Chapter 24

Question 1

Speciation

Answer 1

The process by which one species splits into two or more species. Speciation explains not only difference between species but also similarities between them.

Question 2

Micro evolution

Answer 2

Changes over time in allele frequencies in a population.

Question 3

Macro evolution

Answer 3

The broad pattern of evolution above the species level.

Question 4

Biological Species concept

Answer 4

A group of population whose members have potential to interbreed in nature and produce viable , fertile offspring but do not produce viable , fertile offspring in other groups can not be used for fossil

Question 5

Gene flow

Answer 5

The transfer of allele within a population

Question 6

Reproductive isolation

Answer 6

The existence of biological factor (barriers) that impede member of two species from interbreeding and producing viable, fertile offspring.

Question 7

Hybrid

Answer 7

Offspring that result from inter specific mating

Question 8

Habitat isolation

Answer 8

Two species that occupy different habitats within the same area may encounter each other rarely

Question 9

Temporal isolation

Answer 9

Species that breed during different time of year , different season or different year cannot mix

Question 10

Behavioural isolation

Answer 10

Courtship rituals that attract mates and other behaviours unique to
a species are effective reproductive barriers, even between closely related species.

Question 11

Mechanical isolation

Answer 11

Mating is attempted, but morphological differences prevent its successful completion.

Question 12

Genetic isolation

Answer 12

Sperm of one specie may not be able to fertilise sperm of other species

Question 13

Reduced hybrid viability

Answer 13

The gene of different parent species may interact in ways that impair hybrid or survival in its environment,

Question 14

Reduced hybrid fertility

Answer 14

Even if hybrid are vigorous, they may be sterile. If chromosomes of two parent differ in structure or number, meiosis in hybrid may fail to produce normal gametes.

Question 15

Hybrid breakdown

Answer 15

Some first-generation hybrid are viable and fertile p, but when they mate with other species, o or even with parent species, the next generation is feeble and sterile.

Question 16

Prezygotic barrier

Answer 16

Before the zygote, block fertilisation from occurring

Question 17

Post zygotic barrier

Answer 17

May contribute reproductive isolation after the hybrid zygote is formed.

Question 18

Morphological concept

Answer 18

Characterises a specie by body shape and other structural features and suggest ps that each specie is more morphologically distinct

Question 19

Ecological concept

Answer 19

Views a specie in terms of its ecological niche, the sun ppm of how members of the species interact with non living and living part of their environment. Unlike morphological, it accounts for sexual and asexual reproduction.

Question 20

Phylogenetic species concept

Answer 20

Defines a species as smaller group of individual that share common ancestor forming one branch tree of life.

Question 21

Allopathic speciation

Answer 21

Gene flow is interrupted when population is divided into geographical,y isolated sub populations. Can also occur without geological remodelling. Once geographic separation has occurred, the separated gene pools may diverge. Different mutations arise, and nat- ural selection and genetic drift may alter allele frequencies in different ways in the separated populations. . More variation in specie.

Question 22

Symlatrix speciation

Answer 22

Speciation occurs in a popular that live in same geographic area. Gene flow is reduce due to factor such as polyploidy, habitat differentiation and natural selection.

Question 23

Polyploidy

Answer 23

When a species originate from an accident during cell division that results in extra sets of chromosomes. Botanist 80% of the planing specie that live today are descended formed by polyploid speciation

Question 24

Auto polyploid

Answer 24

is an individual that has more than two chromosome sets that are all derived from a single species.

Question 25

Teraploid

Answer 25

Have 4n | It can produce fertile off springs by self-pollinating or by mating with other tetraploid.

Question 26

Triploid

Answer 26

Have 3n | Reduce fertility

Question 27

What happens when two different specie fertilise

Answer 27

when two differ- ent species interbreed and produce hybrid offspring. Most such hybrids are sterile because the set of chromosomes from one species cannot pair during meiosis with the set of chromosomes from the other species.

Question 28

Allopolyploid

Answer 28

When in a subsequent generation a sterile hybrid develop into fertile polyploid

Question 29

Habitat differentiation

Answer 29

Symmetric speciation can also occur when genetic factor enable a sub population to exploit habitat or resources not used by parent populations,

Question 30

Sexual selection

Answer 30

1-subgroups of the original cichlid populations adapted to different food sources and that the resulting genetic divergence contributed to speciation in Lake Victoria

Question 31

Hybrid zone

Answer 31

A region in number of different specie meet and mate, producing at least some offspring of mixed ancestry. It is formed when two species lacking barrier come together to reproduce.

Question 32

Reinforcement of barrier: strengthen prezygotic barrier

Answer 32

Hybrids are often less fit than members of their parent species. In such cases, natural selection should strengthen prezygotic barriers to reproduction, reducing the formation of unfit hybrids.

Question 33

Fusion , weakening barrier

Answer 33

two species contact one another in a hybrid zone, but the barriers to reproduction are not strong. So much gene flow may occur that reproductive barriers weaken further and the gene pools of the two species become increasingly alike

Question 34

Stability

Answer 34

continued production of hybrid individuals

Question 35

Punctuated equilibrium

Answer 35

Describe period of apparent stasis punctuated by sudden changes

Question 36

Speciation can occur rapidly or slowly and can result from changes in few or many genes

Answer 36

New species can form rapidly once divergence begins but it can take millions of years for that to happen. The time interval between speciation events varies considerably, from a few thousand years to tens of millions of years