生物英语

• A selection that is made by humans instead of nature • People choose what they want to create to become the best.
Artificial Selection
Under artificial selection, breeders choose the traits that contribute the most to the next generation.
• We will use the “Island Model”
True or False Questions
10. Most new mutations are highly deleterious and very quickly removed from populations by natural selection. • TRUE / FALSE
Definitions
7. Population
– A group of individuals that are typically considered the same species that live in the same area and mate with one another to produce viable offspring. – Good Answers:
Population subdivision
• In nature, groups of organisms are often divided into populations
sometimes called…
subpopulations
Population subdivision
• Population = a group of interbreeding individuals and their offspring • (for asexual species, population = group of individuals of the same species living in the same area)
1. Chromosome
– Structure that contains coils of DNA that code for genes. There are 23 pairs of chromosomes in human cells making a total of 46 chromosomes – Good Answers:
Week 10 - Midterm Exam
Monday 8-9 节
12 10
8
6 系列1
4
2
0
0.0-10
10.1-20
20.1-30
30.1-40
40.1-50
50.1-60
60.1-70
70.1-80
Tuesday 4-5 节
16 14
12
10
8 系列1 6
4
2
0
0.0-10
10.1-20
Gene flow
• Gene flow tends to homogenize (to become the same) allele frequencies across populations • How far would this homogenization go without considering other evolutionary forces?
True or False Questions
9. Gene flow between two populations of birds (populations of the same species) would tend to cause the allele frequencies to be more different between the two populations. • TRUE / FALSE
• • • • Made up of DNA Each human has 23 pairs of chromosomes Made of many genes and it can be inherited Something that carries information in the body
20.1-30
30.1-40
40.1-50
50.1-60
60.1-70
70.1-80
Average: 53 Range: 3 - 81
30 25
20
15 系列1
10
5
0
0.0-10
10.1-20
20.1-30
30.1-40
40.1-50
50.1-60
60.1-70
70.1-80
Definitions
Fitness consequences of mutation
True or False Questions
11. The Law of Independent Assortments says that separate genes for separate traits are passed independently of one another from parents to offspring. • TRUE / FALSE
Definitions
3. Discrete variation
– Variation for a particular trait that is one or the other. For example, ear-lobes can either be attached or unattached. – Good Answers:
Definitions
2. Microevolution
– Short-term evolutionary changes that lead to changes in allele frequency in a population. – Good Answers:
• Changes that happened to a creature that are small • A vague term that describes slight changes. • Short-term changes that cause evolua –
All domestic dogs are the descendents of the gray wolf
Definitions
5. Fitness
– A way of measuring how successful one individual will be at passing his or her genes onto the next generation. Has to do with survival to reproduction age and reproduction. – Good Answers:
• Selection that occurs in a fixed direction • Selection through homozygote advantage
Directional Selection: Single Locus Example
Brown Rat in Wales, London
Two-Trait Inheritance
• Dihybrid cross uses true-breeding plants differing in two traits – Observed phenotypes among F2 plants – Formulated Law of Independent Assortment • During gamete formation, each pair of alleles will segregate INDEPENDENTLY of all other alleles • All possible combinations of alleles can occur in the gametes
Definitions
6. Directional selection
– A mode of natural selection that tends to eliminate genetic variation by selecting for an allele and allowing it to go to fixation or where p = 1 or 0. – Good Answers:
Microevolution
Adding what we know from genetics, microevolution… Is defined as any change in allele frequency within a population (heritable changes in a population) Population: a group of interbreeding individuals and their offspring Population genetics: Tracks and looks at what happens to this population over time
• Creatures that adapt to the environment to survive and have offspring • The lifetime contribution to the next generation of genes.