Periods of Nutritional Stress in the Annual Cycles of Endotherms: Fact or Fiction?

An animal's nutritional status depends on (1) nutrient accessibility,(2) nutrient demand, and (3) physiological, metabolic, morphological,and behavioral compensations that avert or minimize discrepancies,if any, between the first two. The main thesis of this essayis that the diversity and potency of such compensatory mechanismshave often been underrated, and hence the frequency and intensityof nutritional stress in free-living animals have often beenexaggerated. This theme is explored in conjunction with an inventoryof the modes of compensation for actual or potential dietarydeficiencies.     

Donor Plant Growth Factors Affecting Anther Culture of Maize and Sweetcorn (Zea mays)

Anthers from seven unselected commercial sweetcorn lines andten experimental maize lines were cultured on a liquid/solidbi-layer culture medium, containing 13 % maltose as the carbonsource. Mean anther efficiencies (number of embryos per 100anthers plated) of 0 to 27.6 % were recorded, with the maximumefficiency of 57.1 % from one plant. The anther efficiency wasfound to be dependent on genotype, microspore developmentalstage and the growth temperatures of donor plants. Immaturemicrospores were found to continue their development duringthe cold pretreatment of the spikes, and this in turn influencedthe level of response to culture. Direct regeneration of embryoidsto plants occurred most frequently when well formed uni- orbi-polar embryos were produced. The quality of embryo producedwas apparently inversely correlated with the number of embryosproduced. Zea mays, haploid culture, embryos, microspores     

Fatty Acids in Chloroplasts and Leaves

The fatty acid composition of green and white leaf tissue inAcer negundo, Zea mais, and Ilex aquifolium, of green and yellowtissue in Ligustrum ovatifolium and of etiolated and green tissuein Vicia faba has been determined. The mesophytic green leavesexamined show a general similarity in fatty acid composition,characterized by a high concentration of non-conjugated octadecatrienoicacid. Chloroplasts were isolated from Vicia and Acer and containan even higher concentration of this acid and only traces ofnon-conjugated octadecadienoic acid. Conjugated diene and trieneacids occur in traces in chioroplasts, but are also found innon-green leaf tissue. The fats of non-green leaves are in generalmore saturated than those from green tissue but vary considerablyin composition. The relationship between fat composition andplastid development is discussed.     

Statistical Modeling of Observational Data With Spatial Dependencies

Abstract I provide a brief introduction to the concept of spatial autocorrelation and its incorporation into regression-type models. Spatial autocorrelation occurs when the response variable is correlated with itself at other locations in the region of interest. The autocorrelation usually takes a specific form where observations close in space are more correlated than those farther apart, and the rate of decay of the correlation is a function of the distance separating 2 locations. I present 2 commonly used models: 1) geostatistical modeling in which data are collected at points in the study region and 2) conditional autoregression (lattice) models in which data are aggregated over small nonoverlapping sub-areas of the study region. I also describe incorporation of explanatory covariates, such as habitat or physico-chemical attributes. I emphasize frequentist methods, but I briefly describe Bayesian approaches. I also provide some advantages, such as obtaining correct standard errors for estimators, and disadvantages, such as requirements for larger sample sizes, of incorporating spatial autocorrelation into the modeling effort. This information can aid researchers in designing and analyzing models of the relationships between species distributions and habitat. As a result, more informative models can be developed which further aid in management of wildlife.     

The beetle tree of life reveals that Coleoptera survived end‐Permian mass extinction to diversify during the Cretaceous terrestrial revolution

Here we present a phylogeny of beetles (Insecta: Coleoptera) based on DNA sequence data from eight nuclear genes, including six single‐copy nuclear protein‐coding genes, for 367 species representing 172 of 183 extant families. Our results refine existing knowledge of relationships among major groups of beetles. Strepsiptera was confirmed as sister to Coleoptera and each of the suborders of Coleoptera was recovered as monophyletic. Interrelationships among the suborders, namely Polyphaga (Adephaga (Archostemata, Myxophaga)), in our study differ from previous studies. Adephaga comprised two clades corresponding to Hydradephaga and Geadephaga. The series and superfamilies of Polyphaga were mostly monophyletic. The traditional Cucujoidea were recovered in three distantly related clades. Lymexyloidea was recovered within Tenebrionoidea. Several of the series and superfamilies of Polyphaga received moderate to maximal clade support in most analyses, for example Buprestoidea, Chrysomeloidea, Coccinelloidea, Cucujiformia, Curculionoidea, Dascilloidea, Elateroidea, Histeroidea and Hydrophiloidea. However, many of the relationships within Polyphaga lacked compatible resolution under maximum‐likelihood and Bayesian inference, and/or lacked consistently strong nodal support. Overall, we recovered slightly younger estimated divergence times than previous studies for most groups of beetles. The ordinal split between Coleoptera and Strepsiptera was estimated to have occurred in the Early Permian. Crown Coleoptera appeared in the Late Permian, and only one or two lineages survived the end‐Permian mass extinction, with stem group representatives of all four suborders appearing by the end of the Triassic. The basal split in Polyphaga was estimated to have occurred in the Triassic, with the stem groups of most series and superfamilies originating during the Triassic or Jurassic. Most extant families of beetles were estimated to have Cretaceous origins. Overall, Coleoptera experienced an increase in diversification rate compared to the rest of Neuropteroidea. Furthermore, 10 family‐level clades, all in suborder Polyphaga, were identified as having experienced significant increases in diversification rate. These include most beetle species with phytophagous habits, but also several groups not typically or primarily associated with plants. Most of these groups originated in the Cretaceous, which is also when a majority of the most species‐rich beetle families first appeared. An additional 12 clades showed evidence for significant decreases in diversification rate. These clades are species‐poor in the Modern fauna, but collectively exhibit diverse trophic habits. The apparent success of beetles, as measured by species numbers, may result from their associations with widespread and diverse substrates – especially plants, but also including fungi, wood and leaf litter – but what facilitated these associations in the first place or has allowed these associations to flourish likely varies within and between lineages. Our results provide a uniquely well‐resolved temporal and phylogenetic framework for studying patterns of innovation and diversification in Coleoptera, and a foundation for further sampling and resolution of the beetle tree of life.     

Do agricultural pollutants affect competition between filter‐feeding caddis fly larvae? Results of laboratory microcosm experiments

1. Predictable changes in the composition of macroinvertebrate communities in response to non‐point source pollution are the basis of macroinvertebrate community indices. However, other factors, such as biotic interactions, also affect the composition of macroinvertebrate communities and may complicate the interpretation of such indices by interacting with abiotic stressors. 2. The effect of agricultural pollutants on competition between two filter‐feeding caddisflies, Brachycentrus appalachia and Hydropsyche spp. was studied in the laboratory using recirculating flow tanks. 3. Experiments were conducted at two densities of Hydropsyche: high (300 per tank) and low (80 per tank). Brachycentrus density was kept constant at 40 per tank in all experiments. Experiments assessed the effect of an agricultural pollutant mix (sand, cow‐manure compost mix) and the presence of the competitor on both taxa. 4. The only negative response to pollutants was a larger number of Hydropsyche drifting in high‐density tanks. In fact, at high densities, mortality of Hydropsyche was higher in controls than in tanks receiving pollutants. 5. Hydropsyche and B. appalachia competed for resources and the presence of pollution did not affect the outcome of this competition. The presence of high densities of Hydropsyche resulted in higher drift and lower condition of B. appalachia. At low densities of Hydropsyche, B. appalachia larvae suffered greater mortality and tended to be in poorer condition. Brachycentrus appalachia may be less successful at even moderate densities of Hydropsyche due to competition between these taxa, most likely for prime feeding positions. 6. Streams receiving non‐point source pollution from agriculture may be able to support higher densities of Hydropsyche, which may further reduce the suitability of these habitats for B. appalachia. 7. This experimental study suggests that competition may complicate interpretation of biotic indices, as changes in benthic invertebrate community structure normally ascribed to pollution may arise from intra‐specific competition.     

Grave Injustice: The American Indian Repatriation Movement and NAGPRA.

Grave Injustice: The American Indian Repatriation Movement and NAGPRA. Kathleen S. Fine-Dare. Lincoln: University of Nebraska Press, 2002. 250 pp.