Rest of the Ecology Unit

Chapters 4 and 5

Weather vs. Climate

• Weather is the day-to-day condition of the atmosphere at a time and space.• It tells you what you should wear each day

• Climate however is the average, year-to-year conditions of a region.• It tells you what clothes you have in your closet

Things that Affect the Climate

• There are many factors, we will look at 3

1. Greenhouse Gases

2. Latitudes

3. Winds and Currents

The main energy behind all this of course is THE SUN!

Greenhouse Gases

• Think of it like a blanket that covers the Earth

• The gases that make up the “blanket”• CO2, Methane, Water vapor, and others

• The blanket works similar to a Greenhouse• We call this the Greenhouse Effect

Don’t gimme non dat Latitude

• The Earth is tilted ~23o

• This created 3 main climate zones because of the amount of sun each area is getting.

• These climates are sectioned off by lines of latitude

Get in the Zone

• Polar: It’s cold here• Sun strikes this area at a very low angle• Occurs from N/S pole and down to the 66.5o

• Temperate: It goes between hot and cold• Depends on the season• Occurs between 66.5o and 23.5o

• Tropical: Tropics, Hot b/c of direct Sun• Located between 23.5o and Equator

The Winds of Change are Coming

• Winds and ocean currents are driven by the unequal heating on Earth

• As winds heat up from equator, they rise• As they cool down, they sink

• Similar situation with the ocean currents

Biotic and Abiotic Factors

• Biotic factors: living factors in ecosystem• Highly dependent on abiotic factors• Examples: All living things

• Abiotic factors: Nonliving factors that shape the ecosystem• Factors often cycled by the biotic• Examples: Climate, soil, wind, nutrients, sun,

water

How these all shape the role of the ecosystem

• They determine the survival and growth of an organism

• They determine the productivity of the ecosystem where the organism lives

I live at 123 Fake Street

• A habitat is where an organism lives and includes all the biotic and abiotic factors

• Think of the habitat as an organisms address

Can you Scratch my Niche

• A niche would be more like an organism’s occupation, It’s knowing your role

• Niche: All biotic and abiotic conditions an organisms lives in and how they use the surroundings

• One of the niches we’ve talked about already…. Food chains!

More Niches

• Includes the food they eat, temp. at which they can live, when and how it reproduces, etc…

• No two species can occupy the EXACT SAME niche in the same habitat• Doesn’t mean they can’t be really similar

Two Types of Niches

• Fundamental Niche: Total range of environmental conditions under which a species can exist

• Realized Niche: Range of environmental conditions used in the presence of another species

Time to Interact

• Competition• Predation• Amensalism• Neutalism• Symbiosis

• Mutualism• Commensalism• Parasitism

Competition (-,-)

• Occurs when two or more similar or different species attempt to use the same resource• Resource: any necessity of life

• Competition always creates a winner and loser, and you don’t want to lose

Competitive Exclusion Principle

• No two species can occupy the same niche in the same habitat at the same time.

• If they did, one would have to die

Types of Competition

• Interference: Blocking access to resources• Ex: Birds nesting sites

• Exploitative: Consumes resource faster• Scramble: Consume as fast as possible (both)• Contest: One suffers less than others

Sexual Competition

• Intrasexual Competition: Male to male or female to female competition to mate

• Intersexual Competition: Different attractiveness of individuals of one sex to another

Intrasexual

• Usually deals with exaggerated secondary sexual characteristics

• Can also be a battle to the death

• Ex: Larger size, aggressiveness, size of other traits, territory, etc…

Intersexual

• Usually the males try to appear more attractive so the female picks him• Rule of Life: Women usually in control

• Usually good appearance means he is healthy and has good genes to pass on

• Ex: Peacocks and their bright feathers

Predation (+,-)

• Interaction where one eats another

• The one killing= predator (+)• The one killed= prey (-)

Symbiosis

• Any relationship where two species are in close contact with each other

• Literally means “living together”

Mutualism (+,+)

• Both species benefit from their relationship

• Ex: Flowers and insects• Flowers need to be pollinated• Insects need nectar

Neutralism (0,0)

• Two species live in the same area but have no effect on each other.

• Extremely unlikely or almost impossible

• Mostly we classify these interactions as insignificant

Amensalism (0,-)

• One species has a negative effect on the other but gains nothing by doing so

• Usually deals with one organism secreting a chemical as part of its metabolism

• Ex: Tree roots, Penicillium, cattle and sheep

Commensalism (+,0)

• One benefits the other doesn’t get squat

• Ex: Barnacles and Whales• Barnacles do nothing for the whale• However, Barnacles get free travel

Parasitism (+,-)

• One organisms lives on another organism (host) and harms it

• Parasitoid: Lives as parasite but kills host

• Usually parasites weaken but don’t kill• Ex: Ticks• Ex: Tapeworms

The Great Succession

• Ecosystems are constantly changing because of natural or human disturbances

• Old die out, new come in causing more changes

• Predictable changes over time are called ecological succession

Leading off

• Primary Succession: Succession that occurs on surfaces where no soil exists

• Ex: Usually occurs after volcanoes or glaciers

• First species to come into this new area and populate are called pioneer species

Following Up

• Secondary Succession: A disturbance (whether natural or human events) occurs and the ecosystems restores to normal

• Ex: Wildfires and Human Farming

Characteristics of Populations

• Geographic distribution (range): the area inhabited by a population

• Population Density: number of individuals per unit area

• Growth rate: We are going to look at this

Range

Three factors affect population size

• Births and Deaths• Pops. increase when births > deaths• Pops. stay the same when births=deaths• Pops. decrease when deaths > births

• Immigration (movement into an area) and Emigration (movement out of an area)

Mortality Rates

• Type I: Low death during the first part of life, towards end of life a lot if not most of pop. dies

• Ex: Humans and other mammals

Type II

• Constant mortality rate across entire lifespan of population

• Ex: Birds, squirrels

Type III

• Extremely high death rate early followed by low mortality later in life.

• Ex: invertebrates, fish, plants

Exponential Growth

• This occurs when the individuals in a pop. reproduce at a constant rate

• First it starts out slow but then takes off like a rocket

• All pops. would grow exponentially under ideal conditions

Logistic Growth

• Exponential growth does not continue naturally for very long.

• As resources becomes less and less, the growth of the pop. slows or stops

• This is referred to as logistic growth

You have Reached Maximum Capacity

• The largest number of individuals that an environment can support

• Anything below will have pop. increase

• Anything above will have pop. decrease

Growth Patterns

R-strategists

• Grow exponentially when conditions allow

• Temporarily large population size

• Live in unpredictable environment

• Reproduce early in life when favorable

• Produce many, small offspring that mature rapidly

• Parents provide little to none care

K-strategists

• Slow growth• Small population size• Stable environment• Reproduce later in life• Produce few, large offspring

that mature slowly• Provides a lot of parental care

Nothing can Grow Forever

• Limiting factor: anything that causes population growth to decrease• Ex: Limiting Nutrient

• Two main types of factors• Density-Dependent• Density-Independent

Density-Dependent

• A limiting factor that depends on pop. Size

• Become limiting only when the pop. Density reaches a certain level

• The factors affect large, dense populations commonly but don’t affect small populations as much

Examples of D-D

• Competition• The more individuals in an area, the sooner

they use up resources (one type of species)

• Two different species compete for the same resources, both are under pressure and will decrease pop. size• Usually leads to evolution into different niches

Predator-Prey Relationships

• Regulation of a prey species by the predator and vice-versa

• This usually creates a cycle of increase and decrease because of evolution

• Much easier to understand this using graphs

Parasitism and Disease

• Parasitic organisms work similarly to predators

• They weaken the host, making it more susceptible to diseases which can lead to death

Density-Independent

• Affects a population regardless of size

• These are events such as natural disasters and human interactions

• These can nearly if not completely wipeout entire populations

Human Growth

• Like most other populations, human population is on the rise.

• About 500 years ago, population became exponential growth

• Currently, we are still on the rise

Demographics

• Demography: The scientific study of human populations.

• Birthrates, death rates, and age structure help predict why some countries grow fast and others slow

Demographic Transition

• Demo. Transition: Dramatic change in birth and death rates.

• Before modern meds, birth and death were high

• With modern meds, death decreased• With education and rise in standard of

living, the birthrate has decreased

The Ageless One

• Age-structure diagrams: population profiles dealing with age of a population

• Key to determine growth: Look at how many are going to be in the reproduction age range. (Humans: ~ages 16-45)

India – ½ population under 25 Japan – large

middle age population

Kenya - many elders and many young

What does this mean for our future?

• Currently, scientists believe that the population will be over 9 million by 2050.

• Our population will eventually hit that logistic growth stage but the question is when?

• We may end up destroying the environment