What is Evolution?

The process of change in the traits of populations over time.

Process by which species' characteristics change over generations.

Evolution does not occur within an individual.

Evolution does not occur within a generation.

Traits must have genetic basis.

Evolution occurs primarily through natural selection

Natural Selection is the process that determines which individuals within a species will reproduce and pass their genes to the next generation.

What is Evolution?

Proposed by Charles Darwin in his book “On the Origin of Species” published in 1859

Species— Those organisms potentially capable of reproducing naturally among themselves, and producing viable offspring.

Genes— Distinct pieces of DNA that determine an individual’s characteristics.

Population—All organisms of the same kind found within a specific geographic region. (have the potential to interact)

Natural selection can occur when: * Individuals within a species show genetically determined variation in traits

-this variation makes some individuals better at surviving and reproducing than others

*Offspring with a particular trait survive better than do those without that trait

*Over several generations, the frequency of that trait increases in the population

* More offspring are produced than survive to reproduce

Relatively constant resourcesand population size over time

Potential forrapid reproduction

Competition for survivaland reproduction

Variability instructures and behaviors

NATURAL SELECTION:On the average, the better adaptedorganisms leave the most offspring

Some variabilityis inherited

EVOLUTION:The genetic makeup of the population

changes over time,driven by natural selection

Observation

Conclusion based on observation

FLOW CHART FOR EVOLUTION

Evolution in action

Pepper Moths in England

two forms: light and dark

Light colored ones could blend in with lichens on trees

Prior to 1845, most moths light colored

Evolution in action

Pepper Moths in England

Light colored moths easy for birds to see on soot-covered tree, dark colored moths harder to see

Increasing pollution led to soot-covered trees without lichens

By 1950, most moths black

Several generations later

Several more generations later

Before 1845 Environment changes, now more black moths and fewer white moths survive to adulthood

1950

Several more generations later

TIME

Evolution in action Resistance to herbicides

Evolution in action Resistance to antibiotics

•Evolution does not just happen on long time scales

•Evolution is important for real-word issues: agricultural, conservation, health

* Disease dynamics

* Invasive species issues

* Antibiotic and pesticide/herbicide resistance

Coevolution:

When two or more species interact closely they can influence

each other’s evolutionary direction. In tightly coevolved interactions, evolutionary change in one species will lead to evolutionary change in other or the second species may go extinct.

Red Queen Hypothesis

Lewis Carroll's Through the Looking Glass: “in this place it takes all the running you can do, to keep in the same place."

Example: host / parasite coevolution

Interactions among organisms

Abiotic – Non-living factorsBiotic – living portion of the environment

What are some biotic factors that contribute to this differential survival and reproduction?

1. Predation

2. Competition

3. Parasitism

4. Commensalism

5. Mutualism

1. Predation (positive for consumer, negative for prey)

One animal consumes another

Interactions among organisms

Types of predators

Active predators: chase & overpower prey

Sit-and-wait predators: motionless until prey close enough to strike

Sit-and-wait predator

Antlion

The best defense is a good offense - chemical warfare

The bombardier beetle

A monarch caterpillar

HOW DO VULNERABLE ORGANISMS PROTECT THEMSELVES?

Cryptic Coloration: blend in with environment

Many prey items have traits that reduce predation

A moth The leafy sea dragon

Florida treehopper insects

A desert plant

The sand dab Nightjar bird

Cryptic Coloration a.k.a. camouflage

Living stone plants

Warning or aposematic coloration

The South American poison arrow frog

Warning Coloration: aposematic coloration - conspicuous to convey threat

Many prey items have traits that reduce predation

Startle coloration

the false-eyed frog

The peacock mothcaterpillar larva of the swallowtail butterfly

ADAPTIVE COLORATION AND MIMICRY

Types of Mimicry• 1. Batesian mimicry: mimic species resemble an

unplatable or venomous species (the model)• 2. Mullerian mimicry: all mimic species have

similar warning coloration. All mimics are usually toxic or harmful and function as both model and mimic.

Batesian Mimicry: defenseless species (mimic) is protected from predation by its resemblance to a species that is dangerous (the model); Henry Walter Bates was an English biologist who described a type of mimicry in tropical butterflies in the 1850's.

fly (bee mimic) bumble bee

coral snake mountain king snake

monarch butterflyviceroy

Naïve Blue Jay and a Monarch Butterfly

Batesian Mimicry in Plants: Stinging Nettle (model)

and the Yellow Archangel (the mimic)

Visual and behavioral mimicry

a jumping spiderthe snowberry fly

Mullerian Mimicry: Two or more distasteful or harmful organisms resemble each other; each serve as model and mimic. Fritz Muller was a German zoologist who described a different type of mimicry in 1878.

Interactions among organisms

1. Predation

Prey is harmed (-) by being eaten

Predator benefits (+) from food

Predation is a (+ / - ) relationship

Competition: organisms compete for the same limited resource

Ex. light, food, mates, habitat, etc.

2. Competition

Competition is a (- / - ) relationship

Interactions among organisms

Intraspecific competition — Members of same species competing for resources

Beetle vs. Beetle Fungus vs. Fungus

Interspecific competition:

Members of different species competing for resources

May lead to competitive exclusion

3. Parasitism

One organism (parasite) living in or on another organism (host), from which it derives nourishment

Ex. Tapeworm

Interactions among organisms

Parasitism is a (+ / - ) relationship

3. Parasitism (+,-) Ectoparasites—Live on host’s surface

(e.g., Fleas, lice, some molds)

Endoparasites—Live inside host.(e.g., worms, protozoa, bacteria, fungi)

Ex. Heartworm

3. Parasitism (+,-)

Parasitoid

Nest Parasitism

Common Yellow-throat

Adult cowbirds don’t build nests

Cowbird

Malaria carrying mosquito

Vectors: animals that carry parasite from one host to another

Examples: Malaria, Lyme Disease, West Nile Virus, Bubonic Plague

Interactions among organisms

4. Commensalism —One organism benefits, while the other is unaffected.

Commensalism is a ( + / 0 ) relationship

Remora and shark

4. Commensalism (+,-)

Interactions among organisms

5. Mutualism - Both species benefit.

Acacia and ants

*Tree provides sugar solution that the ants eats

*Ants defends tree against grazers

5. Mutualism (+,+)

Summary of 5 major Interactions

Predation + -

Competition - -

Parasitism + -

Commensalism + Neutral

Mutualism + +

Individual 1 Individual 2

How have people change these interactions?

1) Introduced species

2) Habitat destruction

Introduction of novel predators and parasites can devastate natural communities.

Over 2,000 species of birds have gone

extinct on islands as a result of habitat loss

and the introduction of predators and

parasites.

Hawaii:

Habitat loss, malaria, rats and mongoose

Points to know:

1.Know what evolution is and how is operates. Understand coevolution.

2.Know the 5 main types of species interactions.

3.Understand who benefits from each type of interaction (one or both participants)

4.Understand how humans may influence these interactions.

On-Line Sources of Information used to create this presentation

• http://www.uta.edu/biology/alie/1282/Lecture2.ppt#260,6,SUMMARY OF EVOLUTION

• http://www.life.uiuc.edu/ib/105/lectures/06_EcolInter.ppt#429,1,Slide