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From Organisms to Ecosystems - Lectures > Lecture 11. Species and Speciation > Flashcards

Lecture 11. Species and Speciation Flashcards

1
Q

What is the species concept ?

A

What is a species ? When does it stop being a sub-species, or a distinct population ?

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2
Q

What does a species describe ?

A

A group of individuals sharing a common gene pool.

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3
Q

What can those who share the same gene pool not do ?

A

They cannot diverge from each other

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4
Q

When can a population diverge ?

A

When it stops exchanging genes and as a result it can follow a separate evolutionary trajectory.

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5
Q

What are the five main ways scientists have considered defining a species ?

A
  1. Biological species concept
  2. Evolutionary species concept
  3. Recognition species concept
  4. Morphological species concept
  5. Genetic difference
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6
Q

What is another name for the biological species concept ?

A

Isolation species concept

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7
Q

What is the biological species concept ?

A

Species are groups of actually or potentially interbreeding natural populations which are reproductively isolated from other such groups

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8
Q

What are some problems with the biological species concept ?

A
  1. Does not specify that the young need to be fertile
  2. Inappropriate for asexual organisms
  3. Too difficult to apply to fossils, as we cant know who they would have bred with
  4. Species isolated on islands are problematic as they never get the chance to show whether they would breed
  5. Organisms which just release gametes - if mating is never observed, it is hard to tell who is mating with whom
  6. Some species which do occasionally interbreed, are clearly good species
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9
Q

What is the evolutionary species concept ?

A

A group of organisms that share an ancestor - a lineage that maintains its integrity with respect to other lineages through both time and space

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10
Q

What are some issues with the evolutionary species concept ?

A
  1. May or may not recognise sub species and recognise sister-species only when they have become distinct enough to be clearly different.
  2. Depends on the evolutionary history being known and the phylogenic tree being correct
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11
Q

What is the recognition species concept ?

A

Species are separated by differences in their fertilisation system

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12
Q

What is the problem with the recognition species concept ?

A

Does not cater for asexual organisms

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13
Q

What is the morphological species concept ?

A

Taxonomists look for discontinuities in the morphological variations between the populations

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14
Q

What are the problems with the morphological species concept ?

A
  1. Polymorphisms
  2. Sexual dimorphisms
  3. Cryptic diversity
  4. Use of genetic markers
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15
Q

How would you determine genetic distance between sister species ?

A

Look at the number differences in bases within the same genes

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16
Q

What are barcoding genes ?

A

Genes used by geneticists for species comparisons

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17
Q

What are barcoding genes ?

A

Genes used by geneticists for species comparisons

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18
Q

What is integrative taxonomy ?

A

Uses several lines of evidence together to make a case to the taxonomists community

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19
Q

What is the Tobias criteria scoring system ?

A

A popular method, using morphology, song, plumage and behavioral traits for separating species

20
Q

What does speciation need to occur ?

A

The two populations need to stop breeding for long enough for them to become different to breed any more

21
Q

What are the 3 possible methods of speciation ?

A
  1. Allopatric speciation
  2. Parapatric speciation
  3. Sympatric speciation
22
Q

What is allopatric speciation ?

A

Some form of barrier splits the population, or part of the population gets stranded on an island

23
Q

Why do isolated populations change ?

A
  1. Founder effect
  2. Genetic drift
  3. Natural selection (in conditions different from those experiences by the founder population)
24
Q

What is a founder effect ?

A

Founding population is unlikely to have all the variation present in the parent population

25
Q

What is genetic drift ?

A

The effect of chance on tiny populations

26
Q

Why is natural selection different on islands ?

A
  1. Traits spread faster in smaller populations
  2. Reduced predation pressure as fewer predators
  3. Niche expansion because of less food of any one type on the island
  4. Less interspecific competition as less species on island
  5. More intraspecific competition because where a species reaches an island, it tends to flourish
27
Q

What is parapatric speciation ?

A

Speciation at a border which does not prevent gene flow entirely

28
Q

When does a hybrid zone narrow ?

A

If hybrid offspring are less fit that the pure breed of each type

29
Q

When does a hybrid zone widen ?

A

If they are equally fit with pure bred offspring

30
Q

What do you often get in hybrid zones ?

A

Character displacement

31
Q

What is character displacement ?

A

Exaggeration of signals, especially those related to breeding, to make the signal stronger and prevent hybridisation

32
Q

What is sympatric speciation ?

A

Requires isolation of a subset of the population within the original population

33
Q

What is founder effect ?

A

A change in allele frequency due to the foundation of a sub-population by an unrepresentative sample of the parent population

34
Q

What is genetic drift ?

A

A change in allele frequency due to chance events

35
Q

What is meant by selectively neutral ?

A

A gene with no fixed effect on fitness

36
Q

What is effective population size ?

A

Those individuals of a population which breed

37
Q

What is fixation ?

A

When one allele survives at a locus

38
Q

What is a population bottleneck ?

A

When a population is reduced to very few individuals

39
Q

What is meant by polymorphic ?

A

Having more than one form

40
Q

What is meant by monomorphic ?

A

Having only one form

41
Q

What is inbreeding depression ?

A

Reductions in fitness due to breeding with close relatives due to increased expression of rare deleterious recessives

42
Q

What is the heterozygote advantage ?

A

Extra vigor due to the genotype being heterozygotic

43
Q

What is assortative mating ?

A

Mate selection on the grounds of sharing the same allele

44
Q

What is disassortative mating ?

A

Mate selection on the grounds of having a different allele

45
Q

What is a stable polymorphism ?

A

A species with more than one form in the population

From Organisms to Ecosystems - Lectures (37 decks)

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