. Here we report new high-resolution magnetostratigraphic results that place stringent age controls on excavated hominin incisors and stone tools from the Yuanmou Basin, southwest China. The hominin-bearing layer resides in a reverse polarity magnetozone just above the upper boundary of the Olduvai subchron, yielding an estimated age of 1.7Ma. The finding represents the age of the earliest documented presence of Homo, with affinities to Homo erectus, in mainland East Asia. This age estimate is roughly the same as for H. erectus in island Southeast Asia and immediately prior to the oldest archaeological evidence in northeast Asia. Mammalian fauna and pollen obtained directly from the hominin site indicate that the Yuanmou hominins lived in a varied habitat of open vegetation with patches of bushland and forest on an alluvial fan close to a lake or swamp. The age and location are consistent with a rapid southern migration route of initial hominin populations into Eastern Asia.     

Genetic parameters of intra- and inter-specific hybrids of Eucalyptus globulus and E. nitens

Intra-specific hybrids within Eucalyptus nitens and E. globulus were compared directly with inter-specific E. nitens × globulus using common parents. Diameter (age 2, 4, 6, 10 years) and Pilodyn (age 6 years) were used as indirect measures of growth and wood density, respectively. Genetic parameters were estimated for all cross types and traits. A direct comparison of the general combining ability with the general hybridising ability was made. Heterosis was estimated for intra- and inter-specific hybrids. The intra-specific hybrids in both species exhibit intermediate heritabilities and levels of additive genetic variance. The inter-specific F1 E. nitens × globulus exhibited high incidence of abnormalities at young ages and high levels of later age mortality. The mean performance of surviving inter-specific F1 hybrids was generally intermediate for all traits, to varying degrees, between the parental intra-specific crosses, and there is little evidence for significant heterosis. Different provenances of E. globulus may exhibit different responses to hybridisation. In this case, the inter-specific F1 hybrids, using Taranna E. globulus, appear to perform worse on average than those using King Island provenance for growth traits. There is evidence that specific hybrid families are produced that outperform most of the pure species families for one or other of the traits examined; however, there is no reliable quantitative genetic method of predicting which parents should be used.     

The Role of Flower Inclination, Depth, and Height in the Preferences of a Pollinating Beetle (Coleoptera: Glaphyridae)

Amphicoma (Glaphyridae) beetles are important pollinators of red bowl-shaped flowers in the Mediterranean. The role of color and shape in flower choice is well studied but the roles of inclination, depth, and height have seldom been investigated. Under field conditions, models were used to experimentally manipulate these three characters and visitation rates of beetles were recorded. Models with red horizontal surfaces were visited significantly more often than models with red vertical surfaces. Shallow flower models were visited significantly more than deeper equivalents. Models below or at the height of natural flower populations elicited significantly more landings than models above the height of flowers. Inclination, depth, and height characteristics are all likely to be important components in the flower preferences exhibited by pollinating beetles.     

An AFLP marker approach to lower-level systematics in Eucalyptus (Myrtaceae)

Genus Eucalyptus, with over 700 species, presents a number of systematic difficulties including taxa that hybridize or intergrade across environmental gradients. To date, no DNA marker has been found capable of resolving phylogeny below the sectional level in the major subgenera. Molecular markers are needed to support taxonomic revision, assess the extent of genetic divergence at lower taxonomic levels, and inform conservation efforts. We examined the utility of 930 amplified fragment length polymorphisms (AFLPs) for analyzing relationships among Tasmanian taxa of subgenus Symphyomyrtus section Maidenaria. Phenetic and cladistic analyses resolved species into clusters demonstrating significant genetic partitioning, largely concordant with series defined in the most recent taxonomic revision of Eucalyptus. Some departures from current taxonomy were noted, indicating possible cases of morphological convergence and character reversion. Although the resolution obtained using AFLP was greatly superior to that of single sequence markers, the data demonstrated high homoplasy and incomplete resolution of closely related species. The results of this study and others are consistent with recent speciation and reticulate evolution in Maidenaria. We conclude that a combination of phylogenetic and population genetic approaches using multiple molecular markers offers the best prospects for understanding taxonomic relationships below the sectional level in Eucalyptus.     

Pollination of a core flowering shrub species in Mediterranean phrygana: variation in pollinator diversity, abundance and effectiveness in response to fire

Fire in Mediterranean-type ecosystems produces catastrophic changes in plant-pollinator systems; the recovery of which has been studied by comparing an unburnt mature forest habitat with that of an adjacent recently burnt area (eight years post-fire). The composition, visitation profiles, and effectiveness of the taxonomically diverse pollinator assemblages found on a core nectar providing species ( Satureja thymbra : Lamiaceae) were examined in these two contrasting habitats. S. thymbra in the freshly burnt area had low nectar standing crop and relatively less diverse bee community than an unburnt area which had twice the nectar standing crop and a higher bee diversity and abundance. Both sites supported bee assemblages dominated by the non-native bumblebee Bombus terrestris . Spatio-temporal heterogeneity of nectar standing crops and microclimatic conditions were sufficient to explain the form and magnitude of the diurnal foraging profiles at each site in relation to species specific foraging and flight abilities. B. terrestris, Apis mellifera and native solitary bees were the three primary guilds visiting S. thymbra and varied in the efficiency with which they delivered conspecific pollen grains to receptive stigmas. A pollinator effectiveness index for these three guilds was calculated based on floral visitation rates and pollen delivery efficiency and reflected the actual levels of effectiveness of each guild within and across the two habitat types. There was no overall inter-community difference in pollination effectiveness as the bee assemblages in both habitats were sufficient to produce maximum fruit set in S. thymbra, though the relative contribution of each guild varied intra-communally. Pollen limitation was not found to occur in either habitat.