The Theory of Evolution Evolution - PowerPoint Presentation

Slide1

The Theory of EvolutionSlide2

Evolution

A mechanism for change in populations.

Any change in the

inherited

traits within a population across generationsSlide3

Individuals better adapted to their environment tend to survive and

produce more offspring

.

Natural Selection is a mechanism for changes in populations (evolution).

Natural SelectionSlide4

Natural Selection

In nature, organisms produce more offspring than can survive

.

Struggle for survivalSlide5

In any population, individuals have variations.

Variation

: Differences between members of the same speciesSlide6

Individuals with certain

useful variations

survive in their environment

,

They

pass

those variations to the next generation.

“

Survival of the Fittest”

Fitness

: How well an individual passes their genes on to the next generationSlide7

Over time, offspring with certain variations make up most of the population

They may

look entirely different from their ancestors.Slide8

Individuals better adapted to their environment tend to survive and

produce more offspring

.

Natural Selection is a mechanism for changes in populations (evolution).

Natural SelectionSlide9
Slide10
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The Weak Link of Natural Selection – Genetics

(The Modern Synthesis)

A major problem in Darwin’s theory was the lack of a mechanism to explain natural selection.

How could favorable variations be transmitted to later generations?

With the rediscovery of Mendel’s work, the missing link was forged.

Darwinian theory supported by genetics is known as the modern synthesis.Slide14

Adaptations

Any variation that aids in an organism

’

s chances of

survival

and

reproduction

in its environment.

Slide15

Forms of adaptations

Structural

Camouflage

Mimicry

Sexual selection

BehavioralSlide16

Behavioral Adaptations

Behavioral adaptations are the

things organisms do to

survive or reproduce

.

Migration, hibernation, nocturnal,

etc

Some types of sexual selection are behavioral.Slide17

Behavioral, cont.

Gerenuk Antelope (Africa) stand upright to feed on the leaves and shoots of Acacia Trees.

This is an example of a behavioral adaptation.

Cuckoo Bird DeceptionSlide18

Types of sexual selection:

Male to male combat- winners receive mating rights with a female or with a herd of females Slide19

Sexual SelectionSlide20

Structural Adaptations

A

change in the structure of the species

.

(

H

ow it looks)

A porcupine’s quills are an adaptation that keeps predators from approaching.Slide21

Sexual Selection

Special form of natural selection where species select on specific traits that indicate their choice is a successful mate

Usually the female is the “choosier” sex while males are left struggling for the possession of femalesSlide22

Sexual Selection:

Mate Choice- specific traits make one mate more attractive than another (ornamentation)

Birds of Paradise

Jumping SpidersSlide23

Camouflage

Camouflage enables species to blend with their surroundings.Slide24
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Mimicry

Mimicry is an adaptation that enables one species to resemble another.

For example, yellow jacket hornets, honeybees, and many other species of wasps all have harmful stings and similar coloration and behavior. Predators may learn quickly to avoid any organism with their general appearance.Slide27

Tree Hopper Mimic

Cyphonia

clavata

(Central America)Slide28
Slide29

Hiding, Camouflage, and Mimicry VideoSlide30

Co-Evolution:

When one species changes and evolves in response to changes in another speciesSlide31

Timing of Evolution

Gradualism

Evolution occurs slowly over the course of many generations (thousands or millions of years) Punctuated Equilibrium

Long periods of little change and then sudden bursts of rapid change

Caused by dramatic changes in environmentCan happen over several decades (or even less)Slide32

High Altitude-MountainsSlide33

DesertSlide34

TropicalSlide35

Convergent vs. Divergent Evolution

Convergent Evolution:

Organisms that are not related independently develop similar traits.Example: Dolphin fins and Shark fins

Divergent Evolution

Differences build up in individuals that can lead to the formation of a new species

Example:

Elephants

and woolymammothsSlide36

Speciation: When one species splits into two species that no longer interbreed and produce fertile offspring

Bird Speciation (8 min)

Crash CourseSlide37

Helpful Terms

Microevolution-

short period of time, populationsMacroevolution- geologic time, fossil record generations

Biodiversity-

the variety of life in the world or in a particular habitat or ecosystemSlide38

Speciation

The evolution of a new species occurs when members of similar populations

no longer interbreed to produce fertile offspring

within their natural environment. Geographic

isolation

occurs whenever a physical barrier divides a population.Slide39

Geographic isolation can lead to speciationSlide40

Homologous Structures

Homologous structures

can be similar in arrangement, in function, or in both

which evolved from some structure in a common ancestor.Slide41
Slide42

Analogous Structures

Analogous Structures

are when the body parts of organisms that do

not have a common evolutionary origin

, but are

similar in function

.

For example, insect and bird wings probably evolved separately when their different ancestors adapted independently to similar ways of life.Slide43

Analogous Structures Slide44

Vestigial Structure

vestigial structure—a

body structure in a present-day organism that no longer serves its original purpose, but was probably useful to an ancestor

, and present-day organism still have them in their

body plan for the species.Slide45

Examples of Vestigial Structures

pelvic bones

in the baleen whale

tiny snake pelvic and

limb bones

and the

eyes

in cave-dwelling salamanders and fish that are completely blindSlide46
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EX.: Wings in flightless birdsSlide49

Fossils

Fossils are an important source of evolutionary evidence because they provide a record of early life and evolutionary history.

https://www.youtube.com/watch?v=I2C-3PjNGok

Slide50

Section 15.1 Summary – pages 393-403

Fossils

Camel Evolution

Age

Organism

Skull and

teeth

Paleocene

65 million

years ago

Eocene

54 million

years ago

Oligocene

33 million

years ago

Limb

bones

Miocene

23 million

years ago

Present Slide51

Evidence for Evolution – The Fossil RecordSlide52

Embryology

Scientists have compared similarities in the origin, growth, and development of an embryo.

These similarities suggest common ancestry. Slide53

Evidence for Evolution - EmbryologySlide54

Comparing DNA

This also provides strong evidence for evolution.

Nearly all organisms share some of the same DNA base pairs.

The more base pairs that are the same the more alike or related the organisms are.Slide55
Slide56
Slide57

Genetic Variation

Populations, not individuals, evolve.

Natural Selection acts on the range of phenotypes of a population.Slide58

Mutations

Mutations – A form of genetic variation

Usually mutations on genes are lethal to an organism.

Occasionally a mutation results in a useful variation and that new gene becomes a part of the populations gene pool.Slide59

Section 15.2 Summary– pages 404-413

The Evolution of Species

When geographic isolation divides a population of tree frogs, the individuals no longer

mate across populations.

Tree frogs are a single population. Slide60

Section 15.2 Summary– pages 404-413

The Evolution of Species

The formation of a river may divide the frogs into two populations. Slide61

Section 15.2 Summary– pages 404-413

The Evolution of Species

Over time, the divided populations may become two species that may no longer interbreed, even if reunited. Slide62

Evidence for Evolution – Evolution Observed

Evolution of drug-resistance in HIVSlide63

Evolution of pesticide resistance in response to selection.Slide64

Evolution

The change in populations over time.