How Populations Evolve Flashcards
(49 cards)
1
Q
Theory of Evolution
A
- Inspired by 5 year voyage
- The idea that Earth’s species are descendants of ancestral species different than those living today
2
Q
Early views on evolution
A
- Some early Greek philosophers suggested that life might change gradually
- Aristotle and Judeo-Christians believed that species are perfect and unchanging
3
Q
Fossils
A
- The imprints or remains of organisms that lived in the past
- In the century prior to Darwin, fossils had been collected which suggested change over time
4
Q
Lamarck’s Theory
A
- Jean-Baptiste Lamarck suggested that organisms evolve by the use of disuse of body parts
- Acquired characteristics are passed to offspring
5
Q
Lyell’s Principles of Geology
A
- Inspired Darwin
- Suggested that natural forces gradually changed the earth and these changes are still happening today
6
Q
Geology & Paleontology
A
- Darwin learned from geology that the earth was very old
- He learned from paleontology that over time, species had changed due to natural processes
7
Q
On the Orgin of Species
A
- Darwin’s book, stated that:
- Evolution is done through natural selection
- As organisms spread, they acquire diverse adaptations specific to their environments
8
Q
Artificial selection
A
- When humans modify a species through selection and breeding
- Also known as selective breeding
- Established by Robert Blackwell during the British Agricultural Revolution
9
Q
Over Population
A
- A connection between natural selection and the ability to over-reproduce
10
Q
Thomas Malthus
A
-Malthus argued that human suffering was due to the human population expanding faster than it’s resources
11
Q
Darwin & Over Population
A
- Darwin concluded that
- Organisms vary in traits and produce more offspring than the environment can handle
- Organisms with better traits leave more offspring
- The unequal reproduction will lead to an accumulation of favorable traits
12
Q
Evolution’s 5 Key Ponts
A
- Individuals don’t evolve, populations do
- Natural selection can increse or decrease any heritable traits
- Acquired trait’s can’t be passed on
- Evolution doesn’t lead to perfection
- Favorable traits vary with environtment changes
13
Q
Darwin’s Finches
A
- Studied by Rosemary & Peter Grant for over 30 years in the Galapagos
- In wet years, small seeds are abundant and small beaks are favorable
- In dry years, largebeaks are favorable because small seeds are in low supply
14
Q
Pesticide Resistance
A
- A small amount of new pesticides may kill 99% of pests, but subsequent spraying’s will be less effective
- Surviving insects have alleles to resist pesticides
- Therefore, the population gets more resistent over time
15
Q
Key points of natural selection
A
- Natural selection is an editing process, not a march to perfection
- Natural selection is contingent on time and place, favoring those characteristics that fit the current environment
16
Q
Fossil Record
A
-The sequence in which fossils appear within the strata of sedimentary rocks
17
Q
Historical sequences
A
- Speicies have evolved in historical sequences
- The oldest known fossils go back 3.5 bil years ao and are prokaryotes
- The oldest eukaryotic fossils are a billion years younger
18
Q
Fossil Links
A
- Fossils often link early, extinct species to living species
- A series of fossils traces the gradual modification of jaws and teeth in mammals
- A series of fossils shows whales coming from land mammals
19
Q
Biogeography
A
- The geographic distribution of a species
- Suggests that organisms evolve from common ancestors
- Daein noted Galapogos animals look more like s. american animals than animals from other islands
20
Q
Comparative anatomy
A
- The comparison of boy structures in different species
- Illustrates that evolution is a remodeling process
21
Q
Homology
A
-The similarity in characteristics resulting from common ancestry
22
Q
Homologous Structures
A
-Have different functions but are structurally similar due to common ancestry
23
Q
Comparative Embryology
A
- The comparison of early stages of development in different organisms
- Reveals homologies not apparent in adults
- Ex all vertabrate embryos have a tail and throat pouches at some point
24
Q
Vestigial Structures
A
- Remains of features that served important functions in an organism’s ancestors
- Ex/ the appendix
25
Advances in molecular biology
- Reveal evolutionary relationships by comparing DNA and amino acid sequences
- Indicates that
- All life forms are related and share a common DNA code for proteins
26
Evolutionary Tree
- Often turned sideways
- Homologous structures can be used to determine the branching sequence
- Include anatomical and molecular structures
27
Population
- A group of individuals of the same species living in the same place at the same time
- May be isolated, which leads to interbreed
28
Gene pool
-The total collection of genes in a population at any time
29
Microevolution
-A change in the relative frequencies of alleles in a gene pool over time
30
Population Genetics
-Shows how populations change genetically over time
31
Modern synthesis
Connects Darwin's theory with population genetics
32
Mutation
- Change the nucleotide sequence of DNA
| - The ultimate source of new alleles
33
Chromosomal Duplication
- Is an important source of genetic variation
| - If a gene is duplicated, the new copy can undergo mutation without it affecting the original copy
34
Sexual reproduction
Shuffles alleles to produce new combos in 3 ways:
- Homologous chromosomes sort independently as they separate during anaphase I of meiosis
- During prophase I of meiosis, homologous chromosomes cross over and exchange genes
- A further variation occurs when a sperm unites with the egg
35
Shuffled alleles
-The frequency of alleles and genotypes do not change
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Hardy- Weinberg
-Allele frequency will remain in equilibrium until outside forces act to change the frequency
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5 Hardy- Weinberg Conditions
- A large population
- No gene flow between populations
- No mutations
- Random mating
- No natural selection
38
Hardy-Weinberg equation
- P^2 + 2pq +q^2=100
| - Homozygous + heterozygous + homozygous recessive
39
Hardy-Weinberg Disruption
- Small population
- Individuals moving in and out of a population
- Mutations can change or delete alleles
- Preferential mating
- Unequal survival and reproductive success (natural selection)
40
Causes of Evolutionary Change
- Natural selection
- Genetic drift
- Gene flow
41
Natural selection
-If individuals differ in their survival and reproductive success, natural selection will alter allele frequencies
42
Genetic drift
-Change in the gene pool due to chance
43
Bottleneck Effect
-Leads to a loss of genetic diversity when a population is greatly reduced
44
Founder Effect
-When few individuals colonize a new habitat
45
Gene flow
-The movement of individuals between populations alters allele frequencies
46
Relative fitness
- An individual's contribution to the next generation compared to others
- The fittest produce the most viable, fertile offspring & pass the most genes
47
Stabilizing selection
-Favors intermediate phenotypes, and acts against extreme ones
48
Directional Selection
-Acts against individuals of one of the phenotype extremes
49
DIsruptive Selections
-Favors individuals at both extremes
