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24 Cards in this Set
- Front
- Back
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Proximate vs. ultimate questions
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Physiology, genetics, biochemistry, etc. concentrate on proximate causation
“What” & “How” questions Ultimate causation: How evolutionary processes (natural selection; adaptation) and evolutionary history shape traits “Why” questions |
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Data Collection
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Systematic & explicit in its methods
Often quantitative Set in a framework for understanding (Hypothesis Testing) |
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Why is it so important in science to be systematic and explicit in your data collection? What is meant by these terms?
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Science has a set way of doing things and we strive to use a set methodology for examining the world (and testing our hypotheses). It's a way of knowing about the world but it requires a transparency in how we collect data and test hypotheses. Being systematic requires that you follow a set of rules or are methodical in your process, and explicit is that you communicate this and are transparent in explaining to others exactly what you did.
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Hypothesis
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Not ungrounded speculation—rather, a statement about what might be true
Must be falsifiable—can be proven wrong with observations |
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Theory
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Well‐tested model that has survived repeated attempts to prove it false
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Great Chain of Being (Scala Naturae)
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All organisms exist in a universal hierarchical ladder
Linear (simple to complex) with continuity Unchanging (Fixity of Species) Humans at top but below gods & angels “Ladder of progress” Concept of “missing link” |
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Inheritance of Acquired Characteristics (Use/Disuse)
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Key figure is French naturalist Jean Baptiste Lamarck
Differential use of body parts; Could pass these traits to offspring |
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Explanatory Model: Uniformitarianism
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Same gradual geological processes we see today were
operating in the past |
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Natural selection
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Two‐step process
Variation (A random process, through mutation) Selection of Variation (A non‐random process, based on survival & reproduction – Differential reproductive rate) |
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Natural selection
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Generate a variety of possible solutions & pick the one that works best for problem at hand
Engineering, computer programming, drug design |
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Natural selection
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Evolution as tinkerer not engineer
Modification/transformation of what already exists Evolutionary change seen in populations, not individuals |
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Evolution by natural selection
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Population variation that is heritable
Environmental pressure (expanding populations and limited resources) Organisms with advantageous variation (“Adaptations”) favored: In their ability to survive, mate, and rear offspring to reproductive age (reproductive success) Thus, they have higher fitness (measure of relative reproductive success): Better but not perfect |
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Darwin’s evidence
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Experimental
Domesticated animals Selective breeding experiments Biogeography Study of the distribution of plants and animals around the world Organisms adapted to their environments |
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Darwin’s evidence
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Geology & Paleontology
Old age of the Earth Fossils of extinct animals Some similarities with living species but the farther back in time the more different But fossils of ancient humans almost completely unknown |
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Darwin’s evidence
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Comparative Anatomy
Homologous Structures: Similar structures, but often with different functions Indicative of common ancestry Vestigial Structures: Retentions with no current function (e.g., pelvic bones in whales) (Appear to be “imperfections”) |
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Darwin’s evidence
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Comparative Embryology: Similarities in embryos but adult differences
Some traits appear early but are later lost (e.g., ape & human tails) Could not explain certain traits if by design e.g., Flounder eyes |
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Darwin’s problems
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Darwin could not explain:
How traits were inherited Proposed that offspring inherited traits from both parents How variation originated and was maintained Genetics later provides us with information on: How traits are inherited DNA—As discrete units, not through blending How variation originates and how it is maintained Mutation |
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Genetics
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Genetics: The study of gene structure and action and the patterns of inheritance of traits from parent to offspring
Provides us with information on the following: The inheritance of traits Links between genes and physical traits Links between genes and behaviors Evolutionary relationships between organisms The ability to measure evolutionary change in populations |
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How are traits inherited from one generation to the next?
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Key concepts:
Particulate Inheritance: Not blending, but instead distinct and independent (effects can be masked but can re‐emerge in later generations) The effects of some traits are dominant They mask the expression of other traits (recessive traits) Traits are typically inherited independently of other traits e.g., Seed color does not influence type of flower This gives us information on variation and change (mutation) |
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The Modern Synthesis / Neo‐Darwinism (begins in the 1930s)
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Unites Natural Selection and Mendelian Genetics
Source of variation & principles of inheritance Selection of variation based on environmental pressure Bridges microevolution (evolution within a species) & macroevolution (evolution at or above level of species) Given enough time, major evolutionary changes can occur |
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A new definition of evolution
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A change in gene frequencies from
one generation to the next. Populations evolve, individuals do not |
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Adaptation
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A trait that increases the fitness
(reproductive success) of an organism Measured in terms of: Differential survivorship (mortality) Differential reproduction (fertility) Produced by natural selection within the context of a particular environment Match & mismatch Environments are constantly changing The Red Queen Effect– Leigh van Valen Species have to "run" (i.e., evolve) in order to stay in the same place (i.e., not go extinct) Evolutionary arms races (hosts vs. parasites) |
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However, adaptations are often imperfect
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Evolution as an incremental process: No huge jumps, only small changes (each of which must be immediately beneficial)
Constrained by evolutionary history Evolution modifies what is already there (“tinkering”) Must use mutations that arise Human gut as a modified primate gut (appendix) Also, blind spots, retinal tears, choking, etc. |
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Social dimensions of the environment
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Social factors shape natural selection & adaptation
Members of your own species Sexual selection: Type of natural selection that operates on only one sex; the result of competition for mates Can lead to sexual dimorphism (physical differences between males and females) Types: Male‐male competition vs. female choice |
