Animal Evolution

Question 1

What is evolution important for?

Answer 1

Medicine, Agriculture and Conservation

Question 2

What is a theory?

Answer 2

Comprehensive explanation of an important feature of nature, supported by facts gathered over time

Question 3

Facts of Evolution:
Direct observations of evolutionary change

Answer 3

Small changes within a population/species

Question 4

Facts of Evolution:
Homology

Answer 4

Present patterns to infer processes in past
Sharing common ancestors

Question 5

Facts of Evolution:
Fossil Record

Answer 5

Evidence of gradual change over time

Question 6

Facts of Evolution:
Biogeography

Answer 6

The scientific study of geographic distributions of species, past and present

Question 7

Micro-Evolution

Answer 7

Small changes within a population/species

Question 8

Macro-Evolution

Answer 8

Large changes over a long period of time

Question 9

What is evolution?

Answer 9

Change in the genetic composition of a population from generation to generation

Question 10

What is natural selection?

Answer 10

A process whereby individuals with certain heritable traits survive and reproduce at higher rates than others

Question 11

What are the four components of natural selection?

Answer 11

Variation, inheritance, selection and time

Question 12

What is the result of natural selection?

Answer 12

Adaptation: Any trait that enhances the chance of survival and reproduction

Question 13

Selection “for”

Answer 13

Phenotypic attributes, causes differential survival and reproductive success

Question 14

Selection “of”

Answer 14

Genotypes from one generation to the next, allows phenotypes to be ‘rebuilt’ each generation.

Question 15

What is sexual selection?

Answer 15

Traits that improve mating chances

Question 16

Intersexual selection

Answer 16

Inter: Traits which facilitate one sex to attract another sex

Question 17

Intra sexual selection

Answer 17

Intra: Traits which facilitate competition within a sex

Question 18

Stabilising Selection

Answer 18

Elimination of extremes
Maintains the average

Question 19

Directional Selection

Answer 19

Increase in extreme phenotype
Common during environmental change
Or migration into a new habitat

Question 20

Disruptive Selection

Answer 20

Increase in two extremes of phenotypes at expense of intermediate forms

Question 21

Biological species concept

Answer 21

Group of distinct organisms capable of interbreeding but reproductively isolated from other species

Question 22

How is interbreeding prevented?

Answer 22

Postzygotic and prezygotic barriers

Question 23

Prezygotic barriers

Answer 23

Habitat, temporal, behavioural, gametic and mechanical isolation

Question 24

Allopatric Speciation

Answer 24

Geographic isolation of populations
Natural selection operates to form sub or separate species

Question 25

Postzygotic barriers

Answer 25

Reduced hybrid variability, reduced hybrid fertility, hybrid breakdown

Question 26

Sympatric Speciation

Answer 26

Ecological diversification, no physical barriers, e.g. due to habitat preference

Question 27

What is a phylogenetic tree?

Answer 27

A branching diagram that represents a hypothesis about the evolutionary history of a group of organism

Question 28

Divergence

Answer 28

When two species diverge from a common ancestor and develop different characteristics

Question 29

Convergence

Answer 29

When two species with different ancestral origins develop similar characteristics

Question 30

Cambrian Explosion

Answer 30

Most major phyla of animals appear Increase in diversity Rise of O2 in atmosphere Predator-prey relationships

Question 31

Colonisation of Land

Answer 31

500 mya Aquatic --> terrestrial - Breathe air - Prevent dehydration - Reproduce on land - Locomotion

Question 32

What causes mass extinction?

Answer 32

Major climate changes Volcanoes Impact theory

Question 33

What caused the distribution of life?

Answer 33

Continental drift 2cm/year Allopatric speciation

Question 34

What controls development genes?

Answer 34

Rate of development Timing of development Spatial pattern of development

Question 35

Hox genes complex steps

Answer 35

1. Hox genes direct development of major body parts 2. Duplication mutation occurred, associated with vertebrates 3. Duplicate gene took on the role of creating a backbone 4. Second duplication mutation occurred leading to greater structural complexity such as jaws and limbs 5. The four clusters of vertebrate hox genes are homologous to the single cluster in invertebrates

Question 36

How does new form arise?

Answer 36

The evolution of anatomy turns out not to be gene changes but changes in the regulation of genes that control development

Question 37

Extinction vortex

Answer 37

Small population Genetic drift + inbreeding Loss of genetic variability Reduction in fitness Lower reproduction + high mortality Smaller population

Question 38

Genetic diversity loss

Answer 38

Long term: Loss of adaptive potential Short term: Reduced ability to respond to environmental changes

Question 39

Genetic Rescue

Answer 39

An increase in population fitness owing to immigration of new alleles