sequence of speciation

Question 1

Speciation

Answer 1

Formation of new and distinct species in the course of evolution

Question 2

Seven steps to become a new species

Answer 2

1. Reproductive Potential 2. Variation
2. Competition
3. Natural Selection
4. Divergence 6. Isolation
5. New Species

Question 3

Step 1 reproductive potential

Answer 3

the relative capacity of a species to reproduce itself under optimum conditions
* All organisms have the potential to reproduce more than the environment can support.
* Genetics are biological factors that differentiate individuals’ reproductive potential.
* Environmental factors have the same importance

Question 4

Reproductive potential charts show

Answer 4

How fast a population can increase

Question 5

Step 2 variation

Answer 5

Individuals do not evolve, populations do.
All individuals in a population have a certain number of traits in common
But all individuals in a population have a certain number of traits that are different.

Question 6

Population

Answer 6

A group of individuals occupying a given area and belonging to the same species

Question 7

3 kinds of variable traits

Answer 7

1. Morphological (morph = form) - External traits
2. Physiological - How their body functions internally 3. Behavioral - How they act/react

Question 8

Several possible sources of variation

Answer 8

• There are several possible sources of variation:
  1. Genetic mutations (the othat creates new species)
  2. Abnormal changes in chromosome structure or number (trisomy, monosomy)
  3. Crossing over and genetic recombination during meiosis.

4. Independent assortment of chromosomes during meiosis
   5 fertilization between genetically different gametes

Question 9

It’s unlikely that another person (other than identical twins) with your exact genetic makeup has ever or will ever exist. There are more than

Answer 9

10 to the 600 combinations of genes possible in human gametes. There are not even 1010 humans alive today.

Question 10

Step 3 competition

Answer 10

In every population there is competition between
individuals for different resources (food, shelter).
* Those who compete and win survive and reproduce.

Question 11

Those who compete and lose..

Answer 11

Die and do not reproduce
Their genes are not passed on to the next generation

Question 12

Intraspecifc competition

Answer 12

Individuals of the same population compete for resources

Question 13

Interspecifc

Answer 13

Two species compete for the same (limited) resource, they will impact each other’s population

Question 14

Competitive exclusion principle

Answer 14

Two similar species competing for the same limited resource cannot coexist together indefinitely

Question 15

Step 4 natural selection

Answer 15

The environment limits the growth of populations by:
- Increasing the rate of death
- Decreasing the rate of reproduction
* Organisms that have a greater number of favorable traits tend to leave more offspring

Question 16

Darwin called the different degrees of successful reproduction among organism in a population…

Answer 16

Natural selection * A population of organisms adapt to their environment as their
proportion of genes for favorable traits increases.

Question 17

The resulting change in the genetic makeup of a population is

Answer 17

Evolution, Natural selection is a passive process. Organisms do not simple decide to acquire certain traits.

Question 18

The environment selects the traits that will

Answer 18

Increase in a population, selection conditions change as the demands of the environment change

Question 19

Types of natural selection : disruptive selection

Answer 19

Individuals with both extreme forms are favored

Question 20

Stabilizing selection

Answer 20

Individuals with the average form are favored

Question 21

Directional selection

Answer 21

Individuals with an extreme form are favored

Question 22

Step 5 divergence

Answer 22

A group within a species may slowly branch off or “diverge” from the main group

Question 23

Allele frequency:

Answer 23

The decimal value of “A” and “a” alleles in the total population.

Question 24

Genotype frequency:

Answer 24

The decimal value of “AA”, “Aa”, and “aa” individuals in the total population. Multiply both allele frequencies. Each person has two alleles (one genotype).

Question 25

Hardy Weinberg principle of genetic equilibrium

Answer 25

Ideal hypothetical population * Analogy: The control group of an experiment

Question 26

To calculate allele frequency

Answer 26

p + q = 1

Question 27

p

Answer 27

Frequency of dominant allele (A)

Question 28

q

Answer 28

Frequency of recessive allele (a)

Question 29

To calculate genotype frequency

Answer 29

p2 + 2pq + q2 = 1

Question 30

p2

Answer 30

Genotype frequency of homozygous dominant AA

Question 31

2pq

Answer 31

Genotype frequency of heterozygous Aa

Question 32

q2

Answer 32

Genotype frequency of homozygous recessive aa

Question 33

Hardy Weinberg principle of genetic equilibrium states that which two equations must be true

Answer 33

p + q = 1 p2 + 2pq + q2 = 1

Question 34

What does Hardy Weinberg equilibrium not have

Answer 34

1. No natural selection - Equal fitness in the environment 2. No mutations - All genes are passed down identically 3. No migration - No new genes entering or leaving the gene pool 4. Large population - Can withstand small changes in the environment 5. Random mating - No sexual selection

Question 35

Step 6 isolation

Answer 35

When two Arts of a formerly interbreeding population stop interbreeding

Question 36

Two types of isolation- geographic isolation:

Answer 36

physical separation of members of a population (e.g., canyon, river, mountains)

Question 37

Reproductive isolation

Answer 37

the result of barriers to successful reproduction between two groups in the same population. This often follows disruptive selection.

Question 38

Two types of reproductive isolation: prezygotic isolation

Answer 38

isolation that occurs before fertilization, e.g. incompatible behavior (the wrong mating call), different mating times

Question 39

Postzygotic isolation

Answer 39

isolation that occurs after fertilization, e.g. the offspring do not develop fully and die, sterile offspring

Question 40

Step 7 new species what makes one species different from another? Two concepts

Answer 40

Morphological and biological

Question 41

Morphological concept of species

Answer 41

Uses the external structure an appearance of an organism to classify it as a species - Positive → Easy to use - Negative → Does not allow for phenotypic differences among individuals in a single population

Question 42

Biological concept of species

Answer 42

A species is a population of organisms that can successfully interbreed but cannot interbreed with other groups - Positive → A useful definition for living organisms - Negative →Useless for extinct organisms; useless for organisms that do not reproduce sexually

Question 43

As a result of these 2 types of variation..

Answer 43

We often combine the two definitions for a a species today (morphological and biological)

Question 44

Thus a species is ….

Answer 44

a population with morphological similarities that interbreed among themselves successfully.

Question 45

Rate of speciation: how fast is this process? (Two perspectives)

Answer 45

Gradualism and punctuated equilibrium

Question 46

Gradualism

Answer 46

Speciation requires millions of years and is caused by evolutionary changes that occur gradually. This is the Darwinian concept

Question 47

Punctuated equilibrium

Answer 47

Speciation that occurs suddenly by rapid shifts in the form of organisms followed by periods of no change. Most scientists today agree with this concept.

Question 48

Patterns of evolution - how do species interact throughout evolutionary time? (3 ways)

Answer 48

Divergent evolution, convergent evolution, and coevolution

Question 49

Divergent evolution

Answer 49

Two or more related populations or species become more different

Question 50

Convergent evolution.

Answer 50

Two organism that appear to be very similar but are not closely related at all, e.g., sharks and porpoises

Question 51

Coevolution

Answer 51

The change in two or more species in close association with each other, e.g., Predators and their prey often coevolve.