944 resultados para Geographic record
Resumo:
Understanding the factors that drive geographic variation in life history is an important challenge in evolutionary ecology. Here, we analyze what predicts geographic variation in life-history traits of the common lizard, Zootoca vivipara, which has the globally largest distribution range of all terrestrial reptile species. Variation in body size was predicted by differences in the length of activity season, while we found no effects of environmental temperature per se. Females experiencing relatively short activity season mature at a larger size and remain larger on average than females in populations with relatively long activity seasons. Interpopulation variation in fecundity was largely explained by mean body size of females and reproductive mode, with viviparous populations having larger clutch size than oviparous populations. Finally, body size-fecundity relationship differs between viviparous and oviparous populations, with relatively lower reproductive investment for a given body size in oviparous populations. While the phylogenetic signal was weak overall, the patterns of variation showed spatial effects, perhaps reflecting genetic divergence or geographic variation in additional biotic and abiotic factors. Our findings emphasize that time constraints imposed by the environment rather than ambient temperature play a major role in shaping life histories in the common lizard. This might be attributed to the fact that lizards can attain their preferred body temperature via behavioral thermoregulation across different thermal environments. Length of activity season, defining the maximum time available for lizards to maintain optimal performance, is thus the main environmental factor constraining growth rate and annual rates of mortality. Our results suggest that this factor may partly explain variation in the extent to which different taxa follow ecogeographic rules.
Resumo:
Capsule We report a review of the occurrence of bats in the Barn Owl diet Tyto alba in Europe. Based on 802 studies reporting 4.02 million prey items identified in pellets, 4949 were bats (0.12%). We found that bat predation decreased during the last 150 years, is more frequent on islands than mainland, and is higher in eastern than western Europe and in southern than northern Europe. Although Barn Owls usually capture bats opportunistically, they can sometimes specialize on them.
Resumo:
The Federal Highway Administration (FHWA) approves the selection of the Reconstruction of All or Part of the Interstate (Construction Alternative) as the Preferred Alternative to provide improvements to the interstate system in the Omaha/Council Bluffs metropolitan area, extending across the Missouri River on Interstate 80 to east of the Interstate 480 interchange in Omaha, Nebraska. The study considered long-term, broad-based transportation improvements along Interstate I-29 (I-29), I-80, and I-480, including approximately 18 mainline miles of interstate and 14 interchanges (3 system, 11 service), that would add capacity and correct functional issues along the mainline and interchanges and upgrade the I-80 Missouri River Crossing.
Resumo:
Palaeobotany applied to freshwater plants is an emerging field of palaeontology. Hydrophytic plants reveal evolutionary trends of their own, clearly distinct from those of the terrestrial and marine flora. During the Precambrian, two groups stand out in the fossil record of freshwater plants: the Cyanobacteria (stromatolites) in benthic environments and the prasinophytes (leiosphaeridian acritarchs) in transitional planktonic environments. During the Palaeozoic, green algae (Chlorococcales, Zygnematales, charophytes and some extinct groups) radiated and developed the widest range of morphostructural patterns known for these groups. Between the Permian and Early Cretaceous, charophytes dominated macrophytic associations, with the consequence that over tens of millions of years, freshwater flora bypassed the dominance of vascular plants on land. During the Early Cretaceous, global extension of the freshwater environments is associated with diversification of the flora, including new charophyte families and the appearance of aquatic angiosperms and ferns for the first time. Mesozoic planktonic assemblages retained their ancestral composition that was dominated by coenobial Chlorococcales, until the appearance of freshwater dinoflagellates in the Early Cretaceous. In the Late Cretaceous, freshwater angiosperms dominated almost all macrophytic communities worldwide. The Tertiary was characterised by the diversification of additional angiosperm and aquatic fern lineages, which resulted in the first differentiation of aquatic plant biogeoprovinces. Phytoplankton also diversified during the Eocene with the development of freshwater diatoms and chrysophytes. Diatoms, which were exclusively marine during tens of millions of years, were dominant over the Chlorococcales during Neogene and in later assemblages. During the Quaternary, aquatic plant communities suffered from the effects of eutrophication, paludification and acidification, which were the result of the combined impact of glaciation and anthropogenic disturbance.
Resumo:
The Cenozoic QuillaguaLlamara basin (northern Chile, Central Andes) is an asymmetrical, intramassif fore-arc basin with a relatively wide northern sector separated from a narrower southward extension by a basement threshold. The north- ern sector was characterised by a noticeable Oligocene?late Neogene alluvial-fan and lacustrine dominated deposition which resulted in sequences up to 900 m thick, whereas the southern sector was often a bypass zone with thinner fluvial and lacustrine sediment accumulation.
Resumo:
This study provides an organic carbon stable isotope (delta(13)C(org)) record calibrated with detailed ammonite biostratigraphy, following the end-Triassic biological crisis. Precise correlation between this crucial fossil group and the delta(13)C(org) record is key to understanding feedbacks between biological and environmental events following mass extinction. The latest Triassic and Hettangian delta(13)C(org) record shows several negative and positive excursions. The end-Triassic negative shift coinciding with the mass extinction interval is followed by a positive excursion in the earliest Hettangian Psiloceras spelae beds, which marks the onset of recovery in the marine ecosystem. This positive trend is interrupted by a second negative delta(13)C(org) excursion in the P. pacificum beds related to a minor ammonite extinction event. This pattern of the delta(13)C(org) curve culminates in the uppermost Hettangian Angulata Zone major positive excursion. This indicates that both the ecosystem and the carbon cycle remained in a state of perturbation for at least 2 Ma, although the recovery of some pelagic taxa already began at the base of Jurassic. The early and late Hettangian positive delta(13)C(org) excursions have been confused in several recent papers. Here, we show that during the Hettangian there are indeed two distinct positive delta(13)C(org) excursions. Phases of anoxia and further pulses of Central Atlantic Magmatic Province volcanism during the Hettangian might have inhibited the full recovery for that interval of time. The main Liasicus-Angulata organic positive CIE (carbon isotope excursion) during the Late Hettangian might be related to gradual decreasing of pCO(2) due to protracted high organic burial, and coincides with a second phase of recovery, as indicated by a pulse of ammonoid diversification.
Resumo:
The Federal Highway Administration (FHWA) approves the selection of the Reconstruction of All or Part of the Interstate (Construction Alternative) as the Preferred Alternative to provide improvements to the interstate system in the Omaha/Council Bluffs metropolitan area, extending across the Missouri River on Interstate 80 to east of the Interstate 480 interchange in Omaha, Nebraska. The study considered long-term, broad-based transportation improvements along Interstate I-29 (I-29), I-80, and I-480, including approximately 18 mainline miles of interstate and 14 interchanges (3 system, 11 service), that would add capacity and correct functional issues along the mainline and interchanges and upgrade the I-80 Missouri River Crossing. FHWA also approves the decisions to provide full access between West Broadway and I-29, design the I-80/I-29 overlap section as a dual-divided freeway, and locating the new I-80 Missouri River Bridge north of the existing bridge. Improvements to the interstate system, once implemented, would bring the segments of I-80 and I-29 (see Figure 1) up to current engineering standards and accommodate future traffic needs. This Record of Decision (ROD) concludes Tier 1 of the Council Bluffs Interstate System (CBIS) Improvements Project. Tier 1 included an examination of the area’s transportation needs, a study of alternatives to satisfy them, and broad consideration of potential environmental and social impacts. The Tier 1 evaluation consisted of a sufficient level of engineering and environmental detail to assist decision makers in selecting a preferred transportation strategy. During Tier 1 a Draft EIS (FHWA-IA- EIS-04-01D) was developed which was approved by FHWA, Iowa DOT, and Nebraska Department of Roads (NDOR) in November 2004 with comments accepted through March 15, 2005. The Draft EIS summarized the alternatives that were considered to address the transportation needs around Council Bluffs; identified reconstruction of all or part of the interstate, the “Construction Alternative,” as the Preferred Alternative; identified three system-level decisions that needed to be made at the Tier 1 level; and invited comment on the issues. The Final EIS (FHWA-IA- EIS-04-01F) further documented the Construction Alternative as the Preferred Alternative and identified the recommended decisions for the three system level decisions that needed to be made in Tier 1. This ROD defines the Selected Alternative determined in the Tier 1 studies.
Resumo:
Our mental representation of the world is far from objective. For example, western Canadians estimate the locations of North American cities to be too far to the west. This bias could be due to a reference point effect, in which people estimate more space between places close to them than far from them, or to representational pseudoneglect, in which neurologically intact individuals favor the left side of space when asked to image a scene.We tested whether either or both of these biases influence the geographic world representations of neurologically intact young adults from Edmonton and Ottawa, which are in western and eastern Canada, respectively. Individuals were asked to locate NorthAmerican cities on a two-dimensional grid. Both groups revealed effects of representational pseudoneglect in this novel paradigm, but they also each exhibited reference point effects. These results inform theories in both cognitive psychology and neuroscience.