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WHAT IS THE DIFFERENCE BETWEEN A POPULATION

AND A SPECIES?

H

armful

A

daptive

N

o Value

Harmful – These types of mutations are detrimental to the organism

Either causing it to be less well adapted for its environment, or by causing a basic life function of the animal to function deficiently or not at all

www.ridacritter.com/ site_map.htm

http://www.ridacritter.com/albino%20sqhttp://www.moosefoundation.org/pictures/albino.jpgrrel%20005.jpg

http://www.ridacritter.com/albino%20squirrel%20http://www.weforanimals.com/free-pictures/wild-animals/moose/1/Bull%20Moose%20Resting%20in%20Vegetation%20-%20Burger,%20Carl%20-%20USFWS.JPG005.jpg

TAKE A MINUTE…

W

rite a brief list of how the albino organisms color

mutation is detrimental to that organism’s survival in

the wild.

A

daptive – These types of mutations cause the

organism to gain some advantage that increases its

ability to survive and reproduce successfully

A

daptive

E

xamples:

T

he ability to utilize another food source

D

isease immunity or resistance

M

akes the organism more competitive

E

xamples:

D

isease immunity or resistance

http://evolution.berkeley.edu/evosite/evo101/images/sicklecell.jpg

M

utations can make

the organism more

competitive

http://www.wonderquest.com/2003-01-31-giraffe-rhino.jpg

http://www.airs.com/ian/giraffe.gif

TAKE A MINUTES…

W

rite down a list of at few adaptations that the Giraffe

posses that increase its fitness within its

environments

N

o Value – These types of mutations do nothing to

either harm the organism or to make them more fit

M

utations assist a species because they cause a

variety of variations to exist within that species.

Adaptive mutations increase the fitness of a species

by providing increased variation

R

ecurrent mutation – a mutation for a trait that is

genetically different from either parent, but is

already present in the population

N

ovel Mutation – a mutation that results in a trait

that is not already present in the population

COMPETITION

C

onflict that arises between individuals or groups in

the process of acquiring limited resources

COMPETITION OCCURS BECAUSE OF….

L

imiting Resource

A

ny factor (usually a nutrient) within an ecosystem

that is in finite quantity and that is required by

individuals in that ecosystem for survival

TYPES OF COMPETITION

I

nterspecific - competition between different species

I

ntraspecific – competition within the same species

2 BIOLOGICAL IMPERATIVES

1

. Survive

2

. Reproduce

A

n organism is FIT if it accomplishes these 2 goals in that order.

I

n fact once an organisms has accomplished both goals that organism

will often expire soon for a variety of different reasons

FITNESS

“

The relative contribution an individual makes to the gene pool to the

next generation”

F

itness describes how successful an organism is at accomplishing the 2

biological imperatives.

C

ambell, Biology

TO CLARIFY…A

niche is what an organism does in its

community, its habitat is where it lives

http://www.job-interview-questions.com/executives.jpg

http://www.nypatriot.com/victorian-house.jpg

2

types

Fundamental niche – the resources (biotic and abiotic) that are

theoretically available to an organism

R

ealized niche – the resources (biotic and abiotic) that are actually

utilized by a given population

(Campbell, Biology)

COMPETITIVE EXCLUSION PRINCIPAL

• “Two species with similar needs for the same limiting resources cannot coexist in the same place” –Campbell, Biology

DARWIN’S OBSERVATIONS

1. If all offspring were able to reproduce successfully populations size would exponentially increase over a few generations

2. In natures populations sizes are relatively stable

3. Limited resources exist in all environments

4. Individuals within the same species have a variety of unique and distinct traits (every individual is different)

5. Many of these variations can be passed on to successive generations

WHAT THIS MEANS…

Competition results when more offspring are produced then can survive because resources are limited

Offspring that posses more beneficial characteristics are more likely to survive and pass on their genes

Because more fit individuals survive most often populations will shift over time to accumulate more beneficial characteristics

T

his is called….

NOTE

A

daptations are not static as environments change so

do the characteristics of a population. The best

combination of traits changes over time

N

ote: species do not develop a trait to cope with an

element in their environment rather a pool of traits

(range of variation) exist within a given population

and those that are best adapted survive more

frequently and reproduce more successfully.

ALSO NOTE

A

rtificial selection – human modification of species

(ex. Selective breeding)

Food

Habitat

Mates

Predation

Disease

Climate

Competition for resources ( invasive species)

NOTE…

O

nly traits that already exist in a population can be selected for

E

very adaptation is also a compromise

E

very adaptation has to be based on a preexisting element of the

organism

T

here cannot be a permanently perfect organism

The drive to reproduce can be strong enough in an organism to trump that organism’s drive for survival

INTRASPECIFIC NATURAL SELECTION…

http://scienceforfamilies.allinfo-about.com/zoo/peacock.jpg

A

feature possessed by a single sex that increases

reproductive fitness (generally in vertebrates)…

IMPORTANT

R

eproductive fitness can (but doesn’t have to) detract

significantly from the environmental fitness of an

individual ie.

T

he Peacock …

http://scienceforfamilies.allinfo-about.com/zoo/peacock.jpg

Please EAT ME!!

My big dumb

tail feathers

make me

easy to SEE!

And

easier to

catch!!!

NOTE

S

exual secondary characteristic can assist the animal

in survival such as a deer’s antlers, but it is often the

females that determine the fitness of a Sexual

dimorphism

ASEXUAL REPRODUCTION

“

the creation of new individual's whose genes all come from

one parents without the fusion of egg and sperm.”

-

Campbell Biology

E

ssentially Cloning the Parent

ASEXUAL REPRODUCTION

Organisms are well adapted to stable environments cloning maintains the “best combination for the current situation”

Less of a chance to introduce detrimental traits into the gene pool

No need to find or compete for mates (saves time and energy and can reproduce in isolation)

Can produce a large amount of offspring in a short amount of time

A

sexual reproduction is best suited to stable environments

in which individuals are already well adapted to survive

T

his is because the “best traits” are identically copied into

each successive generation

ASEXUAL REPRODUCTION

SEXUAL REPRODUCTION

“

the creation of Offspring by the fusion of haploid

gametes to form a zygote, which is diploid.”

-

Campbell Biology

SEXUAL REPRODUCTION

Adds more variety to the population so as a whole the

population is better situated to survive and prosper in rapidly

changing or new environment

B

est in new or rapidly changing environment

The Red Queen in “Alice in Wonder Land” had to run at full speed just to stay in the same place.

This means that “a species must continually evolve to survive in a world full of other evolving species” –the science of ecology

O

ne example are diseases. A cloned (or asexually

reproduced) population is highly susceptible to being

wiped out by a contagion.

P

redator prey relationships are another example

ADAPTIVE RADIATION

T

his process of modification over time to fill a variety

of niches is

TYPES OF NATURAL

SELECTION…

T

his type of selection encourages

the average or status quo

combination of traits.

I

t happens in environments

where there is little change

occurring

STABILIZING SELECTION

DIRECTIONAL SELECTION

T

his type of selection favors a specific

combination of traits that were relatively

rare in the original population

I

t happens in environments where there

is great change occurring or is a species

is moving into a new environment

DIVERSIFYING SELECTION

T

his type of selection favors traits on

either end of the spectrum but not the

middle

I

t happens in environments where there

is change but the new factors favor

multiple variations, this often happens

in a divergence of species

CONVERGENT EVOLUTION

W

hen unrelated groups have analogous but nonhomologous

features (wings in birds and butterflies, fins in squids and

seals), the process is called convergent evolution

(sometimes parallel evolution) - similar needs produce

similar structures, even if they're based on different

architecture.   Both support the concepts of evolutionary

change by selection.

D

ue to similar selection pressures that are consistent

over long periods of time, unrelated organisms (or

distantly related ones) acquire similar traits to deal

with those similar pressures.

CONVERGENT EVOLUTIONA

NATOMY• HOMOLOGOUS STRUCTURES• ANALOGOUS STRUCTURES

Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.

http://evolution.berkeley.edu/evolibrary/home.php

PUT ANOTHER WAY…

I

t is “the emergence of numerous species from a

common ancestor introduced into a new

environment, presenting a diversity of new

opportunities and problems”

– Campbell, Biology

T

his happens in instances when there exist unrealized

opportunities in a new environment.

O

ver time once rare characteristics are emphasized and

beneficial. This s divergent or directional selection

depending on the circumstance

DIVERGENT EVOLUTION

T

raits with similar internal structure

are called homologous traits

W

hen homologous features become used

for different purposes - are no longer

analogous - the process is called

divergent evolution, the splitting of

a family tree in different directions.