Week 8 Flashcards
What evidence supports the theory that dinosaurs were the ancestors of birds?
Fossilised feathers were found on a dinosaur called Anchiornis.
What do fossils of fish and amphibians of the Devonian period have in common?
Bones and limbs
Do these bones of fish and amphibians stay the same over time?
No. There is a gradual change in the structure of the whole limb over time.
Define evolution?
A genetic change in the characteristics of a species over many generations, resulting in the formation of a new species.
Define generation?
The time between the birth of an individual and when that individual produces their own offspring.
The fossil of which animal is a good example of changes over generations?
The horse
How many different genera of the horse have been found and dated?
17
Name the four changes in the horse and the height of each one?
Hyracotherium-0.4 m
Mesohippus-0.6 m
Merychippus-1 m
Equus-1.6 m
How are organisms classified?
On the basis of their structure
What did biologists studying evolution from 150 years ago think about structure.
Organisms that were very similar in structure must be related
Describe natural selection?
An environmental factor acts on a population and some organisms have more offspring that others
What is a selective agent?
The environmental factor that acts on a population
Define biotic factor?
A living thing
Eg: predation, bacterial infection, competition
Define physical factor?
A more environmentally based factor
Eg: susceptibility to fire, soil nutrients
Describe how selective agents that kill individuals act?
By preying on the poorly adapted and less fit individuals
Describe how sexual selection works?
Organisms are selected to breed based on what they look like or their sexual appeal
Describe how selective agents change populations?
Favoured individuals pass on their genes and features to the next generations.
Populations change and they become better suited to their environments.
What is meant by variation?
Natural selections in the population caused by differences in genes.
How is natural selection related to genetics?
Natural selection is the change in the proportion of a genotype of a species over many generations due to the environmental selection of a phenotype.
What did Charles Darwin propose?
Natural selection could result in the formation of new species
What does the theory of evolution propose?
Similar species must be closely related to each other
What does similarity between species indicate?
They had a common ancestor at some time in the past.
Which creature did Darwin study to come up with his theory?
Finches
Which part of the creature caused Darwin to believe that finches had a common ancestor?
Their beaks
What did he believe caused what did Darwin believe caused the difference in the finch’s beaks?
The different beaks had been selected for the different food sources found on different islands
Can you determine if two organisms are from the same species from their anatomy?
No, it’s impossible
What is the test for a species?
To see if two organisms could interbreed to produce fertile offspring under natural conditions.
Give an example of an interbred species?
The mule, produced by crossing a horse and a donkey.
Which method is mostly used by biologists today to see if organisms are the same species?
They study DNA and also identify the similarities in the amino acid and arrangement in the proteins they make.
Define specification?
The process by which one species splits into two or more separate species
Define biodiversity?
The number and range of species that exist, either on the whole Earth or any of Earth’s ecosystems
How is specification related to biodiversity?
Specification has resulted in the high level of biodiversity on the Earth
List the three basic steps of specification?
1) Variation
2) Isolation
3) Selection
Which group of organisms were the ancestors of birds?
Dinosaurs (the theropods)
Under what condition is natural selection able to act?
There must be variation in the population or specification cannot occur
Define isolation?
Where different groups of the breeding population are prevented by some mechanism from interbreeding
What does isolation prevent?
Gene flow throughout the population, stopping any differences in one population from reaching the other population
List some ways that isolation occurs?
By a geographical or climate barrier
After isolation, what does natural selection affect?
The genotype. It also causes changes that prevent the groups breeding
List some changes that can occur that will prevent individuals of different species breeding
Courtship behaviour-animals may develop different breeding songs, displays and rituals
Breeding seasons-animals may breed at a different time of the year
Sterility-animals may breed but the offspring are sterile
Chemical barriers-sperm may be killed by the chemistry of the female
Is isolation only caused by geographical barriers?
No, it is also caused by climate change
Once a change in genotype has occurred, could individuals with different genotypes breed?
No, the changes prevent the groups breeding
How are early fossils different to later fossils?
Early fossils are of fairly simple organisms and later ones are increasing complex.
Explain why early fossils are of simple organisms and later ones are of complex organisms?
New alleles and genes develop from existing genes by mutation
List three species that have become extinct?
Dinosaurs, diprotodons, marsupial lions
Give two examples of transition forms.
Lobe-finned fish: part fish, part amphibian
Archaeopteryx: dinosaurs that had feathers
Define comparative anatomy?
It compares the structures of organisms of both living species and fossils
Give an example of a homologous structure that provides evidence of evolution?
Pentadactyl limbs provide evidence from a single vertebrate ancestor
How are all living cells the same?
They all have the same basic structure basic structure and use the same genetic code
How are proteins produced?
From genes that all come from the same set of amino acids
What is the relationship between genes of different organisms and the similarity of different organisms.
Organisms that seem to be fairly similar, on the basis of comparative anatomy, show more genes in common than organisms that are less alike.
Besides DNA, what else can be used to test for the similarity of species?
Protein amino acid sequence
How it protein amino acid used to determine the similarity of different species.
Comparing how many of the amino acids are found in the same position as the protein chain can provide some idea of how closely related two species are.
Define species distribution?
A map of all the places where a species occurs
Where do unique species tend to occur?
On isolated islands
What part did fossils play in giving evidence for continental drift?
It convinced scientists that continents moved because of the distribution of fossils in particular species.
Would Australia count as an isolated island?
Yes, evidence from plate tectonics shows Australia has been isolated from all the other landmasses from about 40 million years ago
Define embryology?
The study of the development, structure and function of embryos.
What do comparisons of vertebrate embryos show?
Striking similarities in the early stages of their development
How does the development of branchial arches differ between species?
They develop into something different in each species
What did fish’s branchial arches evolve into?
Gills
What did reptile’s branchial arches evolve into?
Their lower jaw
What did human’s branchial arches evolve into?
Their ear bones
What did chick’s branchial arches evolve into?
Their parathyroid gland
Summarise the evidence for evolution?
Fossils Comparative anatomy DNA Protein structure Distribution of species Embryology
How do fossils provide evidence for evolution?
There is an increasing complexity in species, changes over geological time in a linage and transitional forms.
How does comparative anatomy provide evidence for evolution?
Homologous structures can be identified at many different levels of classification, such as the limb bones in classes of vertebrates.
How does DNA provide evidence for evolution?
Species that have similar anatomy have been shown to have many more common genes
How does protein structure provide evidence for evolution?
Closely related species have more similarities in amino acid sequences in particular proteins
How does a high distribution of species provide evidence for evolution?
Isolated islands have unusually high proportions of unique species
How does embryology provide evidence for evolution?
Embryos with similar anatomy share some of the same genes for development of the embryo. These same genes can exert different effects in different species.
What was the premise of the view: organisms that were very similar in structure must be related?
Knowledge that organisms seemed to inherit their characteristics from their parents.
Did modern genetics confirm that organisms seemed to inherit their characteristics from their parents?
Yes, genetics showed that species with the same basic structure have many genes the same or similar in their effect.
Species that have the same genes must have had the same ancestor at the some stage.
By which process are the genes passed on from one generation to the other?
Meiosis
Define homologous structure?
Characteristics that have the same basic structure but not necessarily the same structures in related species
Give three example of homologous structures?
Human hand
Whale flipper
Bat wing
Give three examples of structures that are not homologous?
Cats paw
Insect foot
Horse hoof
What do scientists study about genes?
Chemical structures and function
The more alike two organisms are ….
The more genes they share
As you move from higher levels of classification to lower levels ….
The more alike those genes become
Do homologous structures always have the same function in organisms that share it.
No, humans, bats and whales have five digits at the end of limbs, humans grip and traction, whales propel, bats fly,
Define analogous structures?
Structures that looks similar in genetically different organisms.
Eg: sharks and dolphins-similar body shaped and fins
Does artificial selection occur in the wild?
No, humans choose to breed particular organisms with desirable features
Define artificial selection?
Process where breeders cross (mate) the selected parents and then allow offspring to reach maturity before selecting which will be bread.
Are blue budgies natural?
No, wild budgies are green and yellow.
Are blue budgies mutants?
Yes, the variations in the wild budgie population were all originally results of mutants
Does artificial selection happen fast or slow?
It happens over generations?
Give five examples of breeds of dogs likely produced by artificial selection
Collie, pug, German shepherd, basset hound, Alaskan malemute
Give five examples of cats likely produced by artificial selection?
Persian, Siamese, Burmese, rag doll, munchkin
Two main methods of selective breeding?
Cross breeding
Interbreeding
Define cross breeding?
Combining a desirable feature of one individual with a desired level feature of another
Define interbreeding?
Related individuals are allowed to mate
