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Terrestrial and Aquatic Ecology

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2011

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Articles 1 - 30 of 85

Full-Text Articles in Life Sciences

Limnological Assistance For Lake Mead National Recreation Area: Quarterly Report, Period Ending December 31, 2011, Margaret N. Rees Dec 2011

Limnological Assistance For Lake Mead National Recreation Area: Quarterly Report, Period Ending December 31, 2011, Margaret N. Rees

Limnological Studies

Project 1

  • Technical assistance with the implementation of the Interagency Monitoring Action Plan (IMAP) for Quagga Mussels is ongoing; remaining analyses are underway with report delivery rescheduled for 05/2012.
  • Data have been delivered for Veliger abundance and settlement at different depths of Lake Mead with report delivery re-scheduled for 05/2012.
  • Growth of adult quagga mussels within Las Vegas Wash/Las Vegas Bay
  • The Interagency Quagga Mussel Meeting was held on 11/17/2011; the next meeting is scheduled for 02/16/2011.

Project 2

  • Appendix 7, an addition to the Long-term Limnological and Aquatic Resource Monitoring and Research Plan for Lakes Mead and Mohave, has …


Environmental Influences On Juvenile Fish Abundances In A River-Dominated Coastal System, Laure Carassou, Brian Dzwonkowski, Frank J. Hernandez, Jr., Sean P. Powers, William M. Graham, Kyeong Park, John Mareska Dec 2011

Environmental Influences On Juvenile Fish Abundances In A River-Dominated Coastal System, Laure Carassou, Brian Dzwonkowski, Frank J. Hernandez, Jr., Sean P. Powers, William M. Graham, Kyeong Park, John Mareska

University Faculty and Staff Publications

We investigated the influence of climatic and environmental factors on variations in juvenile abundances of marine fishes in a river-dominated coastal system of the north-central Gulf of Mexico, where an elevated primary productivity sustains fisheries of high economic importance. Fish were collected monthly with an otter trawl at three stations near Mobile Bay from 1982 to 2007. Fish sizes were used to isolate juvenile stages within the data set, and monthly patterns in juvenile fish abundance and size were then used to identify seasonal peaks for each species. The average numbers of juvenile fish collected during these seasonal peaks in …


A Comparison Of The Effectiveness Of Scent Lures On Attracting Mesopredators, Tom Batter Dec 2011

A Comparison Of The Effectiveness Of Scent Lures On Attracting Mesopredators, Tom Batter

Department of Environmental Studies: Undergraduate Student Theses

A mesopredator is a medium-sized middle trophic level predator such as a raccoon (Procyon lotor), red fox (Vulpes vulpes), striped skunk (Mephitis mephitis), or coyote (Canis latrans; Crooks and Soule 1999). Mesopredators have long been trapped for recreational, economic, or academic reasons. Throughout human history trapping has been used to capture animals for food and skins, as well as to prevent personal harm and property damage from predators. In order to increase the probability of success, scent lures are often used as an attractant (Geary 1984, Mills et al. 2010, Schlexer 2008).


Prey Selection By The Northern Watersnake, Nerodia Sipedon, Kyle O' Connell Dec 2011

Prey Selection By The Northern Watersnake, Nerodia Sipedon, Kyle O' Connell

Department of Environmental Studies: Undergraduate Student Theses

Prey selection and composition of the northern waternake, Nerodia sipedon was investigated between 8/2010 and 3/2011 by palpation of stomach contents in the field and conducting laboratory trials. 41 snakes were captured, five yielded prey contents. Fish parts, freshwater mussels, and an insect exoskeleton were found. No amphibians were found despite availability at study sites. Snakes in the laboratory underwent 22 trials, feeding on 11 occasions. Snakes fed on an equal number of both fish species, revealing no selection. Further research is needed to determine the rate of digestion of N. sipedon.


Herpetofaunal Diversity At Yankee Hill State Lake And Wildlife Management Area, Lancaster County, Nebraska, Shelby Klima Dec 2011

Herpetofaunal Diversity At Yankee Hill State Lake And Wildlife Management Area, Lancaster County, Nebraska, Shelby Klima

Department of Environmental Studies: Undergraduate Student Theses

A survey for amphibians and reptiles was conducted in March through October 2011 at Yankee Hill Wildlife Management Area in Lancaster County, Nebraska. The survey was conducted using several different techniques including: visual and auditory encounters, artificial and natural cover objects, aquatic trappings and road surveys. A total of 145 individuals representing 12 species were identified including seven reptiles and five amphibians. A total of 48% of the species that may potentially occur on the site were encountered, all of which are common, widely distributed generalist species. Neither Graham’s Crayfish Snake nor the Massasauga, both target species for this survey, …


Avian Species Abundance In Response To Recreational Trail Use, Carrie A. Wencel Dec 2011

Avian Species Abundance In Response To Recreational Trail Use, Carrie A. Wencel

Department of Environmental Studies: Undergraduate Student Theses

Studies have indicated that non-consumptive outdoor recreation may affect wildlife. Thus, as the nation increases interest in outdoor recreation, data suggests the effect on wildlife will also increase. Previous studies indicate that as disturbance to wildlife increases, both avian species richness will decrease. Knowing how to anticipate effects on native species when planning and managing recreational areas is important in order to both provide for human desires and ensure the least impact to local species diversity.

The goal of this project was to observe and compare avian species richness and diversity between selected trail sites within Shevlin Park, Bend, Oregon …


Effects Of Climate Change On Spring Ecosystem Hydroecology As A Guide To Developing Alternative Water Policies, Scott Mensing, Saxon E. Sharpe, Scott Bassett, Don Sada, Jim Thomas Oct 2011

Effects Of Climate Change On Spring Ecosystem Hydroecology As A Guide To Developing Alternative Water Policies, Scott Mensing, Saxon E. Sharpe, Scott Bassett, Don Sada, Jim Thomas

Climate Change Seminar Series (NNE)

Hydroecology: the interface of ecological systems and water which combines the scientific disciplines of hydrology and ecology

Goal: evaluate the hydrologic and climate history using pollen, loss on ignition, total inorganic carbon, and invertebrates from spring sediments in Spring Valley, Eastern Nevada and Snake Valley, Western Utah


The Lobster Bulletin, Fall 2011, Lobster Institute, University Of Maine Oct 2011

The Lobster Bulletin, Fall 2011, Lobster Institute, University Of Maine

Lobster Bulletin

The Lobster Bulletin newsletter includes research updates, and information on lobsters and the lobster industry. The Lobster Institute at the University of Maine is dedicated to protecting and conserving the lobster resource, and enhancing lobstering as an industry and a way of life.

Headlines in the Fall 2011 issue include:

  • Lobster Institute to Present Two Workshops at the Massachusetts Lobstermen's Association Weekend
  • Number of Right Whales Up in Bay of Fundy
  • Coming 2012 The Lobster Institute's 25th Anniversary
  • A Full House for the Lobster Institute's Holiday Lobster & Wine Fest
  • Research Report: Squid Outweighs Lobster in Rhode Island Fishery
  • Research …


Review Of Grass: In Search Of Human Habitat. By Joe C. Truett. Foreword By Harry W. Greene., Mary Ann Vinton Oct 2011

Review Of Grass: In Search Of Human Habitat. By Joe C. Truett. Foreword By Harry W. Greene., Mary Ann Vinton

Great Plains Research: A Journal of Natural and Social Sciences

Much of the book is devoted to discussing the heavy human dependence on grasslands and whether this relationship can be maintained in company with grassland conservation. Can humans continue to use grasslands for food, fiber, and newer uses like biofuels and carbon banking while still sustaining the ecosystem? Many of us in academic ecology struggle with resolving perceived conflicts between conservation and human grassland use. In many cases, a "win-win" scenario exists in which, for example, the proper use of livestock grazing is perfectly compatible with a healthy grassland ecosystem. In other cases, such as conserving prairie dog populations, tensions …


Review Of A Field Guide To The Amphibians And Reptiles Of Nebraska. By Daniel D. Fogell., Joseph T. Collins Oct 2011

Review Of A Field Guide To The Amphibians And Reptiles Of Nebraska. By Daniel D. Fogell., Joseph T. Collins

Great Plains Research: A Journal of Natural and Social Sciences

A good field guide to any wildlife group includes an identification key, quality photographs, distribution maps, and a natural history summary. The recently published Field Guide to the Amphibians and Reptiles of Nebraska does not fail the reader in this regard, having all of these features and more. Dan Fogell effectively presents all 62 species of amphibians, turtles, and reptiles native to Nebraska as well as four additional species of possible occurrence within the state, and all in a useful and compact guide that can be toted easily on a hike or any other field expedition.

This long-overdue updated field …


Effects Of Coral Stressing On The Feeding Preferences Of The Coral Predator, Acanthaster Planci, Harriet Booth Oct 2011

Effects Of Coral Stressing On The Feeding Preferences Of The Coral Predator, Acanthaster Planci, Harriet Booth

Independent Study Project (ISP) Collection

Coral predators have always been a natural occurrence on coral reefs, but recent studies have begun to focus on the feeding preferences of these predators in relation to bleached and damaged corals. The recent mass bleaching events, mainly resulting from factors of climate change, have motivated researchers to study the effects of predation on the affected corals to determine the extent of harm these large-scale disturbances may be causing to reefs. This study examined how coral stressing affects the feeding preferences of Acanthaster planci, a coral-feeding starfish that has been known to cause widespread damage to coral reefs, especially during …


What Is The Value Of A Sea Turtle?: A Case Study Of The Conservation Ethics Of Sea Turtle Fishermen In The Caribbean Coast Of Nicaragua, Alicia Conte Oct 2011

What Is The Value Of A Sea Turtle?: A Case Study Of The Conservation Ethics Of Sea Turtle Fishermen In The Caribbean Coast Of Nicaragua, Alicia Conte

Independent Study Project (ISP) Collection

The sea turtle populations on the Caribbean Coast of Nicaragua have dramatically decreased as a result of human use and consumption. All species of sea turtles are endangered and at risk of extinction. This is an environmental issue because if sea turtles go extinct, many other plants and animals in marine ecosystems will be negatively impacted by this loss, and the environment will be drastically altered. This is also problematic for locals who depend on this resource for food and as a source of income. Conservation efforts have been initiated by an international NGO, the Wildlife Conservation Society (WCS); however, …


Effects Of Herbicides And Grazing On Floristic Quality Of Native Tallgrass Pastures In Eastern South Dakota And Southwestern Minnesota, Alexander J. Smart, Matthew J. Nelson, Peter J. Bauman, Gary E. Larson Oct 2011

Effects Of Herbicides And Grazing On Floristic Quality Of Native Tallgrass Pastures In Eastern South Dakota And Southwestern Minnesota, Alexander J. Smart, Matthew J. Nelson, Peter J. Bauman, Gary E. Larson

Great Plains Research: A Journal of Natural and Social Sciences

Historic herbicide use and grazing have influenced natural diversity and quality of native pasturelands in the Great Plains. Floristic quality assessments are useful to assist agencies in prioritizing conservation practices to enhance native grasslands. The objective of this study was to determine the effects of past land-use practices on the floristic quality of remnant native pastures in eastern South Dakota and southwestern Minnesota. Floristic quality assessments were conducted on 30 native pastures and categorized by past management practices (herbicide application and grazing intensity). Mean coefficient of conservatism (C) and floristic quality index (FQI) were calculated for each site~Results showed that …


Review Of Rare: Portraits Of America's Endangered Species. By Joel Sartore., Jim Mason Oct 2011

Review Of Rare: Portraits Of America's Endangered Species. By Joel Sartore., Jim Mason

Great Plains Research: A Journal of Natural and Social Sciences

Short of being in the presence of a creature, a really good photograph of one can also make a lasting impression. That is something RARE does compellingly, with exquisite portrait photos of 68 North American species that are dwindling dangerously in numbers or have recently recovered from the brink of extinction. Included are such Great Plains natives as the lesser prairie chicken, the interior least tern, and the black-footed ferret. All creatures were photographed with either a pure white or black background, but unconventional poses surprise the reader with each turn of the page, while creative framing and layout engage …


Limnological Assistance For Lake Mead National Recreation Area: Quarterly Report, Period Ending September 30, 2011, Margaret N. Rees Sep 2011

Limnological Assistance For Lake Mead National Recreation Area: Quarterly Report, Period Ending September 30, 2011, Margaret N. Rees

Limnological Studies

Project 1

  • Technical assistance with the implementation of the Interagency Monitoring Action Plan (I-MAP) for Quagga Mussels is ongoing. During this quarter, processing of all 2010 juvenile/adult samples was completed; remaining analyses are underway. The project team assisted NPS with 2011 collections.
  • A final report on Veliger abundance and settlement at different depths of Lake Mead is in preparation for delivery at the end of November 2011; sample analysis continues for Growth of adult quagga mussels within Las Vegas Wash/Las Vegas Bay with report delivery planned for the end of November 2011.
  • The Interagency Quagga Mussel Meeting was held on …


Limits To Sexual Reproduction In Geothermal Bryophytes, Sarah M. Eppley, Todd N. Rosenstiel, Camille Brianne Graves, Estefanía Llaneza García Sep 2011

Limits To Sexual Reproduction In Geothermal Bryophytes, Sarah M. Eppley, Todd N. Rosenstiel, Camille Brianne Graves, Estefanía Llaneza García

Biology Faculty Publications and Presentations

Previous research suggests that while sexual reproduction generally increases with environmental stress it may decrease with extreme stress, at the edge of eukaryotic life. In this study, we explored the limits to sexual reproduction in an extremophile, bryophyte system to ultimately understand the processes that limit sexual reproduction. We used field data from geothermal sites at Lassen Volcanic National Park, California, to demonstrate that sexual reproduction, as measured by the number of sporophytes per shoot, decreases with increasing environmental stress. We found that the number of sporophytes per shoot is positively correlated with distance from geothermal features. When Pohlia nutans …


Human Pathogen Shown To Cause Disease In The Threatened Elkhorn Coral Acropora Palmata, Kathryn Patterson Sutherland, Sameera Shaban, Jessica L. Joyner, James W. Porter, Erin K. Lipp Aug 2011

Human Pathogen Shown To Cause Disease In The Threatened Elkhorn Coral Acropora Palmata, Kathryn Patterson Sutherland, Sameera Shaban, Jessica L. Joyner, James W. Porter, Erin K. Lipp

Faculty Publications

Coral reefs are in severe decline. Infections by the human pathogen Serratia marcescens have contributed to precipitous losses in the common Caribbean elkhorn coral, Acropora palmata, culminating in its listing under the United States Endangered Species Act. During a 2003 outbreak of this coral disease, called acroporid serratiosis (APS), a unique strain of the pathogen, Serratia marcescens strain PDR60, was identified from diseased A. palmata, human wastewater, the non-host coral Siderastrea siderea and the corallivorous snail Coralliophila abbreviata. In order to examine humans as a source and other marine invertebrates as vectors and/or reservoirs of the APS pathogen, challenge experiments …


Rumbling In The Benthos: Acoustic Ecology Of The California Mantis Shrimp Hemisquilla Californiensis, E. Staaterman, C. Clark, A. Gallagher, M. Devries, T. Claverie, S. Patek Aug 2011

Rumbling In The Benthos: Acoustic Ecology Of The California Mantis Shrimp Hemisquilla Californiensis, E. Staaterman, C. Clark, A. Gallagher, M. Devries, T. Claverie, S. Patek

Faculty Publications, Biological Sciences

Although much research has focused on acoustic mapping and exploration of the benthic environment, little is known about the acoustic ecology of benthic organisms, particularly benthic crustaceans. Through the use of a coupled audio–video system, a hydrophone array, and an autonomous recording unit, we tested several hypotheses about the field acoustics of a benthic marine crustacean, Hemisquilla califor­niensis. Living in muddy burrows in southern California, these large mantis shrimp produce low frequency ‘rumbles’ through muscle vibrations. First, we tested whether acoustic signals are similar in the field and in the laboratory, and discovered that field-produced rumbles are more acoustically and …


Interspecies Comparison Of Αii-Spectrin Abundance Between Chinook Salmon And Steelhead, Brielle D. Kemis, Ann L. Miracle, Katie A. Wagner, Christa M. Woodley Aug 2011

Interspecies Comparison Of Αii-Spectrin Abundance Between Chinook Salmon And Steelhead, Brielle D. Kemis, Ann L. Miracle, Katie A. Wagner, Christa M. Woodley

STAR Program Research Presentations

Salmonids, such as Chinook salmon (Oncorhynchus tshawytscha) and steelhead (O. mykiss), are a staple economic, recreational, tribal, and environmental resource, yet many populations are unsustainable. This study was part of a broad scale effort to monitor the impact of downstream migration obstacles on juvenile salmonid health and survival, which is an essential step towards increasing Smolt-to-Adult Return ratios (SARs). The objective of this study was to determine if juvenile Chinook salmon and steelhead exhibit differing quantities of alphaII-Spectrin Breakdown Products (SBDPs) over two consecutive spring migration periods, indicative of neurogenesis rate and/or biological response to head …


Relationship Of Maternal Flow Environment To Offspring Size In Botrylloides Violaceus, Damion J. Delton, Sarah Cohen Aug 2011

Relationship Of Maternal Flow Environment To Offspring Size In Botrylloides Violaceus, Damion J. Delton, Sarah Cohen

STAR Program Research Presentations

Colonial botryllid tunicates, such as Botrylloides violaceus, brood large, non-feeding offspring with extremely limited larval life spans of minutes to perhaps one day. Despite the importance of this transitory life history stage, there is little information on how environmental factors such as ambient water flow affect larval size among invertebrates. Since adult tunicates feed by filtering particles from the water flowing around the siphons, we reasoned that colonies of B. violaceus in high water flow may produce larger offspring due to greater food availability. We tested to see whether there was a relationship between larval size and water motion in …


Informing Carbon In Arctic Reservoirs Vulnerability Experiment Flight Schedule Based Upon Soil And Vegetation Freeze And Thaw Event Variation Along The Alaska Ecological Transect, Jessica Potter, Kyle Mcdonald, Erika Podest Aug 2011

Informing Carbon In Arctic Reservoirs Vulnerability Experiment Flight Schedule Based Upon Soil And Vegetation Freeze And Thaw Event Variation Along The Alaska Ecological Transect, Jessica Potter, Kyle Mcdonald, Erika Podest

STAR Program Research Presentations

Established in the 1990s, the Alaska Ecological Transect (ALECTRA) is composed of a series of ground stations extending from the Franklin Bluff on Alaska’s North Slope to the Kenai Peninsula, south of Anchorage. At each station, sets of thermistors are deployed to monitor vegetation tissue temperature, air temperature, and soil profile temperatures. Also sensors are deployed for monitoring sap flow in individual trees. The stations are automated, with data loggers recording this data approximately every two hours. Dates marking the spring thaw and fall freeze transitions in soil and vegetation tissues from sites in Coldfoot, Dietrich Valley, and Bonanza Creek …


Discontinuities: Predicting Invasions And Extinctions, Aaron Lotz Jul 2011

Discontinuities: Predicting Invasions And Extinctions, Aaron Lotz

School of Natural Resources: Dissertations, Theses, and Student Research

In this dissertation, I explore multiple tenets of the textural discontinuity hypothesis, which states that hierarchical landscape structures with scale-specific pattern entrain attributes of animals inhabiting the landscape. Landscapes form hierarchies that are structured by vegetative, geomorphological and contagious disturbance processes. The spatial and temporal patterns inherent in landscapes reflect numerous processes, interacting on distinct scales, which shape the assembly of animal communities. Analysis of body mass patterns and functional group distributions has been suggested as methods to provide insight about these underlying hierarchical processes. Scientists have posited that species at the edges of body mass aggregations may be exposed …


The Lobster Bulletin, Summer 2011, Lobster Institute, University Of Maine Jul 2011

The Lobster Bulletin, Summer 2011, Lobster Institute, University Of Maine

Lobster Bulletin

The Lobster Bulletin newsletter includes research updates, and information on lobsters and the lobster industry. The Lobster Institute at the University of Maine is dedicated to protecting and conserving the lobster resource, and enhancing lobstering as an industry and a way of life.

Headlines in the Summer 2011 issue include:

  • Lobster Institute Cooperating Experts Directory a Valuable Asset
  • Atlantic Lobster Sustainability Foundation Hosts First Lobster Science Symposium
  • Research Report: Using the Invasive Green Crab in Food Product Development
  • Research Report: Progress in the war against sea lice
  • Maine Lobster Chef of the Year Finalists to Compete in Portland


Satellite Finds Highest Land Skin Temperatures On Earth, David J. Mildrexler, Maosheng Zhao, Steven W. Running Jul 2011

Satellite Finds Highest Land Skin Temperatures On Earth, David J. Mildrexler, Maosheng Zhao, Steven W. Running

Ecosystem and Conservation Sciences Faculty Publications

The location of the hottest spot on Earth has undoubtedly been an interesting curiosity for centuries. Even with the advent of the instrumental temperature record around the year 1850, the location of the hottest spot on Earth has continued to be the subject of debate and controversy. In 1913, the weather station at Furnace Creek in Death Valley National Park, California, measured an air temperature of 56.7°C (134.1°F) and claimed the title of “hottest place on Earth.” Nine years later in El Azizia, Libya, an air temperature of 57.8°C (136°F) was recorded on land owned by an Italian farmer and …


Virginia's Comprehensive Wetlands Program Plan, Center For Coastal Resources Management, Virginia Institute Of Marine Science Jul 2011

Virginia's Comprehensive Wetlands Program Plan, Center For Coastal Resources Management, Virginia Institute Of Marine Science

Reports

Rivers & Coast is a periodic publication of the Center for Coastal Resources Management, Virginia Institute of Marine Science. The goal of Rivers & Coast is to keep readers well informed of current scientific understanding behind key environmental issues related to watershed rivers and coastal ecosystems of the Chesapeake Bay.


The Distribution And Life Cycle Of Alliaria Petiolata In Lincoln, Nebraska, Caleb Pharris Jul 2011

The Distribution And Life Cycle Of Alliaria Petiolata In Lincoln, Nebraska, Caleb Pharris

Department of Environmental Studies: Undergraduate Student Theses

Alliaria petiolata (Garlic Mustard) is a biennial alien invasive plant species of the Brassicacea family. It is responsible for displacing native plant species throughout North America and its management has proven to be extremely difficult. Recently several populations of Alliaria petiolata have been discovered in southwestern Lincoln, Nebraska. The spread of Alliaria petiolata is a concern for natural resource managers and the general public. Due to the difficulty of its control, Alliaria petiolata is capable of creating monocultures which diminish the aesthetic value of an ecosystem. While most commonly found in the understory of hardwood forests, it is capable of …


Limnological Assistance For Lake Mead National Recreation Area: Quarterly Report, Period Ending June 30, 2011, Margaret N. Rees Jun 2011

Limnological Assistance For Lake Mead National Recreation Area: Quarterly Report, Period Ending June 30, 2011, Margaret N. Rees

Limnological Studies

Project 1

  • Technical assistance with the implementation of the Interagency Monitoring Action Plan (I-MAP) for Quagga Mussels is ongoing. During this quarter, analysis was completed for 42 juvenile/adult samples and analyses of the remaining samples are underway.
  • As of 7/07/11 all sample sets will have been collected for Veliger abundance and settlement at different depths of Lake Mead; sampling continues for Growth of adult quagga mussels within Las Vegas Wash/Las Vegas Bay.
  • The Interagency Quagga Mussel Meeting was held on 05/17/11; the next meeting is scheduled for 08/25/11.

Project 2

  • Appendix 7, an addition to the Long-term Limnological and Aquatic …


Clearcutting Has A Long-Lasting Effect On Habitat Connectivity For A Forest Amphibian By Decreasing Permeability To Juvenile Movements, Viorel Popescu, Malcolm L. Hunter Jr. Jun 2011

Clearcutting Has A Long-Lasting Effect On Habitat Connectivity For A Forest Amphibian By Decreasing Permeability To Juvenile Movements, Viorel Popescu, Malcolm L. Hunter Jr.

Publications

Conservation of forest amphibians is dependent on finding the right balance between management for timber production and meeting species' habitat requirements. For many pond-breeding amphibians, successful dispersal of the juvenile stage is essential for long-term population persistence. We investigated the influence of timber-harvesting practices on the movements of juvenile wood frogs (Lithobates sylvaticus). We used a chronosequence of stands produced by clear-cutting to evaluate how stand age affects habitat permeability to movements. We conducted experimental releases of juveniles in 2008 (n = 350) and 2009 (n = 528) in unidirectional runways in four treatments: mature forest, recent clearcut, …


Life History Benefits Of Residency In A Partially Migrating Pond-Breeding Amphibian, Kristine L. Grayson, Larissa L. Bailey, Henry M. Wilbur Jun 2011

Life History Benefits Of Residency In A Partially Migrating Pond-Breeding Amphibian, Kristine L. Grayson, Larissa L. Bailey, Henry M. Wilbur

Biology Faculty Publications

Species with partial migration, where a portion of a population migrates and the other remains residential, provide the opportunity to evaluate conditions for migration and test mechanisms influencing migratory decisions. We conducted a five-year study of two populations of red-spotted newts (Notophthalmus viridescens), composed of individuals that either remain as residents in the breeding pond over the winter or migrate to the terrestrial habitat. We used multistate mark-recapture methods to (1) test for differences in survival probability between migrants and residents, (2) determine if migrants breed every year or skip opportunities for reproduction, and (3) estimate the frequency …


Population Dynamics Of The Western Prickly Pear, Opuntia Macrorhiza (Cactaceae), Kathleen H. Keeler, Brigitte Tenhumberg Jun 2011

Population Dynamics Of The Western Prickly Pear, Opuntia Macrorhiza (Cactaceae), Kathleen H. Keeler, Brigitte Tenhumberg

School of Biological Sciences: Faculty Publications

Although most cacti that have been studied are long lived, following individually marked plants in Boulder County, Colorado, for >7 years, we determined that average life span of Opuntia macrorhiza, the western prickly pear, is 3 years. A few individuals probably live >10 years. Vegetative reproduction, produced by rooting of cladodes, exceeded reproduction by germination and establishment from seeds. Both types of new recruits, from vegetative reproduction and seeds, had higher death rates than established plants. Size and frequency of flowering increased with age, although size both increased and decreased, sometimes dramatically, between years. Flowering correlated more strongly with …