Adaptation

Question 1

Evolution Definition

Answer 1

• Evolution: Changes in the heritable properties of populations of organisms over the course of generations
  
  • result in a a change in the frequency of alleles with in a gene pool over generations (doesn’t have to be an adaptation)

Question 2

Evidence for evolution (5)

Answer 2

• Fossils: shows transitional forms and new (but similar species that arise)
• Genetic variation w/in existing species
• Relationships between existing species (morphology, beh., genes)
• Imperfections (e.g. whales having small bones for hind legs)
• Can experiment and observe natural selection

Question 3

Common features of Darwin’s Natural Selection (3)

Answer 3

1. Variation in traits (is what selection can act upon)
2. Heredity
3. Differential reproduction (trait survives better in those that can reproduce better)
   
   • aka Darwinian fitness

Question 4

Types of traits and advantage they give

Answer 4

• Unfavourable traits: compromise reproduction (are therefore eliminated)
• Beneficial traits: are spread
• Neutral traits: can reside within population as neither help nor harm an organism

Question 5

Principles of natural selection (4)

Answer 5

• More offspring produced than what can survive
• Variation in particular trait
• Genetic basis of trait means it is inherited
• Differential reproductive fitness (beneficial trait = more offspring produced)

Question 6

Definition;
Biological species
Genotype
Phenotype

Answer 6

• Biological species: Groups of interbreeding natural populations that are reproductively isolated from other such groups
  - explain why members of species resemble each other (form phenetic clusters)
• Genotype: The set of genes carried by an organism
• Phenotype: The actual expression of the genotype (only a subset of genes are actually expressed)

Question 7

2 Modes of Speciation

Answer 7

1. Allopatric Speciation: “Other country”
   
   • Geographical separation of the diverging populations - is some barrier b/w populations
2. Sympatric Speciation: “Same country”
   
   • Without geographic speciation

Question 8

Mechanisms of Speciation (how does it occur)

• Pre-mating isolation (3 types)
• Post-mating isolation (2 types)

Answer 8

1. Pre-mating isolation: Prevents cross breeding before occurs
   
   • Seasonal/habitat isolation: Mates do not meet
   • Behavioral isolation: Meet but do not mate
   • Mechanical isolation: Attempt to mate but cannot
2. Post-mating isolation: Prevents fertilisation or further development
   
   • Hybrid mortality: egg fertilised but hybrid dies
   • Hybrid viable but partially or completely sterile (e.g. mules)

Question 9

Defintion;-

Adaptation

Adaptive traits

Answer 9

• Adaptation: The process, through evolution, that allows organisms (or sets of genes) to better survive in their environment
• Adaptive traits are any physiological or behavioural feature that allows or enhances survival and reproduction
• Can have evolution without adaptations (but adaptation very strong driver for evolution

Question 10

Definition;

• Adaptive Radiation
• Adaptive Niche and e.g.

Answer 10

• Adaptive Radiation: a process of adaptive evolution in which variations of a single species fill different niches and eventually become a new species
• Adaptive Niche: The role of an organism in its community; what and where it eats, and what eats it
  
  • is a finite number and hard to occupy new niche
    
    • e.g. horses; as niches became available, began to fill them = 25 general of horses

Question 11

Divergent Evolution in the Galapagos island

Answer 11

• Repeated colonisation from S america by plants and animals
• Founder effect: small no. of organisms go onto island and then speciate
• many population crashes = reshuffling of gene proportions
• Different islands also had organisms with different morphologies due to differences in environment
  
  • is less competition if animals exploit a range of environmental niches

Question 12

Divergent Finches - Example of Divergent Evolution

Answer 12

• Land on the backs of other birds, open a wound and drink blood
• Probably arose from feeing on external parasites such as ticks
• also roll eggs from nests to break them and feed on contents

Question 13

Hybridization

• what it is and when likely to occur
• e.g. in wild

Answer 13

• Where similar animals come back together and mate, can lead to new species forming
  
  • esp occur after unusal or catastrophic conditions
    
    • many wild geese and ducks hybridise

Question 14

Parallel evolution

Convergent Evolution

Divergent Evolution

Answer 14

Parallel Evolution: Occurs when species with a similar ancestor develop similar traits over time - due to shared environment or pressures

Convergent Evolution: Species that are not related, independently develop similar traits

Divergent Evolution: Where a species evolves into two or more different forms (have a common ancestor)

Question 15

Artificial Selection

Answer 15

• Where humans cause evolution by selecting for some traits

e. g. Trophy hunters for Alberta rams means horn size fell

Question 16

Assortive differences - e.g. of can toads

Answer 16

• Cane toads at front of pack are faster - breed with each other to pass on fitter genes
  
  • means that cane toads in W.A are smaller and fitter than the fat ones in Queensland
• is an example of evolution across space

Question 17

Assortative Selection

Answer 17

• Is a mating pattern and form of sexual selection whereby organisms choose to mate with organisms with similar genotypes or phenotypes more frequently than if they mate randomly
  
  • may increase genetic relatedness w/in a family