Chapter (Ch.16-17

Question 1

Lecture 16

Answer 1

Adaptation and speciation

Question 2

Adaptation

Answer 2

Adaptation : Feature of an organism that improves performance in its environment
Adaptation is the result of natural selection

THEN OVER TIME vvvv

Individuals with inherited characteristics which improve survival replace others with less favorable characteristics

Adaptive evolution

Question 3

Adaptations and its many examples

Answer 3

Shape of moth caterpillars resemble the food they grow on

The flower attracts the bee – mimicking the female bee

Question 4

Adaptations and its many examples 2

Answer 4

Organisms match their environment
Adaptation can be a complex process
Adaptation can result in better feeding, defense against predators, reproduction

All product of evolution

Question 5

Populations adapt to change

Answer 5

More Change means more Adaptation, and so on, forever.

Question 6

Adaptation is not perfect

Answer 6

Limits to adaptation
1. Lack of genetic variation can limit adaptation
One mutation needed for pesticide resistance

2. Multiple effects of developmental genes
   Multiple effects of these genes can limit evolving in a specific direction
3. Ecological trade-offs
   Good looking for mates – good looking for predators

Question 7

Species

Answer 7

Organisms that look very similar
?
Although common sense,
not always true

Organisms that can interbreed, give rise to fertile offspring
Organisms from different species cannot reproduce with each other
Thus, species are reproductively isolated

Question 8

Barriers to reproduction

Answer 8

Prezygotic: before fusion of gametes
»>**no mating *no fertilization

Postzygotic: after fusion of gametes
»>**no offspring *Hybrids are not successful

None or few alleles are exchanged between species
Members of the species share a pool of common genes and alleles
»>
Generally phenotypically similar to one another
Generally phenotypically distinct to members of other species
»»
Complicated definition of ‘species’
Bacteria, viruses, many plants

Question 9

Hybrids

Answer 9

Hybrids- hybridization
Distinct species that are able to interbreed
Many plant species

Question 10

So, ‘species’…..according to Biology

Answer 10

Species : A group of populations or organisms that can interbreed but are reproductively isolated from other such groups

Question 11

Speciation

Answer 11

Diversity on Earth is caused by speciation

Speciation: The process in which one species splits into two or more species reproductively isolated from one another

Speciation is actually the result of evolution of populations

Same factors: mutations, genetic drift, natural selection

       * Evolution of populations 
       * Reproductive isolation

Question 12

Speciation (Allopatric speciation)

Answer 12

Allopatric speciation: allo: ‘other’ – patric: ‘country’
*Speciation from geographic isolation
River, mountain, reaching a new island, etc…

Geographical isolation generally occurs when populations are separated by a distance big enough to limit gene flow

Question 13

Speciation (Sympatric speciation)

Answer 13

Sympatric speciation
Speciation with no geographic isolation

Many times due to ‘polyploidy’ (more than two sets of chromosomes), mostly in plants

Question 14

Lecture #17

Answer 14

History of life

Question 15

Evolution

Answer 15

Evolution: change in genetic characteristics in a population over time

Question 16

Macroevolution

Answer 16

Evolution above the species level
Origin of new genera or higher taxonomic groups
Study emphasizes how life on Earth has changed

Question 17

The Fossil Record

Answer 17

Preserved remains or impressions of organisms

Documents the history of life

Question 18

The fossil record, a guide to the past

Answer 18

Supports evolution

• Absolute dating
  
  • Radio-isotopes
    
    • Unstable, radioactive form of element
• 14C half-life: 5,730 yrs
  
  • Good for fossils younger than 70,000 yrs
• 235U half-life: 700 myrs
  
  • Good for older fossils

*Relative dating
Position in sediments, based on radio-isotopes in the rocks

Question 19

Gaps in the fossil record

Answer 19

Gaps exist because:
Organisms quickly decay
Fossil may be damaged by the environment
Fossils are difficult to locate

Ex: Pakicetus
Early whale ancestor
Bones suggest it was mostly a land animal
Shared features with modern whales
Genetic analysis Suggests whales are related to hoofed animals

Question 20

The missing link

Answer 20

Gaps or ‘missing links’

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