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Principles of Ecology: Evolution and Ecology
evolution be mad fake
Terms in this set (27)
-conservation of matter
-conservation of energy
-evolution never stops
-everything is changing
rules of the game in ecology:
inextricably; survive and reproduce
Evolution and ecology are ______________ linked. Evolution produces traits that organisms use in the real world to _________________. Ecological interactions shape which traits are selected for transmission to the next generation (never-ending feedback process between the two).
the frequency of genes in a population changing from one generation to the next (short-term)<--white deer example
different species arising from a common ancestor over many generations
What are the (4) evolutionary mechanisms?
increasing the frequency of alleles that contribute to an increase in reproduction
continually introduces new alleles (somewhat randomly); can randomly occur within individuals (can be good, bad, or silent)
changes allele frequencies randomly (no always b/c they are advantageous); loss of genes from a population as individuals fail to reproduce (for random reasons; not naturally selected)<--eg. bottleneck
changes allele frequencies when individuals join/leave a population; random with respect to fitness (individuals who are moving are not necessarily more fit); reduces differences between populations (homogenization)
-traits of individuals in a population display variation (caused by sexual reproduction or mutation)
-some traits confer greater reproductive advantages than other traits (fitness)<--which traits are better depends on environmental context (ecology)
-traits can be passed from parents to offspring (heritability)
-more offspring produced than can survive
How does natural selection work?
UV dose rates
-tradeoffs between folate and vitamin D: darker skin: selective pressure to preserve folate; light skin: advantage in low UV intensity environments so can make vit D
skin color example of natural selection:
Race in humans does not have a biological meaning; there is more genetic variation within "races" than there are between "races"; grouping people by physical traits says nothing about their genetics or personality
(type of genetic drift)
-reduction in genetic variation because of reduction in population size
-eg. 12,000 ya bottleneck event in cheetah population; resulted in very low genetic diversity
What is a bottleneck effect?
(type of genetic drift) small subset of a larger population breaks off to colonize a new area
-example #1: polydactyly in Pennsylvania Amish: came from Germany and established a community; interbred with each other; population had a higher % of polydactyly which was then spread throughout genes throughout the generations
-example 32: polydactyly in Hemingway's cats
What is a founder effect? Give some examples.
occurs when natural selection favors one of the extreme variations of a trait (eg. Salt and Pepper moths)
a type of natural selection in which organisms with phenotypes at both extremes of the phenotypic range are favored by the environment (selecting against most common type) (eg. Darwin's finches)
natural selection that favors intermediate variants by acting against extreme phenotypes (eg. human birth weights)
-sexual selection= selection for a specific trait that is attractive to the opposite sex, or enhances competitive ability within one's own sex (no advantage other than being attractive to opposite sex)
(males and females look different)
How is sexual selection a special case of natural selection?
-we select traits based on what we find valuable, not necessarily what is most fit (eg. dog breeds; wild mustard plant)
-not always a good thing (eg. we artificially select for insects that can tolerate pesticides; we select for bacteria that can withstand antimicrobial soap)
What is artificial selection?
-non-random mating (sexual selection)
-genetic drift (bottleneck effect)
-migration (founder effect)
mechanisms of evolution:
-random mating (no sexual selection)
-large population (no bottlenecks)
What if evolution was absent?
-gene frequencies within a population will be constant across generations if evolutionary processes are absent
-does not exist in nature
-can use genotype to predict phenotype (big assumption)
-"null model"-->a default model of how things work that you can then compare the real world to (if evolutionary processes were absent, this is what it would look like)
What is Hardy-Weinberg equilibrium?
review HW equations
a population in H-W equilibrium always has same allele frequencies across generations
-evolution does not just happen at the level of the gene
-species always evolve towards greater complexity
-traits acquired throughout life can be passed onto next generation
-use and disuse (traits that you use will be passed onto children)
eg. giraffe stretching of neck to reach higher leaves caused giraffes to have larger necks
What is Lamarckism?
"above the level of the gene"
-heritable traits that are not solely caused by changes to the DNA sequence
-can be thought of as acquired traits
-a way of controlling gene expression
What is epigenetics?
-evolution produces traits that organisms use in the real world to survive and reproduce
-ecological interactions shape which traits are selected for transmission to the next generation
-never-ending feedback process between the two
-ecological interactions affect patterns of selection and evolution through changes in gene frequencies
-interaction with the environment can have a direct heritable effect on later generations through epigenetic effects
evolution and ecology summary:
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