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Akif F Tezcan - One of the best experts on this subject based on the ideXlab platform.

Jose Maria Fernandezpalacios - One of the best experts on this subject based on the ideXlab platform.

  • quantifying surface area Changes of volcanic islands driven by pleistocene sea level cycles biogeographical implications for the macaronesian archipelagos
    Journal of Biogeography, 2014
    Co-Authors: Kenneth F Rijsdijk, Tom Hengl, Sietze J Norder, Rudiger Otto, Brent C Emerson, Sergio P Avila, Heriberto Lopez, Emiel E Van Loon, Even Tjorve, Jose Maria Fernandezpalacios
    Abstract:

    Aim We assessed the biogeographical implications of Pleistocene sea-level fluctuations on the surface area of Macaronesian volcanic oceanic islands. We quantified the effects of sea-level cycles on surface area over 1000-year intervals. Using data from the Canarian archipelago, we tested whether Changes in island configuration since the late Pleistocene explain species distribution patterns. Location Thirty-one islands of four Macaronesian archipelagos (the Azores, Madeira, the Canary Islands and Cape Verde). Methods We present a model that quantifies the surface-area Change of volcanic islands driven by fluctuations in mean sea level (MSL). We assessed statistically whether Canarian islands that were merged during sea-level lowstands exhibit a significantly higher percentage of shared (endemic) species than other comparable neighbouring islands that remained isolated, using multimodel comparisons evaluated using the Akaike information criterion (AIC). Results Each Macaronesian island exhibited a unique area-Change History. The previously connected islands of Lanzarote and Fuerteventura share significantly more species of Insecta than the similarly geographically proximate island pair of La Gomera and Tenerife, which have never been connected. Additionally, Lanzarote and Fuerteventura contain the highest percentage of two-island endemic Plantae species compared with all other neighbouring island pairs within the Canaries. The multimodel comparison showed that past connectedness provides improved explanatory models of shared island endemics. Main conclusions Pleistocene sea-level Changes resulted in abrupt alterations in island surface areas, coastal habitats and geographical isolation, often within two millennia. The merging of currently isolated islands during marine lowstands may explain both shared species richness and patterns of endemism on volcanic islands. Currently, the islands are close to their long-term minimum surface areas and most isolated configurations, suggesting that insular biota are particularly vulnerable to increasing human impact.

David R Foster - One of the best experts on this subject based on the ideXlab platform.

  • postglacial climate reconstruction based on compound specific d h ratios of fatty acids from blood pond new england
    Geochemistry Geophysics Geosystems, 2006
    Co-Authors: Yongsong Huang, Yi Wang, Bryan N Shuman, William Wyatt Oswald, Edward K Faison, David R Foster
    Abstract:

    We determined hydrogen isotope ratios of individual fatty acids in a sediment core from Blood Pond, Massachusetts, USA, in order to reconstruct climate Changes during the past 15 kyr. In addition to palmitic acid (C16n-acid), which has been shown to record lake water D/H ratios, our surface sediments and down core data indicate that behenic acid (C22n-acid), produced mainly by aquatic macrophytes, is also effective for capturing past environmental Change. Calibration using surface sediments from two transects across eastern North America indicates that behenic acid records δD variation of lake water. Down core variations in δD values of behenic acid and pollen taxa are consistent with the known climate Change History of New England. By evaluating the hypothesis that D/H fractionations of long chain even numbered fatty acids (C24-C32n-acids) relative to lake water provide independent estimates of relative humidity during the growing season, we find that differences between lake-level records and isotopically inferred humidity estimates may provide useful insight into seasonal aspects of the hydrologic cycle. Combined analyses of D/H of short and long chain fatty acids from lake sediment cores thus allow reconstructions of both past temperature and growing season relative humidity. Comparison of δD records from two lakes in New England provides critical information on regional climate variation and abrupt climate Change, such as the 8.2 ka event.

L Zhang - One of the best experts on this subject based on the ideXlab platform.

Fan Gao - One of the best experts on this subject based on the ideXlab platform.