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1981

Ecology and Evolutionary Biology

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Articles 1 - 29 of 29

Full-Text Articles in Life Sciences

The Ecology Of The Raccoon (Procyon Lotor) In Cades Coves, Great Smoky Mountains National Park, Alan Robert Rabinowitz Dec 1981

The Ecology Of The Raccoon (Procyon Lotor) In Cades Coves, Great Smoky Mountains National Park, Alan Robert Rabinowitz

Doctoral Dissertations

From September 1979 through September 1980, 288 captures of 153 raccoons were made in Cades Cove, Great Smoky Mountains National Park, Tennessee. Fourteen raccoons were equipped with radio-transmitters to monitor movements, activity patterns, and denning behavior. Measurements, blood samples, and ectoparasites were taken from all animals.

Population density was estimated to be 1 raccoon/17 ha with sex and age ratios indicating a stable population. Parturition occurred in early June with a mean litter size of 2.8 young. Average longevity of raccoons was 30 months with a maximum longevity of approximately 86 months. There were indications of increased male mortality in …


The Paleoecology Of Carbonaceous (Algal) Material In The Middle Devonian Rockport Quarry Limestone Of The Northeastern Portion Of Michegan's Lower Peninsula, Jeffrey Dean Spruit Dec 1981

The Paleoecology Of Carbonaceous (Algal) Material In The Middle Devonian Rockport Quarry Limestone Of The Northeastern Portion Of Michegan's Lower Peninsula, Jeffrey Dean Spruit

Masters Theses

The Rockport Quarry Limestone of the Lower Traverse Group represents a sequence of laterally contemporaneous carbonate platform sediments characterized in outcrop by four facies: (l) stromatoporoid biolithite, (2) organic-mud packstone, (3) biolithite-micrite transition, and (4) micrite. In facies (l), (2) and (3) dark brown 4-micron microspheres are found grouped or singly in wispy seams of brown carbonaceous material. Three species of filamentous blue-green algae were discovered in insoluble residues of facies (l) and (2). Numerous lamellar stromatoporoids and solitary corals occur with the carbonaceous-rich sediment in facies (l). Coalescing lenses of crinoid and bryozoan debris occur with the carbonaceous sediment …


The Effects Of Copper On Skeletonema Costatum (Greville) Cleve, Susanne Sybille Jackman Oct 1981

The Effects Of Copper On Skeletonema Costatum (Greville) Cleve, Susanne Sybille Jackman

Biological Sciences Theses & Dissertations

Copper levels and dominant phytoplankton species composition were examined from six sites in Kings Creek on Virginia's Eastern Shore from March to August 1980. Creek copper levels were determined by an APDCMIBK extraction procedure and ranged from 0.003 to 0.020 mg/1. Diatoms were the dominant phytoplankters with Skeletonema costatum (Greville) Cleve emerging as a major late summer species.

Subsequent laboratory studies involved 96-hour experiments using Skeletonema costatum (clone Skel) grown in enriched natural seawater. The water was collected from Kings Creek and enriched to Guillard and Ryther's (1962) f/2 media levels. Cupric sulfate was added to the experimental culture media …


The Effect Of Storm Sewer Drainage On An Urban Lake, Jose Ignacio Aizpurua Aug 1981

The Effect Of Storm Sewer Drainage On An Urban Lake, Jose Ignacio Aizpurua

Masters Theses

The present study was undertaken to evaluate the impact from normal precipitation (ra in , snow) into an urbanized lake during 1978- 1980. Several stations were chosen, and various limnological parameters were investigated. Chemical analyses were used to estimate the annual load of nutrients input into the lake by the storm sewer and surface runoff. Excessive phosphorus and nitrogen loads from these sources were discharged into the lake.

Fecal coliform distribution in the lake before, during, and after several storm events was studied. In general, fecal coliform counts increased after storm events. Peak concentrations decreased markedly with distance of the …


The Seasonality Of Occurrence Of Larval And Juvenile Sciaenids In A Virginia Seaside Estuary, James Howard Cowan Jr. Jul 1981

The Seasonality Of Occurrence Of Larval And Juvenile Sciaenids In A Virginia Seaside Estuary, James Howard Cowan Jr.

Biological Sciences Theses & Dissertations

The seasonality of occurrence and relative abundance of larval and juvenile fishes, particularly members of the family Sciaenidae, from a Virginia seaside estuary were determined from ichthyoplankton and trawl collections made from March 1979 to March 1980.

The larvae of 20 species distributed among 15 families were identified from the ichthyoplankton. Larvae of the bay anchovy, Anchoa mitchilli, and the Atlantic silverside, Menidia menidia, dominated the samples and made up 57 and 34%, respectively, of all larvae collected. Peak occurrence began in May and continued through August. Fish larvae were present in the study area all year.

Twenty-eight …


Breeding Birds Of Two Atlantic White Cedar Stands In The Great Dismal Swamp, Karen Terwilliger Jul 1981

Breeding Birds Of Two Atlantic White Cedar Stands In The Great Dismal Swamp, Karen Terwilliger

Biological Sciences Theses & Dissertations

Breeding birds were censused during two years in two Atlantic white cedar stands of the Great Dismal Swamp, and a comparison was made with census results of the predominant swamp community, maple-gum. The maple-gum site had a higher bird species diversity than either cedar site but supported only half the density. The century-old cedar site had the highest species richness while the younger cedar site had the highest density.

Cluster analysis placed the avifauna into distinct groups which closely corresponded to the vegetative strata of the stands. Species were ordered along the height gradient using principal coordinate and detrended correspondence …


The Use Of Microscopic Vegetative Characteristics And Leaf Characteristics And Leaf Deterioration Rates In The Formulation Of Keys Of Some Wetland Plants, Bruce Foy Williams Jul 1981

The Use Of Microscopic Vegetative Characteristics And Leaf Characteristics And Leaf Deterioration Rates In The Formulation Of Keys Of Some Wetland Plants, Bruce Foy Williams

Biological Sciences Theses & Dissertations

Leaves of Spartina alterniflora, Spartina patens, Spartina cynosuroides, Distichlis spicata, Phragmites communis, Juncus roemerianus, Scirpus robustus, Typha latifolia, Iva frutescens, and Baccharis halimifolia were examined microscopically. Characteristics of each species were then used to develop identification keys. In addition, leaf fragments were buried in the marsh substrate to simulate a dredging and/or filling operation. At weekly intervals during each season of the year, a leaf fragment of each species was processed and examined to see if it could be identified.


Decay Rates And Nutrient Dynamics In Confines And Nonconfined Leaf Litter In The Great Dismal Swamp, R. Frederick K. Yates Jul 1981

Decay Rates And Nutrient Dynamics In Confines And Nonconfined Leaf Litter In The Great Dismal Swamp, R. Frederick K. Yates

Biological Sciences Theses & Dissertations

This study was designed to quantitatively compare decay rates and nutrient dynamics by the confined and unconfined litter techniques in a seasonally flooded swamp. In this study both methods indicated the same order of decay rates among sites (cedar>maple-gum>cypress> mixed hardwood), but the unconfined method showed faster decay rates at all sites. As in two years of previous data collection, the stands exhibiting some seasonal flooding showed greater decay rates than the mixed hardwood stand which was not inundated. Nutrient dynamics were not different between litter bag and leaf pack methods.

This study included a preliminary investigation of …


Vegetation Patterns A Half Century Following The Chestnut Blight In The Great Smoky Mountains National Park, Ernesto Arends Jun 1981

Vegetation Patterns A Half Century Following The Chestnut Blight In The Great Smoky Mountains National Park, Ernesto Arends

Masters Theses

Vegetation patterns approximately 50 years after the chestnut blight were examined in forest stands of the Great Smoky Mountains National Park. Specific objectives of this study were: (1) to determine the present composition of replacement stands following the elimination of chestnut, (2) to examine selected site factors and to relate them to tree species composition, (3) to project future trends in the composition of the replacement stands, and (4) to compare these results with earlier results and predictions of Wood and Shanks (1959) concerning chestnut replacement in the same area.

Data were analyzed from 38 sample plots ranging from 2000 …


Effect Of Simulated Tidal Patterns On Growth And Growth Line Formation In The Little Neck Clam, Protothaca Staminea, Orlando Irsula May 1981

Effect Of Simulated Tidal Patterns On Growth And Growth Line Formation In The Little Neck Clam, Protothaca Staminea, Orlando Irsula

Loma Linda University Electronic Theses, Dissertations & Projects

Growth lines in bivalve mollusks have been thought to reflect solar days, circadian rhythms and/or tides. Tides seem to be the dominating influence in some intertidal species. This study provides laboratory evidence suggesting that tides are a major influence in the number of growth lines in the clam Protothaca staminea.

Clams were grown under 4 different "tidal" regimes, (0, 1, 2 and 3 tides per day) for forty-one days. Acetate peels of shell cross sections were used for growth line counting. Photomicrographs and measurements showed a striking difference in the growth and number of growth lines between the 4 tidal …


Higher Plant Acclimation To Solar Ultraviolet-B Radiation, Ronald Robberecht May 1981

Higher Plant Acclimation To Solar Ultraviolet-B Radiation, Ronald Robberecht

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Plant acclimation to natural and intensified solar UV-B irradiance was investigated in three species, Oenothera stricta Ledeb., Rumex obtusifolius L., and R. patientia L. The objectives of this study were to determine: (1) the relationship between plant sensitivity and epidermal UV attenuation, (2) the effect of phenotypic changes in the leaf epidermis, resulting from UV-B exposure, on plant sensitivity to UV radiation, and (3) the plasticity of these changes in the epidermis leading to plant acclimation to UVB radiation.

Epidermal UV transmittance was found to differ in magnitude and spectral distribution among the three species examined in this study. Epidermal …


Fall Regrowth Of Crested Wheatgrass And Fourwing Saltbush, Noor Mohammad May 1981

Fall Regrowth Of Crested Wheatgrass And Fourwing Saltbush, Noor Mohammad

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

During 1980-81, studies with crested wheatgrass (Agropyron desertorum) and fourwing saltbush (Atriplex canescens) were conducted in controlled environment growth chambers as well as under field conditions to achieve the following objectives:

1. To determine the effect of nitrogen fertilizer on the water use efficiency.

2. To determine the effects of various temperature, water stress and nitrogen treatments on the productivity, nitrogen content and carbohydrate reserves.

3. To determine the effects of N fertilization on fall and spring regrowth.

Crested wheatgrass and fourwing saltbush plants were maintained in three growth chambers for 60 days under three temperature …


Effect Of Mild Water Stress And Enhanced Ultraviolet-B Irradiation On Leaf Growth Of Rumex Obtusifolius L. And Rumex Patientia L. (Polygonaceae)., Steve R. Holman May 1981

Effect Of Mild Water Stress And Enhanced Ultraviolet-B Irradiation On Leaf Growth Of Rumex Obtusifolius L. And Rumex Patientia L. (Polygonaceae)., Steve R. Holman

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Leaves of Rumex obtusifolius L. and R. patientia L.were exposed to combinations of mild water stress and enhanced ultraviolet-B irradiation during their ontogeny. Two UV-B treatments (enhanced UV-B and control) and three water stress treatments (-0.0 MPa, -0.2 MPa and -0.4 MPa rooting medium matric potentials) were employed. The impact of the stress interaction was assessed on the basis of changes in leaf area, average adaxial epidermal cell size, and total number of adaxial epidermal cells per leaf. Although the level of UV-B irradiation applied was insufficient to significantly alter leaf growth at any given water stress, UV-B did interact …


The Energy Expenditure Of Heifers Grazing Crested Wheatgrass Rangeland In West-Central Utah, Kris M. Havstad May 1981

The Energy Expenditure Of Heifers Grazing Crested Wheatgrass Rangeland In West-Central Utah, Kris M. Havstad

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The free-roaming ruminant requires energy for the demands of vii grazing, traveling and thermoregulation that are not required by its confined counterpart. Literature estimates of these additional costs range from 10 to 170 percent above maintenance. The uncertain magnitude of this increased demand and the factors that contribute to it impede the ability of the rangeland ruminant nutritionist to establish guidelines for the energy requirements of the free-roaming herbivore. This study was designed to estimate the energy expenditure of yearling Angus heifers while grazing a declining supply of available crested wheatgrass forage (Agropyron cristatum) on rangeland in west-central …


Seasonal Temperature Preference Of Adult Mountain Whitefish, Prosopium Williamsoni, Jean M. Ihnat May 1981

Seasonal Temperature Preference Of Adult Mountain Whitefish, Prosopium Williamsoni, Jean M. Ihnat

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Temperatures selected seasonally by adult mountain whitefish were measured in the laboratory in a horizontal gradient. Final preferendum estimates, based on acute (3-hour) preference tests conducted with fish acclimated to 5, 10, and 15 C each season, were 17.7 C (pre-spawning), 11.9 C (post-spawning), 9.9 C (winter), and 16.3 C (spring). Seasonal influence on temperature selection was evident on the basis of differences in final preferenda, covariance analysis of responses of laboratory-acclimated fish, and temperature selection by fish held at ambient river temperatures. Post-spawning and winter groups selected lower temperatures than did pre-spawning and spring groups. Pre-spawning fish selected temperatures …


Some Morphological And Chemical Responses Of Blackbrush (Coleogyne Ramosissima) To Goat Browsing: Influences On Dietary Blackbrush Selection By Goats And Cattle, Frederick D. Provenza May 1981

Some Morphological And Chemical Responses Of Blackbrush (Coleogyne Ramosissima) To Goat Browsing: Influences On Dietary Blackbrush Selection By Goats And Cattle, Frederick D. Provenza

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Domestic goats were used to modify the growth form of blackbrush, a spinescent shrub occurring in nearly monospecific stands on several million hectares of rangeland in the southwestern United States. The objective of this research was to evaluate goat browsing as a means of improving these rangelands for cattle. Winter goat browsing stimulated spring twig growth from basal and axillary buds which resulted in increased production.

Twig production by heavily browsed plants (>95 percent removal of current season's twigs) was a function of precipitation, soil depth, branch location on the plant, and period of rest after browsing. As precipitation …


Diversity And Production Of Herbaceous Vegetation In A Northern Utah Subalpine Chronosequence, Gary A. Reese May 1981

Diversity And Production Of Herbaceous Vegetation In A Northern Utah Subalpine Chronosequence, Gary A. Reese

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Successional trends in herbaceous plant production and diversity were studied in an age sequence of sites, i.e. chronosequence, inferred to represent a meadow to aspen to fir to spruce-fir sere. Primary production was observed to decrease in a linear fashion with successional development. Three components of diversity; richness, heterogeneity, and equitability or evenness, each had low early successional values, reaching maximum diversity in mid-succession, and declining to intermediate levels with maturity. The magnitude of these trends varied greatly, depending on the methods used to determine plant dominance. Characteristics of various dominance indices and their applicability to this study were examined. …


Economic Analysis Of Long-Term Management Strategies For Two Sizes Of Utah Cattle Ranches, Roger E. Banner May 1981

Economic Analysis Of Long-Term Management Strategies For Two Sizes Of Utah Cattle Ranches, Roger E. Banner

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Utah cattle ranchers realize relatively little profit from ranch ownership and management. This study represents an attempt to identify ranch management strategies that produce more profit over time than do conventional strategies.

To identify optimum management strategies for the long term, analyses of ranches under both normal and adverse ranch operation conditions using the COPLAN linear programming model were made for strategy comparison. To depict these ranch business environmental conditions, production levels were estimated from available biological data and price levels were estimated by indexing 1977 ranch product prices (the most current budget data available for Utah). The variability of …


The Relationship Between Adjacent Residential Development And Breeding Bird Populations, Steven L. Harbron Apr 1981

The Relationship Between Adjacent Residential Development And Breeding Bird Populations, Steven L. Harbron

Dissertations

The breeding bird populations of a 40.9 acre grassland-thicket, the Colony Farm Tract, Kalamazoo, Michigan, were studied over 18 years, from 1961-1979. The purpose of the study was to discover any variations in the avian populations that resulted from the construction of an adjacent residential development. Particular attention was directed toward establishing the kinds of relationships that existed between the breeding bird populations and the adjacent residential development.


Serum And Whole Blood Parameters Of Black Bears In The Great Smoky Mountains National Park, Diane Keiser Beeman Mar 1981

Serum And Whole Blood Parameters Of Black Bears In The Great Smoky Mountains National Park, Diane Keiser Beeman

Masters Theses

During the summers of 1974, 1975, and 1976, blood samples were taken from 124 black bears (Ursus americanus) captured in the Great Smoky Mountains National Park. Hematological data were collected on 96 individual bears and serum parameters on 124 bears.

Counts of red cells, white cells, and platelets were performed on whole blood as well as determinations of hemoglobin concentration and hematocrits. Corrected white cell counts, mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), and mean corpuscular hemoglobin concentration (MCHC) were calculated. Serum samples were analyzed for glucose, blood urea nitrogen (BUN), creatinine, sodium, potassium, chloride, carbon dioxide, uric acid, …


Benthic Insect Community Structure In Cumberland Mountain Streams Twenty-Five Years After Coal Strip Mining, Elizabeth B. Williams Mar 1981

Benthic Insect Community Structure In Cumberland Mountain Streams Twenty-Five Years After Coal Strip Mining, Elizabeth B. Williams

Masters Theses

In order to evaluate long-term impacts of coal strip mining on small stream benthic fauna in the Cumberland Mountains of east Tennessee, four streams, two in watersheds mined twenty-five years ago and two undisturbed, were sampled monthly for six months, January through June, 1979. Benthos was sampled by collecting eight Surber samples, each two ft.2 in area, from similar riffles in each stream. At the collection sites pH, dissolved o2, and velocity were measured. Water samples were analyzed in the laboratory for alkalinity and hardness (measured as mg/1 CaCO3) and dissolved Fe and SO4 …


A Survey Of The Mussels (Pelecypoda: Unionoidia: Unionacea) Of Twelvepole Creek, West Virginia With A Study Of Commensal Algae Found On Selected Mussels, Kevin Joe Smith Jan 1981

A Survey Of The Mussels (Pelecypoda: Unionoidia: Unionacea) Of Twelvepole Creek, West Virginia With A Study Of Commensal Algae Found On Selected Mussels, Kevin Joe Smith

Theses, Dissertations and Capstones

A survey of the Unionacea of Twelvepole Creek, West Virginia was conducted coupled with a qualitative study of commensal algae found on selected mussel species. The naiads and the algae were found to have diverse populations. Naiads collected during the survey were represented by 23 species, 16 genera and 2 families. Corbicula fluminea was found to be confined largely to the main branch of Twelvepole, with no individuals being collected from the East or West Forks and only limited collections near the mouth of Beechfork Creek. Lampsilis radiata luteola and L. ventricosa were found to have the greatest distribution, being …


The Naiads (Mollusca: Unionidae) From Two Prehistoric Sites Along The Ohio River, Mason County, West Virginia, Beverly Dawn Spurlock Jan 1981

The Naiads (Mollusca: Unionidae) From Two Prehistoric Sites Along The Ohio River, Mason County, West Virginia, Beverly Dawn Spurlock

Theses, Dissertations and Capstones

Archeological naiad valves representing 29 species were recovered from two Late Prehistoric Indian villages along the Ohio River, Mason County, West Virginia. Surface collections and limited excavation provided a total of 1,599 identifiable valves and valve fragments. Dif­ferences in species compositions and relative abundances between the two middens were noted. Samples from the Rolf Lee Farm Site (46MS51) contained 28 species while the Lewis-Old Town Farm Site (46MS57) produced only 23 species. Comparisons were made with other nearby prehistoric shell deposits and also with more recent twentieth century collections from this reach of the river. Nine of the archeological species …


Food Habits Of Largemouth Bass, Micropterus Salmoides (Lacepede) And Spotted Bass, Micropterus Punctulatus (Rafinesque), From Beech Fork Reservoir, A New Impoundment In Wayne And Cabell Counties, West Virginia, Michael A. Arcuri Jan 1981

Food Habits Of Largemouth Bass, Micropterus Salmoides (Lacepede) And Spotted Bass, Micropterus Punctulatus (Rafinesque), From Beech Fork Reservoir, A New Impoundment In Wayne And Cabell Counties, West Virginia, Michael A. Arcuri

Theses, Dissertations and Capstones

A study was undertaken to determine the food habits of two game fishes, the largemouth bass Micropterus salmoides (Lacepede) and the spotted bass M. punctulatus (Rafinesque) in Beech Fork Reservoir shortly after its impoundment. A total of 171 largemouth bass and 95 spotted bass were collected from July 1978, through June 1979, and their stomach contents analyzed.

Largemouth bass fed primarily on fishes, particularly young-of-the-year bluegill. Aquatic and terrestrial invertebrates were also important food items, especially during the spring and fall . The dominant aquatic forms were chironomid larvae and pupae while the dominant terrestrial forms were adult dipterans.

Spotted …


A Taxonomic Study Of The Symphitopsyche Pictet And Hydropsyche Ulmer Larvae Of West Virginia (Trichoptera: Hydropsychidae), Charlene Kay Nugen Jan 1981

A Taxonomic Study Of The Symphitopsyche Pictet And Hydropsyche Ulmer Larvae Of West Virginia (Trichoptera: Hydropsychidae), Charlene Kay Nugen

Theses, Dissertations and Capstones

A survey of the larval Symphitopsyche and Hydropsyche of West Virginia revealed fifteen species (S. morosa, S. walkeri, S. bronta, S. slossonae, S. macleodi, S. sparna, S. ventura, H. orris, H. phalerata, H. hoffmani, H. scalaris, H. leonardi, H. hageni, H. dicantha, H. simulans) eleven of which were state records (Table 1). Two species groups (S. bifida group, H. depravata group) were also found in the state possibly adding four more species (S. bifida, S.cheilonis, H. depravata,H. betteni) (Table 1). Hydropsyche phalerata, S. walkeri, and H. leonardi were the most scarce in the state and the H. depravata group had …


Correlation Of Hook-And-Line Vulnerability Of Largemouth Bass (Micropterus Salmoides) With Selected Physicochemical Parameters At Ridge Lake, Dale P. Burkett Jan 1981

Correlation Of Hook-And-Line Vulnerability Of Largemouth Bass (Micropterus Salmoides) With Selected Physicochemical Parameters At Ridge Lake, Dale P. Burkett

Masters Theses

Fluctuation in kilograms of largemouth bass caught per man-hour of fishing pressure (catch rate) in Ridge Lake (a 6.8ha impoundment located in Fox Ridge State Park, Coles County, Illinois) was positively correlated with dissolved oxygen concentration (r=0.7490), conductivity (r=0.7439), pH (r=0.5965), and alkalinity (r=0.7531). Negative correlations were found between largemouth bass catch rate and turbidity (r=-0.5145), as well as ammonia (r=-0.4694). No significant (p<0.05) correlations were found between catch rate and column water temperature, air temperature, barometric pressure, water level, maximum water temperature, minimum water temperature, maximum air temperature, or minimum air temperature.

Models describing the relationships of the most significant physicochemical parameters to catch rate of largemouth bass were chosen to represent the effects of environment …


The Foods And Associated Feeding Behavior Of The Yellow-Bellied Marmot, Marmota Flaviventris, Mark William Jonasson Jan 1981

The Foods And Associated Feeding Behavior Of The Yellow-Bellied Marmot, Marmota Flaviventris, Mark William Jonasson

Theses Digitization Project

No abstract provided.


Revetment Clearing, Its Influence On Riparian Mammal Communities, Robert E. Willis Jan 1981

Revetment Clearing, Its Influence On Riparian Mammal Communities, Robert E. Willis

Dissertations and Theses

Over 115 miles of rock revetment have been constructed in the Willamette Basin to protect river banks. This study examines the effect on riparian mammals of maintaining these revetments by vegetation and debris clearing. Differences between cleared and uncleared revetments were measured using a canopy coverage method of vegetation analysis; mammals were studied by trapping, by direct observation, and by noting such signs as scats, tracks, etc.


A Study Of Leslie Model Under Stochastic Environments, Kamran Shaukat Jan 1981

A Study Of Leslie Model Under Stochastic Environments, Kamran Shaukat

Dissertations and Theses

The prediction and analysis of changes in the numbers of biological populations rest on mathematical formulations of demographic events (births and deaths) classified by the age of individuals. The development of demographic theory when birth and death rates vary statistically over time is the central theme of this work. A study of the standard Leslie model for the demographic dynamics of populations in variable environments is made. At each time interval a Leslie matrix of survival rates and fertilities of a population is chosen according to a Markov process and the population numbers in different age classes are computed. Analytical …