Speciation

Question 1

Biological species concept

Answer 1

2 organisms are from different species if reproductive isolation can be shown to exist

Reproductive isolation: existence of biological barriers that prevents 2 species from reproducing viable, fertile offsprings

Limits:
Can’t be used for asexual species or extinct species
Need to know all breeding partners, Hardin nature
Different species can produce viable offsprings

Question 2

Reproductive barriers

Answer 2

If living ranges don’t overlap, no need for barrier, there is a,ready reproductive isolation

Pre zygote can Barrie’s: before the zygote is made
Postzygotic barriers: reduce viability or fertility

Pre:
Habitat isolation: don’t live near
temporal isolation: mating time is different
Behavioural isolation:distinctive courtship behaviours prevents mating
Mechanicals isolation: structural differences or reproductive organs
Gametic isolation: gamers are incompatible, or sperms can’t survive in the tracts of another species

Post:
Hybrid inviability: zygote formed, hybrid organism, but dies during development
Hybrid sterility: hybride can’t reproduce
Hybrid breakdown: do reproduce, but only for a few generations, offsprings weak

Question 3

Morphological species concept

Answer 3

Species is a group with similar structures and behaviours

Applies to sexual and asexual species, but relies on subjective criteria

Question 4

Phylogenetic species concept

Answer 4

Members of single species are descended from a. common ancestor who all possess a combination of certain defining traits

Species:smallest group of individuals who posses a common set of morphological or genetic traits

Applies to sexual and asexual, but is difficult to determine degree of difference required to indicate different species

Question 5

Patterns of speciation

Answer 5

New species arise by evolution of ancestor species :
Allopathic speciation:2 separate population will evolve differently because of environment
Sympatric speciation: 1 population will evolve into 2 separate species. Could be caused by mutation (ex axolotl)
Habitat differentiation: gene flow stopping because of new ecological niche.

New species arise by hybridization of 2 different species:
Hybrid speciation

Question 6

Polyploidy

Answer 6

Extra set of chromosome (ex 3n)
Autopolyploid:more than 2 sets, derived from a single species, causes new species cause can’t reproduce with another number of sets in original species

Hybridization: fusion of 2 species to create a new species

Question 7

Possible outcomes of new species

Answer 7

Reinforcement: hybrids stop forming (two species stop reproducing together) two separate species are formed
Fusion: species fuse into one
Stability: hybrids keep coming

Hybrid zone: zone of reproduction between species