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Biology Unit 2- Genetics > Speciation > Flashcards

Flashcards in Speciation Deck (17)
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1
Q

species

A

a population that can breed and produce offspring that can also breed, but it is not able to breed successfully with other populations

2
Q

speciation

A
  • process by which an existing population gives rise to a new 
population that no longer has the 
potential to recombine with it as a single 
gene pool.
  • the key to this is reproductive isolation.
  • As long as individuals can share genes freely in a gene pool, that gene pool may 
change over time, but we would not consider it to be a new species unless it had 
changed enough that present members of the population would be unable to 
breed with past members.
3
Q

reproductive isolation (what is it)

A

Reproductive isolation can occur as a result many different 
changes in genetic compatibility that may lower fitness of 
hybrids or changes in phenotype that may provide a barrier 
to successful mating. can happen through post or pre zygotic methods.

4
Q

Post-zygotic isolation

A

occurs when hybrids are formed but have 
reduced fitness.

a) - hybrid viability: offspring dies young
b) - hybrid sterility: when you can’t reproduce with another member of the population is not hybrid
c) - Hybrid Fitness: fitness is reduced because it is not going to survive. it is a mix between the best of the both parents but because it is a mix, it is eaten. if poisonous mates with camouflage, it will be half camouflaged and half poisonous. it doesn’t do either well so it gets eaten

5
Q

prezygotic isolation

A

prevents the formation of hybrids in the first 
place

6
Q

gametic isolation (prezygotic isolation)

A

sperm and egg can’t form zygote. they just don’t fertilize

7
Q

mechanical isolation (prezygotic isolation)

A

parts don’t fit

8
Q

termporal isolation (prezygotic isolation)

A

fertile periods don’t match. ex. one animal is only fertile in spring, others only in fall

9
Q

behavioural isolation (prezygotic isolation)

A

behaviours don’t match. the mating activity they do is different from the mating that the organism is attracted to so they don’t recognize each other as mates

10
Q

habitat isolation (prezygotic isolation)

A

they live so far away that they will never encounter each other. ex. tigers in asia vs lions in africa

11
Q

allopatric speciation

A
  • Speciation requires reproductive isolation. It usually also involves divergence as the two populations become 
different phenotypically.
  • The standard model of speciation assumes that a gene pool MUST BE physically 
split before the two sub-populations can diverge enough to speciate.
12
Q

geographic isolation

A

causes all gee flow to stop between two subpopulations:

- natural disasters, colonization, fragmentation, physical barrier, continental drift

13
Q

microevolution

A

causes two gene pools to diverge from one another.

- genetic drift, natural selection, differential mutation, sexual selection

14
Q

steps in model

A

1) geographic
2) microevolution
3) reproductive isolation

15
Q

types of prezygotic isolation

A

gametic, temporal, behavioural, mechanical and habitat

16
Q

sympatric speciation

A

sympatric (sym = same) speciation, in which reproductive isolation occurs between two sub-groups of a single population before divergence.

17
Q

divergence

A

when two populations start to become different (they are still same species). If they diverge enough, they will speciate