Evolution II Flashcards
What is comparative anatomy?
- The study of the evolutionary relationship between species
- Compares the similarities and difference in anatomy
What are homologous structures?
- Found across different species, have similar patterns and have different functions
- Consequence of divergent evolution
- Basic patterns due to common ancestry
- Different functions or appearance due to environmental conditions
Homologous structure example: pen dactyl limb
- Found in all groups of tetrapods (4 legged vertebrae)
- All limbs follow the same bone pattern: 5,2,1
- 5 fingers
- 2 bones on forearm
- 1 bone in the upper arm
What is comparative embryology?
Study of embryos which highlights evidence towards the theory of evolution
e.g. fish, amphibians, reptiles, birds and mammals
the embryos: all have gills but these will disappear in all but fish
All had tails attached by a tail bone, with the tail disappearing in all but fish
What is molecular biology?
Involves comparing DNA sequencing and amino acid sequences of different species
What is mRNA and what does it do?
- mRNA is messenger ribonucleic acid and a record of DNA
- carries the message from inside the nucleus to outside the nucleus where it can be translated into amino acid sequences which codes for a specific protein
What are the bases in mRNA?
Adenine, Guanine, Cytosine, Uracil (instead of thymine)
Relationship between DNA, mRNA, amino acid sequence and proteins?
DNA sequence determines mRNA sequence determines amino acid sequence determines proteins
What is DNA hybridisation?
- Comparing DNA sequences of different species, give a percentage of the similarities between the species
- Generate a percentage of differences between organisms
- Thus prove the theory of divergent evolution
What are the steps of DNA hybridisation?
- Prepare a section of DNA and separate strands by heating them
- Allow separated DNA strands of different species anneal
- Now have hybrid strands of DNA
- Reheat hybrid strands, until they separate again
Where a lower separating point: the samples are not as closely related due to its less base pairing
Where a higher separating point; the samples are closely related to extensive base paring
How are proteins suggestive of a common ancestor?
- Amino acid code for proteins
- Proteins are common in many different species but have a different number of amino acids coding for that protein
How is haemoglobin suggestive of a common ancestor?
- Found in many different species
- All serve the function of binding oxygen in blood
- Differ in amino acid sequence between species
How is insulin suggestive of a common ancestor?
- Mammals produce insulin to maintain sugar levels in blood
- That insulin from pigs can be used in humans as a replacement
How is cytochrome- c suggestive of a common ancestor?
- Involved in converting energy into a form, cells can use
- The number of cytochrome-c varies
- With fish having 20- 25 more amino acids than we have, but monkey only have 1 more
What does molecular biology reveal about the DNA of humans and chimpanzees?
That their DNA vary by 1%
Classification of humans:
Animalia Chordata Mammalia Primates Homonide Homo Sapien
What is anneal?
Is the heating and slowly cooling to allow re-joining
What is mass extinction?
- Thousands of species dying all over the world due to one cause
- Commonly due to climate change or meteor strikes
What are some factors of modern extinction?
- Deforestation:
- Hunting:
- Introduced species: species brought from foreign countries, may become more advantages than the native species in survival
CASE STUDY: cane toads
- 1936
- Introduced to control beetles that were damaging the sugar cane crops
- Made the beetles extinct but the cane toad became a pest
- Spread and bred quickly whilst poisoning native species and taking their habitat
Why as human we are required to protect endangered species?
- All species have a place in the food web, and removal of one would have a major effect on the rest of the organisms in the food web
- Most of our crops we used for feed were from wild plants and is necessary to maintain them due to rising world populations
- Wild species recycle nutrients back into nature to keep the soil fertile
- All species have the right to exist without threatening survival by human interference
What are some strategies to prevent extinction?
National parks: regions in an ecosystem are being established as ‘national parks’ as the species numbers are monitored. And are area free of human interference, allowing species to breed freely.
Botanical gardens and zoos: Similar to national parks similar to national parks but the animals are held in captivity
Restricted zones: physical barriers around protected land for species to regenerate
CASE STUDY: dodo
- Large flightless birds with a hooked beak
- Extinct in 1681, found on Mauritius
- From an ancestor who could fly
- The island has plenty of food and shelter
- Island had no predators, no need to fly
- Dodo evolved into a flightless birds
Human intervention 1958 - Dodos was hunted for food
- Deforestation reduces habitats and food
- Introduction of pigs, cats and rats destroyed the dodos nest
