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211.
As important marine mesopredators and sensitive indicators of Antarctic ecosystem change, penguins have been a major focus of long-term biological research in the Antarctic. However, the vast majority of such studies have been constrained by logistics and relate mostly to the temporal dynamics of individual breeding populations from which regional trends have been inferred, often without regard for the complex spatial heterogeneity of population processes and the underlying environmental conditions. Integrating diverse census data from 70 breeding sites across 31 years in a robust, hierarchical analysis, we find that trends from intensely studied populations may poorly reflect regional dynamics and confuse interpretation of environmental drivers. Results from integrated analyses confirm that Pygoscelis adeliae (Adélie Penguins) are decreasing at almost all locations on the Antarctic Peninsula. Results also resolve previously contradictory studies and unambiguously establish that P. antarctica (Chinstrap Penguins), thought to benefit from decreasing sea ice, are instead declining regionally. In contrast, another open-water species, P. papua (Gentoo Penguin), is increasing in abundance and expanding southward. These disparate population trends accord with recent mechanistic hypotheses of biological change in the Southern Ocean and highlight limitations of the influential but oversimplified "sea ice" hypothesis. Aggregating population data at the regional scale also allows us to quantify rates of regional population change in a way not previously possible. 相似文献
212.
Most metazoan species have strict maternal inheritance of the mitochondrial genome. In bivalves, a unique inheritance pattern called doubly uniparental inheritance (DUI) occurs in at least seven bivalve families. In this system of mitochondrial inheritance, males inherit and carry mtDNA from both parents, while females only carry mtDNA from the mother. Here, we present evidence of mitochondrial heteroplasmy in deep-sea protobranch bivalves. Divergent 16S rRNA and cytochrome b sequences were obtained within individuals of Ledella ultima. Ledella sublevis also exhibited divergent 16S sequences. Levels of divergence between 16S sequences within individuals were 27 and 15 % for each species, respectively. Ratios of homoplasmic to heteroplasmic individuals were not significantly different from 1:1, in agreement with sex ratios in protobranchs. The results provide the first evidence for mitochondrial heteroplasmy in the protobranchs and suggest DUI might have evolved much earlier in the evolution of the Bivalvia than previously thought. 相似文献
213.
Winter JG Somers KM Dillon PJ Paterson C Reid RA 《Journal of environmental quality》2002,31(6):2015-2025
The influence of golf course operation on benthic macroinvertebrate communities in Precambrian Shield streams was evaluated using rapid bioassessment and the reference condition approach. Streams were sampled for water chemistry and invertebrates in 1999 and 2000, six on operational golf courses, and seven in forested reference locations. Correspondence analysis (CA) was used to determine the major patterns in the macroinvertebrate taxa, and canonical correspondence analysis (CCA) was used to evaluate relationships with environmental variables. The reference streams were used to define the normal range of variation for a variety of summary indices to evaluate the golf course streams. In all cases, golf course streams were higher in nutrients and dissolved ions and more alkaline than the forested reference streams. There was considerable variability in the macroinvertebrate fauna from the golf course streams, which was related to differences in golf course land management practices and to the potential influence of highway runoff. Of the management practices evaluated, fertilizer application rates in particular were important, as was the presence of ponds upstream on the course. Invertebrate taxa with higher abundances in golf course streams included Turbellaria, Isopoda, Amphipoda, Zygoptera, and Trombidiformes. Taxa more common in the reference streams included Ephemeroptera, Megaloptera, Culicidae, and Plecoptera. There were marked differences in the overall benthic macroinvertebrate community in three of the six golf course streams studied relative to the forested reference streams, suggesting that golf course land management on the Precambrian Shield can be associated with significant differences in macroinvertebrate community structure. 相似文献
214.
Jeroen Aerts Marjan Van Herwijnen Ron Janssen Theodor Stewart 《Journal of Environmental Planning and Management》2005,48(1):121-142
This study examines the use of spatial optimization techniques for multi-site land-use allocation problems (MLUA). 'Multi-site' refers to the problem of allocating more than one land-use type in an area, which are difficult problems as they involve multiple stakeholders with conflicting goals and objectives. Spatial optimization methods consist of (1) an optimization model and (2) an algorithm to solve the model. This study demonstrates a goal-programming model to solve the MLUA problem. The model is solved using both simulated annealing and genetic algorithms. Special attention has been given to introduce a spatial compactness objective in the model. It is shown that the compactness objectives in the optimization model generate compact patches of the same land use for using both the simulated annealing procedure and the genetic algorithm. In addition, it appears that using the proper settings of the compactness objectives, connectivity between patches of land use is promoted. The method is tested for a fictive study and then demonstrated for a real case study, both measuring 20 × 20 cells. The genetic algorithm generally performs better than simulated annealing in terms of solution time and achieving compactness. 相似文献
215.
216.
James G. C. Ball Mark A. Burgman Elizabeth D. Goldman Janeth Lessmann 《Conservation biology》2021,35(1):263-273
In pursuit of socioeconomic development, many countries are expanding oil and mineral extraction into tropical forests. These activities seed access to remote, biologically rich areas, thereby endangering global biodiversity. We examined how protection of biodiversity and economic revenues can be balanced in biologically valuable regions. Using spatial data on oil profits and predicted species and ecosystem extents, we optimized the protection of 741 terrestrial species and 20 ecosystems of the Ecuadorian Amazon across a range of opportunity costs (i.e., sacrifices of extractive profit). We also applied spatial statistics to remotely sensed, historic deforestation data to focus the optimization on areas most threatened by imminent forest loss. Giving up 5% of a year's oil profits (US$221 million) allowed for a protected area network that retained an average of 65% of the extent of each species and ecosystem. This performance far exceeded that of the network produced by simple optimization for land area (which required a sacrifice of approximately 40% of annual oil profits [US$1.7 billion]) and used only marginally less land to achieve equivalent levels of ecological protection. We identified what we call emergency conservation targets: regions that are essential components of a cost-effective conservation reserve network but at imminent risk of destruction, thus requiring urgent and effective protection. Governments can use our methods when evaluating extractive-led development options to responsibly manage the associated ecological and economic trade-offs and protect natural capital. 相似文献