Quantifying the erosion of natural darkness in the global protected area system

The nighttime light environment of much of the earth has been transformed by the introduction of electric lighting. This impact continues to spread with growth in the human population and extent of urbanization. This has profound consequences for organismal physiology and behavior and affects abundances and distributions of species, community structure, and likely ecosystem functions and processes. Protected areas play key roles in buffering biodiversity from a wide range of anthropogenic pressures. We used a calibration of a global satellite data set of nighttime lights to determine how well they are fulfilling this role with regard to artificial nighttime lighting. Globally, areas that are protected tend to be darker at night than those that are not, and, with the exception of Europe, recent regional declines in the proportion of the area that is protected and remains dark have been small. However, much of these effects result from the major contribution to overall protected area coverage by the small proportion of individual protected areas that are very large. Thus, in Europe and North America high proportions of individual protected areas (>17%) have exhibited high levels of nighttime lighting in all recent years, and in several regions (Europe, Asia, South and Central America) high proportions of protected areas (32–42%) have had recent significant increases in nighttime lighting. Limiting and reversing the erosion of nighttime darkness in protected areas will require routine consideration of nighttime conditions when designating and establishing new protected areas; establishment of appropriate buffer zones around protected areas where lighting is prohibited; and landscape level reductions in artificial nighttime lighting, which is being called for in general to reduce energy use and economic costs.     

A Habitat-Based Metapopulation Model of the California Gnatcatcher

We present an analysis of the metapopulation dynamics of the federally threatened coastal California Gnatcatcher (Polioptila c. californica) for an approximately 850 km² region of Orange County, California. We developed and validated a habitat suitability model for this species using data on topography, vegetation, and locations of gnatcatcher pair observations. Using this habitat model, we calculated the spatial structure of the metapopulation, including size and location of habitat patches and the distances among them. We used data based on field studies to estimate parameters such as survival, fecundity, dispersal, and catastrophes, and combined these parameters with the spatial structure to build a stage-structured, stochastic, spatially-explicit metapopulation model. The model predicted a fast decline and high risk of population extinction with most combinations of parameters. Results were most sensitive to density-dependent effects, the probability of weather-related catastrophes, adult survival, and adult fecundity. Based on data used in the model, the greatest difference in results was given when the simulation's time horizon was only a few decades, suggesting that modeling based on longer or shorter time horizons may underestimate the effects of alternative management actions.     

Flash competition in male Photinus macdermotti fireflies

Summary The courtship of Photinus macdermotti fireflies involves a flash code in which the male emits a pair of flashes about two seconds apart and the female responds with a flash about 1.2 s after the second flash of the male pair. The male repeats his pair of courting flashes at varying intervals of four seconds or more. Lloyd (1979, 1981 a, b) observed that rival males in Florida sometimes interject flashes between the courtship flashes of the courting male. We have found that the competitive behavior of males of the same species on Long Island, New York, was somewhat different. Rival males timed their competing flashes from either the first or second of the original males's courting flashes. When a competing flash from the rival male was timed from the first courting flash it was synchronized with the original male's second courting flash. When a competing flash was timed from the second courting flash, a delayed flash resulted which appeared after the female's response. In either case the male's display period was preserved, insuring that the female would continue to respond. Either of these rival male flashes could sometimes induce the female to respond in his direction.     

Female guppies shorten brood retention in response to predator cues

Predation risk influences the duration of offspring development in many species where embryos develop from externally shed eggs. Surprisingly, such predator-mediated effects on offspring development have rarely been explored in live-bearers. In this paper, we use the guppy (Poecilia reticulata), a live-bearing freshwater fish, to test whether the duration of brood retention (the time from mating to parturition) is influenced by experimental changes in the perceived level of predation. Because the swimming performance of female guppies is impaired during late pregnancy, we predicted that females would withhold broods for shorter periods when they are exposed to cues that signal a heightened risk of predation on adults rather than on juveniles. We therefore simulated increased risk of predation on adults by using a combination of pike-shaped models (resembling natural predators that prey on adult guppies) and ‘alarm substances’ derived from the skin extracts of adult conspecific females. Our results revealed that, under simulated predation risk, female guppies produced broods significantly more quickly than their counterparts assigned to a control group where predator cues were absent. A subsequent evaluation of offspring swimming performance revealed a significant positive association between neonate swimming speeds and the duration of brood retention, suggesting that by accelerating parturition, females may produce offspring with impaired locomotor skills. These findings, in conjunction with similar results from other live-bearing species, suggest that the conditions experienced by gestating females can generate significant variation in the timing of offspring development with potentially important implications for offspring fitness.     

Populations of Pecos pupfish (<Emphasis Type="Italic">Cyprinodon pecosensis</Emphasis>) differ in their susceptibility to hybridization with sheepshead minnow (<Emphasis Type="Italic">C. variegatus</Emphasis>)

The importance of sexual selection in hybridization between species that evolved in allopatry is poorly understood. Even less is known about differences between populations in their resistance or susceptibility to genetic introgression with a congener. Here we examine behavioral differences between populations of the native Pecos pupfish (Cyprinodon pecosensis) and their potential effects in facilitating or retarding hybridization with an introduced congener, the sheepshead minnow (C. variegatus). We quantified competitive interactions, establishment of territories, and mating success of several naturally occurring C. pecosensis populations and an artificially created laboratory population (control) against C. variegatus. Experiments were conducted in large outdoor tanks during the summer months when high temperatures favor breeding activity in pupfish. C. pecosensis populations differed in agonistic behavior, territoriality, and in mating success when competing against C. variegatus. Differences in the competitive ability of males from different C. pecosensis populations suggest that the rate of introgression with C. variegatus may vary, depending on the population of C. pecosensis it comes in contact with. Our results suggest that large, stable C. pecosensis populations may be relatively resistant to hybridization with C. variegatus. Interpopulation variation in male behavior, shaped by sexual selection, may be important in determining the incidence and rate of hybridization between the two congeners. Experimental studies are a powerful tool in elucidating behavioral processes, such as the action of intrasexual selection, that facilitate or retard the coalescence of lineages through initial hybridization and subsequent genetic introgression after secondary contact between allopatric species.Communicated by M. Abrahams     

Highlights from a new aerospace industry report

Environmental Information Services, Inc. (EIS) publishes detailed reports and offers custom research related to the full spectrum of environmental issues facing corporations. This article highlights several key sections from EIS's new 1998 Aerospace Industry Report. It details the environmental performance, policies, and expenditures of the largest companies in the aerospace industry. EIS industry reports contain data on five key performance criteria—toxic waste management, hazardous waste generation, penalties and enforcement actions, spills, and Superfund sites. Here we examine one of those—penalties and enforcement actions—and the policies of the three largest companies. © 1998 John Wiley & Sons, Inc.