A Remotely Operated Motorized Burrow Probe to Investigate Carnivore Neonates

Abstract: We describe a miniaturized infrared camera mounted on a remotely operated platform (burrow probe system) that we developed to investigate spotted hyena (Crocuta crocuta) cubs while still in their natal dens. In conjunction with the burrow probe system, we used a hook system to retrieve carcasses from within burrows. To test the utility of these systems, we compared results obtained using the burrow probe and hook to results obtained from intensive above-ground monitoring alone. With the probe, we documented births and litter sizes at significantly younger ages than with above-ground monitoring. The probe was instrumental in detecting cubs that died prior to emergence from the natal den. Retrieval of carcasses allowed collection of genetic samples and data on sex and cause of death. Thus, the burrow probe and hook systems can provide scientists and managers with empirical data on productivity and neonatal mortality of carnivores in the wild; data essential to accurately monitor and model population trends.     

Forest soil CO2 flux: uncovering the contribution and environmental responses of ectomycorrhizas

Forests play a critical role in the global carbon cycle, being considered an important and continuing carbon sink. However, the response of carbon sequestration in forests to global climate change remains a major uncertainty, with a particularly poor understanding of the origins and environmental responses of soil CO₂ efflux. For example, despite their large biomass, the contribution of ectomycorrhizal (EM) fungi to forest soil CO₂ efflux and responses to changes in environmental drivers has, to date, not been quantified in the field. Their activity is often simplistically included in the ‘autotrophic’ root respiration term. We set up a multiplexed continuous soil respiration measurement system in a young Lodgepole pine forest, using a mycorrhizal mesh collar design, to monitor the three main soil CO₂ efflux components: root, extraradical mycorrhizal hyphal, and soil heterotrophic respiration. Mycorrhizal hyphal respiration increased during the first month after collar insertion and thereafter remained remarkably stable. During autumn the soil CO₂ flux components could be divided into ∼60% soil heterotrophic, ∼25% EM hyphal, and ∼15% root fluxes. Thus the extraradical EM mycelium can contribute substantially more to soil CO₂ flux than do roots. While EM hyphal respiration responded strongly to reductions in soil moisture and appeared to be highly dependent on assimilate supply, it did not responded directly to changes in soil temperature. It was mainly the soil heterotrophic flux component that caused the commonly observed exponential relationship with temperature. Our results strongly suggest that accurate modelling of soil respiration, particularly in forest ecosystems, needs to explicitly consider the mycorrhizal mycelium and its dynamic response to specific environmental factors. Moreover, we propose that in forest ecosystems the mycorrhizal CO₂ flux component represents an overflow ‘CO₂ tap’ through which surplus plant carbon may be returned directly to the atmosphere, thus limiting expected carbon sequestration from trees under elevated CO₂.     

Threads: Gender, Labor, and Power in the Global Apparel Industry

Threads: Gender, Labor, and Power in the Global Apparel Industry . Jane L. Collins. Chicago: University of Chicago Press, 2003. 207 pp.     

Models of floral pattern in detached flowers of Silene coeli-rosa (L) Godr. (Caryophyllaceae)

Organ number per whorl was analysed in aberrant flowers of the long-day (LD) plant , Silene coeli-rosa , to test a hypothesis that organ number in a whorl takes its cue from an adjacent outer whorl and that perturbed organ number per whorl is not random but defaults to that of closely related taxa or genera of the Caryophyllaceae. When plants were grown under short-days (SD), transferred to LD and the shoot meristem excised and cultured in vitro under SD, the normal pattern of flower development was often disrupted. For example, we observed flowers which comprised floral whorls with an aberrant number of floral organs. In part, this was an effect of tissue culture; however, the over-and-above effect was the establishment of an alternative pattern of development. Our data indicate that two distinct and recurrent patterns occurred in the aberrant flowers we observed in five separate experiments. First, pairs of floral whorls were linked so that aberration in one whorl resulted in the next whorl being more aberrant than normal. Second, the number of organs in aberrant whorls was not random, but defaulted to an organ number which mimicked the flowers of closely related species of Silene or related genera in the Caryophyllaceae.  © 2002 The Linnean Society of London , Botanical Journal of the Linnean Society , 2002, 140 , 229−235.     

The age of the grasses and clusters of origins of C4 photosynthesis

At high temperatures and relatively low CO₂ concentrations, plants can most efficiently fix carbon to form carbohydrates through C₄ photosynthesis rather than through the ancestral and more widespread C₃ pathway. Because most C₄ plants are grasses, studies of the origin of C₄ are intimately tied to studies of the origin of the grasses. We present here a phylogeny of the grass family, based on nuclear and chloroplast genes, and calibrated with six fossils. We find that the earliest origins of C₄ likely occurred about 32 million years ago (Ma) in the Oligocene, coinciding with a reduction in global CO₂ levels. After the initial appearance of C₄ species, photosynthetic pathway changed at least 15 more times; we estimate nine total origins of C₄ from C₃ ancestors, at least two changes of C₄ subtype, and five reversals to C₃. We find a cluster of C₄ to C₃ reversals in the Early Miocene correlating with a drop in global temperatures, and a subsequent cluster of C₄ origins in the Mid‐Miocene, correlating with the rise in temperature at the Mid‐Miocene climatic optimum. In the process of dating the origins of C₄, we were also able to provide estimated times for other major events in grass evolution. We find that the common ancestor of the grasses (the crown node) originated in the upper Cretaceous. The common ancestor of maize and rice lived at 52 ± 8 Ma.