Topic 14 - Speciation

Question 1

Biological species concept

Answer 1

When species are differentiated based on reproductive isolation. It can work well for most living organisms, but cannot be applied to fossils or to asexual species, and may be difficult to apply when there is no geographical overlap. In addition, a certain amount of hybridization often happens between species.

Question 2

Allopatric speciation

Answer 2

Type of speciation that happens when populations live in separate areas. It happens due to the lack of gene flow between the original population and new populations resulting from emigration, or because of an environmental barrier separated the original population into subgroups.

Question 3

Sympatric speciation

Answer 3

Type of speciation that occurs between populations living within the same geographical area.

Question 4

Prezygotic

Answer 4

Type of reproductive barrier which prevents individuals of different species from mating successfully, or prevents fertilization.

Question 5

Postzygotic

Answer 5

Type of reproductive barrier in which the hybrid offspring of matings between members of different species either do not survive or cannot reproduce.

Question 5

Reinforcement

Answer 5

Natural selection for traits that prevent interbreeding between recently diverged species. Occurs as a result of selection acting against the production of hybrid individuals of low fitness.

Question 6

Temporal

Answer 6

Prezygotic barrier in which populations are isolated because they breed at different times.

Question 6

Habitat

Answer 6

Prezygotic barrier in which populations are isolated because they breed in different habitats.

Question 7

Behavioural

Answer 7

Prezygotic barrier in which populations do not interbreed because their courtship displays differ.

Question 8

Gametic

Answer 8

Prezygotic barrier in which matings fail because eggs and sperm are incompatible (don’t have the proper recognition proteins, for example).

Question 9

Mechanical

Answer 9

Prezygotic barrier in which matings fail because male and female reproductive structures are incompatible.

Question 10

Hybrid viability

Answer 10

Postzygotic barrier in which hybrid offspring do not develop normally and die as embryos.

Question 10

Hybrid sterility

Answer 10

Postzygotic barrier in which hybrid offspring mature but are sterile as adults.

Question 11

Reproductive isolation

Answer 11

When organisms are unable to produce viable offspring, or can only produce sterile offspring.

Question 12

Morphological species concept

Answer 12

When species are differentiated based on their size, shape, color or other morphological feature. It is applicable to sexual, asexual, or fossil species. It cannot identify cryptic species, and it could lead to incorrectly separating polymorphic individuals into different spp. Also, morphological features can be subjective.