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.     

Species' traits predict phenological responses to climate change in butterflies

How do species' traits help identify which species will respond most strongly to future climate change? We examine the relationship between species' traits and phenology in a well-established model system for climate change, the U.K. Butterfly Monitoring Scheme (UKBMS). Most resident U.K. butterfly species have significantly advanced their dates of first appearance during the past 30 years. We show that species with narrower larval diet breadth and more advanced overwintering stages have experienced relatively greater advances in their date of first appearance. In addition, species with smaller range sizes have experienced greater phenological advancement. Our results demonstrate that species' traits can be important predictors of responses to climate change, and they suggest that further investigation of the mechanisms by which these traits influence phenology may aid in understanding species' responses to current and future climate change.     

The 2014 Walrus Haul Out: A Case Study of Selective Exposure to Environmental News Coverage

In this article we examine in real time the political selective exposure process involved when the public confronted the “walrus haul out” of October 2014, a news event attributed by some climate change researchers to the effects of the climate change-driven reduction of Arctic sea ice. Analyzing data assessing the amount of major TV and cable news network coverage of the haul out, and evaluating public opinion data collected from a rolling cross-sectional survey of US adults take at the time, we show that coverage of this event was not equitably distributed across news media news sources, that exposure to news source is related to the respondents’ ideological dispositions, and that exposure to coverage of the walrus haul out is related to ideology, the selectivity of political news habits, and climate change knowledge. We conclude with a discussion of the apparent inevitability of selective exposure to media coverage of climate change-related events and the implications for effective climate change communication.     

Modeling the Impacts of Two Bark Beetle Species Under a Warming Climate in the Southwestern USA: Ecological and Economic Consequences

Predicted climate warming is expected to have profound effects on bark beetle population dynamics in the southwestern United States. Temperature-mediated effects may include increases in developmental rates, generations per year, and changes in habitat suitability. As a result, the impacts of Dendroctonus frontalis and Dendroctonus mexicanus on forest resources are likely subject to amplification. To assess the implications of such change, we evaluated the generations per year of these species under three climate scenarios using a degree-day development model. We also assessed economic impacts of increased beetle outbreaks in terms of the costs of application of preventative silvicultural treatments and potential economic revenues forgone. Across the southwestern USA, the potential number of beetle generations per year ranged from 1–3+ under historical climate, an increase of 2–4+ under the minimal warming scenario and 3–5+ under the greatest warming scenario. Economic benefits of applying basal area reduction treatments to reduce forest susceptibility to beetle outbreaks ranged from 7.75/ha (NM) to7.75/ha (NM) to 95.69/ha (AZ) under historical conditions, and 47.96/ha (NM) to47.96/ha (NM) to 174.58/ha (AZ) under simulated severe drought conditions. Basal area reduction treatments that reduce forest susceptibility to beetle outbreak result in higher net present values than no action scenarios. Coupled with other deleterious consequences associated with beetle outbreaks, such as increased wildfires, the results suggest that forest thinning treatments play a useful role in a period of climate warming.     

VARIATION IN ADIRONDACK,NEW YORK,LAKEWATER CHEMISTRY AS FUNCTION OF SURFACE AREA1

ABSTRACT: Data from a recent survey conducted by the Adirondack Lake Survey Corporation were used to evaluate the influence of lake surface area on the acid-base status of lakes in Adirondack State Park, New York. Acid neutralizing capacity (ANC) in the small lakes (< 4 ha) occurred more frequently at extreme values (> 200, < 0 μeq L^?1), whereas larger lakes tended to be intermediate in ANC. Consequently, acidic (ANC ≤ 0) and low-pH lakes were typically small. The small lakes also exhibited lower Ca²⁺ concentration and higher dissolved organic carbon than did larger lakes. Lakes ≥ 4 ha were only half as likely to be acidic as were lakes ≥ 1 ha in area. These data illustrate the dependence of lake chemistry on lake surface area and the importance of the lower lake area limit for a statistical survey of lake water chemistry.     

Signaling effort does not predict aggressiveness in male spring field crickets

The relationship between signaling and aggression is still unclear despite several decades of research. However, there is a growing interest in studying signals that predict aggressive behavior or fighting ability. The goals of our study were threefold: we investigated the relationship between signaling effort and aggression, the relationship between body condition and aggression, and the effect of fighting experience on subsequent signaling behavior in wild-caught and laboratory-reared male spring field crickets (Gryllus veletis). We found that aggressive behavior was not related to signaling effort, body size, or body condition. For contest winners, wild-captured males were more aggressive than laboratory-reared males. Signaling effort was highly repeatable within individuals, but aggressive behavior had low repeatability. We found no evidence for a winner or loser effect on signaling; there was no change in signaling effort when we compared contest winners and losers before and after they participated in aggressive contests. Long-distance acoustic signaling and aggressive behavior appear to be independent of one another in spring field crickets, perhaps serving different functions in female attraction and male–male competition, respectively.