Origin of Species (2)

Question 1

What is speciation?

Answer 1

Speciation, the process by which one species splits into two or more species, accounts for both the unity and diversity of life.

Question 2

What are the 3 ways to define a species?

Answer 2

1. Morphological species concept.
2. Ecological species concept
3. Phylogenetic species concept

Question 3

What is the biological species concept and what does it emphasize?

Answer 3

“A species is a group of populations whose members can interbreed in nature and produce fertile offspring with each other but not with members of other species”

It emphasizes on reproductive isolation.

Question 4

What are the flaws of the biological species concept?

Answer 4

1. Many pairs of species are distinct and yet are capable of interbreeding.
2. There is no way to determine whether organisms known through fossils were able to interbreed.
3. This criterion is useless for organisms such as prokaryotes that reproduce asexually.

Question 5

What is the morphological species concept?

Answer 5

Based on observable physical traits and can be applied to asexual organisms and fossils.

Question 6

What is the ecological species concept?

Answer 6

The ecological species concept defines a species by its ecological niche and focuses on unique adaptations to particular roles in a biological community.

Question 7

What is the phylogenetic species concept?

Answer 7

Phylogenetic species concept defines a species as the smallest group of individuals that share a common ancestor and thus form one branch of the tree of life.

Question 8

What are reproductive barriers and what is their function?

Answer 8

Reproductive barriers:
-serve to isolate the gene pools of species
-prevent interbreeding

Question 9

What are the two classifications of reproductive barriers?

Answer 9

Depending on whether they function before or after zygotes form, reproductive barriers are categorized as: -

prezygotic and postzygotic.

Question 10

What are the prezygotic barriers?

Answer 10

1. Habitat isolation
2. Temporal isolation
3. Behavioural isolation
4. Mechanical isolation
5. Gametic isolation

Hate the behaviour of MGK (acronoym)

Question 11

What are the postsygotic barriers?

Answer 11

1. Reduced hybrid viability
2. Reduced hybrid fertility
3. Hybrid breakdown

Question 12

Explain habitat and temporal isolation with examples.

Answer 12

1. Habitat isolation: lack of opportunities to encounter each other (ex: 2 species of garter snake, one lives in water the other on land)
2. Temporal isolation: Breeding at different times or seasons ( ex: eastern skunk breeds in winter , western skunk breeds in fall)

Question 13

Explain behavioural and mechanical isolation with examples.

Answer 13

1. Behavioural isolation: different courtship rituals (ex: blue-footed bobby and masked booby)
2. Mechanical isolation: physical incompatibility of reproductive parts. ( ex: two species of plants are pollinated by different beaked hummingbirds)

Question 14

What is gametic isolation?

Answer 14

Gametic isolation: molecular incompatibility of sperm and eggs (ex : sea urchins)

Question 15

Explain reduced hybrid viability and fertility with examples.

Answer 15

1. Hybrid Viability: hybrid development or survival is impaired by the interaction of parental genes. Will not survive long enough to reproduce. ( ex: salamander)
2. Hybrid fertility: Hybrids that are healthy but sterile ( ex: mule)

Question 16

Explain hybrid breakdown with example.

Answer 16

Viable and fertile hybrids but their offspring are sterile.

( ex: rice hybrids)

Question 17

What is allopatric speciation and how does it lead to speciation?

Answer 17

Allopatric speciation: the interruption of gene flow between populations of the same species.

Geographically isolated, a small population may become genetically unique as its gene pool is changed by:-
-natural selection
-mutation
-genetic drift.

Question 18

What is sympatric speciation?

Answer 18

Sympatric speciation occurs when a new species arises within the same geographic area as its parent species

Question 19

Sexual selection cannot lead to allopatric and sympatric selection. True or false?

Answer 19

False. Habitat differentiation and sexual selection, usually involving mate choice, can lead to sympatric (and allopatric) speciation

Question 20

What is adaptive radiation?

Answer 20

The evolution of many diverse species from a common ancestor is known as adaptive radiation.

Repeated isolation, speciation, and recolonization events on isolated island chains have led to adaptive radiations

Question 21

What happens when separated populations of closely-related species come back into contact?

Answer 21

1. Hybrid zones: regions where different species meet and mate producing at least some hybrid offspring.
2. Over time, reinforcement may strengthen barriers to reproduction, or fusion may reverse the speciation process as gene flow between species increases.
3. In stable hybrid zones, a limited number of hybrid offspring continue to be produced

Question 22

What are the two models for the tempo of speciation?

Answer 22

-Punctuated equilibria describe an evolutionary pattern in which species change most as they arise from an ancestral species and then change relatively little for the rest of their existence.

-The gradual pattern occurs in other species that appear to have evolved more gradually.