Unit 9: Evolution Flashcards
1
Q
natural selection
A
- mechanism for evolution
- process in which organisms with traits well suited to an environment are more likely to survive and to produce offspring
- the traits being selected contribute to an organism’s fitness in it’s environment
- natural affection can affect the distributions of phenotypes in 3 ways….
1. directional selection
2. stabilizing selection
3. disruptive selection - principles…..
1. Natural variation
2. Overproduction
3. Competition
4. Survival of the fittest
2
Q
evolution
A
- a change in genetic makeup of a species over time
- any change over time in the relative frequencies of alleles in a population
- populations evolve
3
Q
population
A
-all individuals of a species that live together in one place at one time
4
Q
Charels Darwin
A
- English naturalist
- wrote “On the Origin of Species by Means of Natural Selection,” which proposes that species evole ahd how evolution occurs
- presented evidence that evolution has been taking place for millions of years and continues in all living things
- he did this without any knowledge of ehat we know now about genetics
- he compared processes in nature to artificial selection
- realized thathigh burth rates and a shortage of lifes’ basic resources would force organisms to compete for resources
- proposed that fitness is the result of adaptation
- he refered to survival of the fittest as natural selection b/c of its similarities to naturla selection
- Age 22= jouney on the Beagle, as a naturalist
5
Q
fitness
A
-the ability of an individual to survive and reproduce in its specifc environment
6
Q
adaptation
A
- any inherited characteristic that increases an organism’s chance of survival
- become better suited to it’s environment
7
Q
homologous structures
A
- structures that have different mature forms but share a common anscestry
- come from the same embyonic tissues
- not all serve important functions
- EX: forelimbs in vertebrates
8
Q
divergence
A
-the development of differenves between a similar species
9
Q
punctuated equilibrium
A
-the hypothesis that evolution of a species happened in periods of fast change separated by periods of little or no change
10
Q
subspecies
A
- populations of the same species that differ genetically because they have adapted to different living conditions?
11
Q
gradualism
A
- the hypothesis that evolution of differnt species happens at a slow constant rate
- over a ling period of time
12
Q
isolation
A
-condition in which popoulations of the same species cannot breed with one another
13
Q
extinct
A
-when a species permanently disappears
14
Q
mesonychids
A
-one hypothesized link betweenn modern whales and hoofed animals
15
Q
fossil record
A
- how links between major classes of vertebrates are established
- by comparing fossils form older rock layers with fossils from younger rock layers, scientists can document that life on Earth had changed over time
16
Q
scientists agree that……..
A
- the Earth of 4.5 billion years old
- Earth has supported life for most of its history
- living organism share ancestry with earlier, simpler life-forms
17
Q
paleontologist
A
- scientist who studies fossils
- radiometric dating to determine the age of fossils
18
Q
fossils
A
- a trace of long-dead organisms
- form when rapidly buriedin fine sediment
- found in layers of sendimane
- shows a long history of life on Earth.
19
Q
artificial selection
A
- get the best traits from each organism/animal
- Darwin noted that plant and animal breeders would breed only the largest hogs, fastest horses, or cows that produces the most milk
20
Q
Hardy-Weinberg principle
A
- states that the allele frequencies in a population will remain constant unless one or more factor cause those frequencies to change
- p+q=1
- equation= q2+2pq+p2=1
- p= frequency for dominant trait
- q= frequency for recessive trait
- q2= homozygous recessive
- p2= homozygous dominant
- 2pq= heterozygous
21
Q
phylogenetic trees
A
-shows how organisms are related through evolution, by using data obtained from proteins and nucleotides
22
Q
evidence of evolution
A
- fossil records
- geographical distribution
- homologous structures
- similarities in early development (embyo)…….embryology
- universal genetic cods with obvious realationships
23
Q
geographical distribution
A
- simlar but not closely related species
- convergent evolution
24
Q
vestigial organs
A
- stuctures with no funtion that are left from an organism’s evolutionary past
- EX: wings in flightless birds
- organs that are reduced so much in size that they are just traces of homologous organs in other species
- historical remnants of structure that had important function in ancestors
- EX: appendix, tailbone, wisdom teeth
25
similarities in embryology
- embryos of many vertebrates are very similar
- the same groups of embryonic cells develop in the same order and insimilar patters to produce the tissues and organs of all vertebrates
26
Evidence vs Genetic Equilibrium
- 5 conditions are required to maintain genetic equilibrium form generation to generation
1. mating must be random
2. population must be very large
3. no gene flow
4. can be no mutation s
5. no natural selection (all with equal fitness)
27
Genetic Equilibrium
when allele frequencies remain constant
28
random mating
- ensures that each individual has a equal chance of passing on its alleles to offspring
- many species select mates based on particular heritable traits
29
genetic drift
- a change in the gene pool of a population due to chance
- may occur when a small groups of individials colinie a new habitat
- has less effect on a large population
- allele frequencies are less likely to be changed through the process of genetic drift
30
gene pool
- all the alleles for all the genes in a population
| - must be kept separate from gene pool of other populations (no migration)
31
migration
-the movement of individuals into or out of a population
32
mutation
- a change in the nucleotide sequence of an organism's DNA
- the ultimate source of genetic diversity
- if gene mutate, new alleles may be introduced into a population, and allele frequencies will change
33
directional selection
-when individuals at one end of the curve have higher fitness than individuals in the middle or at the end
34
stabilizing selection
-happens when individuals at the center of the curve have higher fitness than individuals at eith end of the curve
35
disruptive selection
-happens when individuals at the upper and lower ends of the curve have higher fitness than individuals near the middle
36
Taxonomy
-the branch of biology that names and classifies species and groups them into broader categories
36
Allopatric speciation
-the formation of a new species in populations that are geographically isolated from one another
37
Sympatric speciation
-when a new species arises within the same geographic area as a parent species
38
Polyploidy
-an organism that has more than 2 complete sets of chromosomes as a result of an accidental cell division
39
Adaptive radiation
-the evolution of many diverse species from a common ancestor
40
Convergent evolution
- adaptive change resulting in non homologous (analogous) similarities among organisms
- species from different evolutionary lineages come to resemble each as a result if living in very similar environments
41
Founder effect
- genetic drift that occurs when a few individuals become isolated from a larger population
- result= the composition of the new population's gene pool is not reflective of that of the original population
42
Genetic variation
-diversity in gene frequencies
43
Bottleneck effect
- genetic drift resulting from a drastic reduction in population size
- typically, the surviving population is no longer genetically representative of the original population
44
Conditions in which Hardy-Weinberg can happen.........
1. mating must be random
2. population must be very large
3. no gene flow
4. can be no mutation s
5. no natural selection (all with equal fitness)
46
Gene flow
-where a population may gain or lose alleles when fertile individuals move in or out of a population or when gametes are transferred between populations
