5.1 Evidence for Evolution

Question 1

Evolution is

Answer 1

the cumulative change in the heritable characteristics of a population over time

Question 2

Cumulative change

Answer 2

small changes upon small changes over many generations

Question 3

Heritable characteristics:

Answer 3

gene-controlled factors that are passed down from parents to offspring

Question 4

Population:

Answer 4

not an individual

Question 5

Evolution occurs by the mechanism of

Answer 5

natural selection

Question 6

The fossil record is

Answer 6

the sum of all discovered and undiscovered fossils and their relative placement in rock

Question 7

As scientists began studying layers (strata) of rocks

Answer 7

it became clear the layers closest to the top are most recent, and layers closer to the bottom are most ancient.

Question 8

dating of rock layers and fossils was determined in the 20th century with

Answer 8

radioisotope dating - the fossil record provides the dimension of time to the study of evolution

Question 9

fossil records as evidence for evolution

Answer 9

Sequence in which fossils matches sequence in which they would be expected to evolve
- Bacteria and simple algae first, then fungi, worms, etc.

Sequence fits with the ecology of organisms
- Plant fossils present before animals, plants on land before animals on land, plants suitable for pollination before insect pollinators

Fossils present that show the transition of ancient species into their present day descendants

Fossils show a chronological (time) sequence in which characteristics appear and develop in complexity

Question 10

There are gaps in the fossil record due to:

Answer 10

Unideal conditions for fossilization
Only hard parts of organism are preserved
Damage of fossils leaving only fragments

Question 11

Transitional fossils

Answer 11

show the links between groups or species by exhibits traits common to both the ancestral group/species and its derived descendant group/species.

Question 12

Archaeopteryx

Answer 12

is a famous example transitional fossils – it gives evidence for the evolution of birds from dinosaurs.

Bird features:
feathers

Dinosaur features include:
jaws with sharp teeth
three fingers with claws
long bony tail

Question 13

Selective breeding (also called artificial selection) is

Answer 13

the process by which humans breed animals and plants for particular traits

Question 14

The effectiveness of artificial selection is shown by the considerable changes that have occurred in domesticated animals over

Answer 14

short periods of time

Question 15

Domestic breeds show great variation compared to wild populations subject to only natural variation.

Examples:

Answer 15

Breeding dogs for herding, e.g. sheepdogs or racing, e.g. greyhounds
Cows are bred for milk yield or meat
Crops have been bred for increased yield and/or disease resistance

Question 16

Selective breeding (also called artificial selection) is

Answer 16

the process by which humans breed animals and plants for particular traits

Question 17

Domestic breeds show great variation

Answer 17

compared to wild populations populations subject to only natural variation.

Question 18

Analogous structures are similar in function

Answer 18

but differ in structure
Analogous structures DO NOT show common ancestry

Question 19

convergent evolution

Answer 19

Darwin believed that these similarities are a result of different organisms adapting to similar environments

Question 20

Comparative anatomy

Answer 20

of groups of animals or plants shows certain structural features are basically similar.

Question 21

Homologous structures

Answer 21

are similar in structure but different in function.

Homologous structures ARE EVIDENCE of a common ancestor.

Question 22

Darwin believed that these structures resulted from similar organisms adapting to different environments/needs –

Answer 22

adaptive radiation

Question 23

Homologous structures are difficult to explain without evolution –

Answer 23

more likely that structures evolved once vs. many times in the history of organisms

Question 24

Vestigial structures

Answer 24

are remnants of organs or structures that had a function in an early ancestor

Darwin referred to these as “rudimentary organs” – they are easily explain by evolution as structures that no longer have a function and so are being gradually lost.

Question 25

The pentadactyl limb in vertebrates is an example of a

Answer 25

homologous structure

Question 26

It is adapted to different mode of locomotion in particular environment. Ex:

Answer 26

dolphin fin for swimming
bat wing for flying
monkey hand for grasping
horse hoof for galloping

Question 27

Populations of a species can gradually diverge into separate species by evolution.

Answer 27

1. If populations, e.g. fruit flies, become separated (e.g. a population is blown by a storm to a distant island). Then it is very likely the population will experience different ecological conditions.
2. Over many generations the characteristics of the two populations (shape of the flies, food preference, mating rituals etc.) will likely diverge as the result of natural selection.
3. The two populations may meet again but they may not easily mate
   Mating rituals are different
   Because of genetic differences the resulting offspring are infertile
4. Because genes flow between the populations is reduced, the island fruit flies are said to have evolved into separate species (this process is called speciation).

Question 28

Speciation often occurs after a population..

Answer 28

extends its range through migrating to an island
This explains the large number of endemic species on islands

Question 29

Endemic species

Answer 29

species that is only found in a certain geographic area

Question 30

The greater the geographical separation and the longer the populations have been separated the

Answer 30

greater the divergence

Question 31

Variation:

Answer 31

Peppered moths (Biston betularia) moths are found in two forms

White (typical)
Black (malanistic)

Question 32

Industrial melanism

Answer 32

development of melanistic insects in polluted areas