J F Basinger

Bio: J F Basinger is an academic researcher. The author has contributed to research in topics: Archipelago & Floristics. The author has an hindex of 1, co-authored 1 publications receiving 102 citations.

The Use of Geological and Paleontological Evidence in Evaluating Plant Phylogeographic Hypotheses in the Northern Hemisphere Tertiary

Abstract: Phylogeography posits that the sequence of speciation events within a clade should parallel the geographic migration and isolation of members of the clade through time. The primary historical features that govern migration and allopatry in land plants are changes in physical geography (e.g., oceans, mountains, and deserts) and in climate (e.g., moisture, temperature, and day length), features that are often interrelated. If we assume that living genera retain physiological stability through time, much as they retain the morphological features that allow their identification, then these environmental features of the geologic past may be used to test phylogeographic hypotheses of living genera based on phylogenetic analysis. The history of the climatic and geographic features of the Tertiary of the Northern Hemisphere agrees with many phylogenetically based phylogeographic hypotheses of living angiosperm genera but indicates that some hypotheses require reanalysis. While the parallel comparison of phylogene...

Life at the top of the greenhouse Eocene world--A review of the Eocene flora and vertebrate fauna from Canada's High Arctic

Abstract: Early–middle Eocene (ca. 53–38 Ma) sediments of the Eureka Sound Group in Canada’s Arctic Archipelago preserve evidence of lush mixed conifer-broadleaf rain forests, inhabited at times by alligators, turtles, and diverse mammals, including primates, tapirs, brontotheres, and hippo-like Coryphodon. This biota reflects a greenhouse world, offering a climatic and ecologic deep time analog of a mild ice-free Arctic that may be our best means to predict what is in store for the future Arctic if current climate change goes unchecked. In our review of the early–middle Eocene Arctic flora and vertebrate fauna, we place the Arctic fossil localities in historic, geographic, and stratigraphic context, and we provide an integrated synthesis and discussion of the paleobiology and paleoecology of these Eocene Arctic forests and their vertebrate inhabitants. The abundance and diversity of tapirs and plagiomenids (both rare elements in midlatitude faunas), and the absence of artiodactyls, early horses, and the hyopsodontid “condylarth” Hyopsodus (well represented at midlatitude localities) are peculiar to the Eocene Arctic. The Eocene Arctic macrofloras reveal a forested landscape analogous to the swamp-cypress and broadleaf floodplain forests of the modern southeastern United States. Multiple climate proxies indicate a mild temperate early–middle Eocene Arctic with winter temperatures at or just above freezing and summer temperatures of 20 °C (or higher), and high precipitation. At times, this high precipitation resulted in freshwater discharge into a nearly enclosed Arctic Ocean basin, sufficient to cause surface freshening of the Arctic Ocean, supporting mats of the floating fern Azolla . Fluctuating Arctic Ocean sea level due to freshwater inputs as well as tectonics produced temporary land bridges, allowing land plants and animals to disperse between North America and both Europe and Asia.

Seasonality, the latitudinal gradient of diversity, and Eocene insects

Abstract: In the modern world, biotic diversity is typically higher in low-latitude tropical regions where there is abundant insolation (light and heat) and low thermal seasonality. Because these factors broadly covary with latitude, separating their possible effects on species diversity is difficult. The Eocene was a much more equable world, however, with low temperature seasonality extending into lower-insolation higher, cooler latitudes, allowing us to test these factors by comparing insect species diversity in (1) modern, temperate, low-insolation, highly seasonal Harvard Forest, Massachusetts, U.S.A., 42°29′N; (2) modern, tropical, high-insolation, low-seasonality La Selva, Costa Rica, 10°26′N, and; (3) Eocene, temperate, low-insolation, yet low-seasonality McAbee, British Columbia, Canada, above 50°N paleolatitude. We found insect diversity at McAbee to be more similar to La Selva than to Harvard Forest, with high species richness of most groups and decreased diversity of ichneumon wasps, indicating that seasonality is key to the latitudinal diversity gradient. Further, midlatitude Eocene woody dicot diversities at McAbee, Republic (Washington, U.S.A.), and Laguna del Hunco (Argentina) are also high, similar to modern tropical samples, higher than at the modern midlatitude Harvard Forest. Modern correlations between latitude, species diversity, and seasonal climates were established some time after the Eocene.

Early Tertiary Vegetation of Arctic Canada and Its Relevance to Paleoclimatic Interpretation

Abstract: Early Tertiary fossil plants representing polar Arcto-Tertiary vegetation are found on Ellesmere and Axel Heiberg islands, northernmost of the Canadian Arctic Archipelago. Growing at a paleolatitude of 75–80 °N, these forests experienced prolonged periods of continuous daylight in the summer and continuous darkness in winter. The primarily deciduous vegetation, including members of the Taxodiaceae, Cupressaceae, Pinaceae, Ginkgoaceae, Platanaceae, Juglandaceae, Betulaceae, Menispermaceae, Cercidiphyllaceae, Ulmaceae, Fagaceae, and Magnoliaceae, clearly indicates that summer growing conditions were mild and moist, a conclusion supported by breadth and uniformity of annual growth increments of wood and by estimates of structure and productivity of forests. More significantly, probable frost-sensitive members of, for example, the Taxodiaceae, as well as fossil crocodilians and other frost-sensitive animals indicate that severe frost never occurred, even during the long, dark winter. Cold month mean temperatures of 0–4 °C, warm month mean of >25 °C, and mean annual temperature of 12–15 °C are estimated. These estimates are higher than those derived from physiognomic analogy, probably because dark polar winters in the high paleolatitudes and cold winter temperatures in the modern mid-latitudes similarly effect vegetation and enforce deciduousness. The transition from ‘greenhouse’ to icehouse’ began during the mid-Tertiary. The onset of climatic decline may be apparent in the appearance of diverse evergreen Pinaceae in the Eocene Axel Heiberg Island assemblages and other contemporaneous floras of the Eocene mid- to high latitudes. Neogene floras of northern Canada indicate that mixed evergreen coniferous/deciduous broad-leaved vegetation typical of modern boreal ecosystems persisted throughout the Arctic Archipelago until the onset of Pleistocene glaciation.