Natural Selection/speciation

Question 1

What are 3 observations made by Darwin when developing the theory of natural selection?

Answer 1

1. More offspring are produced than what can be supported by the environment
2. There is variation in the traits among individuals, some of the variation is passed on
3. individuals with traits that are beneficial to survival are more likely to survive and reproduce

Question 2

What is natural selection?

Answer 2

Natural process by which organisms better adapted to their environment are more likely to survive and pass on those traits

Question 3

What causes genetic variation?

Answer 3

Mutations, recombination, new combinations of alleles via sex

Question 4

What can a species do when conditions exceed its optimal range?

Answer 4

• migrate to a more suitable location
• go dormant
• adapt to the changing conditions

Question 5

What is a gene pool/?

Answer 5

All alleles present in a population

Question 6

What is evolution?

Answer 6

Change in gene frequencies within a gene pool

Question 7

What is the goal of evolution?

Answer 7

No goal. Evolution is ongoing and species aren’t striving towards anything

Question 8

What are the 5 causes of evolution?

Answer 8

1. Small population (more prone to genetic drift)
2. non-random mating
3. mutations
4. gene flow
5. natural selection

Question 9

What is a phenotype and what creates the variation phenotypic expression?

Answer 9

Outward expression of genes.

Phenotype = genotype + environment

Question 10

What is phenotypic plasticity?

Answer 10

Variation among individuals is due to environmental conditions

Question 11

What is an ecotype?

Answer 11

A locally adapted population of a species that is genetically distinct

Question 12

What is the Hardy-Weinberg principle and why is it important?

Answer 12

In the absence of the 5 things that cause evolution, allele frequencies will remain constant. Provides a null hypothesis

Question 13

What are 4 conditions for natural selection?

Answer 13

1. levels of success differs between individuals
2. variations in heritable traits among individuals
3. variation results in different levels of survival and reproduction
4. traits associated with fitness are inherited by offspring

Question 14

What is stabilizing selection?

Answer 14

Middle/average phenotypes are favoured. Extreme phenotypes are selected against, can eliminate any harmful mutations

Question 15

What is directional selection?

Answer 15

One extreme is favoured. New beneficial mutations become fixed in the population.

Question 16

What is disruptive selection?

Answer 16

Both extremes are favoured, average phenotypes are selected against. Is responsible in part for sympatric speciation

Question 17

What is the difference between microevolution and macroevolution?

Answer 17

Micro operates at a population level, macro operates at the species level.

Question 18

What is a species according to the biological concept?

Answer 18

A group of organisms reproductively isolated from other similar groups.

Question 19

What is a cline/ecocline?

Answer 19

Gradual change in genotype/phenotype of a species over a large geographical area

Question 20

What are the 4 pre-reproductive isolating mechanisms?

Answer 20

1. Mechanical -> morphology differences
2. Behavioural -> not attracted to each other
3. Temporal -> breed at different times
4. Ecological -> different habitats

Question 21

What are the 5 post-reproductive isolating mechanisms?

Answer 21

1. developmental -> embryo won’t form or survive
2. Genetic -> genetics prevent formation of zygote
3. No fertilization occurs -> egg doesn’t recognize the sperm
4. Hybrid sterility
5. Hybrid inviability -> can’t survive in the environment very well

Question 22

What is allopatric speciation?

Answer 22

New species forms from geographic isolation

Question 23

What is parapatric speciation?

Answer 23

A habitat expansion, new genes dominate and excel in the new habitat, populations can still mix

Question 24

What is sympatric speciation?

Answer 24

Speciation from a subset in the population exploiting a new niche and genetic drift occurring in this subset

Question 25

What is hybrid speciation?

Answer 25

Hybridization between 2 species leads to a new species that is reproductively isolated from the parent species

Question 26

How can a hybrid form persist in the environment?

Answer 26

It will need to be able to exploit the available resources better than the parent species

Question 27

What is genetic barcoding used for?

Answer 27

Documenting biodiversity, is a bar code based on G,T,C,A sequences in CO1 gene

Question 28

What is environmental DNA? (eDNA)

Answer 28

The aquatic environment retains the DNA of residing species, and can be used to detect species that haven’t been observed