10.4 Evidence for Evolution Flashcards
Where did Darwin carry out his observations?
Galápagos Islands
What did Charles Darwin notice on Galápagos Islands?
Different islands had different finches. The birds were similar in ways and thus closely related, but their breaks and claws were different shapes and sizes
What were the 4 observations made by Charles Darwin?
-Individual species are not identical, there is variation within species
-Traits are passed on from generation to generation
-More offspring are born than can survive
-Only the survivors of the competition for resources will reproduce. The variation of individuals give some members of the species advance in competition to survive and reproduce. Those advantageous traits will be passed to the next generation
What did Alfred Wallace find to help with studies on evolution?
-Went to the amazon in 1848, found/concluded that only the fittest individuals survive
Definition of natural selection
The process by which organisms best suited to their environment survive and reproduce, passing on their characteristics to their offspring through their genes
What was Darwin and Wallaces theory?
Evolution occurred by natural selection
What are the different types of evidence for evolution?
-Palaeontology
-Comparative anatomy
-Comparative biochemistry
What is palaeontology?
The study of fossils and the fossil record
What is Comparative anatomy?
The study of similarities and differences between an organism anatomy
What is Comparative biochemistry?
The study of similarities and differences between the chemical makeup of organisms
How has palaeontology provided evidence for evolution?
-Fossils of the simplest organisms (eg. bacteria and simple algae) are found in the oldest rocks, whilst fossils of more complex organisms (eg. Vertebrates) are found in more recent rocks. This supports the theory of evolution that simple life forms gradually evolved over an extremely long periods of time into more complex ones
-The sequence of which the organisms are found matches their ecological links to each other (eg. Plant fossils appear before animal fossils), this supports the fact that animals need plants to survive
-Studying similarities in the anatomy of fossil organisms, scientists can see how closely related organisms have evolved from the same ancestor, this lineage is based on structural similarities in fossils
-Allow relationships between extinct and living organism to be investigated
How are fossils formed?
When an animal or plant remains are preserved in rocks. Over long periods of time, sedimented is deposited on earth to form layers of rock
What is comparative anatomy provided evidence for evolution?
-The basic structures of all vertebrae limbs are very similar, the same bones have just been adapted to carry our different functions
-Provides an explanation that all vertebrates have evolved from a common ancestor
-Provides evidence for divergent evolution
What are homologous structures?
Structures that appear superficially different in different organisms, but have the same underlying structures
What is divergent evolution?
Species diverge over time into two different species, resulting in a new species becoming less like the original one
When does divergent evolution occur?
When a closely related species diversify to adapt to new habitats as a result of migration or loss of habitat
What is convergent evolution?
Organisms evolve similarities because the organisms adapt to similar environments or other selection pressures
What are analogous structures?
Structures that have adapted to perform the same function but have a different origin
How does comparative biochemistry provide evidence for evolution?
-Molecular sequences of particular molecules are compared, by looking at their DNA bases or the order of amino acids in a protein
-The number of difference that exist are plotted again the rate the molecule undergoes neutral base pair substitution
-From this information scientists can estimate the point at which the two species last shared a common ancestor
-Species that are closely related have more similar DNA and proteins
-Ribosomal RNA has a very slow rate of substitution, so is commonly used together will fossil information to determine relationships between species
What are common molecules studied for comparative biochemistry?
RNA, cytochrome c (protein involved in respiration)
Definition of evolution (LOOK AT BOOK TO COMPARE)
A change in the frequency of alleles in a population across time
