What is Evolution? The process of change in the traits of populations over time. Process by which...
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Transcript of What is Evolution? The process of change in the traits of populations over time. Process by which...
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 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
The best defense is a good offense - chemical warfare
The bombardier beetle
A monarch caterpillar
HOW DO VULNERABLE ORGANISMS PROTECT THEMSELVES?
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
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
Endoparasites—Live inside host.(e.g., worms, protozoa, bacteria, fungi)
Ex. Heartworm
3. Parasitism (+,-)
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
Interactions among organisms
5. Mutualism - Both species benefit.
Acacia and ants
*Tree provides sugar solution that the ants eats
*Ants defends tree against grazers
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