Scott A. Elias

Biological and physical signs of climate change: focus on mosquito-borne diseases

The Intergovernmental Panel on Climate Change concluded that there is “discernible evidence” that humans—through accelerating changes in multiple forcing factors—have begun to alter the earths climate regime. Such conclusions are based primarily upon so-called “fingerprint” studies, namely the warming pattern in the midtroposphere in the Southern Hemisphere, the disproportionate rise in nighttime and winter temperatures, and the statistical increase in extreme weather events in many nations. All three aspects of climate change and climate variability have biological implications. Detection of climate change has also drawn upon data from glacial records that indicate a general retreat of tropical summit glaciers. Here the authors examine biological (plant and insect) data, glacial findings, and temperature records taken at high-elevation, mountainous regions. It is concluded that, at high elevations, the overall trends regarding glaciers, plants, insect range, and shifting isotherms show remarkable intern...

The residues of feasting and public ritual at Early Cahokia

Archaeological remains excavated from the stratified layers of a pre-Columbian borrow pit in the middle of the Cahokia site inform our understanding of how ritual events were related to the social and political foundations of that enormous center. Ordinary and extraordinary refuse, ranging from foods and cooking pots to craft-production debris and sumptuary goods, are associated with a series of large-scale, single-event dumping episodes related to activities that occurred in the principal plaza. Taken as a set, the layers of ceramic, lithic, zooarchaeological, archaeobotanical, osteological, paleoentomological, and sedimentological materials reveal that the construction of Cahokias Mississippian order was an active, participatory process.

Late Wisconsin environments of the Bering Land Bridge

Abstract Late Wisconsin paleobotanical and fossil insect data from the central and northern sectors of the Bering Land Bridge indicate widespread mesic shrub-tundra environments even during the last glacial maximum. Vegetation before the last glacial maximum was a birch-heath-graminoid tundra with few or no steppe elements. Shrubs were not an important element of the vegetation, but were present in small numbers. During the interval 20,000–14,000 yr BP, land-bridge vegetation was dominated by birch-graminoid tundra with small ponds containing aquatic plants. Heaths were relatively unimportant. Insects from this interval were indicative of arctic climate, with drier tundra than during the late glacial. During the late-glacial interval (14,000–11,000 yr BP), land-bridge vegetation was dominated by birch-heath-graminoid tundra with small ponds choked with aquatic plants. The insect record indicates open-ground habitats dominated by mesic tundra. By 11,000 yr BP, insect data suggest that summer temperatures on the emergent Bering Shelf were warmer than present-day upland regions in western Alaska; summer temperatures on the Chukchi Shelf were warmer than the present-day North Slope of Alaska. Contrary to previous hypotheses, we found no evidence of steppe-tundra on the land bridge. New accelerator mass spectrometer (AMS) 14C dates show that much of the land bridge was above sea level and thus available for human and animal migration until as late as 11,000 yr BP.

Paleoecology of late-glacial peats from the bering land bridge, Chukchi Sea shelf region, northwestern Alaska

Abstract Insect fossils and pollen from late Pleistocene nonmarine peat layers were recovered from cores from the shelf region of the Chukchi Sea at depths of about 50 m below sea level. The peats date to 11,300−11,000 yr B.P. and provide a limiting age for the regional Pleistocene-Holocene marine transgression. The insect fossils are indicative of arctic coastal habitats like those of the Mackenzie Delta region (mean July temperatures = 10.6–14°C) suggesting that 11,000 yr ago the exposed Chukchi Sea shelf had a climate substantially warmer than modern coastal regions of the Alaskan north slope. The pollen spectra are consistent with the age assignment to the Birch Interval (14,000–9000 yr B.P.). The data suggest a meadow-like graminoid tundra with birch shrubs and some willow shrubs growing in sheltered areas.

Non-Destructive Sampling of Ancient Insect DNA

Background A major challenge for ancient DNA (aDNA) studies on insect remains is that sampling procedures involve at least partial destruction of the specimens. A recent extraction protocol reveals the possibility of obtaining DNA from past insect remains without causing visual morphological damage. We test the applicability of this protocol on historic museum beetle specimens dating back to AD 1820 and on ancient beetle chitin remains from permafrost (permanently frozen soil) dating back more than 47,000 years. Finally, we test the possibility of obtaining ancient insect DNA directly from non-frozen sediments deposited 3280-1800 years ago - an alternative approach that also does not involve destruction of valuable material. Methodology/Principal Findings The success of the methodological approaches are tested by PCR and sequencing of COI and 16S mitochondrial DNA (mtDNA) fragments of 77–204 base pairs (-bp) in size using species-specific and general insect primers. Conclusion/Significance The applied non-destructive DNA extraction method shows promising potential on insect museum specimens of historical age as far back as AD 1820, but less so on the ancient permafrost-preserved insect fossil remains tested, where DNA was obtained from samples up to ca. 26,000 years old. The non-frozen sediment DNA approach appears to have great potential for recording the former presence of insect taxa not normally preserved as macrofossils and opens new frontiers in research on ancient biodiversity.

Insects and climate change

ecent research on fossil insect remains from Quaternary deposits (from 1.7 million years ago to recent times) has shed considerable light on the nature of glacial and interglacial environments and the timing and intensity of climate changes during this highly variable period. Since paleontologist G. R. Coope began his pioneering study of British Pleistocene insects at the Chelford site in England (Coope 1959), hundreds of Quaternary insect fossil assemblages have been examined. Most of the fossils studied are from

Human ecology of Beringia

Preface: Lost Continent1. An Introduction to Beringia2. Beringian Landscapes3. Settlement of Northern Asia4. The Beginning of the Lateglacial5. The End of the Lateglacial Interstadial6. The Younger Dryas and the End of Beringia7. Beringia and the New WorldNotesBibliographyIndex

Late Wisconsin climate in northeastern USA and southeastern Canada, reconstructed from fossil beetle assemblages

Mean July and January temperatures are reconstructed from radiocarbon-dated fossil beetle assemblages, yielding a synthesis of palaeoclimatic history of the regions south of the Laurentide Ice Sheet in North America from 35 000 to 8500 yr BP. Mean July temperatures close to the last glacial maximum were 11–12°C colder than present; mean January temperatures were possibly 10–19°C colder. Mutual climatic range analyses of the beetle assemblages show warming of mean summer temperatures as early as 13.7 kyr, although ice-proximal sites were consistently about 5°C cooler than ice-distal sites. Late-glacial mean summer temperatures peaked between 12 and 11 kyr, then remained fairly constant through the early Holocene. Mean winter temperatures did not reach modern values until after 10 kyr.

Fossil insect evidence for late Quaternary climatic change in the Big Bend region, Chihuahuan Desert, Texas

Abstract A series of 50 packrat midden assemblages from the Big Bend region of the Chihuahuan Desert, ranging in age from >36,000 yr B.P. to recent, yielded abundant, diverse arthropod faunas. The mesic nature of regional Wisconsin age climates is substantiated by the fauna from 30,000–12,000 yr B.P., especially during the middle Wisconsin (30,000–20,000 yr B.P.). Late Wisconsin faunas contained grassland species which are confined today to cooler, moister regions. Following 12,000 yr B.P., most of these temperate species were replaced either by desert species or by more cosmopolitan taxa, marking the climatic shift from late Wisconsin to postglacial time. Insects indicative of more severe aridity are first recorded at about 6000 yr B.P., but some temperate species persisted until about 2500 yr B.P. After this, only desert dwellers are recorded.

Out of Beringia

A shrub tundra refugium on the Bering land bridge may have played a pivotal role in the peopling of the Americas. Based on the distribution of tundra plants around the Bering Strait region, Eric Hultén proposed in the 1930s that the now-submerged plain between Chukotka and Alaska—the Bering land bridge—became a refugium for shrub tundra vegetation during cold periods (1), which include the last glacial maximum (LGM) between ∼28,000 and 18,000 cal BP (calibrated radiocarbon years before the present). Adjoining areas to the west and east supported drier plant communities with a higher percentage of grasses during glacial periods. According to Hultén, when warmer and wetter conditions returned to these areas, the land bridge, which he named Beringia, became a center of dispersal for tundra plants. Now it appears that it also may have been a glacial refugium and postglacial center of dispersal for the people who first settled the Americas.