1. Ecology
The study of how organisms interact with each other and their environment

2. Key Elements of the Environment
Temperature – most organisms require a narrow range (humans excluded)
Water – very important, much more diversity in rainforest than in desert
Sunlight – where almost all energy originates from
Soil – pH, minerals, nitrogen, phosphorus affect the ability of plants to grow

3. Population properties
Population size – number of individuals
Population density – number of individuals in a given unit
Los Angeles – 7544 people/square mile
South Sioux City, NE – 2725 people/square mile
Manila, Philippines – 111,576 people/square mile
New York City – 27,012 people/square mile
Population dispersion
clumped
uniform
random

4. Population growth
Population at current time = population from past time + births during that time – deaths during that time + immigration – emigration
Simulation of population growth – start off with 10 people (5 couples) – each couple has 4 kids
How many offspring? - 20
20 children become adults and each couple has 4 kids
How many offspring? – 40
Doubles each generation – so let’s draw a graph

5. Population growth
Exponential growth – the larger the population, the more it will grow
Eventually this has to stop
Space
Availability of resources
Carrying capacity – the max population
This type of growth is called logistic growth (sometimes called a sigmoid curve)

6. Factors that influence population density
Density-independent events
Severe weather (floods, drought, etc.)
Severe geological disturbances (volcanoes, earthquakes, etc.)
Density-dependent events
Aggressive behaviors (defending territory)
Emigration

7. Maximizing population productivity
Demand for fish has increased due to general health benefits and increase in global population
Overharvesting has caused population decline in wild salmon
Salmon farms have helped alleviate the problems of overharvesting
Farms have negative health and ecological impact
Toxins in fish
Fish lice and viruses are becoming common if farmed salmon, which are passing them on to wild salmon
overharvesting
Wasting resources
Maximum sustainable yield

8. Demography The study of populations using statistics
Cohort – A group of individuals that are the same age
Fecundity – Number of offspring produced in a standard time (for example, a year)
Mortality – The number of individuals that die in that time
Proportion of males to females is called the sex ratio

9. Survivorship curve Type I – Most live a long time, then suddenly die
Type II – constantly die off
Type III – many die off young, the ones that survive live for quite some time

10. Community and Ecosystem
Community - all the species in a given area
Ecosystem – all the species and all the non-living components in a given area

11. The Niche and Competition
Niche – all the ways in which an organism uses its habitat
Habitat – the place where an organism lives
Competition – when two organisms attempt to use the same resource
Interspecific – between two different species
Intraspecific – between the same species

12. Fundamental Niche vs. Realized Niche
Fundamental Niche – where a given species is ABLE to live
Realized Niche – where a given species actually lives because of competition

13. Competition
Competitive exclusion - If two species are competing for the same resource, the one that uses it more efficiently will out grow the other
Population
Time
P. Bursaria grown separately
No two species can occupy the same niche if resources are limited. If two species coexist…
Resources are not limited
They do not occupy the same niche

14. Resource partitioning
Competition between two species is rare in nature because of 2 reasons:
One would outcompete OR
A new niche would be formed by dividing up resources – resource partitioning
Sympatric – closely related species that divide up resources – must live close to each other
Allopatric – closely related species that do not divide up resources – so usually do not live close to one another
Allopatric species look more alike than sympatric species – called character displacement

15. Character Displacement
Character displacement is not the same as disruptive selection

16. Coevolution
Symbiosis – two organisms that live together and whose existence is altered because of this relationship
Mutualism – both benefit
Commensalism – one benefits, other is unharmed
Parasitism – one benefits, other is harmed
Sometimes parasitism can be considered a predator-prey relationship

17. Predator/Prey cycles
Predation – the consuming of one organism by another
Predator – the one doing the eating
Prey – the one being eaten

18. Defense against predators
Plants
Thorns
Spikes
Prickles
Chemicals (pungent tastes usually associated with toxicity)
Many others
Animals
Poisons
Warning coloration
Camouflage
Speed

19. Mimicry – a type of defense
Batesian mimicry – non-harmful organism mimics the look of a harmful organism
Mullerian mimicry – similar pattern development between harmful organisms
Self-mimicry – one body part looks like another body part
Mullerian
Batesian
Mullerian
poisonous
Non-poisonous
venomous

20. Ecological succession
Succession – more complex communities replace simpler ones as time goes on
Primary Succession – occurs on a substrate that never had life prior
Examples: volcanoes, rocks, lakes left by glaciers
Secondary Succession – occurs on a substrate that had life prior, but was almost completely wiped out
Deforestation, flood, fire