Using the Price Equation to partition the effects of biodiversity loss on ecosystem function

Species loss can impact ecosystem functioning, but no general framework for analyzing these impacts exists. Here I derive a general partitioning of the effects of species loss on any ecosystem function comprising the summed contributions of individual species (e.g., primary productivity). The approach partitions the difference in ecosystem function between two sites (a "pre-loss" site, and a "post-loss" site comprising a strict subset of the species at the pre-loss site) into additive components attributable to different effects. The approach does not assume a particular experimental design or require monoculture data, making it more general than previous approaches. Using the Price Equation from evolutionary biology, I show that three distinct effects cause ecosystem function to vary between sites: the "species richness effect" (SRE; random loss of species richness), the "species composition effect" (SCE; nonrandom loss of high- or low-functioning species), and the "context dependence effect" (CDE; post-loss changes in the functioning of the remaining species). The SRE reduces ecosystem function without altering mean function per species. The SCE is analogous to natural selection in evolution. Nonrandom loss of, for example, high-functioning species will reduce mean function per species, and thus total function, just as selection against large individuals in an evolving population reduces mean body size in the next generation. The CDE is analogous to imperfect transmission in evolution. For instance, any factor (e.g., an environmental change) causing offspring to attain smaller body sizes than their parents (imperfect transmission) will reduce the mean body size in the next generation. Analogously, any factor causing the species remaining at the post-loss site to make smaller functional contributions than at the pre-loss site will reduce mean function per species, and thus total function. I use published data to illustrate how this new partition generalizes previous approaches, facilitates comparative analyses, and generates new empirical insights. In particular, the SCE often is less important than other effects.     

Carnivore-Caused Livestock Mortality in Trans-Himalaya

The loss of livestock to wild predators is an important livelihood concern among Trans-Himalayan pastoralists. Because of the remoteness and inaccessibility of the region, few studies have been carried out to quantify livestock depredation by wild predators. In the present study, we assessed the intensity of livestock depredation by snow leopard Uncia uncia, Tibetan wolf Canis lupus chanku, and Eurasian lynx Lynx l. isabellina in three villages, namely Gya, Rumtse, and Sasoma, within the proposed Gya-Miru Wildlife Sanctuary in Ladakh, India. The three villages reported losses of 295 animals to these carnivores during a period of 2.5 years ending in early 2003, which represents an annual loss rate of 2.9% of their livestock holdings. The Tibetan wolf was the most important predator, accounting for 60% of the total livestock loss because of predation, followed by snow leopard (38%) and lynx (2%). Domestic goat was the major victim (32%), followed by sheep (30%), yak (15%), and horse (13%). Wolves killed horses significantly more and goats less than would be expected from their relative abundance. Snow leopards also killed horses significantly more than expected, whereas they killed other livestock types in proportion to their abundance. The three villages combined incurred an estimated annual monetary loss of approximately $USD 12,120 amounting to approximately $USD 190/household/y. This relatively high total annual loss occurred primarily because of depredation of the most valuable livestock types such as yak and horse. Conservation actions should initially attempt to target decrease of predation on these large and valuable livestock species.     

A rare inherited euchromatic heteromorphism on chromosome 1

Extra genetic material that is euchromatic is generally regarded to be associated with phenotypic abnormalities. However, recent studies suggest that this is not always the case. Chromosome analysis was performed on amniotic fluid cells from a 37-year-old phenotypi-cally normal patient referred for advanced maternal age. All the cells analysed showed a karyotype of 46, XY, 1p-K The 1p+ chromosome had extra genetic material of uncertain origin in chromosome band region 1p21 →31. Chromosome analysis on the father revealed a normal 46, XY male karyotype. The mother's karyotype showed the same 1p+ chromosome. C and Q banding, as well as silver staining studies, in both the mother and the fetus support the interpretation that the extra chromosomal material was euchromatic in nature. This 1p + chromosome may be characterized as a euchromatic heteromorphism. Euchromatic hetero-morphisms not associated with phenotypic abnormalities have been reported for chromosomes 9 and 16. To the best of our knowledge, this is the first report involving this type of cytogenetic anomaly on chromosome number 1 in a phenotypically normal mother and infant.     

Morphological change and phenotypic plasticity in native and non-native pumpkinseed sunfish in response to competition

Non-indigenous species are oftentimes exposed to ecosystems with unfamiliar species, and organisms that exhibit a high degree of phenotypic plasticity may be better able to contend with the novel competitors that they may encounter during range expansion. In this study, differences in morphological plasticity were investigated using young-of-year pumpkinseed sunfish (Lepomis gibbosus) from native North American and non-native European populations. Two Canadian populations, isolated from bluegill sunfish (L. macrochirus) since the last glaciation, and two Spanish populations, isolated from bluegill since their introduction in Europe, were reared in a common environment using artificial enclosures. Fish were subjected to allopatric (without bluegill) or sympatric (with bluegill) conditions, and differences in plasticity were tested through a MANOVA of discriminant function scores. All pumpkinseed populations exhibited dietary shifts towards more benthivorous prey when held with bluegill. Differences between North American and European populations were observed in body dimensions, gill raker length and pelvic fin position. Sympatric treatments induced an increase in body width and a decrease in caudal peduncle length in native fish; non-native fish exhibited longer caudal peduncle lengths when held in sympatry with bluegill. Overall, phenotypic plasticity influenced morphological divergence less than genetic factors, regardless of population. Contrary to predictions, pumpkinseeds from Europe exhibited lower levels of phenotypic plasticity than Canadian populations, suggesting that European pumpkinseeds are more canalized than their North American counterparts.     

Growth, fire history, and browsing recorded in wood rings of shrubs in a mild temperate climate

Separate effects of abiotic and biotic factors on the structure and dynamics of ecological communities may be recorded in growth rings of woody plants. We used Ceanothus cuneatus rigidus and Arctostaphylos pumila to tease apart the roles of fire, rain, and herbivores on the histories and community structure of four areas in a coastal mediterranean-type climate in central California with mild winters and mild summers. Ring widths of both species were related to rainfall in two of the areas; heavy deer browsing on Ceanothus overwhelmed the climate signal in the others. Ceanothus germination was more closely related to heavy rainfall, especially during ENSO years, than to fire events. In a related greenhouse experiment that evaluated these observations, the same proportions of new Ceanothus seeds germinated after burning and after receiving regular water for several months, but germination of old seeds responded primarily to the fire treatment. In areas where heavy browsing by mammals reduces recruitment and growth of Ceanothus and increases mortality, the continuance of the Ceanothus population must rely heavily on germination from the persistent seed bank during unusually wet years or after occasional fires. Because Arctostaphylos can produce new stems from underground roots, individual plants may survive and produce seeds until another fire.     

MODELING THE BIG BLACK RIVER: A COMPARISON OF WATER QUALITY MODELS1

ABSTRACT: The Mississippi Department of Environmental Quality uses the Steady Riverine Environmental Assessment Model (STREAM) to establish effluent limitations. While the U.S. Environmental Protection Agency has approved of its use, questions arise regarding the model's simplicity. The objective of this research was to compare STREAM with the more commonly utilized Enhanced Stream Water Quality Model (QUAL2E). The comparison involved a statistical evaluation procedure based on sensitivity analyses, input probability distribution functions, and Monte Carlo simulation with site‐specific data from a 46‐mile (74‐km) reach of the Big Black River in central Mississippi. Site specific probability distribution functions were derived from measured rates of reaeration, sediment oxygen demand, photosynthesis, and respiration. Both STREAM and QUAL2E reasonably predicted daily average dissolved oxygen (DO) based on a comparison of output probability distributions with observed DO. Observed DO was consistently within 90 percent confidence intervals of model predictions. The STREAM approach generally overpredicted while QUAL2E generally matched observed DO. Using the more commonly assumed lognormal distribution as opposed to a Weibull distribution for two of the sensitive input parameters resulted in minimal differences in the statistical evaluations. The QUAL2E approach had distinct advantages over STREAM in simulating the growth cycle of algae.     

Evaluation of environmental impacts of large scale physical development in central Galilee: Role of experts and policy makers

This article reports on the content and process used to evaluate environmental impacts caused by the development of 50 new settlements in the central Galilee region in northern Israel between 1978 and 1988. Some 60 different environmental and developmental factors and their interrelationships were identified. Selected physical changes that were defined as impacts were later evaluated. The evaluation method was based on intensive use of interviews with resource scientists and decision makers as experts. The data from interviews were used as the basis for factors identification, impact screening, and their rating. Experts used three types of criteria in the latter process: intensity of impact, the potential for its mitigation and compatibility with existing natural resource conservation, and environmental quality protection policy. Researchers concluded that reliance on experts with broad local experience eliminated the need for a more structured and detailed assessment method. The case study shows that experts provided creditable and reliable findings. They substituted the need for long periods of observation and largescale and costly data gathering, analysis, and evaluation.     

Staying in place during times of change in Arctic Alaska: the implications of attachment,alternatives, and buffering

The relationship between stability and change in social-ecological systems has received considerable attention in recent years, including the expectation that significant environmental changes will drive observable consequences for individuals, communities, and populations. Migration, as one example of response to adverse economic or environmental changes, has been observed in many places, including parts of the Far North. In Arctic Alaska, a relative lack of demographic or migratory response to rapid environmental and other changes has been observed. To understand why Arctic Alaska appears different, we draw on the literature on environmentally driven migration, focusing on three mechanisms that could account for the lack of response: attachment, the desire to remain in place, or the inability to relocate successfully; alternatives, ways to achieve similar outcomes through different means; and buffering, the reliance on subsidies or use of reserves to delay impacts. Each explanation has different implications for research and policy, indicating a need to further explore the relative contribution that each makes to a given situation in order to develop more effective responses locally and regionally. Given that the Arctic is on the front lines of climate change, these explanations are likely relevant to the ways changes play out in other parts of the world. Our review also underscores the importance of further attention to the details of social dynamics in climate change impacts and responses.