Chapter 4

Characteristics of Populations  Geographic distribution  Density  Growth Rate  Age structure

Population Density  Number of organisms you have in a certain area

Population Density  Compare population density of:  Trees  Shrubs  Grasses  Different species in an ecosystem have different densities

Population Dispersal  Populations are not equally dispersed

Population growth  Population sizes can change  Three factors effect population size:  Births  Deaths  Individuals that enter or leave  Healthy populations increase and decrease at the same rate

Population trends  No matter the organism, we all follow the same population trend

Population Growth Compare & contrast the following graphs:

Population Growth  Linear Growth  Always increasing at the same rate (constant slope)  Exponential Growth  Rate always increasing (increasing slope) Which one accurately represents population growth?

Exponential Population Growth  Under ideal conditions, a population would grow exponentially  Unlimited resources  No competition

Can a population increase forever?  No- it eventually flattens out

What happened?  As resources become less available, growth of a population slows or stops  It has been limited by some factor

Carrying Capacity  Reached when the population starts to level off (birth = death)  All that an environment can support

Limiting Factors Population Size Competition Natural DisastersDiseasePredators Human Involvement

Which ones…? Population Size Competition Natural DisastersDiseasePredators Human Involvement

Limiting Factors  DENSITY DEPENDENT  Depends on population size  Usually biotic  Competition  Predation  Parasitism  Disease

Limiting Factors  DENSITY INDEPENDENT (usually abiotic)  Affect all populations in similar ways, regardless of population size  Unusual weather  Natural disasters  Seasonal cycles  Human involvement

Limiting Factors  Limiting factors are responsible for bringing an ecosystem to its carrying capacity Why isn’t this a straight line?

Carrying Capacity  What would happen if a population exceeded it’s carrying capacity?  What would this look like on a graph?  Need to examine a population’s LIFE-HISTORY PATTERN

Life History Patterns  Depends on the organism  Bacteria reproduce fast  E. coli takes 12 minutes!  Elephants reproduce slowly  Almost 2 years! (22 months)

Life History Patterns RAPID LIFE HISTORY SLOW LIFE HISTORY  Small bodies  Short life spans  Many offspring in short time  Can handle readily changing environments  Large bodies  Long life spans  Reproduce less frequently  Live in more stable environment

Life History Patterns RAPID LIFE HISTORY SLOW LIFE HISTORY

Chapter 5

Section 5.1

Biological Diversity Consider a Rainforest What will we find?  A single rainforest reserve in Peru is home to more species of birds than the entire United States  One single tree in Peru was found to harbor forty-three different species of ants - a total that approximates the entire ant species in the British Isles  One hectare has 400 species of plants.

Biological Diversity  BIODIVERSITY  Measure of the variety of species in a specific area  How can you tell when one area is more diverse than another?

Biodiversity  Which has more biodiversity?  A field with 300 corn plants?  A forest with 6 pine trees and 7 oak trees?  One of these has a higher SPECIES RICHNESS  Number of species

BIODIVERISTY INDEX  Calculates level of diversity in an area Biodiversity Index = total of each individual species total number of individuals in the area Σ 2

Biodiversity Index  The closer the B.I. to 1, the more diverse

Where is biodiversity found? EVERYWHEREEVERYWHERE BUT…

…Which location has more?

Biodiversity in nature

 Living things are interdependent  Populations are adapted to live together in communities  Losing one species may result in the loss of another, and another, etc…

Compare the following  A potato field with one species of potato is attacked by pests.  Rainforest with many different species of plants is attacked by pests. Which one will the pests affect more? Why?

Which will survive? Potato field –All the same species –All planted next to each other –All the potatoes are destroyed Rainforest –All different species –All randomly dispersed –Only one species destroyed

Biodiversity Brings Stability  The rainforest will more easily cope with the loss of one species  A diverse ecosystem remains stable

Importance to Humans

Did you get it? How would the over-hunting of white-tail deer affect the community in which it lives?

Did you get it? Which of the following would be the ideal distribution of a population of trees to prevent it from being destroyed by pests?

Did you get it? Would it help or hinder the trees if they were separated by different species of plants?

Loss of Biodiversity  What are some reasons we are losing biodiversity?

Loss of Biodiversity  It is natural for certain species to become extinct over time  It is not natural to lose one species every 20 minutes!  Human activities have increased the rate of species loss

Loss of Biodiversity THREATENED--> (Close to becoming endangered) ENDANGERED--> (Close to becoming extinct) EXTINCT (Species has disappeared)

Reasons for the Loss of Biodiversity  HABITAT LOSS  Clearing for farmland  Demolition to build houses  Increased water temps damage coral reefs

Reasons for the Loss of Biodiversity  HABITAT FRAGMENTATION  Separation of wilderness areas from other wilderness areas

Habitat Fragmentation  Leads to:  Loss of species due to relocation  Increased extinction of local species  New opportunities for invasions by introduced or exotic species

Reasons for the Loss of Biodiversity  EDGE EFFECT- differing conditions along the boundaries of 2 ecosystems  Forest meets field; water meets land; road cuts through wooded area

Edge Effect  Edges tend to have more biodiversity  Different habitats with different species meet  When a new edge is made, some animals habitats may be exposed  Why might this be a problem?

Reasons for Loss of Biodiversity  HABITAT DEGREDATION-  Damage to a habitat by pollution

Habitat Degradation  ACID PRECIPITATION (RAIN)  Factories release sulfur dioxide and nitrogen oxides and they combine with water (become acidic)  Why might this be a problem?

Habitat Degradation  Water pollution  Excess fertilizers wash into water  Increased nutrients cause an algal bloom  Why might this be a problem?

Habitat Degradation  OZONE DEPLETION  Ozone layer protects us from ultraviolet rays  Holes in the ozone layer allow move UV to come through  Why might this be problem?

Habitat Degradation  Land Pollution  Excess garbage  Use of pesticides  A pesticides effects are magnified as it moves up a food chain  BIOLOGICAL MAGIFICATION

Your Footprint What mark do your actions leave on our environment? Let’s find out!

Conservation of Biodiversity Section 5.2

Today’s Goals Describe the ways in which we keep plants, animals and their environments safe and healthy

What is CONSERVATION BIOLOGY? Why is it important?

Conservation Biology  CONSERVATION BIOLOGY  study and carrying out of ways to protect biodiversity

Conservation Biology  NATURAL RESOURCES  Parts of the environment needed by living organisms  Sun, water, air, etc

Conservation Biology  Not an easy task  Sometimes a complete reverse of major changes to an environment  Restoring a strip mine to a grassland  We work harder not to prevent loss rather than reverse it

Protecting Species and Habitats  In the US, we have passed laws to protect endangered and threatened species  Endangered Species Act of 1973

Protecting Species and Habitats  Habitats must be preserved as well  Created national parks or reserves Yellowstone National ParkCrater Lake National Park

Conservation Biology  Remember HABITAT FRAGMENTATION?  How could we fix the problem?  HABITAT CORRIDORS  Strips of land connecting two fragmented areas  Allows organisms to move between

Conservation Biology  SUSTAINABLE USE  Using the natural resources in ways that benefit them yet still maintain the ecosystem

Conservation Biology  REINTRODUCTION PROGRAMS  Take members of an endangered species and breed and raise them in protected habitats  Black footed ferret

Conservation Biology  CAPTIVITY  Organisms kept by humans  Kept in captivity to increase numbers  Eventually returned to the wild