This document provides an overview of key concepts in ecology. It defines ecology as the study of the interactions between organisms and their environment. It describes several core ecological concepts including biomes, ecosystems, niches, succession, energy flow through ecosystems, and population dynamics. Factors that influence population growth such as biotic potential, carrying capacity, and limiting factors are also discussed.

1. Ecology
AN INTRODUCTION

2. Key Words
SOME THINGS YOU NEED TO KNOW

3. Ecology
 from Greek: oikos, meaning
“house”.
 First coined by Ernst
Haeckel, a German
biologist, in 1866.
 He related houses as the
levels of organization.

4. Biosphere
 Portions of the planet
in which life exists.
 Self-contained and
self-regulating
 Patchy

5. Ecosystem & Ecotone
 Ecosystem
 Not self-contained
 Abiotic ↔ Biotic
 Removing biotic elements can dramatically affect an
ecosystem’s abiotic conditions
 Ecotone
 The overlap between two or more ecosystems/ biomes

6. Habitat & Niche
 Habitat
 The area where an organism lives
 An organism’s home or address
 Niche
 Conditions in which an organism lives
 The way an organism uses these conditions
 An organism’s job or occupation

7. Ecological Succession
PIONEERS TO GENTLEMEN

8. Types of Successions
 Ecological Succession
 An existing community is replaced by another
community
 Directional
 Usually predictable
 Primary Succession
 Starts with virtually lifeless area; the soil has not formed
yet or has been destroyed
 Secondary Succession
 Occurs when an existing community has been cleared
by some disturbance without destroying the soil

9. Communities
 Pioneer Community
 Colonizes areas where no community exists
 Climax Community
 A fairly stable collection of organisms that results from
ecological succession
 Dominant Species
 Most obvious or numerous species in a community

10. Biomes
DESERT TO DESSERT

11. Tundra
 Coldest
 Dry
 Northern Hemisphere
 Flora
 Stunted trees , dwarf woody shrubs , mosses , lichen ,
grass
 Fauna
 Reindeer , migratory animals (feed on plants during the
summer0 , wolves , foxes , mosquitoes ,

12. Grassland
 Warm to Hot
 Wet and Dry seasons
 All continents except Antarctica
 Flora
 Grasses , few trees
 Fauna
 Mammals ( giraffes , zebras , lions , etc. ) , birds , insects

13. Desert
 Extreme Temperature
 Very Dry
 Tropical and Temperate Zones
 Flora
 Cactus , sage bush , dwarf shrubs , short woody trees
 Fauna
 Kangaroo mice , lizards , insects , scorpions , snakes , birds

14. Taiga
 A.K.A.
 Coniferous Forest
 Cool Year-round
 Adequate Rainfall
 Underneath Tundra Biomes
 Flora
 Conifers
 Fauna
 Black Bears , wolves , moose , migratory birds (during
summer)

15. Deciduous Forest
 Seasons
 Summer , fall , winter , spring
 Adequate Rainfall
 Temperate Zones
 Flora
 Deciduous Trees

16. Tropical Rainforest
 Always Warm
 Very Wet
 Between Tropics of Cancer and Capricorn
 Flora
 Vines , palms , orchids , ferns

17. Freshwater
 Less than 1% salinity
 Standing water
 Littoral Zone
 Near Shore
 Limnetic Zone
 Near-surface Open Water
 Profundal Zone
 Deep Water
 Flowing water

18. Estuarine
 Salinity is more than 1% but less than 3%
 Organisms are highly tolerant to salt
 Spawning Grounds
 High Biodiversity per unit area
 Highly Productive
 Because of the nutrients deposited by the river or stream,
low depth and high light exposure

19. Marine
 More than 3% salinity
 Zones
 Intertidal
 Low/high tide area
 Pelagic
 Open Ocean
 Benthic
 Ocean Floor
 Abyssal
 Deep Ocean

20. Energy Flow
PYRAMIDS AND CHAINS

21. Ecological Pyramids
 Shows the relative amounts of energy/matter
contained at each trophic level

22. Feeding Relationships
 Food Chain
 Organisms transfer energy by eating and being eaten
 Food Web
 Network of complex feeding relationships
 Only 10% of the energy of an organism is passed
on to the organism that eats it

23. Population Dynamics
PLUS MINUS

24. Characteristics of a Population
 Geographic Distribution or Range
 The natural arrangements of organisms in particular
geographic locations
 Population Density
 The number of individuals per unit area
 Population Dispersion
 Pattern in spacing between other members of the
population
 Clumped ,
uniform ,
and random

25. Characteristics of a Population
 Age Structure
 Distribution of the
population to different
age groups.
 Growth rate
 3 Factors affecting the
population size
 Natality
 Mortality
 Migration
 Number of organisms
added or taken away
from a population

26. Growth Rate
 Exponential
 Individuals in a population reproduce at a constant rate.
 Logistic
 A populations growth stops after a period of exponential
growth
 Biotic Potential
 Maximum growth rate under ideal conditions
 Carrying Capacity
 Maximum population size an environment can sustain
 Environmental Resistance
 Environmental conditions that limit a population’s growth

27. Population Pyramid
 Types
 Growing
 Stable population growth
 Expanding Stationary Contracting
 Exponential population growth
 Stationary
 No population growth
 Contracting
 Decreasing population growth Expanding Growing

28. Core Concepts
 Five important characteristics of a population
 Three factors affect a population’s size
 Biotic potential of an ecosystem is affected by
environmental resistance , thus resulting in a
maximum carrying capacity
 Factors that limit population growth include
both density-dependent and density-
independent factors
 Understanding the patterns in human
population growth is important in addressing
population problems around the world

29. Factors Limiting Population Growth
 Limiting factor
 A factor that causes the population growth to decrease
 Density-dependent factors
 Becomes limiting when a population reaches a certain size
 Competition
 Diseases
 Density-independent factors
 Not affected by the size of the population
 Natural Disasters