1. Environmental Science Chapter 4: Population Ecology

2. February 3, 2014- SIGN IN Page: 89 questions: 1,2,3
Get an environmental science book (FROG on it)
Do the following questions…DO NOT WRITE the question, only the answers
Page: 89 questions: 1,2,3
Page : 94 questions: 23,24,25
Page : 103 questions: 1,2,3
Page : 109 questions: 1,3,4
Page : 117 questions: 1,2,3

3. What is ecology?
The study of how organisms interact with each other and with their environments
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4. Defining an ecosystem
Ecosystem: all the organisms living in an area together
Forest Ecosystem
Pond Ecosystem
Vacant Lot Ecosystem
Desert Ecosystem
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5. All Ecosystems are connected
How does your ecosystem impact the Atlantic Ocean?
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6. Parts of an ecosystem
In order for an ecosystem to survive there must be certain basic parts
Energy
Mineral nutrients
Carbon dioxide
Water
Oxygen and more
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8. Biotic vs. Abiotic Biotic: living parts of the ecosystem
Plants, animals, bacteria, etc.
Abiotic: nonliving parts of the ecosystem
Sunlight, soil, air, temperature
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9. Organizing Biotic Parts
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10. Smallest Unit
Organism: an individual living thing like you, a tree, a fox, a rose
Species are groups of organisms
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11. Species Species: groups of organisms that resemble each other in:
appearance
Behavior
Chemistry
genetic makeup
able to reproduce VIABLE offspring
3.6 to 100 million species (1.4 identified)
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12. Population
Population: all the members of the same species that live in the same place at the same time
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13. Community
Community: a group of various species that live in the same place and interact with each other.
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14. Ecosystem: all the organisms living in an area together
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15. Biosphere
All parts of the Earth where life is found
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16. Habitat
Habitats provide an organism with resources—anything an organism needs to survive and reproduce, including food, shelter, and mates.
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17. Review: What is a population?
Population: all the members of the same species that live in the same place at the same time
Field mice living in a corn field, grizzly bears of Yellowstone Park area
Wolves in Yellowstone NP

18. Population Size Why care about the size of the population?
How can scientists estimate the population (say of Elephant Seals on a beach in CA)?
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19. Population Size
The number of individuals in a population at a given time
Sudden and dramatic decreases in population size can indicate an unhealthy population headed toward extinction.
Ecologists often use sampling techniques to estimate population size.
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20. Estimating Population
How can you estimate the population of trees in this valley?
WHY NOT COUNT THEM ALL?
WHY IS SAMPLING NEEDED?

21. Population Density Measure of how crowded a population is
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Measure of how crowded a population is
Larger organisms generally have lower population densities.
Low population density: More space, resources; finding mates can be difficult
High population density: Finding mates is easier; tends to be more competition; more infectious disease; more vulnerability to predators

22. Population Distribution
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How organisms are arranged within an area:
UNIFORM
RANDMOM
CLUMPED
Occurs where resources needed are found throughout, wildflowers in meadow
Occurs when individuals hold territory or compete for space. Plants in desert
Most Common. Occurs where resources are together. Water hole in desert, humans in cities

23. Population Distribution
Uniform distribution: Organisms evenly spaced
Random distribution: Organisms arranged in no particular pattern
Clumped distribution: Organisms grouped near resources; most common distribution in nature
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24. Sex Ratios Proportion of males to females
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Sex Ratios
Proportion of males to females
Age structure diagrams give information about sex ratios.
For a monogamous species, the ideal sex ratio is 50:50.
Why is 50/50 not as important in non-monogamous populations?

25. Survivorship
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Individuals of different ages have different probabilities of dying
Survivorship curves show how the likelihood of death varies with age.

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Type I survivorship curves are for species that have a high survival rate of the young, live out most of their expected life span and die in old age. Humans are a good example of a species with a Type I survivorship curve
Type II survivorship curves are for species that have a relatively constant death rate throughout their life span. Death could be due to hunting or diseases. Examples of species exhibiting a Type II survivorship curve are coral, squirrels, honey bees and many reptiles.

27. Type III survivorship curves are found in species that have many young, most of which die very early in their life. Plants, oysters and sea urchins are examples of species that have Type III survivorship curves.
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28. Patterns of Growth EXPONETIAL GROWTH
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EXPONETIAL GROWTH
Population increases by a fixed percentage every year.
Normally occurs only when small populations are introduced to an area with ideal environmental conditions
Rarely lasts long
WHAT SHAPE DOES EXPONENTIAL GROWTH LOOK LIKE?
Starts slowly, then takes off – “J-Shaped Curve”

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30. Limiting Factors
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Limiting Factor Principle: too much or too little of any abiotic factor can limit or prevent growth of a population, even if all other factors are near or above optimum.

31. Carrying Capacity
Limiting Factors lead to Carrying Capacity: the largest population an environment can sustain.
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32. Biotic Potential
An organism’s maximum ability to produce offspring in ideal conditions
Many factors influence biotic potential, including gestation time and generation time.
Organisms with high biotic potential can recover more quickly from population declines than organisms with low biotic potential.
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33. Open Book to page 122 Answer questions 17-23 25-26
Class work
Open Book to page 122
Answer questions
17-23
25-26

34. Open Book to page 123 Answer question number 32
Bellringer
Open Book to page 123
Answer question number 32