Lecture 2- Evidence For Evolution

Question 1

What is a homologous structure

Answer 1

The similarity of form/ structure of a characteristic, but with different function. This supports the theory of descent with modification from a common ancestor

Question 2

Give an example of homology

Answer 2

Mammals have the same forelimb arrangement from shoulder to the tips of the digits, but use them for different functions. Eg. Whale for swimming, humans for walking

Question 3

What is a homoplastic character

Answer 3

A trait with similar function between two species, but these have evolved separately without a common ancestor

Question 4

Give an example of a homoplastic structure

Answer 4

Wings in dragonflies and bones

Era in humans and octopi

Question 5

What is a vestigial structure

Answer 5

An anatomical feature or behaviour retained in the evolutionary process. It was a key function in the organisms ancestor, but is irrelevant now

Question 6

Give two examples of vestigial structures

Answer 6

The skeletons of some snakes retain pelvis and leg bones

Humans retain an appendix

Question 7

What is embryology

Answer 7

Structures that are absent in the adult forms of organism but are found in their embryonic forms. This similarity shows common ancestry

Question 8

What structures do all vertebrate organisms have in the embryo?

Answer 8

Gill slits
Tails
Pharyngeal arches

Question 9

What do pharyngeal arches develop into?

Answer 9

Ears in humans

Gills in fish

Question 10

What type of evolution is homology a product of

Answer 10

Divergent ( as a single ancestor has split)

Question 11

What type of evolution is homoplasy a product of

Answer 11

Convergent ( different species develop, not inherit, different traits)

Question 12

What is biogeography

Answer 12

The study of the distribution of species and ecosystems in geographical space, which gives information on how and when they may of evolved

Question 13

What is allopatric speciation

Answer 13

Where one species is separated ( eg. From the disappearance of a land bridge or the formation of a river) and therefore evolve in DIFFERENT environments

Question 14

What is an endemic species

Answer 14

A species that cannot be found elsewhere in the world. This relates to the founder effect, where colonists from the mainland adapted to their new environment, this forming a new species

Question 15

What is convergent evolution

Answer 15

The independent evolution of similar features from different lineages

Question 16

When does convergent evolution occur? Give an example

Answer 16

This occurs when unrelated animals have evolved in similar environment in different ways, giving rise to similar characteristics.
Eg. Wings of insects, birds and bats

Question 17

Which evolutionary effect is an example of biogeography?

Answer 17

The founder effect. This is where invaders arrive at oceanic islands from the mainland, and over millions of years they evolve their form and function into a new species. However, they share a common ancestor with those on the mainland

Question 18

Give an example of evolution through bio geography

Answer 18

Ratites ( emus, ostrich, Rheas) all evolved from a common ancestor. This common ancestor was separated in the breakup of Pangea, and the species evolved separately from that point onwards is allopatric speciation

Question 19

How did biogeography work in New Zealand?

Answer 19

The only native land mammals in New Zealand were two species of bats. Humans introduced mammals to the country starting in 1769, when they migrated. This introduced new mammals which evolved in isolation, forming new species ( to their ancestors from the mainland)

Question 20

Which environments are fossils more common in and why?

Answer 20

Fossils are more common in aquatic environments, as terrestrial processes often destroy evidence of fossils and rates of burial are quicker in aquatic environments

Question 21

How does a fossil form?

Answer 21

1. the animal dies and begins to decay, with the soft parts of the organism breaking down first
2. Sediment accumulates stop of the fossil and sedimentation occurs
3. Increased temperature and pressure over time causes diagenesis, which forms the rock
4. Often the original fossil is worn away, but cast and moulds from mineral precipitates can form

Question 22

Explain the archaeopteryx fossil

Answer 22

Fossil that underwent exceptional preservation and is from the Jurassic period. Shows the direct evolutionary link of birds evolving from reptiles. This transition species shows evidence for evolution

Question 23

Explain how fossils show evolution

Answer 23

They show direct evidence of past organisms and these can be compared to modern species

Question 24

How can fossils be placed into the correct time zone

Answer 24

Litho stratigraphic correlation
Biostratigraphic correlation
Relative dating 
MOST IMPORTANT absolute dating 
This can be used to place organism in their correct zonations, and give a timeline for evolution

Question 25

List the 7 pieces of evidence for evolution

Answer 25

1. biogeography
2. direct experiment
3. Homology, vestigial strictures, homoplasy
4. the fossil record
5. embryology
6. comparative behaviour and biochemistry
7. hierarchial organisation of life

Question 26

Explain biochemistry as evidence for evolution

Answer 26

The dna contains a record of evolutionary change. Mutations result in changes in these genes occurring, and selection can then occur on the gene frequency.
Evolution results in continuous changes within genetic composition. Sequencing of this dna ( once changes have occurred) allows the genetic similarity between species to be measured. Closely related organisms have fewer genetic differences

Question 27

Explain how comparative behaviour provides evidence for evolution

Answer 27

Social behaviour is often more similar in species that are closely related( eg. Within primates), which can show common ancestor. However, this is not a strong line of evidence

Question 28

Explain how hierarchical organisation shows evidence for evolution

Answer 28

The ability to divide the living world into a hierarchy of units shows history of divergence, showing that they’re must of been a common ancestor

Question 29

What is a phylogenetic tree?

Answer 29

A tree that shows evolutionary relationships between organisms. Patterns of branching show how evolution from a common ancestor have occurred