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Ecology Part 2 Chapter 5-6. 1. Explain and identify the factors that affect population growth. (5.1 ). What was our definition of population? Researchers study populations in the following ways: Geographic Range Density and Distribution Growth Rate Age Structure. Geographic Range.
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1. Explain and identify the factors that affect population growth. (5.1) • What was our definition of population? • Researchers study populations in the following ways: • Geographic Range • Density and Distribution • Growth Rate • Age Structure
Geographic Range • Definition: The area inhabited by a population • Range can differ depending on the species • Bacteria vs. Humans vs. Cod
Density and Distribution • Population Density is the number of individuals per unit area • It is like a class roster, we have so many people in this room at this time. • Populations of different species can be different even in the same environment
Density and Distribution • Distribution is how individuals are spaced out across the range. • The three are Random, Uniform, or Clumped
Growth Rate • Growth rate determines whether the population increases, decreases, or stays the same. • What could lead to increases? • Decreases? • Staying the same?
Increases Decreases • Birth • Immigration: moving into the area • Death • Emigration: moving out of the area
Age Structure • Age structure is the number of males and females of each age in a population • Why would we need to know this?
2. Distinguish between exponential growth and logistic growth. (5.1) • If you provide a group of animals with food, shelter, healthcare, and everything else they need to survive, how will they grow?
Exponential Growth • Growth pattern where the population reproduces at a constant rate • The larger the population gets, the faster it grows • With unlimited resources, a population will grow exponentially
Reproducing Rapidly (Hours) • Bacteria Graph
Reproducing Slowly (100’s of years) • Graph example
New Environment • Graph example
What did you notice about each situation? • Eventually they all created a “J-shape” curve at the end • This is the key characteristic of the exponential growth curve graph.
Logistic Growth • So what happens if an animal does not have ideal conditions and protection from everything? • It slows or even stops growing! • Logistic growth: occurs when a population’s growth slows and then stops, following a period of exponential growth
What can slow population growth? • All of these contribute to creating the carrying capacity • This makes the line have an “S-shape” curve OBJECTIVE # 5!!!!! • Carrying capacity: the max number of individuals of a particular species that a particular environment can support.
6. Describe the factors that determine a carrying capacity. (Limiting Factors) (5.2) • Limiting factor is a factor (something) that controls the growth of a population • We’ve mentioned one of the types at the end of last chapter… • Limiting factors determine the carrying capacity
7. Compare and contrast density-dependent and density-independent limiting factors. (5.2) • Density-Dependent: operates when population density (# of species in the area) reaches a certain level.
Types of Density-Dependent factors • Competition… Why? • More individuals living in the area, the sooner they use up resources which leads to decrease of both species • Parasitism and Disease… Why? • The more individuals (hosts), the easier it is for the parasites to spread. This can cause lower births of host and sometimes death from disease
Density-Dependent factors • Overcrowding…. Why? • Too many leads to not very many food source, shelters, etc… which will cause lower births and higher deaths • Predator-Prey…. Why? • Both predator and prey will go up and down over the course of the years. • Each one keeps the other in balance. • Easier to look at a graph.
Density-Independent Factors • These factors happen to all populations regardless of population size and density. • Can be things like weather conditions (hurricanes, tornadoes, droughts) and natural disasters (wildfires)
11. Describe human activities that can affect the biosphere. (6.1) • Agriculture: produces a dependable supply of food that can be stored for later use. • Critical to our survival • It has led to doubling the worlds food over 50 years • Impacts natural resources like water and soil • How? • Fertilizers and Farm Equipment use Fossil Fuels • Why is this bad?
Development • The development of cities and housing • Cities led to suburbs developing on the outside • Why is this bad? • Human communities produce lots of waste • If not disposed, can affect air, water and soil • Housing splits farmland and divides natural habitats
Industry • Provides us with all of our modern gadgets and gizmos • How would this be bad? • Take a lot of energy to produce (burns fossil fuels) • Usually discards waste directly in air, water, or soil
12. Distinguish between resource use and sustainable development. (6.1) • Much like our Economy, Ecosystems provide us with “good and services” • This is anything that benefit the human economy • These are classified as renewable resources and nonrenewable resources
Renewable Nonrenewable • Can be produced and replaced by a health ecosystem • Ex: Trees • We can cut one down and another one can grow in its place • Natural processes cannot replenish them within a reasonable amount of time • Ex: Fossil fuels like coal, oil, and natural gas • These are formed from buried organic materials over millions of years. • When they are gone, its essentially forever.
Sustainable Development • This provides for human needs while preserving the ecosystems that produce natural resources • What would we want it to look like? • No long term damage to soil, water, and climate • Flexible to survive environmental stresses • It must no only help us survive, but improve our lives
13. Explain how humans affect soil, water sources, and air sources. (6.2) • Healthy soil helps both agriculture and forestry • Bad things that we can do to the soil • Desertification: over farming, overgrazing, seasonal drought, and climate change that turns a farmland into desert. • Deforestation: loss of forests • Bad because trees help keep soil in place with roots
Water sources • We need it for: drinking water, industry, transportation, energy, and waste disposal • How we affect it: • Pollutants: harmful material that can enter a biosphere • EX: DDT • How we try to fix it: • Pollution control, Water Cycle, conservation
Air Sources • We need it for: Breathing, Greenhouse effect • How we affect it: • Smog: a gray-brown haze formed by pollutants in air • Acid Rain: Burning fossil fuels causes this and will damage buildings and plant life • Greenhouse Gases • Particulates • How we are fixing it: • Filters, unleaded gasoline