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15 Cards in this Set
- Front
- Back
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Natural History |
About observation and appreciation of nature, rather than understanding through experimentation
the description of how organisms in a particular area are influenced by factors such as climate, soils, predators, parasites, and competitors, involving field observations rather than carefully controlled experimentation or statistical analyses of patterns |
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Evolution |
a change in gene frequencies within a population over time |
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Natural selection |
differential reproduction and survival of individuals in a population due to environmental influences on the population |
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Genetic drift |
change in gene frequencies in a population due to chance or random events |
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Speciation |
lineage splitting event that produces two or more species |
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Voya'ge of the Beagle |
Charles Darwin
1831 for a 5-year voyage at the age of 22
inspired by the Galapagos Islands |
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Key elements of Natural Selection |
1) More offspring are produced each generation than can be supported by the environment
2)Some heritable variation in physical, physiological, and behavioural traits among in a population
3)Some traits give some individuals an advantage over other members of the population – individuals with said traits will have higher chance of surviving
4)Traits that result in increased fitness will become more common within a population over subsequent generations |
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Fitness |
the number of offspring contributed by an individual relative to the number of offspring produced by other members of the population |
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Adaptation |
an evolutionary process that changes anatomy, physiology or behaviour that results in an increased ability of a population to live in a particular environment |
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Stabilizing Selection |
Extreme phenotypes in a population have lower rates of reproduction and survival
(peak in the middle)
(ex. Frog color, predicted green but red is preferred) |
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Directional Selection |
Phenotypes have lower reproduction and survival compared to exceptional phenotypes
(Shifted to one side)
(human induced, larger horns=better breeders but more hunted... small horns=direction) |
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Disruptive Selection |
Phenotypes have lower reproduction and survival compared to the extremes in the population
(dip in the middle)
(ex. dogs) |
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Allopatric speciation |
Speciation that occurs when isolating mechanisms evolve among geographically separated populations |
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Sympatric speciation |
Speciation that occurs when isolation mechanisms evolve among populations with overlapping geographic ranges
(ex. three-spine stickleback,Geographic barrier has led to speciation among marine and freshwater individuals)
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Parapatric speciation |
speciation that occurs when a population expands into a new habitat type within the pre existing range of the parent species
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