Tuesday April 15th

• Essential Question: What resources are essential for an organism to survive

• Have out Cytochrome C activity from yesterday

• Today how does competition lead to evolution.

Evolution Flowchart

• Populations can either be evolving or stagnant. In order for a population to evolve the following must occur

1. There must be competition for resources and survival between individual

2. There must be variation in the population

3. The traits must be heritable

What Resources does an Organism Need

Brainstorm a list of items that an organism needs in order to survive and reproduce.

Resources an Organism Needs

• Organisms need a habitat that will provide them with

• Food (either a location with sun/thermal vents for consumers, prey for consumers, other organisms for decomposers)

• Access to water • Shelter from the environment and predation• Access to mates of the same species

Organisms are in competition for these resources

• Interspecific competition is competition between members of different species.

• I.E. The lion and hyena compete for the same food source

• What is another example?

This leads to changes

• Extinctions occur when my adaptations can no longer gain me the resources needed for survival

• Invasive species are a concern because they increase competition and change food chain at many levels

Competition

• Individual also compete with members of their own species. There are two ways that this happens. Biology has coined them contest and Scrambles

Contests

• Contests are when organisms directly fight over resources due to the species hierarchical structure (think head of the pack)

Scramble

• When organisms are looking for the same prey or resource but need to hunt for it on their own. They are indirectly competing.

Wednesday April 16th

• Essential Question: What events could lead to changes in the gene pool of a population

• Finish Notes from Yesterday

• Complete Study Guides

• Turn in Keystone Practice Exams!!!

Microevolution• Microevolution is the change in the gene pool over

short periods of time. This can be due to.• Mutations• Gene flow• Genetic Drift• Nonrandom mating (A mate is not chosen based on who is

easily available but on their traits)• Natural Selection (Certain traits in the population are better

suited for the environment leading to selection for those traits)

Mutations • A mutation introduces a

new gene to the population

• Mutations to the HOX genes that effect development lead to large scale changes in an organism

• Normally these mutations are negative

Gene Flow• A migration of new

individuals across and geographic barrier that has different traits or different ratios of traits. (gene flow)

Genetic Drift• A random series of events

where one of the possible genes is not passed to any member of the next generation (genetic drift).

Selection

• Sexual Selection or Nonrandom Mating– A mate is not chosen based on who is easily

available but on their traits

• Natural Selection – Certain traits in the population are better suited

for the environment leading to selection for those traits

Speciation

• In Order for new species to form they must stop Breeding

Types of Speciation

• Behavioral- Species only chose to mate with certain individuals based on specific traits.

• Geographic- Species are separated due to differences in the geography. One side of the mountain or another.

• Temporal- Members of the species breed at different times

Full Speciation

• Speciation is only complete when species can no longer successfully mate

• This can occur in two ways– Prezygotic (species physically can’t mate, have a

different number of chromosomes, or incompatible reproductive structures)

– Postzygotic (species can mate and breed but their hybrids are unsuccessful)