Signaling and priming communication: Independent roles in the reproductive isolation of spatially-separated populations of rodents

Summary This research concerned the relative potential for signaling and priming incompatibilities to promote reproductive isolation in rodents. Signaling is defined here as involving behavioral responses, while priming involves endocrine responses. Compatibility of both types of communications was tested between two widely separated and markedly diverging populations of deermice, and between equally separated but much less divergent populations of house mice. Signaling compatibility was assessed by comparing the amount of aggression toward young females by adult males when the two sexes were of the same vs the different stock of the same species. Priming compatibility was tested by measuring the relative amounts of uterine growth induced in young females by exposure to adult males.No signaling or priming incompatibilities were detected during cross-testing of the house mouse stocks. A degree of developing reproductive isolation was observed between the two deermouse populations, however, and this isolation was reinforced by independently occurring incompatibilities of both the signaling and the priming type. The signaling incompatibility was particularly dramatic, manifesting itself in the killing of young females by adult males.The present results provide the first demonstration of a priming incompatibility supporting reproductive isolation in diverging populations of a mammal. Furthermore, our results suggest that signaling and priming systems are independently subject to evolutionary change even when both systems probably operate through the same sensory modality.     

Sensitivity of amounts and distribution of tropical forest carbon credits depending on baseline rules

One of the largest sources of global greenhouse gas emissions can be addressed through conservation of tropical forests by channeling funds to developing countries at a cost-savings for developed countries. However, questions remain to be resolved in negotiating a system for including reduced emissions from deforestation and forest degradation (REDD) in a post-Kyoto climate treaty. The approach to determine national baselines, or reference levels, for quantifying REDD has emerged as central to negotiations over a REDD mechanism in a post-Kyoto policy framework. The baseline approach is critical to the success of a REDD mechanism because it affects the quantity, credibility, and equity of credits generated from efforts to reduce forest carbon emissions. We compared outcomes of seven proposed baseline approaches as a function of country circumstances, using a retrospective analysis of FAO-FRA data on forest carbon emissions from deforestation. Depending upon the baseline approach used, the total credited emissions avoided ranged over two orders of magnitude for the same quantity of actual emissions reductions. There was also a wide range in the relative distribution of credits generated among the five country types we identified. Outcomes were especially variable for countries with high remaining forest and low rates of deforestation (HFLD). We suggest that the most credible approaches measure emissions avoided with respect to a business-as-usual baseline scenario linked to historic emissions data, and allow limited adjustments based on forest carbon stocks.     

Sex differences in the energy allocation strategies of house mice

Summary Sex differences in energy allocation were studied in wild stock house mice (Mus domesticus). Peripubertal animals of both sexes, either intact or gonadectomized, were subjected for 8 weeks to one of two feeding requirements by using a caging system in which a pellet dispenser was controlled by activity on a running wheel. Recently weaned animals were required to run 200 vs 300 or more wheel revolutions to obtain a pellet of food. The 200 revolution requirement allowed normal body growth and reproductive development; the 300+ requirement was adjusted weekly to maintain food intake at a level that allowed survival but did not permit normal body growth. Reproductive development was completely inhibited in intact females at 300+ revolutions whereas intact males at 300+ revolutions, despite stunted growth, all experienced normal sexual development. At both feeding requirements, however, females exhibited more total locomotor activity and consumed more food than males, regardless of gonadectomy. Furthermore, at the 200 revolution requirement we often observed extensive running activity beyond that needed to generate the amount of food actually eaten, especially among females. This extra locomotor activity was gonad-dependent in males, but not so in females. These results suggest that male and female house mice employ different strategies when relating their behavior and reproductive development to existing foraging conditions. Females appear more resource-dependent than males.     

New perspectives on sustainable development and barriers to relevant information

Sustainable development may mean different things to people with different worldviews. We sketch four worldviews, drawing on a schema developed by Bryan Norton. Of these four worldviews, i.e. exploitist, utilitist, integrist and inherentist, the third is the most consistent with the Brundtland Report (WCED 1987) and the Great Lakes Water Quality Agreement (GLWQA 1987).The integrist perspective combines analytic reductionistic study with comparative contextual study, with emphasis on the latter. This integrative approach moves from over-reliance on utilist information services such as impact assessment towards transactive study. Our own compromise emphasizes a stress-response approach to a partial understanding of complex cultural-natural interactions within ecosystems. Both cultural and natural attributes of ecosystems must be addressed.Currently the federal Canadian government tends toward an exploitist worldview; current government R&D funding and subsidies reflect this view. Old-fashioned scientists who rely on a monocular analytical vision of the world's minutiae may find contextual historical study offensive; these scientists hold sway on some advisory boards and hence research funding. Difficulty in finding funding for integrist information services should not be interpreted as a lack of need for this information; rather this difficulty results from resistance to a changing worldview.     

Commodity production as restoration driver in the Brazilian Amazon? Pasture re-agro-forestation with cocoa (<Emphasis Type="Italic">Theobroma cacao</Emphasis>) in southern Pará

The increasing demand for agricultural commodities is a major cause of tropical deforestation. However, pressure is increasing for greater sustainability of commodity value chains. This includes the demand to establish new crop plantations and pasture areas on already deforested land so that new forest clearing for agriculture is minimized. Where tree crops are planted as part of agroforestry systems on deforested land, this amounts to a form of re-agro-forestation which can generate environmental benefits in addition to crop production. Here, we discuss a case where agroforestry systems based on cocoa (Theobroma cacao) are being established on crop and pasture land in the south of Pará state, Brazilian Amazon. The adoption of cocoa by farmers and ranchers of the region is stimulated by the coincidence of (1) favorable prospects for cocoa on the national and international markets including the expectation of a global cocoa supply gap; (2) environmental policies obliging land owners to reforest excess cleared land with native trees, with agroforests based on the native cocoa tree being an economically attractive option; and (3) biophysical conditions (especially soil fertility) favorable for growing cocoa in part of the region. We show that in the state of Pará at least 1.26 million hectares of naturally high-fertility soils in deforested areas outside legally protected and indigenous lands are potentially suitable for cocoa production with low agrochemical inputs, sufficient to make a significant contribution to closing the predicted supply gap. Their actual suitability depends on their state of degradation after years of pasture use and the availability of technologies and finance to convert them into tree crop agroforests. We discuss the significant environmental benefits of pasture re-agro-forestation with cocoa-based systems, including reduced emissions of up to 135 Mg of carbon per hectare compared to the historically common scenario of planting cocoa after forest clearing. We identify important research questions related to the scaling up of this practice and the maximization of its environmental benefits. We conclude that the coincidence of the afore-mentioned factors could drive a re-agro-forestation frontier in this part of the Amazon, with potential for positive outcomes in terms of commodity production while generating social and environmental benefits.