Density independent and density dependent factors can limit population growth. Density independent factors like natural disasters, temperature, sunlight and human activities affect populations regardless of density. Density dependent factors like competition, predation, disease and crowding only impact populations at high densities. For example, yellow perch populations in Lake Winnipeg are limited by density independent factors like drought, which could lower water levels and temperatures, as well as density dependent factors like predation from northern pike and walleye when populations are high.
Community ecology, study of the organization and functioning of communities, which are assemblages of interacting populations of the species living within a particular area or habitat.
Temperature – limiting factor [autosaved] newSumer Pankaj
Temperature is the degree or the intensity of heatness or coldness of any object surroundings or organism and it plays a major role in development and growth of organisms in various ways like affect on metabolism, reproduction, sex ratio, morphology etc. Some organisms are adapted to extreme high temperatures and extreme low temperatures, which make them to sustain their life easily. There are many ways by which organisms can sustain themselves in these areas like occurrence of hibernation, activation, morphological and physiological changes etc. Though organisms have made their lives very much easier, temperature plays a major role in their growth and development.
Energy Flow in Environment : Ecological EnergeticsKamlesh Patel
What is Energy:
The ability or capacity to do work,
Radiant, Chemical, thermal, mechanical, nuclear, electrical.
What is Energy Flow:
The existence of flora and fauna in ecosystem depends upon the cycle of minerals and flow of energy. Energy is needed for all the biotic activities. The only source of this energy is the sun. The entrance, transformation and diffusion of energy in ecosystem are governed by laws of thermodynamics.
There are two laws of thermodynamics. On the other hand in our universe sun is the source of energy. Green plants are the only producer. Plants make their own food by sunlight with the help of water and carbon dioxide. Other animals get energy by consuming green plants, plant products and other animals. Hence the energy is cycle. So the ecosystem proves the two laws of thermodynamics.
Ecological Succession is the process of change in the species structure of an ecological community over a period of time.
But, over a long period of time, the climate conditions of an ecosystem is bound to change.
No ecosystem has existed or will remain unchanged over a Geological Time Scale.
Community ecology, study of the organization and functioning of communities, which are assemblages of interacting populations of the species living within a particular area or habitat.
Temperature – limiting factor [autosaved] newSumer Pankaj
Temperature is the degree or the intensity of heatness or coldness of any object surroundings or organism and it plays a major role in development and growth of organisms in various ways like affect on metabolism, reproduction, sex ratio, morphology etc. Some organisms are adapted to extreme high temperatures and extreme low temperatures, which make them to sustain their life easily. There are many ways by which organisms can sustain themselves in these areas like occurrence of hibernation, activation, morphological and physiological changes etc. Though organisms have made their lives very much easier, temperature plays a major role in their growth and development.
Energy Flow in Environment : Ecological EnergeticsKamlesh Patel
What is Energy:
The ability or capacity to do work,
Radiant, Chemical, thermal, mechanical, nuclear, electrical.
What is Energy Flow:
The existence of flora and fauna in ecosystem depends upon the cycle of minerals and flow of energy. Energy is needed for all the biotic activities. The only source of this energy is the sun. The entrance, transformation and diffusion of energy in ecosystem are governed by laws of thermodynamics.
There are two laws of thermodynamics. On the other hand in our universe sun is the source of energy. Green plants are the only producer. Plants make their own food by sunlight with the help of water and carbon dioxide. Other animals get energy by consuming green plants, plant products and other animals. Hence the energy is cycle. So the ecosystem proves the two laws of thermodynamics.
Ecological Succession is the process of change in the species structure of an ecological community over a period of time.
But, over a long period of time, the climate conditions of an ecosystem is bound to change.
No ecosystem has existed or will remain unchanged over a Geological Time Scale.
This PowerPoint was one very small part of my Ecology Interactions Unit from the website http://sciencepowerpoint.com/index.html .This unit includes a 3 part 2000+ Slide PowerPoint loaded with activities, project ideas, critical class notes (red slides), review opportunities, challenge questions with answers, 3 PowerPoint review games (125 slides each) and much more. A bundled homework package and detailed unit notes chronologically follow the PowerPoint slideshow.
Areas of Focus within The Ecology Interactions Unit: Levels of Biological Organization (Ecology), Parts of the Biosphere, Habitat, Ecological Niche, Types of Competition, Competitive Exclusion Theory, Animal Interactions, Food Webs, Predator Prey Relationships, Camouflage, Population Sampling, Abundance, Relative Abundance, Diversity, Mimicry, Batesian Mimicry, Mullerian Mimicry, Symbiosis, Parasitism, Mutualism, Commensalism, Plant and Animal Interactions, Coevolution, Animal Strategies to Eat Plants, Plant Defense Mechanisms, Exotic Species, Impacts of Invasive Exotic Species.
If you have any questions please feel free to contact me. Thank you again and best wishes.
Sincerely,
Ryan Murphy M.Ed
www.sciencepowerpoint@gmail.com
By Aditya Sood and Vladimir Smakhtin. Presented at the "Water in the Anthropocene: Challenges for Science and Governance. Indicators, Thresholds and Uncertainties of the Global Water System" conference in Bonn, Germany May 2013.
Presentation about ecological footprint, and the biospherical limits in the frame of the summer course "Social Nestworks: Globalization and inequality" hosted by the University of León (Spain)
Slides of talk presented at various forums on occasion of the 40th anniversary of the launching of Limits to Growth, the first report to the Club of Rome published in 1972. This book was one of the earliest scholarly works to recognize that the world was fast approaching its sustainable limits. Forty years later, the planet continues to face many of the same economic, social, and environmental challenges as when the book was first published.
Climate change and biodiversity are closely linked: climate change has severe direct and indirect impacts on biodiversity and is predicted to be a dominant driver of future biodiversity loss; at the same time, the loss of biodiversity magnifies the adverse effects of climate change.
This presentation elaborates the economic crisis in Sri Lanka. It explains the causes of economic instability in Sri Lanka and the factors worsening it. Such miserable economic situation is presenting valuable lessons for other sister asian countries to counter their economic instability. Pakistan, a sister country of Sri Lanka is facing severe political and economic instability these days. Pakistan is learning from the Sri Lankan economic situation and tending to improve its economy but the extreme political instability is hurdling and exacerbating the economic crisis. However, policies are underway to counter the economic crisis and more probably Pakistan will escape the Sri Lankan experience.
Nutraceutical market, scope and growth: Herbal drug technologyLokesh Patil
As consumer awareness of health and wellness rises, the nutraceutical market—which includes goods like functional meals, drinks, and dietary supplements that provide health advantages beyond basic nutrition—is growing significantly. As healthcare expenses rise, the population ages, and people want natural and preventative health solutions more and more, this industry is increasing quickly. Further driving market expansion are product formulation innovations and the use of cutting-edge technology for customized nutrition. With its worldwide reach, the nutraceutical industry is expected to keep growing and provide significant chances for research and investment in a number of categories, including vitamins, minerals, probiotics, and herbal supplements.
Introduction:
RNA interference (RNAi) or Post-Transcriptional Gene Silencing (PTGS) is an important biological process for modulating eukaryotic gene expression.
It is highly conserved process of posttranscriptional gene silencing by which double stranded RNA (dsRNA) causes sequence-specific degradation of mRNA sequences.
dsRNA-induced gene silencing (RNAi) is reported in a wide range of eukaryotes ranging from worms, insects, mammals and plants.
This process mediates resistance to both endogenous parasitic and exogenous pathogenic nucleic acids, and regulates the expression of protein-coding genes.
What are small ncRNAs?
micro RNA (miRNA)
short interfering RNA (siRNA)
Properties of small non-coding RNA:
Involved in silencing mRNA transcripts.
Called “small” because they are usually only about 21-24 nucleotides long.
Synthesized by first cutting up longer precursor sequences (like the 61nt one that Lee discovered).
Silence an mRNA by base pairing with some sequence on the mRNA.
Discovery of siRNA?
The first small RNA:
In 1993 Rosalind Lee (Victor Ambros lab) was studying a non- coding gene in C. elegans, lin-4, that was involved in silencing of another gene, lin-14, at the appropriate time in the
development of the worm C. elegans.
Two small transcripts of lin-4 (22nt and 61nt) were found to be complementary to a sequence in the 3' UTR of lin-14.
Because lin-4 encoded no protein, she deduced that it must be these transcripts that are causing the silencing by RNA-RNA interactions.
Types of RNAi ( non coding RNA)
MiRNA
Length (23-25 nt)
Trans acting
Binds with target MRNA in mismatch
Translation inhibition
Si RNA
Length 21 nt.
Cis acting
Bind with target Mrna in perfect complementary sequence
Piwi-RNA
Length ; 25 to 36 nt.
Expressed in Germ Cells
Regulates trnasposomes activity
MECHANISM OF RNAI:
First the double-stranded RNA teams up with a protein complex named Dicer, which cuts the long RNA into short pieces.
Then another protein complex called RISC (RNA-induced silencing complex) discards one of the two RNA strands.
The RISC-docked, single-stranded RNA then pairs with the homologous mRNA and destroys it.
THE RISC COMPLEX:
RISC is large(>500kD) RNA multi- protein Binding complex which triggers MRNA degradation in response to MRNA
Unwinding of double stranded Si RNA by ATP independent Helicase
Active component of RISC is Ago proteins( ENDONUCLEASE) which cleave target MRNA.
DICER: endonuclease (RNase Family III)
Argonaute: Central Component of the RNA-Induced Silencing Complex (RISC)
One strand of the dsRNA produced by Dicer is retained in the RISC complex in association with Argonaute
ARGONAUTE PROTEIN :
1.PAZ(PIWI/Argonaute/ Zwille)- Recognition of target MRNA
2.PIWI (p-element induced wimpy Testis)- breaks Phosphodiester bond of mRNA.)RNAse H activity.
MiRNA:
The Double-stranded RNAs are naturally produced in eukaryotic cells during development, and they have a key role in regulating gene expression .
THE IMPORTANCE OF MARTIAN ATMOSPHERE SAMPLE RETURN.Sérgio Sacani
The return of a sample of near-surface atmosphere from Mars would facilitate answers to several first-order science questions surrounding the formation and evolution of the planet. One of the important aspects of terrestrial planet formation in general is the role that primary atmospheres played in influencing the chemistry and structure of the planets and their antecedents. Studies of the martian atmosphere can be used to investigate the role of a primary atmosphere in its history. Atmosphere samples would also inform our understanding of the near-surface chemistry of the planet, and ultimately the prospects for life. High-precision isotopic analyses of constituent gases are needed to address these questions, requiring that the analyses are made on returned samples rather than in situ.
Richard's aventures in two entangled wonderlandsRichard Gill
Since the loophole-free Bell experiments of 2020 and the Nobel prizes in physics of 2022, critics of Bell's work have retreated to the fortress of super-determinism. Now, super-determinism is a derogatory word - it just means "determinism". Palmer, Hance and Hossenfelder argue that quantum mechanics and determinism are not incompatible, using a sophisticated mathematical construction based on a subtle thinning of allowed states and measurements in quantum mechanics, such that what is left appears to make Bell's argument fail, without altering the empirical predictions of quantum mechanics. I think however that it is a smoke screen, and the slogan "lost in math" comes to my mind. I will discuss some other recent disproofs of Bell's theorem using the language of causality based on causal graphs. Causal thinking is also central to law and justice. I will mention surprising connections to my work on serial killer nurse cases, in particular the Dutch case of Lucia de Berk and the current UK case of Lucy Letby.
(May 29th, 2024) Advancements in Intravital Microscopy- Insights for Preclini...Scintica Instrumentation
Intravital microscopy (IVM) is a powerful tool utilized to study cellular behavior over time and space in vivo. Much of our understanding of cell biology has been accomplished using various in vitro and ex vivo methods; however, these studies do not necessarily reflect the natural dynamics of biological processes. Unlike traditional cell culture or fixed tissue imaging, IVM allows for the ultra-fast high-resolution imaging of cellular processes over time and space and were studied in its natural environment. Real-time visualization of biological processes in the context of an intact organism helps maintain physiological relevance and provide insights into the progression of disease, response to treatments or developmental processes.
In this webinar we give an overview of advanced applications of the IVM system in preclinical research. IVIM technology is a provider of all-in-one intravital microscopy systems and solutions optimized for in vivo imaging of live animal models at sub-micron resolution. The system’s unique features and user-friendly software enables researchers to probe fast dynamic biological processes such as immune cell tracking, cell-cell interaction as well as vascularization and tumor metastasis with exceptional detail. This webinar will also give an overview of IVM being utilized in drug development, offering a view into the intricate interaction between drugs/nanoparticles and tissues in vivo and allows for the evaluation of therapeutic intervention in a variety of tissues and organs. This interdisciplinary collaboration continues to drive the advancements of novel therapeutic strategies.
Observation of Io’s Resurfacing via Plume Deposition Using Ground-based Adapt...Sérgio Sacani
Since volcanic activity was first discovered on Io from Voyager images in 1979, changes
on Io’s surface have been monitored from both spacecraft and ground-based telescopes.
Here, we present the highest spatial resolution images of Io ever obtained from a groundbased telescope. These images, acquired by the SHARK-VIS instrument on the Large
Binocular Telescope, show evidence of a major resurfacing event on Io’s trailing hemisphere. When compared to the most recent spacecraft images, the SHARK-VIS images
show that a plume deposit from a powerful eruption at Pillan Patera has covered part
of the long-lived Pele plume deposit. Although this type of resurfacing event may be common on Io, few have been detected due to the rarity of spacecraft visits and the previously low spatial resolution available from Earth-based telescopes. The SHARK-VIS instrument ushers in a new era of high resolution imaging of Io’s surface using adaptive
optics at visible wavelengths.
Slide 1: Title Slide
Extrachromosomal Inheritance
Slide 2: Introduction to Extrachromosomal Inheritance
Definition: Extrachromosomal inheritance refers to the transmission of genetic material that is not found within the nucleus.
Key Components: Involves genes located in mitochondria, chloroplasts, and plasmids.
Slide 3: Mitochondrial Inheritance
Mitochondria: Organelles responsible for energy production.
Mitochondrial DNA (mtDNA): Circular DNA molecule found in mitochondria.
Inheritance Pattern: Maternally inherited, meaning it is passed from mothers to all their offspring.
Diseases: Examples include Leber’s hereditary optic neuropathy (LHON) and mitochondrial myopathy.
Slide 4: Chloroplast Inheritance
Chloroplasts: Organelles responsible for photosynthesis in plants.
Chloroplast DNA (cpDNA): Circular DNA molecule found in chloroplasts.
Inheritance Pattern: Often maternally inherited in most plants, but can vary in some species.
Examples: Variegation in plants, where leaf color patterns are determined by chloroplast DNA.
Slide 5: Plasmid Inheritance
Plasmids: Small, circular DNA molecules found in bacteria and some eukaryotes.
Features: Can carry antibiotic resistance genes and can be transferred between cells through processes like conjugation.
Significance: Important in biotechnology for gene cloning and genetic engineering.
Slide 6: Mechanisms of Extrachromosomal Inheritance
Non-Mendelian Patterns: Do not follow Mendel’s laws of inheritance.
Cytoplasmic Segregation: During cell division, organelles like mitochondria and chloroplasts are randomly distributed to daughter cells.
Heteroplasmy: Presence of more than one type of organellar genome within a cell, leading to variation in expression.
Slide 7: Examples of Extrachromosomal Inheritance
Four O’clock Plant (Mirabilis jalapa): Shows variegated leaves due to different cpDNA in leaf cells.
Petite Mutants in Yeast: Result from mutations in mitochondrial DNA affecting respiration.
Slide 8: Importance of Extrachromosomal Inheritance
Evolution: Provides insight into the evolution of eukaryotic cells.
Medicine: Understanding mitochondrial inheritance helps in diagnosing and treating mitochondrial diseases.
Agriculture: Chloroplast inheritance can be used in plant breeding and genetic modification.
Slide 9: Recent Research and Advances
Gene Editing: Techniques like CRISPR-Cas9 are being used to edit mitochondrial and chloroplast DNA.
Therapies: Development of mitochondrial replacement therapy (MRT) for preventing mitochondrial diseases.
Slide 10: Conclusion
Summary: Extrachromosomal inheritance involves the transmission of genetic material outside the nucleus and plays a crucial role in genetics, medicine, and biotechnology.
Future Directions: Continued research and technological advancements hold promise for new treatments and applications.
Slide 11: Questions and Discussion
Invite Audience: Open the floor for any questions or further discussion on the topic.
The increased availability of biomedical data, particularly in the public domain, offers the opportunity to better understand human health and to develop effective therapeutics for a wide range of unmet medical needs. However, data scientists remain stymied by the fact that data remain hard to find and to productively reuse because data and their metadata i) are wholly inaccessible, ii) are in non-standard or incompatible representations, iii) do not conform to community standards, and iv) have unclear or highly restricted terms and conditions that preclude legitimate reuse. These limitations require a rethink on data can be made machine and AI-ready - the key motivation behind the FAIR Guiding Principles. Concurrently, while recent efforts have explored the use of deep learning to fuse disparate data into predictive models for a wide range of biomedical applications, these models often fail even when the correct answer is already known, and fail to explain individual predictions in terms that data scientists can appreciate. These limitations suggest that new methods to produce practical artificial intelligence are still needed.
In this talk, I will discuss our work in (1) building an integrative knowledge infrastructure to prepare FAIR and "AI-ready" data and services along with (2) neurosymbolic AI methods to improve the quality of predictions and to generate plausible explanations. Attention is given to standards, platforms, and methods to wrangle knowledge into simple, but effective semantic and latent representations, and to make these available into standards-compliant and discoverable interfaces that can be used in model building, validation, and explanation. Our work, and those of others in the field, creates a baseline for building trustworthy and easy to deploy AI models in biomedicine.
Bio
Dr. Michel Dumontier is the Distinguished Professor of Data Science at Maastricht University, founder and executive director of the Institute of Data Science, and co-founder of the FAIR (Findable, Accessible, Interoperable and Reusable) data principles. His research explores socio-technological approaches for responsible discovery science, which includes collaborative multi-modal knowledge graphs, privacy-preserving distributed data mining, and AI methods for drug discovery and personalized medicine. His work is supported through the Dutch National Research Agenda, the Netherlands Organisation for Scientific Research, Horizon Europe, the European Open Science Cloud, the US National Institutes of Health, and a Marie-Curie Innovative Training Network. He is the editor-in-chief for the journal Data Science and is internationally recognized for his contributions in bioinformatics, biomedical informatics, and semantic technologies including ontologies and linked data.
Richard's entangled aventures in wonderlandRichard Gill
Since the loophole-free Bell experiments of 2020 and the Nobel prizes in physics of 2022, critics of Bell's work have retreated to the fortress of super-determinism. Now, super-determinism is a derogatory word - it just means "determinism". Palmer, Hance and Hossenfelder argue that quantum mechanics and determinism are not incompatible, using a sophisticated mathematical construction based on a subtle thinning of allowed states and measurements in quantum mechanics, such that what is left appears to make Bell's argument fail, without altering the empirical predictions of quantum mechanics. I think however that it is a smoke screen, and the slogan "lost in math" comes to my mind. I will discuss some other recent disproofs of Bell's theorem using the language of causality based on causal graphs. Causal thinking is also central to law and justice. I will mention surprising connections to my work on serial killer nurse cases, in particular the Dutch case of Lucia de Berk and the current UK case of Lucy Letby.
1. LIMITING FACTORS
All living things need food, water, shelter and space to survive. As long as organisms
have all of these things available to them their population will continue to grow. However,
populations cannot grow forever. Some form of environmental resistance will stop the
population’s growth. The form of environmental resistance is called a limiting factor since it
limits the population. However, limiting factors may also increase a population
ClassificationOfLimiting Factors
Limiting factors can be divided into two classes as follows----
1) Density independent factors
2) Density dependent factors
DENSITY INDEPENDENT FACTORS
Factors that limit population size, regardless of population density.
These are usually abiotic factors
Examples are natural disasters, temperature, sunlight, human activities, physical
characteristics and behaviors of organisms affect any and all populations regardless of
their densities.
1) Natural Disasters
Natural disasters such as droughts, floods, hurricanes and fires can be devastating to
aquatic life. For example, a severe drought could lower the water levels of Lake Winnipeg
and decrease its carrying capacity. Thus, the fish population would decrease.
2) Temperature
Temperature influences the activity and growth of organisms. Temperature also determines
which type of organisms can live in a lake. Usually, the higher the water temperature, the
greater the activity in a lake. However, all aquatic species have a preferred temperature range.
If temperatures vary too much out of this range the species will either die or move to a
different location. Temperature also influences the chemical properties of water. The rate of
chemical reactions in the water increases as temperature increases. For example, warm water
holds less oxygen than cool water, so even though there is more activity in warm water there
may not be enough oxygen for the activity to continue for long periods of time.
3) Sunlight
Sunlight can only penetrate to a depth of 30 meters in water. Thus most photosynthesis in
aquatic environments occurs near the surface. This means that most plants cannot grow if
they are at the bottom of a deep lake.
4) Human Activities
Human activities can also affect population dynamics. For instance, lake sturgeon spawn in
fast water and sometimes use the “tailraces” of hydroelectric dams. However, the water level
in this location often drops suddenly and the eggs die because they become exposed.
5) Physical Characteristics
Physical characteristics of organisms can affect their population. Many organisms have
adapted and evolved in order to increase their chance of survival. For example, some species
of fish have colored markings to warn predators that they may be toxic. Or, some species use
camouflage colors to help them hide and avoid being eaten.
2. 6) Behaviors
Behaviors of organisms can also affect their population. For example, some species
migrate to find new food sources or to mate. Some organisms create societies or feeding
territories. For instance, white bass live in schools and work together to drive emerald shiners
to the surface for feeding. Some species may have mating or courtship behaviors that affect
their population.
Fire as an ecological density independent limiting factor
Animals display a range of abilities to cope with fire, but they differ from plants in that they
must avoid the actual fire to survive.
Birds are vulnerable when nesting, they are generally able to escape a fire; indeed
they often profit from being able to take prey fleeing from a fire and to recolonize
burned areas quickly afterwards.
Mammals are often capable of fleeing a fire, or seeking cover if they can burrow.
Amphibians and reptiles may avoid flames by burrowing into the ground or using the
burrows of other animals. Amphibians in particular are able to take refuge in water or
very wet mud.
Some arthropods also take shelter during a fire, although the heat and smoke may
actually attract some of them, to their peril.
Microbial organisms in the soil vary in their heat tolerance but are more likely to be
able to survive a fire the deeper they are in the soil. An increase in available nutrients
after the fire has passed may result in larger microbial communities than before the
fire
The Boise National Forest is a US national forest located north and east of the city of Boise,
Idaho. Following several uncharacteristically large wildfires, an immediately negative impact
on fish populations was observed, posing particular danger to small and isolated fish
populations. In the long term, however, fire appears to refresh fish habitats by causing
hydraulic changes that increase flooding and lead to silt removal and the deposition of a
favorable habitat substrate. This leads to larger post-fire populations of the fish that are able
to recolonize these improved areas. But although fire generally appears favorable for fish
populations in these ecosystems, the more intense effects of uncharacteristic wildfires, in
combination with the fragmentation of populations by human barriers to dispersal such as
weirs and dams, will pose a threat to fish populations.
DENSITY DEPENDENT FACTORS
Any factor in the environment that depends on the number of members in a
population per unit area
These are usually biotic factors
Examples are competition, predation, disease, parasitism, crowding, and stress are all
factors that only affect populations with high densities.
1) Competition
Competition can occur between many organisms that live in the same habitat. Resources
are limited in a habitat so organisms must compete for food, water, space, and shelter.
Competition for limited resources can occur between individuals of different species, and it
can occur between individuals of the same species. The first kind of competition is called
3. interspecific competition, or between-species competition, and the second kind is called
intraspecific competition, or within-species competition.
For example, both northern pike and walleye prey on yellow perch and so they compete for
the same food source. However, this competition is only apparent when the populations of
northern pike and walleye have high densities OR the population of yellow perch has a low
density.
Even sperm compete! Sperm competition is when a female mates with more than one male,
and the sperm compete to fertilize one egg. This occurrence is thought to produce the most
viable offspring and contribute to diversity in the population.
Competitive interactions can end in one of two ways:
1. Either one species will win, and the other will go extinct in that environment
2. Or, like good girls and boys, the species will learn to get along by dividing the goods
into two distinct niches.
The first result, or when one species wins, is called competitive exclusion. The second, or
when both species adapt and "learn" to get along, is called resource partitioning.
2) Predator/prey relationships
Predator/prey relationships play a big role in animal populations. If the balance between
predator and prey is changed, populations are changed. Predation occurs when the population
density of predators is high. The predators will consume their prey and increase their own
population. However, the population of the prey will decrease. On the other hand, the lack of
predation (when the population density of predators is low) will cause problems for the prey’s
population. When there are few predators, the prey’s population increases very quickly and
this can lead to the depletion of resources and increase disease.
The white-tailed deer population in some areas has grown too large because there are no
natural predators. Mountain lions and wolves are the natural predators of the white-tailed
deer. Wolf and mountain lion populations have been lowered due to over-hunting and habitat
loss. This loss of a natural predator for the white-tailed deer, along with other factors, has led
to overpopulation of the white-tailed deer in some areas.
3) Disease
Disease in a population increases with the density of that population. High densities makes it
easier for parasites to find hosts and spread the disease.
4) Parasitism
Parasitism is a relationship in which one species benefits at the expense of the other. A
parasite is an organism that lives in or on another organism (called a host) to get nourishment.
While the parasite benefits from this relationship the host is harmed or killed.
4. 5) Crowding
Crowding only occurs at high densities. Over-crowding can cause depletion of resources,
disease and stress.
6) Stress
Stress usually has a negative effect on populations. Stress can make organisms weak and
more prone to disease.
YELLOW PERCH IN LAKE WINNIPEG explains limiting factors in an ecosystem
Location of lake Winnipeg
Located 217 m above sea level, Lake Winnipeg is a shallow lake composed of two basins: a
wide north basin and a narrow south basin. On average, Lake Winnipeg is only 12 meters
deep and receives 517 mm of precipitation annually.
Habitation in lake winnipeg
Lake Winnipeg provides a habitat for over 50 different species of fish including yellow
perch, chestnut lampreys and rainbow smelt.
Yellow perch preferences and accommodation
Water current
Yellow perch prefer water that has little current. They can tolerate moderate tubidity
Temperature range
They prefer a temperature range of 18 to 20 degrees Celsius. If the temperature of the water
varies too much above this range, yellow perch will either move to a new location or die.
Spawning season
Yellow perch spawn in May or early June when water temperatures are above 6 degrees
Celsius.
Migration
First, they migrate to tributaries and then several males attend a female while she releases her
eggs. Yellow perch can grow to 302 mm in length. Their life span is approximately 9 years. If
there is a lack of resources or too many of them (over-population), yellow perch adapt by
stunting. This means that instead of starving, they simply do not grow as large as normal.
Thus, they are able to live off less food.
Feeding habits
Yellow perch feed in midwater or on the bottom of Lake Winnipeg. They eat a wide variety
of invertebrates, and fish such as emerald shiners. The eyes of yellow perch allow them to see
almost 360 degrees around them. Thus, they are better able to spot their prey and evade
predators.
Predators of yellow perch in lake Winnipeg
In Lake Winnipeg, yellow perch are eaten by northern pike and walleye. They are also
5. caught for food by commercial fishers and anglers.
Lake winnipeg , an excellent home
Chestnut lampreys are also found in Lake Winnipeg. Lampreys are parasitic fish that attach
to other species of fish (such as yellow perch) to feed on their blood and tissues.
Recently, rainbow smelt have been introduced into Lake Winnipeg. Rainbow smelt are a very
invasive and competitive species. They have been thought to have caused a decrease in the
emerald shiner population.
Lake Winnipeg provides a home for many species of fish. However, a severe drought
could disrupt this ecosystem greatly. Lake Winnipeg’s water level would drop, the
temperature could change and it could become more turbid. Thus, the carrying capacity of the
lake would change.
But, in its current condition, Lake Winnipeg is an excellent habitat for many species of fish.