Orginis Of Species

Question 1

What is speciation ?

Answer 1

Process by which one species splits into two species

Question 2

Speciation produced…

Answer 2

The diversity of life

Question 3

Factors to consider when defining a species

Answer 3

Morphology, ecology, physiology and genetics

Question 4

What is the biology species concept (BSC)?

Answer 4

A group of populations whose members have the potential to interbreed and produce viable, fertile offspring

Question 5

BSC has an emphasis on…

Answer 5

Reproductive isolation

Question 6

Species do not produce viable, fertile offspring with…

Answer 6

Other groups

Question 7

What is reproductive isolation?

Answer 7

Biological factors (barriers) impede members of two species from interbreeding and producing viable, fertile offspring

Question 8

In reproductive isolation, barriers block…

Answer 8

Gene flow

Question 9

In reproductive isolation, it limits…

Answer 9

The formation of hybrids

Question 10

What are hybrids?

Answer 10

Offspring that result from inter specific mating (mating between two different species)

Question 11

What are the limitations of the BSC?

Answer 11

Cannot apply to fossils
Does not apply to asexual organisms
Cannot apply to geographically isolated populations
Designated by “absence of gene flow”
But there are morphologically and ecologically distinct species that can, mate and produce viable/fertile offspring

Question 12

What is the morphological species concept (MSC)?

Answer 12

Distinguishes a species by body shape and other structural features

Question 13

MSC applies to…

Answer 13

Asexual and sexual organisms

Question 14

Limitations of the MSC

Answer 14

Disagreement on what features are most important in distinguishing a species
Intra-species (within species) morphological variation often greater that inter-species variation

Question 15

What is the Ecological Species Concept(ESC)?

Answer 15

Defines a species in terms of its ecological niche or the sum of how species interact with biotic and abiotic parts of their environment

Question 16

ESC accommodates…

Answer 16

Sexual and asexual species

Question 17

ESC emphasizes…

Answer 17

The role of disruptive natural selection

Question 18

Limitations if ESC

Answer 18

Might separate species that still have gene flow
Required specific understanding of species ecological niche

Question 19

Two main types of barriers

Answer 19

Pre-zygotic barriers
Post-zygotic barriers

Question 20

What is Perozygotic barriers?

Answer 20

Before zygote, anything that prevents mating and/or fertilization from occurring

Question 21

What is habitat isolation?

Answer 21

Two species occupy different habitats within same area but may meet each other (even without physical barriers)

Question 22

What is temporal isolation?

Answer 22

Two species have timing differences in breeding

Question 23

What is behavioral isolation?

Answer 23

Courtship rituals unique to a species can be effective reproductive barriers

Question 24

What is mechanical isolation?

Answer 24

Mating is attempted but morphological differences prevent successful completion

Question 25

What is gametic isolation?

Answer 25

Sperm of one species may not be able to fertilize the eggs of another species (may not survive, may not get through a biochemical barrier)

Question 26

What is postzygotic barriers?

Answer 26

After zygote, reproductive isolation after hybrid zygote is formed, usually, hybrid offspring do not survive or are sterile

Question 27

What is reduced hybrid viability?

Answer 27

Genes of different parent species may interact to impair hybrids development or survival, most do not survive the embryonic phase

Question 28

What is reduced hybrid fertility?

Answer 28

Hybrids maybe sterile, often result in differences in number or structure of parental chromosomes so meiosis in hybrids fail to produce normal gametes

Question 29

What is allopathic speciation?

Answer 29

Occurs between physically or geographically isolated populations

Question 30

What is Sympathetic speciation?

Answer 30

Occurs without physical or geographic isolation

Question 31

Vicariance (type 1): Allopatric Speciation

Answer 31

Large population split into two or more sub-popukations
Usually due to emerging geographic barriers
New populations isolated genetically —> no gene flow
Subpopulations diverge genetically

Question 32

Dispersal/ Colonization (type 2): Allopatric Speciation

Answer 32

Small # of individuals disperse to a new habitat
Founder effect increases likelihood of genetic drift
If environment is different, selective pressure will be different
Ex. Commonly found in species on islands

Question 33

What is the importance of Allopatric speciation?

Answer 33

Regions that are isolated typically have more species than other regions
-Island endemics (local species)
-areas broken up by mountain ranges/ water features

Question 34

What is sympathetic speciation?

Answer 34

Occurs without physical isolation
Natural selection overwhelms gene flow

Question 35

What are the three main mechanisms of sympathetic speciation?

Answer 35

Polyploidy
Sexual selection
Habitat differentiation

Question 36

What is polyploidy?

Answer 36

Species may originate from accident during cell division that results in an extra set of chromosomes

Question 37

Botanists estimate that…

Answer 37

> 80% of plant species today are descended from ancestors that formed by polyploidy speciation

Question 38

What is habitat differentiation?

Answer 38

In the same area, but there is a niche that is specific to a certain species

Question 39

What happens when there is incomplete reproductive isolation?

Answer 39

Hybrid zones can form

Question 40

What is a hybrid zone?

Answer 40

Region in which members of what are considered different species meet and mate producing at least some offspring of mixed ancestry