A4.1 Evolution and Speciation

Question 1

Evolution

Answer 1

The process of cumulative change in the heritable characteristics of a population.

Question 2

Why is evolution referred to as a theory?

Answer 2

Because it cannot be definitely proven even though it is highly unlikely it will be disproven as it accounts for so many different observations

Question 3

Heritable

Answer 3

the changes are passed on genetically from one generation to the next

Question 4

Modern synthesis theory/neo-Darwinism

Answer 4

A combination of Darwins ideas with the newer ideas of genetics supporting it. Gives insight into common ancestry.

Question 5

Lamarckism

Answer 5

Organisms acquire characteristics throughout their lifetime and then pass them onto their offspring.

Question 6

What data can be compared to investigate the evolutionary relationships between species?

Answer 6

the nucleotides in DNA/RNA or amino acid sequences

Question 7

Evidence for the theory of evolution

Answer 7

Includes: selective breeding, sequence data of nucleotide or amino acid sequences.

Question 8

Selective Breeding

Answer 8

Humans choosing the animals with the most desirable traits and breeding them together to produce offspring with the same traits. It is artificial selection as it is humans driving the evolution by choosing what animals will mate.

Question 9

How is artificial selection in plant crops done

Answer 9

By farmers saving the seeds from the plants with the most desirable characteristics and only planting those seeds the next season

Question 10

Homologous structures

Answer 10

structures derived from the same body part of an ancestor

Question 11

Pentadactyl limbs

Answer 11

Limbs with the same general, five fingered, form

Question 12

Analogous Structures

Answer 12

Structures that serve the same function but don’t necessarily come from the same body part and don’t indicate a common ancestor.

Question 13

Example of an analogous structure

Answer 13

Wings, many animals have evolved to have them without having a common ancestor with wings.

Question 14

Phylogeny

Answer 14

The way a species has split from other species

Question 15

Convergent evolution

Answer 15

Different species becoming more alike over time, results in organisms developing analogous structures.

Question 16

Divergent evolution

Answer 16

Results in organisms becoming less similar to each other, though they may still have homologous structures.

Question 17

Tasmanian tiger example of analogous features

Answer 17

It was a marsupial that looked and behaved similarly to wolves and tigers from other continents.

Question 18

Species

Answer 18

Organisms that can reproduce and produce viable offspring together.

Question 19

Speciation

Answer 19

When a subset of a reproducing population gets separated from the main population and evolves differently, to the point where the species can no longer reproduce together and produce viable offspring.

Question 20

What must happen for speciation to occur?

Answer 20

Some of the species must become isolated in a different environment that will require different traits.

Question 21

Speciation ____ the overall number of species whereas extinction ____ it.

Answer 21

Increases, decreases

Question 22

How are new species formed?

Answer 22

Speciation

Question 23

Barriers/reproductive isolating mechanisms that induce speciation

Answer 23

Geographical (physical isolation), behavioural and temporal (referring to time eg nocturnal/diurnal).

Question 24

Effect of reproductive isolating mechanisms

Answer 24

These barriers have the effect of making the two population face different selection pressures causing them to undergo divergent evolution.

Question 25

Reproductive isolation

Answer 25

The mechanisms that prevent different populations from interbreeding, ultimately leading to the formation of new species.

Question 26

An example of a geographical reproductive isolating mechanism

Answer 26

The Congo river which serves as a physical barrier between the chimpanzees and the bonobos on either side of the river from interbreeding. The primates have developed different characteristics to each other as a result of their different environments.

Question 27

Adaptations of the Chimpanzees by the Congo river

Answer 27

Aggressive and territorial, Male dominated social structure

Question 28

Adaptations of the Bonobos by the Congo river

Answer 28

Peaceful and nomadic, Matriarchal with the males playing a role in decision making

Question 29

When does differential selection occur

Answer 29

When one environment favours certain traits and another environment favours different ones.

Question 30

Allopatric speciation

Answer 30

When a new species forms because the population is separated by a physical barrier

Question 31

Sympatric speciation

Answer 31

When a new species is formed while the populations are existing without a physical barrier between them. Instead it is caused by temporal or behavioural isolation.

Question 32

Temporal isolation

Answer 32

Incompatible timeframes that prevent population and their gametes from encountering each other.

Question 33

Behavioural isolation

Answer 33

Part of the population develops a behaviour that isolates it from the rest of the population.

Question 34

Temporal isolation examples

Answer 34

Different breeding seasons, nocturnal vs diurnal, different migration times

Question 35

Behavioural isolation example

Answer 35

A population of songbirds develops a different mating call that the other part of the population doesn’t recognise and therefore they don’t interbreed.

Question 36

Adaptive radiation

Answer 36

When many similar but distinct species evolve relatively rapidly from a single or small number of species

Question 37

What does adaptive radiation allow?

Answer 37

The variation in the population allows certain members of that population to occupy different niches.

Question 38

Niche

Answer 38

A position or a role within a community

Question 39

How does adaptive radiation increase biodiversity?

Answer 39

It allows closely related species to coexist without competing.

Question 40

Hybrid organism

Answer 40

An organism that has been generated by fertilisation between two different species.

Question 41

Courtship behaviour

Answer 41

A type of behavioural isolation. The mating rituals of one species will not attract members of another species = no reproduction.

Question 42

Polyploidy

Answer 42

When a cell contains three or more sets of chromosomes

Question 43

3n

Answer 43

triploid

Question 44

4n

Answer 44

tetraploid

Question 45

5n

Answer 45

pentaploid

Question 46

When does polyploidy happen in animals

Answer 46

During the production of sex cells. If the copies of chromosomes aren’t completely separated into distinct nuclei they will end up in the same cell.

Question 47

When does polyploidy happen in plants

Answer 47

When two species fuse their genetic makeup to make a polyploid hybrid.

Question 48

What does polyploidy cause in plants?

Answer 48

More vigorous plants that produce bigger fruits or food storage organs and are more resistant to disease.

Question 49

Allopolyploid speciation

Answer 49

A type of speciation that occurs when a new plant species arises from the doubling of chromosomes after two different species hybridise.

Question 50

Abrupt speciation

Answer 50

The rapid development of new species

Question 51

Polyploidy Persicaria example

Answer 51

The genus Persicaria has diploid, tetraploid and hexaploid members. The multiples of the same number of chromosomes within a genus of plants it suggests polyploidy has taken place.

Question 52

How does polyploidy allows sterile hybrid plants to become fertile again?

Answer 52

It makes it possible for a plant to produce seeds and pollen with the same number of chromosomes, which can then produce fertile offspring.