BIO SCI 94 Study Guide - Midterm Guide: Mesozoic, Polyploid, Paraphyly
Course CodeBIO SCI 94
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5 FUNDAMENTAL CHARACTERISTICS OF A LIVING ORGANISM:
-Energy: to stay alive and reproduce.
-Cells: membrane-bound units; help regulate the passage of materials between exterior and interior spaces.
-Information: genes to encode information; react to the surroundings.
-Replication: the main goal is to replicate.
-Evolution: populations have been evolving and still evolve.
EVOLUTION BY NATURAL SELECTION.
1. Natural selection (acts on individuals):
-The environment selects individuals based on traits.
-For natural selection to occur, a population needs various heritable traits and some traits that increase fitness.
2. Evolution (acts on populations):
-Change in alleles in a population over time.
-Theory of evolution: all organisms have a common ancestor; each generation has descent with modification.
THE TREE OF LIFE
-Speciation: natural selection causing a population or more of a species to diverge into a new species.
-All organisms are part of a genealogy of species and that all species can be traced to a common ancestor.
-The closer a species is related, the more similar their genetics are.
-Woese used RNA to build a phylogenetic tree.
1. Asking questions.
2. Forming hypotheses as well as null hypotheses.
3. Making predictions.
5. Interpreting results.
6. Drawing conclusions.
CHAPTER 25: EVOLUTION BY NATURAL SELECTION
TWO COMPONENTS OF A THEORY
-Pattern: something that occurs in the natural world.
-Process: responsible for creating the pattern.
HISTORY OF THE THEORY OF EVOLUTION
-Typological thinking (Plato): species do not change and variations are unimportant.
-The Great Chain of Being (Aristotle): species are fixed and some are more complex than others.
-Evolution (Lamarck): species change through time and evolution strives to make better species.
-Population thinking (Darwin and Wallace): variation in traits is vital; lead to evolution by natural selection.
THEORY OF EVOLUTION
1. The changes in species over time:
-The age of the Earth and existence of extinct species.
-Modern species resemble fossils.
-Transitional fossils (fish’ fins).
-The existence of vestigial traits (monkey tail and human coccyx).
-Species are still changing today.
2. All species are related via a common ancestor:
-Closely related species are geographically close.
-Genetic, developmental (embryo in human and animals), and structural (phalanges) homologies.
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4 POSTULATES OF EVOLUTION (DARWIN)
1. The individual organisms that make up a population vary in the traits they possess (size and shape).
2. Some of the trait differences are heritable.
3. In each generation, many more offspring are produced than can possibly survive.
4. Individuals with certain characteristics produce more offspring than others (natural selection).
THEORY OF EVOLUTION BY NATURAL SELECTION
1. Overproduction: every species tends to produce more individuals than can survive to maturity.
2. Variation: the individuals of a population have many characteristics that differ.
3. Selection: some individuals survive longer and reproduce more than others do.
4. Adaptation: the traits of those individuals will become more common in a population.
Eg: Antibiotic resistant bacterium and Galapagos Finches).
-Natural selection doesn’t change organisms.
-Acclimatization is not adaptation.
+ are simply chosen by the environment: no need; non is better or worse (some are just ill-suited).
-Evolution acts on population and is not aggressive.
-Mutations occur by chance.
-Not all traits are adaptive. Eg: fitness trade-offs.
CHAPTER 26: EVOLUTIONARY PROCESSES
HARDY-WEINBERG (HW) PRINCIPLE
States that the genotype frequencies will not change in a population over time if these assumptions are met:
-No nonrandom mating.
-No natural selection.
-No genetic drift.
-No gene flow.
The HW principle is a null hypothesis: if the hypothesis
fails, the null hypothesis must be true.
-Some individuals have greater chance of mating than
-Eg: Inbreeding: mating between relatives that share a
+ Changes genotype frequency, not allelic
frequencies (no evolution).
+ Induces breeding depression.
+ Lower fitness due to increased homozygosity
(unhealthy) and lowered heterozygosity (healthy).
+ Increases rate at which natural selection
eliminates recessive deleterious alleles that lower fitness.
-Disruptive selection: can lead to speciation.
-Frequency-dependent selection: the fitness of a
phenotype increases as it becomes more common.
-Ecological/Environmental selection: favors traits that
aren’t involved with sexual selection.
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