Does including physiology improve species distribution model predictions of responses to recent climate change?

Thermal constraints on development are often invoked to predict insect distributions. These constraints tend to be characterized in species distribution models (SDMs) by calculating development time based on a constant lower development temperature (LDT). Here, we assessed whether species-specific estimates of LDT based on laboratory experiments can improve the ability of SDMs to predict the distribution shifts of six U.K. butterflies in response to recent climate warming. We find that species-specific and constant (5 degrees C) LDT degree-day models perform similarly at predicting distributions during the period of 1970-1982. However, when the models for the 1970-1982 period are projected to predict distributions in 1995-1999 and 2000-2004, species-specific LDT degree-day models modestly outperform constant LDT degree-day models. Our results suggest that, while including species-specific physiology in correlative models may enhance predictions of species' distribution responses to climate change, more detailed models may be needed to adequately account for interspecific physiological differences.     

Stochastic population dynamics in populations of western terrestrial garter snakes with divergent life histories

Comparative evaluations of population dynamics in species with temporal and spatial variation in life-history traits are rare because they require long-term demographic time series from multiple populations. We present such an analysis using demographic data collected during the interval 1978-1996 for six populations of western terrestrial garter snakes (Thamnophis elegans) from two evolutionarily divergent ecotypes. Three replicate populations from a slow-living ecotype, found in mountain meadows of northeastern California, were characterized by individuals that develop slowly, mature late, reproduce infrequently with small reproductive effort, and live longer than individuals of three populations of a fast-living ecotype found at lakeshore locales. We constructed matrix population models for each of the populations based on 8-13 years of data per population and analyzed both deterministic dynamics based on mean annual vital rates and stochastic dynamics incorporating annual variation in vital rates. (1) Contributions of highly variable vital rates to fitness (lambda(s)) were buffered against the negative effects of stochastic variation, and this relationship was consistent with differences between the meadow (M-slow) and lakeshore (L-fast) ecotypes. (2) Annual variation in the proportion of gravid females had the greatest negative effect among all vital rates on lambda(s). The magnitude of variation in the proportion of gravid females and its effect on lambda(s) was greater in M-slow than L-fast populations. (3) Variation in the proportion of gravid females, in turn, depended on annual variation in prey availability, and its effect on lambda(s) was 4 23 times greater in M-slow than L-fast populations. In addition to differences in stochastic dynamics between ecotypes, we also found higher mean mortality rates across all age classes in the L-fast populations. Our results suggest that both deterministic and stochastic selective forces have affected the evolution of divergent life-history traits in the two ecotypes, which, in turn, affect population dynamics. M-slow populations have evolved life-history traits that buffer fitness against direct effects of variation in reproduction and that spread lifetime reproduction across a greater number of reproductive bouts. These results highlight the importance of long-term demographic and environmental monitoring and of incorporating temporal dynamics into empirical studies of life-history evolution.     

Island Extinction Rates from Regular Censuses

Regular censuses conducted over a long time allow the calculation of both extinction and immigration rates. We present formulae for estimation of those rates. We use them on bird censuses of three British islands. These formulae improve on previous estimators of extinction but reaffirm that smaller populations have a higher probability of becoming extinct. On the other hand, they suggest no correlation between extinction rate and either body size or migratory status among birds.     

Delayed onset of vocal recognition in Australian sea lion pups (Neophoca cinerea)

In pinnipeds, maternal care strategies and colony density may influence a species’ individual recognition system. We examined the onset of vocal recognition of mothers by Australian sea lion pups (Neophoca cinerea). At 2 months of age, pups responded significantly more to the calls of their own mothers than alien female calls demonstrating a finely tuned recognition system. However, newborn pups did not respond differentially to the calls of their mother from alien female calls suggesting that vocal recognition had not yet developed or is not yet expressed. These findings are in stark contrast to other otariid species where pups learn their mother’s voice before their first separation. Variance in colony density, pup movements, and natal site fidelity may have reduced selective pressures on call recognition in young sea lions, or alternatively, another sensory system may be used for recognition in the early stage of life.     

Health benefits from reducing indoor air pollution from household solid fuel use in China--three abatement scenarios

According to the World Health Organization (WHO), indoor air pollution (IAP) from the use of solid fuels in households in the developing world is responsible for more than 1.6 million premature deaths each year, whereof 0.42 million occur in China alone. We argue that the methodology applied by WHO--the so-called fuel-based approach--underestimates the health effects, and suggest an alternative method. Combining exposure-response functions and current mortality and morbidity rates, we estimate the burden of disease of IAP in China and the impacts of three abatement scenarios. Using linear exposure-response functions, we find that 3.5 [0.8-14.7 95% CI] million people die prematurely due to IAP in China each year. The central estimate constitutes 47% of all deaths in China. We find that modest changes in the use of cooking fuels in rural households might have a large health impact, reducing annual mortality by 0.63 [0.1-3. 2 95% CI] million. If the indoor air quality (IAQ) standard set by the Chinese government (150 microg PM(10)/m(3)) was met in all households, we estimate that 0.9 [0.2-4.8] million premature deaths would be avoided in urban areas and 2.8 [0.7-12.4] million in rural areas. However, in urban areas this would require improvements to the outdoor air quality in addition to a complete fuel switch to clean fuels in households. We estimate that a fuel switch in urban China could prevent 0.7 [0.2-4.8] million premature deaths. The methodology for exposure assessment applied here is probably more realistic than the fuel-based approach; however, the use of linear exposure-response relationships most likely tends to overestimate the effects. The discrepancies between our results and the WHO estimates is probably also explained by our use of "all-cause mortality" which includes important causes of death like cardiovascular diseases, conditions known to be closely associated with exposure to particulate pollution, whereas the WHO estimate is limited to respiratory diseases.     

A capabilities approach to the prioritization of critical infrastructure

As a consequence of the U.S. effort to increase infrastructure security and resilience, the Department of Homeland Security (DHS) and other U.S. federal agencies have identified 16 critical infrastructure sectors that are considered vital to the nation’s well-being in terms of economic security, public health, and safety. However, there remains no articulated set of values that justify this particular list of infrastructure systems or how decision-makers might prioritize investments towards one critical sector over another during a crisis. To offer a more integrated and holistic approach to critical infrastructure resilience, this research employs the capabilities approach to human development, which offers an alternative view of critical infrastructure that focuses on the services that infrastructure provides rather than its physical condition or vulnerability to threats. This service-based perspective of infrastructure emphasizes the role of infrastructure in enabling and supporting central human capabilities that build adaptive capacity and improve human well-being. We argue that the most critical infrastructure systems are those that are essential for providing and/or supporting central human capabilities. This paper examines the DHS designation of criticality from a capabilities perspective and argues for a capabilities basis for making distinctions between those systems that should be considered most critical and those that might be temporarily sacrificed. A key implication of this work is that an across sector approach is required to reorganize existing critical infrastructure efforts around the most valuable infrastructure end-services.     

Modeling change in forest biomass across the eastern US

Environmental and Ecological Statistics - Predictions of above-ground biomass and the change in above-ground biomass require attachment of uncertainty due the range of reported predictions for...