All living organisms are limited by factors in the environment

POPULATION ECOLOGY CHAPTER 3.1 & 4.1 In Chapter 2, you learned that organisms depend on one another for survival. You also learned about abiotic factors and that abiotic factors affect individual organisms. How, then, might these factors affect communities and populations?

Key Terms  Population  Species  Limiting factor  Population growth rate  Carrying capacity  Biodiversity

1 st Essential Theme Interdependence of Organisms For populations to grow & survive they must have resources

REVIEW TERMS CHAPTER 2  Population is a group of individuals of the same type (or species)  Species is a group of organisms that can interbreed and produce fertile offspring

POPULATION DYNAMICS: Measurements of populations P  Population size = # of individuals  Population density = # of individuals per area  Population range = total space occupied by species  Population dispersion = pattern of spacing within an area

POPULATION GROWTH RATE: How fast a population grows P. 97 Birthrate = # of individuals born in a given amount of time Death rate = # of deaths that occur in the population during a given period Migration = movement into/out of a population ○ Immigration = movement in ○ Emigration = movement out

BIRTH EMIGRATIONIMMIGRATION DEATH

POPULATIONS GROW WHEN… There are more births than deaths and more immigration than emigration.

How does predation affect populations?  With small predator numbers (wolf) how is the prey (moose) population affected?  With large prey numbers how is the predator population affected?  With large predator numbers how is the prey population affected?  With small prey numbers how is the predator population affected?

Predator-Prey Relationship

Why does this happen?  With 2 wolves and 24 moose, how much competition for food was there among the wolves?  With 14 wolves and 10 moose, how much competition for food was there among the wolves?

LIMITING FACTOR P. 61  Any biotic or abiotic factor that restricts the numbers of organisms ○ Resource availability – how much food, water, shelter, sun, soil… ○ Natural phenomena – tornadoes, flooding, climate change, drought ○ Man-made disturbances – dam building, pollution, deforestation

DENSITY-DEPENDENT FACTORS BIOTIC FACTORS ARE… P. 94  Affect a population with greater magnitude or strength or rate because of greater population density  Usually include predation, disease, parasites, and competition Think – predation occurs more frequently and disease spreads faster because the population is dense.

DENSITY-INDEPENDENT FACTORS ABIOTIC FACTORS ARE… P. 94  Affect a population with the same magnitude or strength or rate regardless of population size  Usually include natural disasters, weather & climate change, and human changes to environment (pollution or dam building) Think – fires, tornadoes, and pollution do not occur more often or intensify in more dense populations.

2 nd Essential Theme Stability Populations maintain stability in response to each other

Review Habitat & Niche  Habitat is the place.  Niche is the place, what is eaten, the lifestyle.  Habitat : Address :: Niche : Job

FUNDAMENTAL NICHE The full range of physical and biological conditions in which an organism lives and way in which the organism uses those conditions.

EXPONENTIAL GROWTH CURVE  Population growth is NOT limited  Takes on an J-shape  Ideal and doesn’t normally occur in most populations  What kinds of organisms might have exponential growth and why?

REALIZED NICHE The range of resources a species actually used; it’s a portion of the fundamental niche.  A species may have to restrict its activity to avoid predators, or competition with other species may prevent it from using a resource.

CARRYING CAPACITY THIS RESTRICTED RANGE IS SET BY A…  The maximum number of individuals that can be supported by the ecosystem.  The limit is determined by the availability of resources and by their interactions with other organisms.

Populations grow, especially during plentiful times Population growth slows as factors decrease survival

LOGISTIC GROWTH CURVE  Population growth is limited by factors in the environment  Takes on an S-shape  Marked by a carrying capacity

What happens when there is competition for a niche? Competitive exclusion (extinction), one species moves out, or niche partitioning (resource sharing)

3 rd Essential Theme Evolution Genetic variability impacts survival

REPRODUCTIVE PATTERNS P. 98  Species of organisms vary in the number of births per reproductive cycle, in the age that reproduction begins, and in the life span of the organism. ○ R-strategist ○ K-strategist

R-strategist P. 98  Small organism (fruit fly or a mouse)  Short life span  Produce many offspring  Strategy is to produce as many offspring as possible in a short time in order to take advantage of some environmental factor  Populations are controlled by density- independent factors (changes in abiotic factors)

K-strategist (also called Carrying Capacity Strategy) P. 99  Large organism (elephant)  Long life span  Produce fewer offspring but invest a lot of care  Strategy is to produce only a few offspring who have a better chance of living due the care they get from parents  Populations are controlled by density- dependent (biotic factors)

Which are you? R-strategistK-strategist

BIODIVERSITY P  Variety of life in an area – the # of different species in that area why do you think this is?  Increases stability of an ecosystem – why do you think this is?

3 TYPES of BIODIVERSITY P  Genetic diversity ○ Variety of genes in a population ○ Example: color of corn or maize ○ Increases the chances that some species will survive changing environmental conditions

3 TYPES of BIODIVERSITY P  Species diversity ○ # of different species and how many individuals of each species in an area ○ Example: medicinal plants in the rainforest

3 TYPES of BIODIVERSITY P  Ecosystem diversity ○ Variety of ecosystems present in biosphere ○ Example: Jungles of Peru support tropical birds, plants, mammals, etc ○ Ecosystem diversity results in species diversity in a healthy biosphere.