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Population dynamics

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Articles 31 - 40 of 40

Full-Text Articles in Population Biology

Conus: First Comprehensive Conservation Red List Assessment Of A Marine Gastropod Mollusc Genus, Howard Peters, Bethan C. O'Leary, Julie P. Hawkins, Kent E. Carpenter, Callum M. Roberts Jan 2013

Conus: First Comprehensive Conservation Red List Assessment Of A Marine Gastropod Mollusc Genus, Howard Peters, Bethan C. O'Leary, Julie P. Hawkins, Kent E. Carpenter, Callum M. Roberts

Biological Sciences Faculty Publications

Marine molluscs represent an estimated 23% of all extant marine taxa, but research into their conservation status has so far failed to reflect this importance, with minimal inclusion on the authoritative Red List of the International Union for the Conservation of Nature (IUCN). We assessed the status of all 632 valid species of the tropical marine gastropod mollusc, Conus (cone snails), using Red List standards and procedures to lay the groundwork for future decadal monitoring, one of the first fully comprehensive global assessments of a marine taxon. Three-quarters (75.6%) of species were not currently considered at risk of extinction owing …

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Distributions Of Sharks Across A Continental Shelf In The Northern Gulf Of Mexico, J. Marcus Drymon, Sean P. Powers, John Dindo, Brian Dzwonkowski, Terry A. Henwood Dec 2010

Distributions Of Sharks Across A Continental Shelf In The Northern Gulf Of Mexico, J. Marcus Drymon, Sean P. Powers, John Dindo, Brian Dzwonkowski, Terry A. Henwood

University Faculty and Staff Publications

Declines in shark populations have sparked researchers and fishery managers to investigate more prudent approaches to the conservation of these fish. As managers strive to improve data collection for stock assessment, fisheries-independent surveys have expanded to include data-deficient areas such as coastal regions. To that end, a catch series from a nearshore survey off Alabama was combined with data from a concurrent offshore survey with identical methodology to examine the depth use of sharks across the continental shelf (2–366 m). The combined data set contained 22 species of sharks collected from 1995 to 2008: 21 species in the offshore data …

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Modeling And Analysis Of Biological Populations, Joan Lubben Jul 2009

Modeling And Analysis Of Biological Populations, Joan Lubben

Department of Mathematics: Dissertations, Theses, and Student Research

Asymptotic and transient dynamics are both important when considering the future population trajectory of a species. Asymptotic dynamics are often used to determine whether the long-term trend results in a stable, declining or increasing population and even provide possible directions for management actions. Transient dynamics are important for estimating invasion speed of non-indigenous species, population establishment after releasing biocontrol agents, or population management after a disturbance like fire. We briefly describe here the results in this thesis.

(1) We consider asymptotic dynamics using discrete time linear population models of the form n(t + 1) = An(t) where …

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Population Ecology Of The Golden Mouse, Robert K. Rose Jan 2008

Population Ecology Of The Golden Mouse, Robert K. Rose

Biological Sciences Faculty Publications

An understanding of the population dynamics of a species requires knowledge of the major life-history parameters of a population, including age at maturity, distribution of age classes, and lifetime reproductive contribution of the sexes, sex ratio, length of the breeding season, mean litter size, rates of growth and survival, and life span. Because few long-term studies have been conducted with Ochrotomys nuttalli as the focal species of investigation, only fragmentary information is available for many population parameters. As importantly, densities of golden mice often are low, making them difficult to evaluate statistically. Little has been published on age at maturity …

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An Age-Structured Resource-Consumer Dynamical Model, Jean M. Tchuenche Jun 2007

An Age-Structured Resource-Consumer Dynamical Model, Jean M. Tchuenche

Applications and Applied Mathematics: An International Journal (AAM)

Many dynamical systems in population biology in which agents compete for resources may exhibit chaotic fluctuations. This short letter develops Gamarra and Solé's previous work. We briefly review a classical model of population with complex dynamics, and proceed to study the dynamics of an age-structured resource-consumer model, in which the fertility coefficients are density independent. Implicit or first integral solutions of the model are obtained, and conditions for which they are stable given. It is observed that resource availability at any time depends on the number of potential consumers present.

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Impact Of Minimum Winter Temperatures On The Population Dynamics Of Dendroctonus Frontalis, J. KhảI TrầN, Tiina Ylioja, Ronald F. Billings, Jacques Régnière, Matthew P. Ayres Apr 2007

Impact Of Minimum Winter Temperatures On The Population Dynamics Of Dendroctonus Frontalis, J. KhảI TrầN, Tiina Ylioja, Ronald F. Billings, Jacques Régnière, Matthew P. Ayres

Dartmouth Scholarship

Predicting population dynamics is a fundamental problem in applied ecology. Temperature is a potential driver of short-term population dynamics, and temperature data are widely available, but we generally lack validated models to predict dynamics based upon temperatures. A generalized approach involves estimating the temperatures experienced by a population, characterizing the demographic consequences of physiological responses to temperature, and testing for predicted effects on abundance. We employed this approach to test whether minimum winter temperatures are a meaningful driver of pestilence from Dendroctonus frontalis (the southern pine beetle) across the southeastern United States. A distance-weighted interpolation model provided good, spatially explicit, …

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Surviving A Drought: Population Dynamics Of Ochotona Pallasi Pricei In A Dry Steppe, Gobi Altai, Mongolia, Karin Nadrowski, Georg Miehe Jan 2007

Surviving A Drought: Population Dynamics Of Ochotona Pallasi Pricei In A Dry Steppe, Gobi Altai, Mongolia, Karin Nadrowski, Georg Miehe

Erforschung biologischer Ressourcen der Mongolei / Exploration into the Biological Resources of Mongolia, ISSN 0440-1298

Two distinct life history traits are described from the genus Ochotona, the group of “burrowing” species exhibiting high but fluctuating population densities and the “non-burrowing” species exhibiting relatively stable low population densities. The life history traits are linked to ecosystem dynamics with climatically variable steppe environments hosting “burrowing” species and relatively stable mountainous and rocky habitats hosting “non-burrowing” species. There are few intermediate species, living in both steppe and rocky environments. This study presents survival rates, reproductive rates and a tentative model of population dynamics for Ochotona pallasi pricei, an intermediate species with respect to habitat preference. We …

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Bottom-Up Forcing And The Decline Of Steller Sea Lions (Eumetopias Jubatus) In Alaska: Assessing The Ocean Climate Hypothesis, Andrew W. Trites, Arthur J. Miller, Michael A. Alexander, Steven J. Bograd, John A. Calder, Antonietta Capotondi, Kenneth O. Coyle, Emanuele Di Lorenzo, Bruce P. Finney, Edward J. Gregr, Chester E. Grosch, Thomas C. Royer Jan 2007

Bottom-Up Forcing And The Decline Of Steller Sea Lions (Eumetopias Jubatus) In Alaska: Assessing The Ocean Climate Hypothesis, Andrew W. Trites, Arthur J. Miller, Michael A. Alexander, Steven J. Bograd, John A. Calder, Antonietta Capotondi, Kenneth O. Coyle, Emanuele Di Lorenzo, Bruce P. Finney, Edward J. Gregr, Chester E. Grosch, Thomas C. Royer

CCPO Publications

Declines of Steller sea lion ( Eumetopias jubatus) populations in the Aleutian Islands and Gulf of Alaska could be a consequence of physical oceanographic changes associated with the 1976–77 climate regime shift. Changes in ocean climate are hypothesized to have affected the quantity, quality, and accessibility of prey, which in turn may have affected the rates of birth and death of sea lions. Recent studies of the spatial and temporal variations in the ocean climate system of the North Pacific support this hypothesis. Ocean climate changes appear to have created adaptive opportunities for various species that are preyed upon …

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Linking Dispersal To Local Population Dynamics: A Case Study Using A Headwater Salamander System, Winsor H. Lowe Jan 2003

Linking Dispersal To Local Population Dynamics: A Case Study Using A Headwater Salamander System, Winsor H. Lowe

Dartmouth Scholarship

Dispersal can strongly influence local population dynamics and may be critical to species persistence in fragmented landscapes. Theory predicts that dispersal by resident stream organisms is necessary to offset the loss of individuals to downstream drift. However, there is a lack of empirical data linking dispersal and drift to local population dynamics in streams, leading to uncertainty regarding the general demographic significance of these processes and the power of drift to explain observed dispersal patterns. I assessed the contribution of dispersal along a first-order stream to population dynamics of the headwater salamander Gyrinophilus porphyriticus (Plethodontidae). I conducted mark–recapture surveys of …

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Egg Collection And Recruitment Of Young Of The Year In The Aransas/Wood Buffalo Population Of Whooping Cranes, John R. Cannon, Brian W. Johns, Thomas V. Stehn Jan 2001

Egg Collection And Recruitment Of Young Of The Year In The Aransas/Wood Buffalo Population Of Whooping Cranes, John R. Cannon, Brian W. Johns, Thomas V. Stehn

Proceedings of the North American Crane Workshop

We present data for 61 years (1938 to 1998) on the recruitment of juvenile (i.e., young-of-the-year) whooping cranes (Grus americana) for the 1 natural wild population that nests in the vicinity of Wood Buffalo National Park (WBNP) in Canada and migrates annually to wintering grounds in the vicinity of Aransas National Wildlife Refuge (ANWR) on the Gulf coast of Texas in the United States. We divide these years into 2 data sets: years during which 1 of 2 eggs was collected from WBNP nests (to develop captive populations and to conduct reintroduction experiments), and years during which no …

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