chap 15 Flashcards
common descent with modification; changes or adaptions that occur over time to assist organisms with survival
evolution
What are the two components of evolution?
- descent from a common ancestor
- adaption to the environment
- proposed to be the mechanism by which evolutionary changes occur; also referred to as “survival of the fittest”
- states that individuals of a species have variations that can be inherited
natural selection
- a more accurate way of describing evolutionary changes
- adaptions are changes that help a species become more suited to its environment
- are a product of natural selection
adaptations
one that enables an organism to have increased survival rates and thus increased reproductive rates in future generations
adaptive characteristics
How is the hypothesis of common descent supported?
by the fossil record, by biogeographical evidence, by anatomical evidence, by biochemical evidence
- a naturalist hired by the British Navy to go around the world in a ship called the HMS Beagle and survey natural resources found in different locations
- concurred with geologist Lyell that geological changes were caused by slow, continuous processes and that the Earth was very old
- found fossils that suggested modern forms of life were descended form now extinct forms of life that changed over time
- observations he made ultimately led him to help to develop the concept of biological evolution as the method by which species arise and change
Charles Darwin
How did Darwin’s observations support the theory of evolution?
- he concluded that Earth was very old and its geologic changes slow in coming
- since he saw similar species in similar habitats, he reasoned that related species were modified over time according to the environment in which they lived
study of range and geographic distribution of life
biogeography
How does biogeography provide support for evolution?
- similar organisms in different areas might have had a common ancestor that would describe their similarities
- their differences would be described by the adaptations they made to live in different habitats
all members of a single species living in a particular area at the same time
population
evolutionary changes observed at the population level
microevolution
give two examples of how natural selection can be witnessed
- industrial melanism with peppered moths
- finches’ beaks changing with changes in precipitation
give examples of artificial selection carried out by humans
- the variety of purebred dogs today
- the diversity among plants grown for food
one that shows a common ancestor for two different groups of organisms
transitional fossil
give an example of how biogeography provides evidence for evolution
most marsupial mammals are only found in Australia; placental mammals (and only a few marsupials) are found in all the other continents
structures that are anatomically similar and found in a wide range of organisms
homologous structures
Why are homologous structures important?
they provide evidence of a common ancestor
What anatomical evidence is there for evolution?
all vertebrate embryos have a post-anal tail and paired pharyngeal (gill) pouches
What is meant by there being biochemical evidence for evolution?
- all living organisms use the same DNA triplet code
- all living organisms have proteins made from the same 20 amino acids
- organisms with the most similar base pairs are more closely related than those with fewer base pair similarities (this finding is consistence with evidence from the fossil record and evidence from comparative anatomy)
