Influence of Summer and Autumn Nutrition on Body Condition and Reproduction in Lactating Mule Deer

ABSTRACT Recent work suggests that availability and quality of forage in late summer and early autumn, a time when female ungulates face multiple energetic demands, is critical to reproduction in wild ungulates. Therefore, we examined direct links between nutritional quality of diets, body condition, and reproduction of lactating mule deer. Using captive mule deer, we tested the hypothesis that females consuming diets with lower digestible energy (DE; kJ/g) would have lower DE intake rates (DEI; MJ/day), have less body fat and muscle, have later estrus cycles, and have lower pregnancy and twinning rates. Deer fed lower DE diets had lower DEI during summer and autumn. In turn, deer with lower DEI, regardless of diet DE, had lower body mass, body fat, and muscle thickness. When nutritional quality of diets began to decline earlier in the summer, relationships between food quality, DEI, and body condition were stronger. Although DEI did not influence estrus date for deer that became pregnant before 21 December, deer with lower DEI had a lower probability of becoming pregnant and had a lower probability of producing twins. Measures of body condition in October (i.e., body mass, body fat, and muscle depth) predicted pregnancy and twinning rates in mule deer. Serum concentration of hormones leptin and Insulin Growth Factor 1 were not good predictors of body condition or reproduction. These findings suggest that managers concerned with productivity of mule deer populations should consider focusing on assessing and improving quality of forage available in summer and autumn.     

Disturbance affects spatial patterning and stand structure of a tropical rainforest tree

The distribution and spatial patterns of plant populations in natural ecosystems have recently received much attention; yet the impacts of human‐induced disturbances on these patterns and underlying processes remain poorly understood. We used the sub‐canopy tree, Ryparosa kurrangii (Achariaceae), to explore the possible effects of such disturbances on stand structure and spatial patterning in an Australian tropical rainforest. We studied three populations that differed in their extent of habitat modification: anthropogenic disturbance (proximate settlement and roads) and internal damage by an invasive alien species, the feral pig (Sus scrofa). Populations were mapped, characterized, and three size cohorts (seedlings, saplings, trees) were analysed using a suite of spatial point pattern analyses (univariate: Diggle's G and F and Ripley's K; bivariate: Diggle's G and Ripley's K). Ryparosa kurrangii has a typical stand structure for a sub‐canopy tree species, but occurs at high densities locally (>400 stems ha^?1). At all sites, the tree cohort were randomly distributed and saplings were spatially aggregated at distances of up to 2–3 m. Between sites there were distinct differences in the size structure and spatial pattern of seedlings, the cohort most affected by recent habitat modification. That is, the least disturbed site had no aggregation among seedlings, the site with the greatest anthropogenic disturbance had many small, clustered seedlings that were spatially associated with trees, and the site with pig damage had clustered seedlings that had no spatial relationship with trees. We propose that habitat modification by anthropogenic and pig disturbance disrupts seed dispersal and establishment regimes, which leads to altered seedling spatial patterns. These disturbances could have long‐term implications for the population structure and health of R. Kurrangii.     

Ethylene Evolution from Bracts and Leaves of Poinsettia, Euphorbia pulcherrima Willd

Woodrow, L. and Grodzinski, B. 1987. Ethylene evolution trombracts and leaves ol Poinsettia, Euphorbia pulcherrima Willd.—J.exp. Bot. 38: 2024–2032. Ethylene release from fully expanded, red and white bracts andleaves of poinsettia, Euphorbia pulcherrima Willd., was compared.On a laminar (area) basis leaves contained about 50 times morechlorophyll and demonstrated 10 times the photosynthetic rateof the bracts. Both tissues contained starch, however, solublecarbohydrate in the bracts consisted primarily of reducing hexoseswhile the leaves contained mainly sucrose for translocation.The total free alpha-amino nitrogen content of the bract tissuewas twice that of the leaf tissue. The leaves contained moreACC (1-aminocyclopropane-1-carboxylic acid) and produced proportionallymore endogenous C²H⁴ than either the red or white bracts. ACC-stimulated₂H₄ release was also greatest from the green tissue indicatingthat the EFE (ethylene forming enzyme) was most active in theleaves. The specific activity of the ¹⁴C₂H₄/¹²C₂H₄ releasedfrom [2,3-¹⁴C]ACC confirmed ACC as the primary precursor ofC₂H₄ in this tissue. Ethylene release from the non-photosynthetic,bract tissue was not markedly affected by alterations in CO₂or light conditions. In green leaf tissue endogeneous ethylenerelease increased from 1·5 to 6·0 pmol C₂H₄ cm^–2h^–1 while ACC-stimulated ethylene release increased from10 to 35 pmol C₂H₄ cm^2– h^1– as the CO₂ partial pressureincreased from 100 to 1 200 µbar. Key words: Poinsettia, ethylene, bracts     

Revisions of Rump Fat and Body Scoring Indices for Deer,Elk, and Moose

Abstract: Because they do not require sacrificing animals, body condition scores (BCS), thickness of rump fat (MAXFAT), and other similar predictors of body fat have advanced estimating nutritional condition of ungulates and their use has proliferated in North America in the last decade. However, initial testing of these predictors was too limited to assess their reliability among diverse habitats, ecotypes, subspecies, and populations across the continent. With data collected from mule deer (Odocoileus hemionus), elk (Cervus elaphus), and moose (Alces alces) during initial model development and data collected subsequently from free-ranging mule deer and elk herds across much of the western United States, we evaluated reliability across a broader range of conditions than were initially available. First, to more rigorously test reliability of the MAXFAT index, we evaluated its robustness across the 3 species, using an allometric scaling function to adjust for differences in animal size. We then evaluated MAXFAT, rump body condition score (rBCS), rLIVINDEX (an arithmetic combination of MAXFAT and rBCS), and our new allometrically scaled rump-fat thickness index using data from 815 free-ranging female Roosevelt and Rocky Mountain elk (C. e. roosevelti and C. e. nelsoni) from 19 populations encompassing 4 geographic regions and 250 free-ranging female mule deer from 7 populations and 2 regions. We tested for effects of subspecies, geographic region, and captive versus free-ranging existence. Rump-fat thickness, when scaled allometrically with body mass, was related to ingesta-free body fat over a 38–522-kg range of body mass (r² = 0.87; P < 0.001), indicating the technique is remarkably robust among at least the 3 cervid species of our analysis. However, we found an underscoring bias with the rBCS for elk that had >12% body fat. This bias translated into a difference between subspecies, because Rocky Mountain elk tended to be fatter than Roosevelt elk in our sample. Effects of observer error with the rBCS also existed for mule deer with moderate to high levels of body fat, and deer body size significantly affected accuracy of the MAXFAT predictor. Our analyses confirm robustness of the rump-fat index for these 3 species but highlight the potential for bias due to differences in body size and to observer error with BCS scoring. We present alternative LIVINDEX equations where potential bias from rBCS and bias due to body size are eliminated or reduced. These modifications improve the accuracy of estimating body fat for projects intended to monitor nutritional status of herds or to evaluate nutrition's influence on population demographics.     

Ethylene Exchange in Lycopersicon esculentum Mill. Leaves During Short- and Long-Term Exposures to CO2

The effects of long-term and transient exposure to elevatedCO₂ concentrations on photosynthetic gas exchange and ethylenerelease by tomato leaves were investigated. The net CO₂ assimilationrate was enhanced when leaf tissue grown at ambient (35 Pa CO₂)levels was assayed at 100 Pa CO₂. Leaf tissue grown at high(130 Pa) CO₂ exhibited a lower net CO₂ assimilation rate athigh CO₂ levels than leaf tissue grown at ambient (35 Pa) CO₂.This decrease in CO₂ exchange rate in response to growth athigh CO₂ is typical of C₃ species. Rates of endogenous and 1-aminocyclopropane-l-carboxylicacid (ACC)-stimulated ethylene release from leaf tissue wereenhanced by exposure to elevated CO₂ levels whether the leaftissue had been grown at ambient or enriched CO₂ levels. Thedata demonstrate that CO₂ enhanced C₂H₄ release from leaf tissuein response to both short-term perturbations in CO₂ concentrationand long-term growth and development under high CO₂. Prolongedgrowth at elevated CO₂ concentrations induced a higher endogenousrate of C₂H₄ release relative to that of leaf tissue grown atlower CO₂ levels. Leaf tissue from all leaf positions of plantsgrown at high CO₂ consistently evolved more C₂H₄ than correspondingtissue from ambient-grown plants when assayed under standardizedconditions. Endogenous (ACC) tissue contents and rates of ACC-stimulatedethylene release were also higher at all leaf positions in CO₂-enrichedtissue. Thus the higher rates appeared to be due to both higherendogenous precursor (ACC) levels in the tissue and greaterACC to C₂H₄ conversion capacity. Growth at elevated CO₂ levelsresulted in a persistent increase in the rate of endogenousC₂H₄ release in leaf tissue. The capacity for increased ethylenerelease in response to CO2 did not decline after prolonged growthat high CO₂. Key words: CO₂enrichment, ethylene, leaves, tomato     

Effects of Ethylene on Photosynthesis and Partitioning in Tomato, Lycopersicon esculentum Mill

The extended period of ethylene release from ethephon (2-chloroethylphosphonicacid) after application to intact tomato plants has provideda model system in which the effects of ethylene on photosyntheticmetabolism and carbon partitioning has been studied. Ethylenerelease from leaf tissue after ethephon treatment was 10 timesgreater than that from untreated control leaves. The specificactivity of 14C2H4 released from [14C] ethephon remained constantover several days demonstrating that the ethylene was derivedfrom the applied ethephon. The ethephon-treated plants exhibitedextreme epinasty of the leaves and 24 h after application theflower buds in the first visible cluster had abscised, leafexpansion at the apex had ceased and developing adventitiousroots were visible on the lower stem. Rates of steady-state photosynthesis, respiration, photorespirationand transpiration were the same in treated and control leaves24 h after ethephon application. Both treated and control leavespartitioned similar proportions of newly-fixed 14C from 14CO²into neutral (46.4%), acidic (14.0%), basic (5.0%) and insoluble(34.0%) leaf fractions under steady-state conditions. The speedof 11C-assimilate movement in the stems of control plants (3.62±0.42cm min-1 towards the apex and 4.03±0.15 cm min-1 towardsthe roots) was more rapid than in the ethephon-treated plants(2.90±0.31 cm min-1 upwards and 2.59±0.22 cm min-1downwards). Furthermore, in the control plants 20.0±5.4%of the 14C exported to the plant from the source leaf was transportedtowards the developing flower cluster and young leaves. Twenty-fourhours after ethephon application only 6.5 ±1.7% of theexported 14C was translocated towards the shoot. Contrary tosome reports ethylene did not affect steady-state gas exchangeprocesses while carbon partitioning was significantly alteredindicating that ethylene effects on photosynthetic carbon metabolismare indirect and not due to direct effects on photosyntheticprocesses per se. Key words: Ethylene, photosynthesis, partitioning     

Nitrogen supply and cyanide concentration influence the enrichment of nitrogen from cyanide in wheat (Triticum aestivum L.) and sorghum (Sorghum bicolor L.)

Cyanide assimilation by the β‐cyanoalanine pathway produces asparagine, aspartate and ammonium, allowing cyanide to serve as alternate or supplemental source of nitrogen. Experiments with wheat and sorghum examined the enrichment of ¹⁵N from cyanide as a function of external cyanide concentration in the presence or absence of nitrate and/or ammonium. Cyanogenic nitrogen became enriched in plant tissues following exposure to ¹⁵N‐cyanide concentrations from 5 to 200 µm , but when exposure occurred in the absence of nitrate and ammonium, ¹⁵N enrichment increased significantly in sorghum shoots at solution cyanide concentrations of ≥50 µm and in wheat roots at 200 µm cyanide. In an experiment with sorghum using ¹³C¹⁵N, there was also a significant difference in the tissue ¹³C:¹⁵N ratio, suggestive of differential metabolism and transport of carbon and nitrogen under nitrogen‐free conditions. A reciprocal ¹⁵N labelling study using KC¹⁵N and ¹⁵NH₄⁺ and wheat demonstrated an interaction between cyanide and ammonium in roots in which increasing solution ammonium concentrations decreased the enrichment from 100 µm cyanide. In contrast, with increasing solution cyanide concentrations there was an increase in the enrichment from ammonium. The results suggest increased transport and assimilation of cyanide in response to decreased nitrogen supply and perhaps to ammonium supply.     

Control of photosynthetic carbon dioxide fixation by the boundary layer, stomata and ribulose 1,5-biphosphate carboxylase/oxygenase

Abstract Coefficients describing the sensitivity of the rate of photosynthetic carbon dioxide fixation to small changes in the stomatal conductance and boundary layer conductance are derived. These sensitivity or ‘control’ coefficients, together with those for the carboxylase and oxygenase activities of ribulose 1,5-bisphosphate carboxylase/oxygenase, are calculated from standard gas exchange data and apply under conditions where leaf temperature and water vapour concentration at the leaf surface remain largely constant. It is shown that the magnitude of the control coefficients depends on conditions such as photon flux density, ambient CO₂ concentration and relative humidity at the leaf surface. The extension of this analysis to encompass the sensitivity of the photosynthetic fluxes to changes in enzyme concentrations and kinetic properties is also discussed.     

Validating Predictive Models of Nutritional Condition for Mule Deer

Abstract: We developed new, and validated existing, indices of nutritional condition for live and dead mule deer (Odocoileus hemionus). Live animal indices included a body condition score (BCS), thickness of subcutaneous fat and selected muscles using ultrasonography, and body mass. Dead animal indices included femur, metatarsal, and mandible marrow fat, 3 kidney fat indices, and 2 carcass scoring methods. We used 21 female deer and 4 castrates (1-11 yr old) varying widely in nutritional condition (2-28% ingesta-free body fat). Deer were euthanized and homogenized for chemical analysis of fat, protein, water, and ash content. Estimates of fat and gross energy (GE) were regressed against each condition indicator using regression. Subcutaneous fat thickness, a rump BCS, and rLIVINDEX (an arithmetic combination of subcutaneous fat thickness and the rump BCS) were most related to condition for live animals (r² ≥ 0.87, P < 0.001) whereas the Kistner score and kidney fat were most related to fat and GE for dead animals (r² ≥ 0.77, P < 0.001). We also evaluated range of usefulness and sensitivity to small changes in body condition for all models. In general, indices with moderate or highly curvilinear statistical relations to body fat or those based on only one fat depot or a small number of ranking scores will have limitations in their use. Our results identify robust tools for a variety of research and monitoring designs useful for evaluating nutrition's effect on mule deer populations.     

The diversity of ant–plant interactions in the rainforest understorey tree, Ryparosa (Achariaceae): food bodies, domatia, prostomata, and hemipteran trophobionts

Ant–plant relationships, with variability in both intimacy and the trophic structure of associations, are described for the Austro-Malesian rainforest tree genus Ryparosa (Achariaceae). The range of associations involves opportunistic interactions between plants and foraging ants, mediated by food bodies, and tighter associations in which ant colonies, tending hemipteran trophobionts, reside permanently in plant structures with different degrees of adaptation to house ants. Our study provides strong baseline data to suggest that Ryparosa could become a new model system for examining the evolutionary radiation of ant-related traits. To define the diversity of ant–plant associations in Ryparosa , we first present a review of ant-plant terminology and an outline of its use in this study. Field studies of ant interactions with food bodies in myrmecotrophic R. kurrangii from Australia and the association between myrmecoxenic R. fasciculata and two Cladomyrma plant-ant species on the Malay Peninsula provide detailed examples of ant–plant interactions. An examination of herbarium material revealed a diverse range of ant–plant associations in other Ryparosa taxa. All 27 species had evidence of food body production, seven species had evidence of stem inhabitation by ants, five species had specialized stem domatia, and the domatia of R. amplifolia featured prostomata. Variation in the specificity of Ryparosa ant–plant interactions is discussed in relation to known ant partners and other ant–plant associations.  © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society , 2007, 154 , 353–371.