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Climatic Patterns (climatic + pattern)
Selected AbstractsPrimate communities: Past, present, and possible futureAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue S39 2004Kaye E. Reed Abstract An understanding of the fundamental causes of the structure of primate communities is important for studies of primate evolutionary history, primate behavioral ecology, and development of conservation strategies. Research into these structuring factors has benefited from new perspectives such as consideration of primate phylogenetic history, metacommunities, and interactions with predators and nonprimate competitors. This review presents the underlying factors of primate community structure within the biogeographic regions of Madagascar, the Neotropics, Africa, and Asia. One of the major differences among these locations likely resulted from the initial primate taxa that colonized each region (a single colonization event in the case of Madagascar and South America, and multiple radiations of higher-level taxa in Africa and Asia). As most primates live in forests, the differences among the forests in these locations, caused by various climatic influences, further influenced speciation and the development of primate communities. Within these habitats, species interactions with different groups of organisms were also instrumental in developing community dynamics. Through an investigation of these fundamental factors, we identify some of the most important effects on primate communities in each region. These findings suggest that low primate richness in Asia may be caused by either the abundance of dipterocarp trees or high levels of monsoon rains. High numbers of frugivores and a lack of folivores in neotropical communities may be associated with competiton with sloths that were already present at the time of initial radiation. Climatic patterns which affect forest structure and productivity in Madagascar may be responsible for high numbers of folivorous lemurs. The identification of these factors are important for the conservation of existing primate communities, and indicate directions for future studies. Yrbk Phys Anthropol 47:2,39, 2004. © 2004 Wiley-Liss, Inc. [source] LATITUDINAL VARIATION IN SPECIATION MECHANISMS IN FROGSEVOLUTION, Issue 2 2010Xia Hua Speciation often has a strong geographical and environmental component, but the ecological factors that potentially underlie allopatric and parapatric speciation remain understudied. Two ecological mechanisms by which speciation may occur on geographic scales are allopatric speciation through niche conservatism and parapatric or allopatric speciation through niche divergence. A previous study on salamanders found a strong latitudinal pattern in the prevalence of these mechanisms, with niche conservatism dominating in temperate regions and niche divergence dominating in the tropics, and related this pattern to Janzen's hypothesis of greater climatic zonation between different elevations in the tropics. Here, we test for latitudinal patterns in speciation in a related but more diverse group of amphibians, the anurans. Using data from up to 79 sister-species pairs, we test for latitudinal variation in elevational and climatic overlap between sister species, and evaluate the frequency of speciation via niche conservatism versus niche divergence in relation to latitude. In contrast to salamanders, we find no tendency for greater niche divergence in the tropics or for greater niche conservatism in temperate regions. Although our results support the idea of greater climatic zonation in tropical regions, they show that this climatic pattern does not lead to straightforward relationships between speciation, latitude, and niche evolution. [source] THE FALL LINE: A PHYSIOGRAPHIC-FOREST VEGETATION BOUNDARY,GEOGRAPHICAL REVIEW, Issue 4 2007David Shankman ABSTRACT. The range boundaries for many tree species in the southeastern United States correspond to the Fall Line that separates the Coastal Plain from the Appalachian Highlands. Trees in the Coastal Plain with northern range boundaries corresponding to the Fall Line occur exclusively in alluvial valleys created by lateral channel migration. These species grow mostly on lower bottomland sites characterized by a high water table, soils that are often saturated, and low annual water fluctuation. In contrast to the Coastal Plain, the southern Appalachian Highlands are occupied mostly by bedrock streams that have few sites suitable for the regeneration of these species. The Fall Line is also an approximate southern boundary for trees common in the southern Appalachians that typically occur on either dry, rocky ridgetops or in narrow stream valleys, habitats that are uncommon on the relatively flat Coastal Plain. The ranges for many trees in eastern North America are controlled by large-scale climatic patterns. Tree species with range boundaries corresponding to the Fall Line, however, are not approaching their physiological limits caused by progressively harsher climatic conditions or by competition. Instead, the Fall Line represents the approximate boundary of habitats suitable for regeneration. [source] Do changes in climate patterns in wintering areas affect the timing of the spring arrival of trans-Saharan migrant birds?GLOBAL CHANGE BIOLOGY, Issue 1 2005Oscar Gordo Abstract The life cycles of plants and animals are changing around the world in line with the predictions originated from hypotheses concerning the impact of global warming and climate change on biological systems. Commonly, the search for ecological mechanisms behind the observed changes in bird phenology has focused on the analysis of climatic patterns from the species breeding grounds. However, the ecology of bird migration suggests that the spring arrival of long-distance migrants (such as trans-Saharan birds) is more likely to be influenced by climate conditions in wintering areas given their direct impact on the onset of migration and its progression. We tested this hypothesis by analysing the first arrival dates (FADs) of six trans-Saharan migrants (cuckoo Cuculus canorus, swift Apus apus, hoopoe Upupa epops, swallow Hirundo rustica, house martin Delichon urbica and nightingale Luscinia megarhynchos), in a western Mediterranean area since from 1952 to 2003. By means of multiple regression analyses, FADs were analysed in relation to the monthly temperature and precipitation patterns of five African climatic regions south of the Sahara where species are thought to overwinter and from the European site from where FADs were collected. We obtained significant models for five species explaining 9,41% of the variation in FADs. The interpretation of the models suggests that: (1) The climate in wintering quarters, especially the precipitation, has a stronger influence on FADs than that in the species' potential European breeding grounds. (2) The accumulative effects of climate patterns prior to migration onset may be of considerable importance since those climate variables that served to summarize climate patterns 12 months prior to the onset of migration were selected by final models. (3) Temperature and precipitation in African regions are likely to affect departure decision in the species studied through their indirect effects on food availability and the build-up of reserves for migration. Our results concerning the factors that affect the arrival times of trans-Saharan migrants indicate that the effects of climate change are more complex than previously suggested, and that these effects might have an interacting impact on species ecology, for example by reversing ecological pressures during species' life cycles. [source] Climatic effects on the phenology of lake processesGLOBAL CHANGE BIOLOGY, Issue 11 2004Monika Winder Abstract Populations living in seasonal environments are exposed to systematic changes in physical conditions that restrict the growth and reproduction of many species to only a short time window of the annual cycle. Several studies have shown that climate changes over the latter part of the 20th century affected the phenology and population dynamics of single species. However, the key limitation to forecasting the effects of changing climate on ecosystems lies in understanding how it will affect interactions among species. We investigated the effects of climatic and biotic drivers on physical and biological lake processes, using a historical dataset of 40 years from Lake Washington, USA, and dynamic time-series models to explain changes in the phenological patterns among physical and biological components of pelagic ecosystems. Long-term climate warming and variability because of large-scale climatic patterns like Pacific decadal oscillation (PDO) and El Niño,southern oscillation (ENSO) extended the duration of the stratification period by 25 days over the last 40 years. This change was due mainly to earlier spring stratification (16 days) and less to later stratification termination in fall (9 days). The phytoplankton spring bloom advanced roughly in parallel to stratification onset and in 2002 it occurred about 19 days earlier than it did in 1962, indicating the tight connection of spring phytoplankton growth to turbulent conditions. In contrast, the timing of the clear-water phase showed high variability and was mainly driven by biotic factors. Among the zooplankton species, the timing of spring peaks in the rotifer Keratella advanced strongly, whereas Leptodiaptomus and Daphnia showed slight or no changes. These changes have generated a growing time lag between the spring phytoplankton peak and zooplankton peak, which can be especially critical for the cladoceran Daphnia. Water temperature, PDO, and food availability affected the timing of the spring peak in zooplankton. Overall, the impact of PDO on the phenological processes were stronger compared with ENSO. Our results highlight that climate affects physical and biological processes differently, which can interrupt energy flow among trophic levels, making ecosystem responses to climate change difficult to forecast. [source] Ice regime of the lower Peace River and ice-jam flooding of the Peace-Athabasca DeltaHYDROLOGICAL PROCESSES, Issue 19 2006Spyros Beltaos Abstract The Peace-Athabasca Delta (PAD) in northern Alberta is one of the world's largest inland freshwater deltas, home to large populations of waterfowl, muskrat, beaver, and free-ranging wood bison. Beginning in the mid-1970s, a paucity of ice-jam flooding in the lower Peace River has resulted in prolonged dry periods and considerable reduction in the area covered by lakes and ponds that provide a habitat for aquatic life in the PAD region. Using archived hydrometric data and in situ observations, the ice regime of the lower Peace is described and quantified, setting the stage for identification of the conditions that lead to ice-jam flooding and replenishment of Delta habitat. The first such condition is the occurrence of a mechanical, as opposed to a thermal, breakup event; second, the river flow should be at least 4000 m3/s; and third, an ice jam should form within the last 50 km of the Peace River. The type of breakup event depends on the freeze-up stage and spring flow. The former has increased as a result of flow regulation, and the latter has decreased owing to changing climatic patterns. Both trends tend to inhibit the occurrence of mechanical breakups and contribute to less frequent ice-jam flooding. Potential mitigation strategies are discussed. Copyright © 2006 Crown in the right of Canada. Published by John Wiley & Sons, Ltd. [source] Wavelet analysis of the Lisbon and Gibraltar North Atlantic Oscillation winter indicesINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 5 2006S. Barbosa Abstract The North Atlantic Oscillation (NAO) is one of the most important climatic patterns in the Northern Hemisphere. Indices based on the normalised pressure difference between Iceland and a southern station, such as Lisbon or Gibraltar, have been defined in order to describe NAO temporal evolution. Although exhibiting interannual and decadal variability, the signals are statistically rather featureless and therefore it is difficult to discriminate between different types of stochastic models. In this study, Lisbon and Gibraltar NAO winter indices are analysed using the discrete wavelet transform discrete wavelet transform(DWT). A multi-resolution analysis (MRA) is carried out for a scale-based description of the indices and the wavelet spectrum is used to identify and estimate long-range dependence. The degree of association of the two NAO indices is assessed by estimating the wavelet covariance for the two signals. The scale-based approach inherent to the discrete wavelet methodology allows a scale-by-scale comparison of the signals and shows that although the short-term temporal pattern is very similar for both indices, the long-term temporal structure is distinct. Furthermore, the degree of persistence or ,memory' is also distinct: the Lisbon index is best described by a long-range dependent (LRD) process, while the Gibraltar index is adequately described by a short-range process. Therefore, while trend features in the Lisbon NAO index may be explainable by long-range dependence alone, with no need to invoke external factors, for the Gibraltar index such features cannot be interpreted as resulting only from internal variability through long-range dependence. Copyright © 2006 Royal Meteorological Society. [source] Reproductive phenology over a 10-year period in a lowland evergreen rain forest of central BorneoJOURNAL OF ECOLOGY, Issue 4 2007FRANCIS Q. BREARLEY Summary 1The aim of this study was to document patterns in tree reproductive phenology in a rain forest of central Borneo and examine relationships between phenology and climatic patterns. 2A 10-year data set (1990,2000) of monthly observations of flowering and fruit production of 171 trees (including 39 members of the Dipterocarpaceae) at Barito Ulu, Central Kalimantan, Indonesia, showed that most trees (73%) underwent reproductive activity on a supra-annual timescale. 3There were three general flowering (GF) events, in 1991, 1994 and 1997, which were preceded by major drought periods (30-day sliding total rainfall of less than 100 mm for more than 10 days) in which at least 40% of dipterocarps and at least 18% of all other trees underwent synchronized reproductive activity; there was also a minor event in 1990. Around 1.3% of trees flowered and 3.8% produced fruit in months outside of these four events. 4At the community level, the strongest negative correlation was found between the percentage of flowering individuals and total rainfall in the preceding 150 days. 5Within three genera of dipterocarps examined in more detail (Dipterocarpus, Shorea and Vatica) there were clear and consistent patterns of sequential flowering with certain species flowering early in the GF events and others towards the end of these events. 6Our results confirm the importance of large-scale climatic fluctuations (El Niño-Southern Oscillation) on plant reproductive phenology in South-east Asian tropical forests and indicate that drought may be a more important cue than low night-time temperatures. [source] Is the human population a large-scale indicator of the species richness of ground beetles?ANIMAL CONSERVATION, Issue 5 2010A. M. Barbosa Abstract Empirical evidence has often shown a large-scale positive co-occurrence of biodiversity-rich and densely populated regions. This biogeographical pattern has important implications for conservation biology. Previous studies have supported two of the potential mechanisms behind this pattern: the distributions of biodiversity and of human beings tend to match climatic patterns, and human beings have settled in regions of higher habitat heterogeneity or they may have increased it. There has been little testing and evidence for an artefactual explanation: more populated regions may show more species only because of a more thorough sampling. Using a new country-wide dataset, we tested whether the human population density correlates with the species richness of ground beetles in Italy's regions, provinces and 10 × 10 km (UTM) grid cells. As expected, the observed and estimated (Chao index) number of species increases significantly with increasing human population density for regions, while there is no significant variation for provinces. But this is not the case when controlling for sampling effort. Variations in observed and estimated species richness are primarily associated with the available number of records, which is in turn well correlated with human population size. These results were confirmed for endemic and widespread species richness. At the UTM level, when controlling for sampling effort and area, there was a significant positive correlation between the total/widespread species richness and variation in the human population size, while the correlation was negative for endemic species. We found no significant role of habitat heterogeneity in the above relationships. The available distributional data of Carabidae in Italy suggest (1) that the species richness of bio-indicators may not be a reliable measure for regional biological assessment; (2) that some broad-scale human population,biodiversity correlations can be artefactual. [source] Conservation importance of semi-arid streams in north-eastern Brazil: implications of hydrological disturbance and species diversityAQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 7 2006L. Maltchik Abstract 1.Intermittent streams in the semi-arid region of Brazil are distinctive landscape features existing as dry watercourses for most of the time. It has been recognized that the extremes of flooding and total absence of water flow are the principal hydrological characteristics of rivers and streams in this region. This is a consequence of complex climatic patterns that lead to an irregular distribution of the small amount of rainfall and low thermal amplitude. The latter is the main climatic difference between the Brazilian semi-arid region and other semi-arid lands. 2.The expansion of water resource development has been a threat to the natural flow regime and the ecological integrity of rivers and streams in semi-arid Brazil. Efforts to manage and conserve the natural flow regime of these systems are hampered by limited scientific information on the ecological processes driving their flora and fauna and the responses of biota to the high natural variability in flow regime. 3.The most important issues in the conservation of streams in semi-arid Brazil are the need for their recognition as important sites of biodiversity and that this diversity is closely associated with natural patterns of flow and the hydrological disturbances. Without the understanding of how the extremes of flooding and drought affect the aquatic fauna, the conservation strategies for Brazilian semi-arid streams and their fauna will not be effective. 4.Therefore, conservation efforts in semi-arid Brazil must ensure that the processes sustaining biodiversity are maintained at multiple-scale and landscape levels and that the natural integrity of the riparian zone is maintained Copyright © 2006 John Wiley & Sons, Ltd. [source] | ||||||||||