67 research outputs found
Ancient DNA of the Extinct Lava Shearwater (Puffinus olsoni) from the Canary Islands Reveals Incipient Differentiation within the P. puffinus Complex
The loss of species during the Holocene was, dramatically more important on islands than on continents. Seabirds from islands are very vulnerable to human-induced alterations such as habitat destruction, hunting and exotic predators. For example, in the genus Puffinus (family Procellariidae) the extinction of at least five species has been recorded during the Holocene, two of them coming from the Canary Islands
An Evolutionary Upgrade of Cognitive Load Theory: Using the Human Motor System and Collaboration to Support the Learning of Complex Cognitive Tasks
Cognitive load theory is intended to provide instructional strategies derived from experimental, cognitive load effects. Each effect is based on our knowledge of human cognitive architecture, primarily the limited capacity and duration of a human working memory. These limitations are ameliorated by changes in long-term memory associated with learning. Initially, cognitive load theory's view of human cognitive architecture was assumed to apply to all categories of information. Based on Geary's (Educational Psychologist 43, 179-195 2008; 2011) evolutionary account of educational psychology, this interpretation of human cognitive architecture requires amendment. Working memory limitations may be critical only when acquiring novel information based on culturally important knowledge that we have not specifically evolved to acquire. Cultural knowledge is known as biologically secondary information. Working memory limitations may have reduced significance when acquiring novel
Multiple Geographic Origins of Commensalism and Complex Dispersal History of Black Rats
The Black Rat (Rattus rattus) spread out of Asia to become one of the world's worst agricultural and urban pests, and a reservoir or vector of numerous zoonotic diseases, including the devastating plague. Despite the global scale and inestimable cost of their impacts on both human livelihoods and natural ecosystems, little is known of the global genetic diversity of Black Rats, the timing and directions of their historical dispersals, and the risks associated with contemporary movements. We surveyed mitochondrial DNA of Black Rats collected across their global range as a first step towards obtaining an historical genetic perspective on this socioeconomically important group of rodents. We found a strong phylogeographic pattern with well-differentiated lineages of Black Rats native to South Asia, the Himalayan region, southern Indochina, and northern Indochina to East Asia, and a diversification that probably commenced in the early Middle Pleistocene. We also identified two other currently recognised species of Rattus as potential derivatives of a paraphyletic R. rattus. Three of the four phylogenetic lineage units within R. rattus show clear genetic signatures of major population expansion in prehistoric times, and the distribution of particular haplogroups mirrors archaeologically and historically documented patterns of human dispersal and trade. Commensalism clearly arose multiple times in R. rattus and in widely separated geographic regions, and this may account for apparent regionalism in their associated pathogens. Our findings represent an important step towards deeper understanding the complex and influential relationship that has developed between Black Rats and humans, and invite a thorough re-examination of host-pathogen associations among Black Rats
A Reassessment of Factors, Particularly Rattus rattus L., That Influenced the Decline of Endemic Forest Birds in the Hawaiian Islands
Between 1892 and 1930, 58 percent (30 taxa) of Hawaiian
endemic forest birds either were greatly reduced or became extinct. The order
in which the islands experienced major declines of several forest birds is Oahu
(ca. 1873-1887), Hawaii (1892-1900), Mo10kai (1893-1907), Maui (1894-1901),
Kauai (after 1900), and Lanai (1926-1932). Loss of habitat, reduced
food supply, introduced avian diseases, as well as predation by man, feral cats,
mongooses, and Norway rats (Rattus norvegicus) all appear to have reduced
some species of birds, but none of these factors adequately explains the accelerated
rates of decline of forest birds that occurred after 1892.
Although it has been assumed that roof rats (Rattus rattus) reached Hawaii
with the first European ships at the end of the 18th century, there is circumstantial
evidence, independent of the bird decline data, that indicates that this
rat did not arrive until after 1840, probably between 1870 and 1880. The
hypothesis is advanced that after its establishment on Oahu in the 1870s,
R. rattus spread to the remaining large islands in the group, resulting in a
stepwise accelerated decline of forest birds on each island in turn. Hawaii thus
parallels some other Pacific islands where major reductions of birds have
followed the establishment of R. rattus. The need for precautions to prevent
rats from reaching rat-free islands in the Hawaiian group is emphasized
Successional Trends in the Coastal and Lowland Forest of Mauna Loa and Kilauea Volcanoes, Hawaii
Three trends in forest succession are described from the coastal and
lowland lava flows (<1,000 feet) of Mauna Loa and Kilauea in Hawaii. All begin
on bare rock in a region of high rainfall (75 to 150 inches). One trend is in
coastal forest and involves the replacement of Metrosideros polymorpha vegetation
by Pandanus tectorius forest. The other trends occur inland and give rise to Metro-,
sideros polymorpha and Metrosideros polymorpha/Diospyros ferrea forests with in
400 years. No consistent differences in successional trends were observed between
pahoehoe and aa flows. Seasonal distribution of rainfall was considered to be important
in differentiating the Metrosideros/Diospyros succession, while exposure to
wind-carried salt may differentiate the Pandanus succession . There is need to protect
representative areas of these forests for future study
Climatic limits of temperate rainforest tree species are explained by xylem embolism resistance among angiosperms but not among conifers
*Hydraulic failure explains much of the increased rates of drought-induced tree mortality around the world, underlining the importance of understanding how species distributions are shaped by their vulnerability to embolism. Here we determined which physiological traits explain species climatic limits among temperate rainforest trees in a region where chronic water limitation is uncommon.*We quantified the variation in stem embolism vulnerability and leaf turgor loss point among 55 temperate rainforest tree species in New Zealand and tested which traits were most strongly related to species climatic limits.*Leaf turgor loss point and stem P50 (tension at which hydraulic conductance is at 50% of maximum) were uncorrelated. Stem P50 and hydraulic safety margin were the most strongly related physiological traits to climatic limits among angiosperms, but not among conifers. Morphological traits such as wood density and leaf dry matter content did not explain species climatic limits.*Stem embolism resistance and leaf turgor loss point appear to have evolved independently. Embolism resistance is the most useful predictor of the climatic limits of angiosperm trees. High embolism resistance in the curiously overbuilt New Zealand conifers suggests that their xylem properties may be more closely related to growing slowly under nutrient limitation and to resistance to microbial decomposition.Plateforme d'Innovation " Forêt-Bois-Fibre-Biomasse du Futur "COntinental To coastal Ecosystems: evolution, adaptability and governanc
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