Chapter 16 - Evolution

Question 1

Evolution – Chapter Summary

Answer 1

Evolution is quite simply the change in the inherited traits of a population of organisms from one generation to another. This change over time can be traced to 3 main processes: Variation, Reproduction and Selection

The major mechanisms that dive evolution are natural selection and genetic drift.

Question 2

Natural selection

The premises in natural selection 6x

Answer 2

Natural selection is the non-random differential survival and reproduction from one generation to the next. Natural selection contains the following premises:

1) Genetic and phenotypic variability exists in populations. (Offspring show variability compared with their parents)
2) More individuals are produced than live to grow up to reproduce.
3) The population competes to survive.
4) Individuals with some genes are more likely to survive that those with other genes.
5) Individuals that are more likely to survive transmit these favorable variations (genes) to their offspring so that these genes become more dominant in the gene pool.

Question 3

What is a Phenotype?

Answer 3

A phenotype is an individual’s observable traits, such as height, eye color, and blood type. The genetic contribution to the phenotype is called the genotype. Some traits are largely determined by the genotype, while other traits are largely determined by environmental factors.

Question 4

3x forms of natural selection

1) Stabalising

Answer 4

Stabilising selection

Where genetic diversity decrease as the population stabilises on an average phenotype. This is the most common form.
Favours intermediate phenotypes as opposed to extreme phenotypes.

Question 5

3x forms of natural selection

2) Directional selection

Answer 5

Favoring an extreme phenotype as opposed to an intermediate one causing the allele frequency continually shifting in one direction. Most often occurs when a population migrates and causes new environmental pressures.

Question 6

3x Forms of natural selection

3) Disruptive Selection

Answer 6

Where both extremes are selected over the average phenotype. Bird only eats medium sized seeds. Leaving only medium sized seeds.

Question 7

Speciation

Answer 7

Speciation is the evolutionary process by which populations evolve to become distinct species.

Question 8

Genetic Drift

Answer 8

Genetic drift is a mechanism of evolution in which allele frequencies of a population change over generations due to chance (sampling error). Genetic drift occurs in all populations of non-infinite size, but its effects are strongest in small populations.

Question 9

Patterns of evolution

1: Divergent Evolution

Answer 9

Patterns of evolution
1: Divergent Evolution
Two or more species from a common ancestor.

Question 10

Patterns of evolution

2: Convergent Evolution:

Answer 10

2: Convergent Evolution:
Two unrelated species become more alike as they evolve due to similar ecological conditions. The traits that resemble one another are called analogous traits.

Question 11

Patterns of evolution

3: parallel Evolution:

Answer 11

3: parallel Evolution:
This describes two related species that have evolved similarly after their divergence from a common ancestor. For example, the appearance of similarly shaped leaves in many genera of plant species.

Question 12

Patterns of evolution

4: Convolution:

Answer 12

4: Convolution:
This is the evolution of one species in response to adaptations gained by another species. This most often occurs in predator/prey relationships where an adaptation in the prey species that makes them less vulnerable leads to new adaptations in the predator species to help them catch their prey.

Question 13

Macroevolution

Answer 13

Describes evolution across groups of species as opposed to individual species.