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91.
We examined the relationship between breeding success and juvenile sex ratio in two gamebirds with differing degrees of sexual size dimorphism. We used breeding success as an indicator of the level of environmental stress the birds had experienced. Capercaillie Tetrao urogallus and Black Grouse T. tetrix wing samples were collected from hunters in northern Sweden during 1977-86. In both species, annual juvenile sex ratio (percentage of males) increased with annual breeding success, i.e. with reduced environmental stress. We attribute this to the higher energy requirements during growth, vulnerability to environmental stress, and mortality of juvenile males compared with females, especially under adverse conditions. Moreover, the relationship between breeding success and juvenile sex ratio was stronger in Capercaillie than in Black Grouse. This reflects the higher degree of sexual size dimorphism in Capercaillie, and consequent larger mortality difference between juvenile males and females. 相似文献
92.
TIM J. CLOUGH KELLY ADDY† DOROTHY Q. KELLOGG† BARBARA L. NOWICKI† ARTHUR J. GOLD† PETER M. GROFFMAN‡ 《Global Change Biology》2007,13(7):1528-1537
Few data are available to validate the Intergovernmental Panel on Climate Change's (IPCC) emission factors for indirect emissions of nitrous oxide (N2O). In particular the N2O emissions resulting from nitrogen leaching and the associated groundwater and surface drainage (EF5-g) are particularly poorly characterized. In situ push–pull methods have been used to identify the fate of NO3− in the groundwater. In this study, we adapted a previously published in situ denitrification push–pull method to examine the fate of 15N2O introduced into the subsoil–groundwater matrix. Enriched 15N2O was manufactured, added to groundwater via a closed system in the laboratory, and then introduced into the groundwater–subsoil matrix in an upland-marsh transition zone of a salt marsh and a forested alluvial riparian zone. Conservative tracers (SF6 and Br−) and 15N2O were injected into the groundwater and left for 1–4 h after which the groundwater was sampled. Added 15N2O behaved in a conservative manner at one site while the other site showed variability with some injections showing significant consumption (3–8 μg N2O-15N kg−1 soil day−1) of 15N2O. Our results show that the fate and dynamics of N2O in groundwater are complex and variable and that these dynamics should be considered in the development of improved IPCC inventory calculations. 相似文献
93.
How landscape structure, land-use intensity and habitat diversity affect components of total arthropod diversity in agricultural landscapes 总被引:13,自引:1,他引:13
FREDERIK HENDRICKX† JEAN-PIERRE MAELFAIT† WALTER VAN WINGERDEN‡ OLIVER SCHWEIGER§ MARJAN SPEELMANS† STÉPHANIE AVIRON¶ ISABEL AUGENSTEIN REGULA BILLETER†† DEBRA BAILEY¶ ROMAN BUKACEK‡‡ FRANÇOISE BUREL§§ TIM DIEKÖTTER†† JOLANDA DIRKSEN‡ FELIX HERZOG¶ JAAN LIIRA¶¶ MARTINA ROUBALOVA VIKI VANDOMME ROB BUGTER‡ 《Journal of Applied Ecology》2007,44(2):340-351
94.
95.
We used data on the world's woodpeckers to test for patterns in the geographic distributions of a single group of closely related species. The frequency distribution of woodpecker geographic range sizes is approximately lognormal. Most variation in range sizes is explained by differences between species within genera; that is, range size seems to be an evolutionarily labile trait. The largest woodpecker ranges are found in Eurasia, both when absolute differences are compared and when range size is measured as a proportion of estimated available habitat. Notably, there is a negative relationship between the mean range sizes attained by species in a genus or tribe in South America and the mean ranges attained by species in the same tribe or genus in North America. Large-bodied species tend to be more widely distributed and to live at higher latitudes, but both tendencies disappear if the taxonomic relatedness of species is controlled for. Species living at high latitudes also tend to be more widely distributed. This relationship seems largely due to the effect of North American woodpeckers, which show it even when the taxonomic relatedness of species is controlled. Small continents generally have more woodpecker species than do large ones. Woodpecker geographic range sizes are smaller the more woodpecker species inhabit an area. Species show less overlap in their geographic ranges with species of similar than with species of dissimilar body size. The implications of these results for our understanding of patterns in geographic range sizes are discussed. 相似文献
96.
97.
Here we describe the complete nucleotide sequence of the mitochondrial genome (16 583/4 bp) of the zebra finch (Taeniopygia guttata). Primers were designed based on highly conserved regions of an alignment of three passerine complete mitochondrial DNA (mtDNA) sequences. A combination of overlapping long polymerase chain reaction (PCR) purification, followed by fully nested PCR and sequencing was used to determine the complete mtDNA genome. Six birds, from distinct maternal lineages of a pedigreed population were sequenced. Five novel haplotypes were identified. These sequences provide the first data for sequence variation across the whole mitochondrial genome of a passerine bird species. 相似文献
98.
NILS CORDES FREDERIK ALBRECHT LEIF ENGQVIST TIM SCHMOLL MARKUS BAIER CAROLINE MÜLLER KLAUS REINHOLD 《Ecological Entomology》2015,40(1):34-41
1. Variation in larval food composition can have far‐reaching effects on the adult phenotype of insects. To maximise reproductive output, it is therefore beneficial if insects are able to plastically adapt to nutritional cues in their larval diet. 2. The expression of sexual traits implicated in pre‐ and postcopulatory sexual selection of the lesser wax moth, Achroia grisella Fabricius, across different rearing environments of varying diet composition was investigated. 3. Moths reared on diet with relatively low amounts of carbohydrate, but more protein and fats, had lower survival rates, decreased body mass, and longer development times. Males reared on this diet produced songs with higher pulse pair rates (which are attractive to females) and transferred more sperm per copulation than males reared on the alternative diets. 4. There was no evidence for a trade‐off between pre‐ and postcopulatory traits. Interestingly, individuals with both higher pulse pair rates and more transferred sperm came from the treatment group with higher mortality rates and generally poorer development. The present results suggest that both of these sexual characteristics are developmentally plastic, but that only moths reared on the protein‐rich diet were able to benefit from this plasticity. 相似文献
99.
We investigated soil carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) exchanges in an age‐sequence (4, 17, 32, 67 years old) of eastern white pine (Pinus strobus L.) forests in southern Ontario, Canada, for the period of mid‐April to mid‐December in 2006 and 2007. For both CH4 and N2O, we observed uptake and emission ranging from ?160 to 245 μg CH4 m?2 h?1 and ?52 to 21 μg N2O m?2 h?1, respectively (negative values indicate uptake). Mean fluxes from mid‐April to mid‐December across the 4, 17, 32, 67 years old stands were similar for CO2 fluxes (259, 246, 220, and 250 mg CO2 m?2 h?1, respectively), without pattern for N2O fluxes (?3.7, 1.5, ?2.2, and ?7.6 μg N2O m?2 h?1, respectively), whereas the uptake rates of CH4 increased with stand age (6.4, ?7.9, ?10.8, and ?23.3 μg CH4 m?2 h?1, respectively). For the same period, the combined contribution of CH4 and N2O exchanges to the global warming potential (GWP) calculated from net ecosystem exchange of CO2 and aggregated soil exchanges of CH4 and N2O was on average 4%, <1%, <1%, and 2% for the 4, 17, 32, 67 years old stand, respectively. Soil CO2 fluxes correlated positively with soil temperature but had no relationship with soil moisture. We found no control of soil temperature or soil moisture on CH4 and N2O fluxes, but CH4 emission was observed following summer rainfall events. LFH layer removal reduced CO2 emissions by 43%, increased CH4 uptake during dry and warm soil conditions by more than twofold, but did not affect N2O flux. We suggest that significant alternating sink and source potentials for both CH4 and N2O may occur in N‐ and soil water‐limited forest ecosystems, which constitute a large portion of forest cover in temperate areas. 相似文献
100.
MARÍA MARTÍNEZ-JAUREGUI ALFONSO SAN MIGUEL-AYANZ ATLE MYSTERUD† CARLOS RODRÍGUEZ-VIGAL‡ TIM CLUTTON-BROCK§ ROLF LANGVATN¶ TIM COULSON 《Global Change Biology》2009,15(7):1727-1738
There are multiple paths via which environmental variation can impact herbivore ecology and this makes the identification of drivers challenging. Researchers have used diverse approaches to describe the association between environmental variation and ecology, including local weather, large-scale patterns of climate, and satellite imagery reflecting plant productivity and phenology. However, it is unclear to what extent it is possible to find a single measure that captures climatic effects over broad spatial scales. There may, in fact, be no a priori reason to expect populations of the same species living in different areas to respond in the same way to climate as their population may experience limiting factors at different times of the year, and the forms of regulation may differ among populations. Here, we examine whether the same environmental indices [seasonal Real Bioclimatic Index (RBI), seasonal Normalized Difference Vegetation Index (NDVI) and winter North Atlantic Oscillation (NAO)] influence body size in different populations of a large ungulate living in Mediterranean Spain, Western Scotland and Norway. We found substantial differences in the pattern of weight change over time in adult female red deer among study areas as well as different environmental drivers associated with variation in weight. The lack of general patterns for a given species at a continental scale suggest that detailed knowledge regarding the way climate affects local populations is often necessary to successfully predict climate impact. We caution against extrapolation of results from localized climate–population studies to broad spatial scales. 相似文献