Open Access. Powered by Scholars. Published by Universities.®

Ecology and Evolutionary Biology Commons

Open Access. Powered by Scholars. Published by Universities.®

Theses/Dissertations

Growth

Discipline
Institution
Publication Year
Publication

Articles 1 - 30 of 35

Full-Text Articles in Ecology and Evolutionary Biology

Individual And Population Responses To Hydrologic Variability In A Headwater Stream Salamander, Madaline Cochrane Jan 2023

Individual And Population Responses To Hydrologic Variability In A Headwater Stream Salamander, Madaline Cochrane

Graduate Student Theses, Dissertations, & Professional Papers

Understanding how organisms respond to environmental variability is a central goal in ecology – a goal made even more pressing by the herculean challenge global climate change presents to all organisms. Climate change is increasing the frequency and intensity of floods and droughts, which will likely have disproportionate effects on freshwater organisms. Many stream-associated species have multi-stage life histories. However, we lack an empirical understanding of life history and movement responses of these organisms to hydrologic disturbances, and how these responses may influence demographic rates. In my dissertation, I used a combination of growth, developmental, movement, and demographic data to …


Benthic Community Dynamics And Stony Coral Demographics In Florida In Relation To Acute Disturbances And Chronic Pressures, Nicholas P. Jones Aug 2022

Benthic Community Dynamics And Stony Coral Demographics In Florida In Relation To Acute Disturbances And Chronic Pressures, Nicholas P. Jones

All HCAS Student Capstones, Theses, and Dissertations

The persistence of coral reef communities is threatened by a suite of pressures operating at varying spatial and temporal scales. In general, acute disturbances (short term stochastic events such as marine heatwaves or hurricanes) and chronic pressures, such as ocean warming, have caused the most significant changes to stony coral assemblages (order Scleractinia) and continue to impair recovery potential. Additionally, many coral reefs are subject to local chronic anthropogenic pressures resulting in poor water quality or sedimentation, which further impact stony corals and shape benthic community structure, particularly near urbanized coastlines. For the viability of communities on coral reefs, a …


Thermal Ecophysiology Of Juvenile Anadromous River Herring, Lian W. Guo Feb 2022

Thermal Ecophysiology Of Juvenile Anadromous River Herring, Lian W. Guo

Doctoral Dissertations

Temperature controls the rate of all biochemical processes, and thus can significantly influence the physiology and ecology of all living organisms on earth. Understanding how temperature influences fitness can therefore provide insight into mechanisms affecting population size, dynamics, and geographic distributions, especially in the context of climate change. Early life stages of fishes experience significant selective pressure to grow large and accumulate energy reserves in order to avoid predation and starvation. Increasing temperatures will increase routine metabolic rates, which may result in less energy being available for growth and energy storage. In this thesis, I examine the effects of temperature, …


Effects Of Snake Fungal Disease On The Survival And Growth Of The Queensnake (Regina Septemvittata), Andrew Jerome Ibach Jan 2022

Effects Of Snake Fungal Disease On The Survival And Growth Of The Queensnake (Regina Septemvittata), Andrew Jerome Ibach

Theses and Dissertations--Forestry and Natural Resources

Having only emerged as a threat to snakes in 2006, relatively little is known of snake fungal disease’s (SFD) impacts on demographic processes, particularly survival and growth. I used data from an extensive capture-mark-recapture study to examine survival and growth in central Kentucky Queensnake (Regina septemivittata) populations. I found that diseased snakes and healthy snakes possessed similar monthly survival estimates (SFD positive 0.9687, 95% CI 0.8444 to 0.9944; SFD negative 0.8735, 95% CI 0.7518 to 0.9402) and that disease state transition probability from SFD negative to SFD positive, and SFD positive to SFD negative were also similar (N-P …


Smallmouth Bass (Micropterus Dolomieu) Population Characteristics And An Evaluation Of Management Responses In Two West Virginia Watersheds, Jacob D. Harrell Jan 2022

Smallmouth Bass (Micropterus Dolomieu) Population Characteristics And An Evaluation Of Management Responses In Two West Virginia Watersheds, Jacob D. Harrell

Graduate Theses, Dissertations, and Problem Reports

Smallmouth Bass (Micropterus dolomieu) population characteristics were examined within the Tygart and Cheat River watersheds of north-central West Virginia. Growth, mortality and recruitment were examined for each individual population prior to modeling potential effects of various management schemes. Smallmouth Bass were sampled for total length and weight, aged using sagittal otoliths and sexed through observations of gonadal or ovarian development. Growth for each population was examined using von Bertalanffy growth models and assessed for variation among populations. Population demographic characteristics differed between and among populations, most noticeably between riverine and lacustrine habitat, whereby growth, mortality and recruitment were higher …


Trophic Ecology Of Juvenile Lean And Siscowet Lake Trout (Salvelinus Namaychush) From U.S. Waters Of Lake Superior, Will Otte Dec 2021

Trophic Ecology Of Juvenile Lean And Siscowet Lake Trout (Salvelinus Namaychush) From U.S. Waters Of Lake Superior, Will Otte

All NMU Master's Theses

In this study, I investigated the spatial overlap, diet similarity, and isotopic niches of juvenile Lean and Siscowet Lake Trout ecotypes across six ecoregions of Lake Superior. Spatially, Lean and Siscowet were observed in overlapping depth distributions. Leans were most abundant in shallow waters (60m). The greatest levels of cohabitation were observed in waters from 40-60m. Trophic position (as measured by δ 15N) was similar for both ecotypes at small sizes (mm), but Siscowet exhibited a higher trophic position than Lean Lake Trout at larger sizes (>400mm) and older ages (>5 years). Base of production (as measured by …


Smallmouth Bass Feeding Dynamics And Growth In Headwater Streams Of The Interior Highlands, Brandon C. Plunkett May 2021

Smallmouth Bass Feeding Dynamics And Growth In Headwater Streams Of The Interior Highlands, Brandon C. Plunkett

ATU Theses and Dissertations 2021 - Present

Smallmouth Bass have been extensively studied, but knowledge of the effects of temperature and hydrologic regime on populations in the Interior Highlands of Arkansas remains lacking. In 2018, I monitored diet characteristics of Smallmouth Bass, located in streams prone to dryness and representing a range of water temperatures, and presence of potential competitors. Diet characteristics of Smallmouth Bass, Green Sunfish, and Creek Chub were studied in the Boston Mountains ecoregion of Arkansas during the summer of 2018. In 2019, I expanded the scope of the project to search for relationships between Smallmouth Bass growth and hydrologic regime. My objectives were …


An Invasive Species As A Threat To Native Biodiversity: Larval Competition Between Native Anurans And An Invasive Treefrog, Mckenzie Wasley Dec 2020

An Invasive Species As A Threat To Native Biodiversity: Larval Competition Between Native Anurans And An Invasive Treefrog, Mckenzie Wasley

Electronic Theses and Dissertations

Cuban Treefrogs (Osteopilus septentrionalis) are established in Florida and Louisiana and have invasive potential further westward, possibly impacting native anurans at multiple life stages. In anurans, competition at the larval stage can decrease adult fitness through slower development and smaller size at metamorphosis, ultimately decreasing recruitment rates. To examine the potential impacts of O. septentrionalis at the larval life-history stage, I quantified activity levels and growth of their tadpoles and those of two anurans native to eastern Texas: Green Treefrogs (Hyla cinerea) and Gulf Coast Toads (Incilius nebulifer). Tadpoles of the three species were …


Pismo Clams (Tivela Stultorum) In Califorina: Population Status, Habitat Associations, Reproduction, And Growth, Alexandria R. Marquardt May 2020

Pismo Clams (Tivela Stultorum) In Califorina: Population Status, Habitat Associations, Reproduction, And Growth, Alexandria R. Marquardt

Master's Theses

Marine shellfish play a vital role in intertidal ecosystems and coastal communities, but many of these fisheries are small-scale and lack the necessary monitoring to ensure long-term sustainability. Effective management often requires information on key demographic parameters, such as population status, reproduction and growth. Pismo clams (Tivela stultorum) are a culturally important and iconic species in California, which supported a thriving commercial and recreational fishery throughout much of the 1900’s. However, Pismo clam populations have declined statewide in recent decades and are attributed to human harvest and predation by California sea otters (Enhydra lutris); However, no …


Population Demographics Of Silver Carp Hypophthalmichthys Molitrix In Kentucky Lake, Allison M. Lebeda Jan 2020

Population Demographics Of Silver Carp Hypophthalmichthys Molitrix In Kentucky Lake, Allison M. Lebeda

Murray State Theses and Dissertations

Invasive species continue to threaten aquatic ecosystems in the United States. Silver Carp Hypophthalmichthys molitrix have successfully infiltrated much of the Mississippi River Basin, including Kentucky Lake – a large reservoir located on the Tennessee River in Western Kentucky. Although Silver Carp have been present in Kentucky Lake for at least a decade, until recently, very little was known about the population, how often successful reproduction is occurring, or the environmental conditions that facilitate strong year-classes. Hence, it is difficult for managers to predict the potential impact of Silver Carp on native species. Silver Carp were collected from Kentucky Lake …


The Effects Of Boring Sponge Infestation On Condition, Growth, And Sex Change In Crepidula Fornicata, Nicole L. Kleinas Jan 2020

The Effects Of Boring Sponge Infestation On Condition, Growth, And Sex Change In Crepidula Fornicata, Nicole L. Kleinas

Electronic Theses and Dissertations

The Atlantic slipper limpet, Crepidula fornicata, is a sequential hermaphrodite whose size at sex-change is plastic with respect to social and population cues. As an organism allocates energy between growth, reproduction and maintenance, an increased cost of one process may affect another. In this paper, I evaluate whether the presence of an epibiotic sponge (Cliona celata) affects the growth, condition and sex-change of C. fornicata individuals. Population surveys demonstrate a variable effect of Cliona presence on C. fornicata condition. The results of a twelve-week in situ experiment demonstrated a decrease in growth when C. celata was present. …


Pre-Juvenile Naked Goby (Gobiosoma Bosc) Age And Growth, Annamaria Deitz, Juliana Harding Dec 2019

Pre-Juvenile Naked Goby (Gobiosoma Bosc) Age And Growth, Annamaria Deitz, Juliana Harding

Honors Theses

Due to the abundance of larval naked gobies, Gobiosoma bosc, within the estuarine ichthyoplankton, it is important to understand their age and growth. Naked gobies are a largely distributed, both geographically and within an estuary, small, benthic fish species. There are 3 pairs of otoliths, calcium carbonate structures within the ear canal, that detect vibrations and record the age of the fish, both daily and annually. Using laboratory-reared gobies of a known age (Tremont et al. 2015), daily signatures on the sagittal otoliths were first validated to be daily, then a growth curve for the wild caught larvae was …


Growth And Survival Of Wild And Head-Started Blanding’S Turtles (Emydoidea Blandingii), Callie Klatt Golba Jan 2019

Growth And Survival Of Wild And Head-Started Blanding’S Turtles (Emydoidea Blandingii), Callie Klatt Golba

Graduate Research Theses & Dissertations

Blanding’s Turtles (IUCN Endangered) are long-lived reptiles with delayed sexual maturity. Anthropogenic landscape changes have increased threats to juvenile turtles, resulting in unnaturally low recruitment. Head-starting has become a popular conservation strategy that aims to increase juvenile recruitment by avoiding the increased predation of the vulnerable nest and hatchling age-class. However, there is still debate about whether or not it is an effective management tool. Assessments of head-starting are becoming more prevalent, but long-term studies are needed to critically evaluate the success of such interventions. In particular, information is needed on how head-starts fare compared to wild-born turtles. The Lake …


Causes And Possible Consequences Of Hybridisation In Angelfishes At Christmas Island, Federico Vitelli Jan 2019

Causes And Possible Consequences Of Hybridisation In Angelfishes At Christmas Island, Federico Vitelli

Theses: Doctorates and Masters

The angelfishes (family Pomacanthidae) have the greatest proportion (~30%) of hybridising species, compared to other families of reef fishes, with 26 species implicated in hybridisation. However, very little is known about hybridisation in angelfish, especially in terms of fitness of the hybrids and possible ecological consequences. Hybrids between three species (C. flavissima, C. eibli and C. vroliki) in the genus Centropyge have previously been reported from Christmas island, where these have been observed in heterospecific harems and interbreeding. This provides the unique opportunity to examine the breakdown in assortative mating in marine fishes. The broad aim of this …


The Effect Of Shelter Availability On Foraging In Atlantic Salmon (Salmo Salar), Christian A. Therrien Sep 2018

The Effect Of Shelter Availability On Foraging In Atlantic Salmon (Salmo Salar), Christian A. Therrien

Electronic Thesis and Dissertation Repository

Shelter is an environmental feature that provides protection from danger and its use is an important anti-predator behavior for juvenile Atlantic salmon (Salmo salar). However, how shelter availability influences the foraging of these fish in the wild is not well documented. I predicted that juvenile Atlantic salmon would alter their foraging behavior in a low shelter environment and that this effect would differ between individuals from two populations that are targeted for reintroduction into Lake Ontario. I measured the foraging activity of juvenile Atlantic salmon from the two populations while they were held in pens in a Lake …


Analysis Of Temperature And Salinity Effects On Growth And Mortality Of Oysters (Crassostrea Virginica) In Louisiana, Troy Sehlinger Aug 2018

Analysis Of Temperature And Salinity Effects On Growth And Mortality Of Oysters (Crassostrea Virginica) In Louisiana, Troy Sehlinger

University of New Orleans Theses and Dissertations

Salinity (S) and temperature (T) control every facet of the eastern oyster (Crassostrea virginica) life cycle, principally reproduction, development, growth, and mortality. Previous studies conducted in in the Breton Sound (BR) and Barataria (BA) estuaries have reported differences in growth and mortality rates between the basins. In the present study, environmental conditions were synchronized to compare growth and mortality rates between basins at similar combinations of T and S. Results indicate that when T and S are the same (synchronized), seasonal oyster growth and mortality rates differ between BR and BA. Seasonal analyses revealed that as salinities increased …


Sensitivity Of Quagga Mussels (Dreissena Rostriformis Bugensis) To Cyanobacteria At Multiple Life History Stages, Anna Boegehold Jan 2018

Sensitivity Of Quagga Mussels (Dreissena Rostriformis Bugensis) To Cyanobacteria At Multiple Life History Stages, Anna Boegehold

Wayne State University Dissertations

Quagga mussels (Dreissena rostriformis bugensis) originate from brackish waters of the Ponto-Caspian area and are nuisance invasive species in North American and European freshwaters. Their invasion has caused major economic and ecological damages in the Laurentian Great Lakes. Through selective filter feeding, quagga mussels have promoted the growth of cyanobacteria. Harmful cyanobacteria blooms have the potential to produce toxins, which can be toxic to humans and wildlife. Although quagga mussels can increase the prevalence of cyanobacteria blooms, it is unknown how they are physiologically affected by cyanobacteria and understanding these dynamics can be useful in the management of this invasive …


Evidence Of Multidecadal Recruitment In The Ocean Quahog, Arctica Islandica In The Western Atlantic Ocean, Sara M. Pace Aug 2017

Evidence Of Multidecadal Recruitment In The Ocean Quahog, Arctica Islandica In The Western Atlantic Ocean, Sara M. Pace

Master's Theses

Ocean quahogs (Arctica islandica) are the longest-lived, non-colonial animals known today, with a maximum life span exceeding 500 years. Limited information is available regarding recruitment, making the sustainable management of this valuable fishery a challenge. The objective of this research was to describe the age structure and growth rates for four populations of ocean quahogs from the mid-Atlantic stock to evaluate long-term recruitment trends. Clams were sectioned for age estimation to develop population age frequencies. Initial colonization began approximately 175-250 years ago depending upon site. All sites experienced an increase in recruitment beginning in the late 1800’s to …


Beyond Age And Stage: Consequences Of Individual Variation In Demographic Traits, Erin Elizabeth Feichtinger Jul 2017

Beyond Age And Stage: Consequences Of Individual Variation In Demographic Traits, Erin Elizabeth Feichtinger

USF Tampa Graduate Theses and Dissertations

Within natural populations, individuals vary in their propensity to grow, survive and produce offspring. Additionally, fates of individuals are often correlated and non-independent as a result of shared genes, rearing environment or both. Variation in demographic traits can change population dynamics over time. The effects of variation in individual growth rate on population growth rate, net reproductive rate and generation time are examined, along with quantifying the sources of variation in survival of a long-lived cooperatively breeding bird, the Florida Scrub-Jay (Aphelocoma coerulescens). I built a 2 stage population model with two growth phenotypes, fast and slow, and …


Effects Of Wildfires On Rattlesnake (Crotalus Oreganus) Growth And Movement In Washington State, Joseph Chase Jan 2017

Effects Of Wildfires On Rattlesnake (Crotalus Oreganus) Growth And Movement In Washington State, Joseph Chase

All Master's Theses

Fire is a dominant force in the Pacific Northwest that shapes ecosystems and influences wildlife, yet little is known of its effects on local predators. Northern Pacific rattlesnakes (Crotalus oreganus) comprise an excellent model to investigate how fire may influence wildlife because they are important predators that contribute to controlling prey populations, but are also unable to readily escape from wildfires. We developed a novel technique to assess growth rates of rattlesnakes by using digital photography to analyze differences in widths of their rattle segments laid down over time. We compared growth rates of rattlesnakes in habitats that …


Effects Of A Large-Scale Habitat Enhancement Project On Largemouth Bass Behavior, Feeding, And Growth In Grand Lake, Texas, Chance Kirkeeng Jan 2017

Effects Of A Large-Scale Habitat Enhancement Project On Largemouth Bass Behavior, Feeding, And Growth In Grand Lake, Texas, Chance Kirkeeng

Electronic Theses and Dissertations

The quality of habitat, or the environment suitable for an organism to survive and reproduce, is often described by the type of features present and the quantity and condition of such features. Habitats in many ecosystems are declining and the loss of important habitats likely affects the success of organisms reliant upon those features. Habitats in reservoir ecosystems are especially at risk because of aging processes that are degrading reservoir habitats at faster rates than habitats in other ecosystems. Habitat enhancement projects are one tool used to combat the effects of aging reservoirs but the benefits of these management actions …


Assessment Of A Hatchery Based Rainbow Smelt Supplementation Effort, Andrew O'Malley May 2016

Assessment Of A Hatchery Based Rainbow Smelt Supplementation Effort, Andrew O'Malley

Electronic Theses and Dissertations

Rainbow Smelt (Osmerus mordax) are an important fish distributed throughout northeastern North America with both anadromous and landlocked populations. Abundance, size at age, and maximum size vary widely among populations and life histories. In order to compare anadromous and landlocked populations, we collected spawning adults in 2014 from four anadromous and three landlocked populations. Scales and otoliths from the anadromous fish were examined and compared for estimates of bias and precision in ageing. Analysis of both scales and otoliths provided age estimates that were acceptable, but estimates from scales were more precise and had less bias. Otoliths were …


An Investigation Of Juvenile Alewife (Alosa Pseudoharengus) Habitat Use And Growth Using Natural Markers, Gregory Norman Labonte Ms Jan 2016

An Investigation Of Juvenile Alewife (Alosa Pseudoharengus) Habitat Use And Growth Using Natural Markers, Gregory Norman Labonte Ms

All Student Scholarship

This research attempts to connect patterns in growth and migration of an anadromous species. The goal of this research was to understand habitat movements and growth of juvenile alewives (Alosa pseudoharengus) in the Penobscot Estuary and Bay through the use of otolith microchemistry, otolith growth increments, and a laboratory stable isotope turnover study. Understanding the connection between growth and movement of juvenile alewives may lead to more accurate and sophisticated conservation and restoration methods for anadromous species.


Application Of Otolith Increment Analysis To The Study Of Maturation Timing In Female Kokanee Salmon, Yelin Xu Dec 2014

Application Of Otolith Increment Analysis To The Study Of Maturation Timing In Female Kokanee Salmon, Yelin Xu

Electronic Thesis and Dissertation Repository

I investigated the influence of growth history on the expression of female reproductive tactics in kokanee salmon (Oncorhynchus nerka) from Meadow Creek Spawning Channel, British Columbia, Canada. Female kokanee either arrive at the spawning area with red nuptial coloration, or less commonly, sexually immature with silver coloration. Silver- and red-arriving females may reflect different reproductive strategies in the population. I used otolith increment measurements to determine fish growth. In contrast to earlier studies, silver- and red-arriving females in 2013 did not differ in age at maturity (mostly were age 3+) or size at maturity (length from eye to …


Activated Carbon Decreases Invasive Plant Growth By Mediating Plant-Microbe Interactions, Nicole E. Nolan May 2014

Activated Carbon Decreases Invasive Plant Growth By Mediating Plant-Microbe Interactions, Nicole E. Nolan

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

To restore lands invaded by dense, non-native vegetation, it may be necessary to develop targeted restoration tools than can remove the mechanism used by these non-native species as a competitive advantage. Activated carbon (AC) is one such tool, with the ability to disrupt the mechanisms of plant to plant communication (allelopathy) and positive plant to microbe communication commonly used by non-native species. Previous studies have shown the success of high concentrations, 1000g/m2, of AC in native plant community restoration on a small scale. Here, our goals are twofold: first, to test AC effectiveness in restoring desirable plant communities …


Understanding Basin Specific Life History Characteristics Of Lake Mead Quagga Mussels (Dreissena Bugensis) And A Potential Treatment Using Uv Radiation In Laboratory Studies, Melissa Thaw Aug 2013

Understanding Basin Specific Life History Characteristics Of Lake Mead Quagga Mussels (Dreissena Bugensis) And A Potential Treatment Using Uv Radiation In Laboratory Studies, Melissa Thaw

UNLV Theses, Dissertations, Professional Papers, and Capstones

The quagga mussel (Dreissena bugensis) is an aquatic invasive species that is spreading throughout Lake Mead and other western waterways. Unlike their native waters in Eurasia, Lake Mead exhibits year round warm temperatures, high calcium levels and a lack of natural predators, all of which are very favorable conditions for their growth and spread. Dreissena bugensis reproduce and colonize hard surfaces rapidly, where they filter large amounts of water. They disrupt the aquatic food chain and interfere with infrastructure that is exposed to lake water. There is an urgent need to understand Dreissena bugensis life history characteristics within this new …


Brody-Bertalanffy Growth Curves From Tag And Recapture Studies On Cabezon (Scorpaenichthys Marmoratus) And Gopher Rockfish (Sebastes Carnatus) Of The Central Coast, Christie Yorke Dec 2011

Brody-Bertalanffy Growth Curves From Tag And Recapture Studies On Cabezon (Scorpaenichthys Marmoratus) And Gopher Rockfish (Sebastes Carnatus) Of The Central Coast, Christie Yorke

Biological Sciences

No abstract provided.


Comparative Ecology Of Narrowly Sympatric Horned Lizards Under Variable Climatic Conditions, Kevin V. Young May 2010

Comparative Ecology Of Narrowly Sympatric Horned Lizards Under Variable Climatic Conditions, Kevin V. Young

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

We studied the Flat-tailed Horned Lizard, Phrynosoma mcallii, and the Sonoran Horned Lizard, P. goodei, in an area of narrow sympatry near Yuma, Arizona, and found they overlapped broadly in use of available food resources, body size, and growth rates. We compared diet (Chapter 2), growth and reproduction (Chapter 3), and survivorship (Chapter 4) of P. mcallii and P. goodei during two years of drought followed by a year of higher-than-average rainfall. We predicted that P. mcallii would be more tolerant of drought conditions than its congener, since P. mcalliiis found only in an extremely arid region while …


Growth And Water Relations Of Native Wheatgrass Populations, Brian P. Bell May 2008

Growth And Water Relations Of Native Wheatgrass Populations, Brian P. Bell

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Screening populations for development into released plant materials can be done inexpensively and in a timely manner. A common approach has been to quantify the amount of shoot dry mass produced as a surrogate for competitiveness. Besides dry mass production , other morphological characteristics have been employed , but physiological parameters have received less emphasis. Dry mass production may be an important characteristic, but identifying the traits responsible can be just as imperative . Populations with greater drought tolerance may be less impacted by competition for water from weeds, which could lead to greater establishment of desirable grasses on disturbed …


Examination Of The Ecological Differences Between Two Closely Related Endemic Whitefish In Relation To Growth Conditions And Predation Risk, Benjamen M. Kennedy May 2005

Examination Of The Ecological Differences Between Two Closely Related Endemic Whitefish In Relation To Growth Conditions And Predation Risk, Benjamen M. Kennedy

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Benthic Bear Lake whitefish (Prosopium abyssicola) and Bonneville whitefish (P. spilontus) are closely related, yet the extent of ecological separation remains poorly understood. We described their spring and summer distribution and diet in Bear Lake and examined how these were related to environmental growth conditions, and predation risk. In spring and summer, Bonneville whitefish dominated shallower depths (5-30 m), whereas Bear Lake whitefish dominated deeper depths (45-55 m). At intermediate depths (35-40 m), low numbers of both species occurred. Bonneville whitefish ate mostly Chironomidae, whereas Bear Lake whitefish ate mostly Ostracoda. Habitats occupied by Bonneville whitefish …