ECOLOGY &

EVOLUTION Topic 5

IB Biology

Miss Werba

TOPIC 5 – ECOLOGY AND EVOLUTION

5.4 – EVOLUTION

1. DEFINE evolution.

2. OUTLINE the evidence for evolution provided by the fossil record, selective breeding of domesticated

animals and homologous structures.

3. STATE that populations tend to produce more offspring than the environment can support.

4. EXPLAIN that the consequence of the potential overproduction of offspring is a struggle for survival.

5. STATE that the members of a species show variation.

6. EXPLAIN how sexual reproduction promotes variation in a species.

7. EXPLAIN how natural selection leads to evolution.

8. EXPLAIN two examples of evolution in response to environmental change; one must be antibiotic

resistance in bacteria.

- 5.4 –

EVOLUTION

5.4.1

“The _________________ change in _________________ _________________

of a _________________”

• Cumulative change:

• Heritable characteristics:

• Population:

5.4.3 , 5.4.4, 5.4.5

This causes a

struggle for survival.

Finding, catching

Shelter, nesting sites

Attracting, fertilising

Catching, avoiding

Avoiding, tolerating

Resulting from…

5.4.7

• Variations that give an _________________ are selected for:

– The individual which can _________________ best in the _________________ for

_________________ will survive long enough to _________________ – and

_________________ the trait.

– _________________ of these _________________ will _________________ and over time,

the population will _________________.

• Variations that give an _________________ are selected against:

– The individual is _________________ to the _________________, making it

_________________________________ for them to survive. The individual is less likely to

pass on the trait.

– Frequency of these genes will _________________.

• Steps:

1. _________________ of _________________ OR _________________ _________________

2. _________________ for _________________ (due to selection pressures)

3. _________________ _________________ in a population

4. _________________ variations are _________________ _________________

5. _________________ to _________________ and pass on _________________

6. _________________ _________________ _________________ and _________________

becomes more common in population

5.4.8

• Some species have a _________________ _________________ time and

_________________ _________________ _________________

can be _________________ _________________.

• Most species have a _________________ generation time and the evolutionary changes are

_________________ – so there is only _________________ evidence for evolution.

• Examples of evolution:

– ___________________________________________________

– ___________________________________________________

Antibiotic resistant bacteria

• Most individuals in a bacterial colony are

_________________ _________________.

•

• Some of these variations will result in _________________ to

certain _________________.

• The _________________ _________________ will _________________.

• Resistance genes are passed on and the _________________________________________________.

• eg. Staphyloccoccus aureus bacteria (__________________________________) is usually treated

with methycillin.

• There is now a _________________ -_________________ strain of Golden Staph (MRSA).

• This is could cause big problems in the future, as bacteria could become _________________ to

_________________ _________________.

• Could create a colony of “_________________”!

• Worried? Go study _________________ and research new antibiotics!!!!!

5.4.8

Melanism in the peppered moth

• Up until mid 19th century, most peppered moths were _________________ in colour, but

_________________ _________________ did exist.

• Their light colour allowed them to _________________ against _______________________________

on the trees and rocks.

• _________________ produced _________________ and _________________. This soot covered the

trees and killed then lichen.

• The black mutant was now able to camouflage against the _____________________________ trees.

Its population _________________, while the population of white moths _________________ due to

_________________ by _________________.

5.4.2

• Some examples of the evidence for evolution:

– The ______________________ _____________________

– ______________________ ______________________ (or artificial selection)

– ______________________ ______________________

– Embryological similarities between different species

– Vestigial organs

– Similarity in body chemistry between different species

– Geographical distribution of different species

The fossil record

• A fossil is a ______________________ of an ______________________ which lived in the past.

• Examples of fossils include ______________________, ______________________, imprints, etc

• Fossils are _______________________________________

– and even _______________________________________!

• So the fossil record is ______________________.

• However, one of the most complete fossil records found has been that of the

evolution the horse.

• The study of fossils allows ______________________ about form and function, age, habitat,

locomotion, diet, etc.

• They clearly ______________________ a ______________________ of ______________________

______________________ over time.

• The fossil record shows that ______________________________________________________

____________________________________________________________________________

• ______________________ ______________________ have been discovered that demonstrate

change over time

• eg. Archaeopteryx lithographica

– Has _____________________________________

of bird/reptile characteristics

– Bird: wings, feathers, wishbone, bipedal

– Reptile: claws on wings, teeth, bony tail, scales

–

Selective breeding of domesticated animals

• Humans have been able to breed ______________________ traits in domesticated animals for

centuries.

• This is an ______________________ ______________________ ______________________,

______________________ the process of natural selection outlined by Darwin.

• When a desirable trait is observed, that individual will be allowed to

______________________, ______________________ the

______________________.

• Unlike natural selection, ___________________________________

_______________________________________________________

_______________________________________________________

Homologous structures

• ______________________ in ______________________ between different species, which may have

been ______________________ for ______________________ ______________________.

• This is evidence of shared or ______________________ ______________________ between the two

species.

• This provides ______________________ of ______________________ ______________________

(changing to suit one’s ______________________ ______________________).

• eg. the ______________________ ______________________ ______________________

– pent=5; dactyl=fingers

– They all have the ______________________, although the relative size of the bones may

differ

– However the ____________________ of the limb _______________ from flying to swimming

Sample questions

Topic 5.4:

1. Explain how natural selection can lead to evolution using antibiotic resistance in bacteria as an

example. [9]

2. Outline the evidence for evolution provided by homologous structures. [6]