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Evolution (evidence of evolution (fossil Records (fossils are found in…
Evolution
evidence of evolution
fossil Records
- fossils are found in sedimentary rock. The farther down, the older it is
- remains of living things will be organic and will contain some radioactive isotopes of Carbon
- isotopes decay at a constant rate called Half Life
- half life: length of time for 1/2 of an isotope to decay
geographic distribution
- Biogeography - study of the distribution of plants and animals throughout the world
comparative anatomy
- related species have similar physical anatomy
- homologous structures
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comparative embryology
- the more similar the states of development between two organisms are, the more likely they were to follow similar evolutionary paths
- ontogeny recapitulates phylogeny
comparative biochemistry
some things are the same for ALL living organisms
- similar proteins, structure & function of DNA, same bases, similar mechanisms for protein synthesis
- DNA and protein sequence homologies (similarities)
- natural selection acts on phenotypes, not genotypes, however this process determines the relative frequencies of alleles
Important people
darwin
- natural selection is the force behind which populations evolve
- based on 3 main principles
= competition
= survival of the fittest
= descent with modification
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lamarck
-species change over time
- use/disuse: most useful traits are emphasized, least useful traits disappear
- implied that acquired traits could be passed on
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cuvier
fossils suggest different organisms lived in an area at different times. Major changes occurred suddenly
Mechanisms of evolution
genetic drift
- evolution without natural selection
- chance occurrences change allele frequency
= such as bottlenecking
- more common in small populations
- can lead to the founder effect
= a portion of the population separates from the old population to start a new population with different allele frequencies
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Natural Selection
- the force behind which populations evolve
- based with the idea that in a population, genetic variation ALREADY exists
- Competition
- members of a population are in competition with each other for key resources
- food
- shelter
- suitable mate
- water
- Survival of the fittest
- natural variation in a population yields some organisms with advantages over others
- this gives those organisms an edge in terms of competition and survival
- Those with higher fitness pass on more of their genes to the next generation
- Fitness includes:
- mutations
- Genetic Recombination
- Sexual Reproduction
- Migration
- Descent with modification
- As new favorable characteristics become established in a population, the species as a whole changes as long periods of time pass.
- More individuals will have the "best" variation plus new mutations and combinations (aka w/ modification)
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Vocab:
- founder effect - a population is separated for long enough that when they come back together they can't interbreed
- adaptive radiation - single species evolves into several different species that life in different ways. No Predators!