Speciation

Question 1

Morphospecies concept

Answer 1

people name species based on morphological similarities and differences
adv:
1. widely applicable, can be identified in living or existing species
dis:
1. can be unclear if not applied carefully, different researchers may not be able to compare
2. groups like bacteria, fungi, archaea have few morphological characteristics

Question 2

Phylogenetics species concept

Answer 2

species identified by estimating phylogeny of closely related populations, and using monophyletic groups (lineages that have all descendants of a common ancestor).
adv:
1. can be applied to any organism
dis:
1. which trait to use
2. different sources give different phylogeny

Question 3

Biological Species Concept

Answer 3

criteria for identifying evolutionary independence is reproductive isolation (fail to produce fertile offspring)
adv:
1. proves lack of gene flow
dis:
1. difficult to test, eg if nearby populations do not come in contact

instead they have to say “if these populations were to meet in the future, we believe they would not interbreed”.

Question 4

Allopatric speciation

Answer 4

barrier appears reducing gene flow to zero
1. genetic drift
2. local selection
3. morphological divergence
4. genetic divergence

if species come back and meet, hybrids would be sterile, become two new species.

eg. shrimps in carribean are closely related to shrimps in pacific, so panama was the barrier between them that separated them.

Question 5

Peripatric speciation

Answer 5

subset of ind find new niche
1. genetic drift
2. inbreeding
3. local adaptation
(founder effect)

eg. polar bears from irish brown bears moved further up north and occupied a new niche, became white to remain hidden

Question 6

Sympatric speciation

Answer 6

selection within population, no barrier

eg. apple maggot, all insects eat hawthorn, apple tree introduced and some eat apple. Now insects each only species of plant.

Question 7

Hybrid speciation

Answer 7

meet and hybridise, parental alleles give advantage, new species arise

either get
prezygotic isolation: hybrid offspring never formed because mating between species does not occur

postzygotic isolation: hybrid offspring have reduced fitness/ sterile