252 research outputs found
Sulfuric acid and OH concentrations in a boreal forest site
As demonstrated in a number of investigations, gaseous sulfuric acid
plays a central role in atmospheric aerosol formation. Using
chemical ionization mass spectrometer the gas-phase sulfuric acid
and OH concentration were measured in Hyytiälä, SMEAR II
station, Southern Finland during 24 March to 28 June 2007. Clear
diurnal cycles were observed as well as differences between new
particle formation event days and non-event days. Typically, the
daily maximum concentrations of gas phase sulfuric acid varied from
3×105 to 2×106 molec cm−3 between
non-event and event days. Noon-time OH concentrations varied from
3-6×105 molec cm−3 and not a clear difference
between event and non-events was detected. The measured time series
were also used as a foundation to develop reasonable proxies for
sulfuric acid concentration. The proxies utilized source and sink
terms, and the simplest proxy is radiation times sulfur dioxide
divided by condensation sink. Since it is still challenging to
measure sulfuric acid in ambient concentrations, and due to its
significant role in atmospheric particle formation, reasonable
proxies are needed. We use all together three different proxies and
one chemical box model and compared their results to the measured
data. The proxies for the sulfuric acid concentration worked
reasonably well, and will be used to describe sulfuric acid
concentrations in SMEAR II station, when no measured sulfuric acid
data is available. With caution the proxies could be applied to
other environments as well
Negative phenotypic and genetic associations between copulation duration and longevity in male seed beetles
Reproduction can be costly and is predicted to trade-off against other characters. However, while these trade-offs are well documented for females, there has been less focus on aspects of male reproduction. Furthermore, those studies that have looked at males typically only investigate phenotypic associations, with the underlying genetics often ignored. Here, we report on phenotypic and genetic trade-offs in male reproductive effort in the seed beetle, Callosobruchus maculatus. We find that the duration of a male's first copulation is negatively associated with subsequent male survival, phenotypically and genetically. Our results are consistent with life-history theory and suggest that like females, males trade-off reproductive effort against longevity
How to halt the global decline of lands
The assessment of land degradation and restoration by the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services shows that land degradation across the globe is a wide and severe issue and is showing no signs of slowing down. This trend must be halted and reversed
Good Genes and Sexual Selection in Dung Beetles (Onthophagus taurus): Genetic Variance in Egg-to-Adult and Adult Viability
Whether species exhibit significant heritable variation in fitness is central for sexual selection. According to good genes models there must be genetic variation in males leading to variation in offspring fitness if females are to obtain genetic benefits from exercising mate preferences, or by mating multiply. However, sexual selection based on genetic benefits is controversial, and there is limited unambiguous support for the notion that choosy or polyandrous females can increase the chances of producing offspring with high viability. Here we examine the levels of additive genetic variance in two fitness components in the dung beetle Onthophagus taurus. We found significant sire effects on egg-to-adult viability and on son, but not daughter, survival to sexual maturity, as well as moderate coefficients of additive variance in these traits. Moreover, we do not find evidence for sexual antagonism influencing genetic variation for fitness. Our results are consistent with good genes sexual selection, and suggest that both pre- and postcopulatory mate choice, and male competition could provide indirect benefits to females
The Perils of Picky Eating: Dietary Breadth Is Related to Extinction Risk in Insectivorous Bats
Several recent papers evaluate the relationship between ecological characteristics and extinction risk in bats. These studies report that extinction risk is negatively related to geographic range size and positively related to habitat specialization. Here, we evaluate the hypothesis that extinction risk is also related to dietary specialization in insectivorous vespertilionid bats using both traditional and phylogenetically-controlled analysis of variance. We collected dietary data and The World Conservation Union (IUCN) rankings for 44 Australian, European, and North American bat species. Our results indicate that species of conservation concern (IUCN ranking near threatened or above) are more likely to have a specialized diet than are species of least concern. Additional analyses show that dietary breadth is not correlated to geographic range size or wing morphology, characteristics previously found to correlate with extinction risk. Therefore, there is likely a direct relationship between dietary specialization and extinction risk; however, the large variation in dietary breadth within species of least concern suggests that diet alone cannot explain extinction risk. Our results may have important implications for the development of predictive models of extinction risk and for the assignment of extinction risk to insectivorous bat species. Similar analyses should be conducted on additional bat families to assess the generality of this relationship between niche breadth and extinction risk
Sexual Display and Mate Choice in an Energetically Costly Environment
Sexual displays and mate choice often take place under the same set of environmental conditions and, as a consequence, may be exposed to the same set of environmental constraints. Surprisingly, however, very few studies consider the effects of environmental costs on sexual displays and mate choice simultaneously. We conducted an experiment, manipulating water flow in large flume tanks, to examine how an energetically costly environment might affect the sexual display and mate choice behavior of male and female guppies, Poecilia reticulata. We found that male guppies performed fewer sexual displays and became less choosy, with respect to female size, in the presence of a water current compared to those tested in still water. In contrast to males, female responsive to male displays did not differ between the water current treatments and females exhibited no mate preferences with respect to male size or coloration in either treatment. The results of our study underscore the importance of considering the simultaneous effects of environmental costs on the sexual behaviors of both sexes
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