speciation

Question 1

Define natural selection

Answer 1

Natural selection is the process whereby organisms that are better suited towards the environment tend to survive and produce offspring

Question 2

the overall effect of natural selection

Answer 2

those with a genotype or phenotype (dependent on the question) which suits their environments biological niche will be more likely to survive and pass on those advantageous genes into the gene pool

Question 3

what is stabilising natural selection

Answer 3

natural selection for those individuals with a combination of both phenotypic extremities meaning those with one extremity and less likely to survive

Question 4

What is directional natural selection

Answer 4

natural selection for one extreme phenotype at the expense of another

Question 5

What is disruptive natural selection

Answer 5

natural selection against the average, natural selection for both extremities, over time this leads to a bimodal distribution of phenotypes

Question 6

What is a deme

Answer 6

Local populations/sub-groups where phenotypic variations reflect the local environmental factors. there is limited gene flow between the two groups

Question 7

What is a cline

Answer 7

the geographical gradient in the phenotype of individuals of the same species. Often occurs in relation to changing latitude or altitude

Question 8

what is allopatric speciation

Answer 8

a group the becomes geographically isolated

Question 9

what is sympatric speciation

Answer 9

Gene flow is altered/stopped by something other than geographical, for example temporal

Question 10

Define reproductive isolating mechanisms

Answer 10

any factor that prevents two organisms from different species from mating and producing fertile offspring

Question 11

what is geographical reproductive isolation

Answer 11

two groups are geographically issolated and therefore gene flow is limited (this is allopathic speciation)

Question 12

what is Temporal reproductive isolation

Answer 12

The timing of activity or reproduction does not overlap eg diurnal vs nocturnal

Question 13

what is ecological reproductive isolation

Answer 13

Closely related species (could produce fertile offspring) occupy different niches within the same environment eg sparrow and ground sparrow occupy a forest

Question 14

what is ethological reproductive isolation

Answer 14

courting/ mating rituals that are species specific eg a fantail not recognizing a peacock dance

Question 15

What is structural reproductive isolation

Answer 15

structural variations between species preventing reproduction
eg incompatible sex organs

Question 16

What is convergent evolution

Answer 16

Species with similar niches develop similar adaptations despite having different ancestors due to having similar selection pressures.

Question 17

define analogous organs

Answer 17

Organs that have the same basic structure and function but evolved independently from different ancestral organs in unrelated species, eg flippers on a dolphin vs shark

Question 18

Define ecological equivalents

Answer 18

Species with different origins develop similar adaptations because they occupy similar niches in different geographical areas

Question 19

What is divergent evolution/ when does it occur

Answer 19

when two or more related groups develop different adaptations over time because they occupy differently niches

Question 20

What is adaptive radiation?

Answer 20

a type of divergent evolution when a number of different species develop from a common ancestor

Question 21

What is homologous organs/ evolution

Answer 21

Found in related species that evolved from a common ancestral organ. They have different functions but similar structures, for example, tibias in dolphins’ flippers and humans’ legs

Question 22

Parallel evolution

Answer 22

Similar features evolve in species with a common ancestor. This is because they’re subjected to similar selection pressures (for example, woolly mammoths and elephants.) they evolve parallel because of similar selection pressure.

Question 23

What is co-evolution

Answer 23

the reciprocal evolutionary effect that two species can have on each other when they react. Each species provides a natural influence on each other and evolves together, for example, flowering plants have co-evolved with other pollinating partners

Question 24

What is aneuploidy

Answer 24

1 too many or 1 two lesschromosomes (n+1, see above) and after an aneuploidy cell fertilisatises a normal gamete.

Question 25

Euploidy

Answer 25

is a gamete that has more than one set of chromosomes. This also comes from nondisjunction occurring during meiosis. In an organism that is diploid, nondisjunction occurring means the resulting gametes with both sets of chromosomes

Question 26

Amphiploid

Answer 26

offspring is when doubling of chromosomes happen which means an even chromosome set. This means it is fertile.

Question 27

Autopolyploidy

Answer 27

may be the result of somatic doubling. It is when a normal 2n cells chromosome replicate before mitosis, and then cytokinesis does not occur and
this cell does not divide.

Question 28

Allopolyploidy

Answer 28

s sets of chromosomes that come from different species which forms hybrid offspring