scholarly journals Late Pleistocene proboscidean population dynamics in the North American Midcontinent

Boreas ◽  
2017 ◽  
Vol 46 (4) ◽  
pp. 772-782 ◽  
Author(s):  
Chris Widga ◽  
Stacey N. Lengyel ◽  
Jeffrey Saunders ◽  
Gregory Hodgins ◽  
J. Douglas Walker ◽  
...  
Keyword(s):  
Population Dynamics ◽  
Late Pleistocene ◽  
North American ◽  
The North

scholarly journals On selection-regulated population dynamics in birds and mammals

2021 ◽  
Author(s):  
Lars Witting
Keyword(s):  
Growth Rate ◽  
Population Dynamics ◽  
Population Dynamic ◽  
North American ◽  
Dynamic Equilibrium ◽  
New Paradigm ◽  
Breeding Bird ◽  
The North ◽  
Dynamic Growth ◽  
Dynamic Growth Rate

I use the North American Breeding Bird Survey (Sauer et al. 2017) to construct 462 population trajectories with about 50 yearly abundance estimates each. Applying AIC model-selection, I find that selection-regulated population dynamics is 25,000 (95%:0.42-1.7e17) times more probable than density-regulated growth. Selection is essential in 94% of the best models explaining 82% of the population dynamics variance across the North American continent. Similar results are obtained for 111, 215, and 420 populations of British birds (BTO 2020), Danish birds (DOF 2020), and birds and mammals in the Global Population Dynamic Database (GPDD 2010). The traditional paradigm---that the population dynamic growth rate is a function of the environment, with maximal per-capita growth at low population densities, and sub-optimal reproduction from famine at carrying capacities with strong competition for limited resources---is not supported. Selection regulation generates a new paradigm where the world is green and individuals are selected to survive and reproduce at optimal levels at population dynamic equilibria with sufficient resources. It is only the acceleration of the population dynamic growth rate, and not the growth rate itself, that is determined by the density-dependent environment, with maximal growth occurring at the densities of the population dynamic equilibrium.

Glacially-influenced late Pleistocene stratigraphy of a passive margin: New Jersey's Record of the North American ice sheet

2005 ◽  
Vol 218 (1-4) ◽  
pp. 155-173 ◽  
Author(s):  
John S. Carey ◽  
Robert E. Sheridan ◽  
Gail M. Ashley ◽  
Jane Uptegrove
Keyword(s):  
Late Pleistocene ◽  
North American ◽  
Ice Sheet ◽  
Passive Margin ◽  
The North

scholarly journals Spatially explicit analysis sheds new light on the Pleistocene megafaunal extinction in North America

Paleobiology ◽  
2017 ◽  
Vol 43 (4) ◽  
pp. 642-655 ◽  
Author(s):  
Meaghan M. Emery-Wetherell ◽  
Brianna K. McHorse ◽  
Edward Byrd Davis
Keyword(s):  
North America ◽  
Great Lakes ◽  
Human Activity ◽  
Late Pleistocene ◽  
North American ◽  
Human Populations ◽  
Great Lakes Region ◽  
Radiocarbon Dates ◽  
The North ◽  
Primary Driver

AbstractThe late Pleistocene megafaunal extinctions may have been the first extinctions directly related to human activity, but in North America the close temporal proximity of human arrival and the Younger Dryas climate event has hindered efforts to identify the ultimate extinction cause. Previous work evaluating the roles of climate change and human activity in the North American megafaunal extinction has been stymied by a reliance on geographic binning, yielding contradictory results among researchers. We used a fine-scale geospatial approach in combination with 95 megafaunal last-appearance and 75 human first-appearance radiocarbon dates to evaluate the North American megafaunal extinction. We used kriging to create interpolated first- and last-appearance surfaces from calibrated radiocarbon dates in combination with their geographic autocorrelation. We found substantial evidence for overlap between megafaunal and human populations in many but not all areas, in some cases exceeding 3000 years of predicted overlap. We also found that overlap was highly regional: megafauna had last appearances in Alaska before humans first appeared, but did not have last appearances in the Great Lakes region until several thousand years after the first recorded human appearances. Overlap in the Great Lakes region exceeds uncertainty in radiocarbon measurements or methodological uncertainty and would be even greater with sampling-derived confidence intervals. The kriged maps of last megafaunal occurrence are consistent with climate as a primary driver in some areas, but we cannot eliminate human influence from all regions. The late Pleistocene megafaunal extinction was highly variable in timing and duration of human overlap across the continent, and future analyses should take these regional trends into account.

TREE-RING EVIDENCE OF CLIMATE VARIABILITY OF LATE PLEISTOCENE DEGLACIATION IN THE NORTH AMERICAN MIDCONTINENT

2016 ◽  
Author(s):  
William N. Mode ◽  
◽  
Irina P. Panyushkina ◽  
Valerie N. Livina ◽  
Steven W. Leavitt
Keyword(s):  
Climate Variability ◽  
Tree Ring ◽  
Late Pleistocene ◽  
North American ◽  
The North

Fungi associated with the North American spruce beetle, Dendroctonus rufipennis

2003 ◽  
Vol 33 (9) ◽  
pp. 1815-1820 ◽  
Author(s):  
Diana L Six ◽  
Barbara J Bentz
Keyword(s):  
Population Dynamics ◽  
North American ◽  
Mycelial Fungus ◽  
Dendroctonus Rufipennis ◽  
Ophiostoma Piceae ◽  
The North ◽  
Spruce Beetle ◽  
Tree Defenses ◽  
A Minor

Fungi were isolated from individual Dendroctonus rufipennis (Kirby) collected from six populations in Alaska, Colorado, Utah, and Minnesota, U.S.A. In all populations, Leptographium abietinum (Peck) Wingfield was the most commonly isolated mycelial fungus (91–100% of beetles). All beetles in all populations were associated with yeasts and some with only yeasts (0–5%). In one population, Ophiostoma ips (Rumbold) Nannf. was also present on 5% of the beetles but always in combination with L. abietinum and yeasts. Ophiostoma piceae (Munch) H. & P. Sydow was found on 2% of beetles in another population. Ceratocystis rufipenni Wingfield, Harrington & Solheim, previously reported as an associate of D. rufipennis, was not isolated from beetles in this study. Ceratocystis rufipenni is a virulent pathogen of host Picea, which has led to speculation that C. rufipenni aids the beetle in overcoming tree defenses and therefore contributes positively to the overall success of the beetle during colonization. However, our results, considered along with those of others, indicate that C. rufipenni may be absent from many populations of D. rufipennis and may be relatively rare in those populations in which it is found. If this is true, C. rufipenni may be only a minor or incidental associate of D. rufipennis and, as such, not likely to have significant impacts on beetle success or population dynamics. Alternatively, the rarity of C. rufipenni in our and others isolations may be due to difficulties in isolating this fungus in the presence of other faster growing fungi such as L. abietinum.

1588: The Bicalutamide Early Prostate Cancer Program: Findings of the North American Trial at 7.7 Years' Median Follow-Up

2006 ◽  
Vol 175 (4S) ◽  
pp. 511-512
Author(s):  
David G. McLeod ◽  
Ira Klimberg ◽  
Donald Gleason ◽  
Gerald Chodak ◽  
Thomas Morris ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
North American ◽  
Early Prostate Cancer ◽  
The North ◽  
Cancer Program
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