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speciation Flashcards

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Biology 101 flashcards
1
Q

What is a species?

A

A species is a group of individuals that share a common gene pool and are reproductively isolated from other species.

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2
Q

How does speciation occur?

A

when there is no gene flow, this causes populations to become reproductively isolated from other and ancestral populations.

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3
Q

Deme

A

a local population that has limited gene flow with members of the larger population

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4
Q

cline

A

a pattern of variation between individuals of a species; there is a continuous increase or decease in some phenotypes between adjacent populations.

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5
Q

How are deme and cline different?

A

while a deme is a population with a certain circumstance, a cline is a pattern/trend of varying phenotypes seen in populations.

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6
Q

What is a gene pool?

A

the total number of alleles in a population. (or species)

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7
Q

What is an indication of evolution in a gene pool?

A

any changes in the allel frequency of the gene pool.

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8
Q

What are all the processes that contribute to changes in allele frequency in the gene pool and evolution?

A

mutations, natural selection, and gene flow.

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9
Q

What is speciation?

A

the formation of new species as a result of reproductive isolation

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10
Q

What is homologous structure?

A

similar organs or skeletal elements that suggest a common ancestor; evidence for divergent evolution.

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11
Q

What is analogous structure?

A

individuals/populations with similar biological structures that don’t come from a common ancestor; evidence of convergent evolution.

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12
Q

What is all the evidence used for scientific evolution?

A

fossil evidence, comparative anatomy (homologous or analogous), molecular biology (DNA and proteins), and biogeography.

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13
Q

Explain fossils

A

Fossils are preserved remains or impressions by organisms that lived in the past and are found in sedimentary rocks. It provides evidence for speciation, extinction, gradualism, punctuated equalibrium, divergence and adaptive radiation.

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14
Q

What is punctuated equilibrium?

A

sudden, rapid bursts of a change of form/structure over time

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15
Q

What is looked at in comparative anatomy?

A

the comparison of body structures between different species, looking at fossil records and living individuals.

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16
Q

What part of molecular biology is used in evolutionary studies?

A

Molecular biology refers to the large organic molecules all organisms are made up of; the most important molecules for evolutionary studies is DNA and proteins.

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17
Q

What part of an organism is able to provide significant evidence for evolutionary relationships?

A

Genome/DNA/protein analysis; genome is the complete set of DNA in an organism, including all genes. this analysis from both fossils and living is able to provide significant evidence for evolutionary relationships!

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18
Q

What indicates two species have a recent common ancestor?

A

the more similar DNA proteins are between different species, the more closely related they are and the more recently they shared a common ancestor.

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19
Q

what is the only way mtDNA can change?

A

mtDNA is mitochondrial DNA that is inherited from the egg only. it is not able to be subject to natrual selection or independent assortment, thus the ONLY way it can change is through random mutations in the DNA.

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20
Q

What is a molecular clock?

A

The rate at which mutations occur in the mtDNA, and used to determine the approximate time of divergence between species.

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21
Q

What is a phylogenetic tree?

A

diagrams that show the evolutionary relationships between groups; shows divergent evolution from a common ancestor.

22
Q

Explain how a phylogenetic tree is constructed.

A

Taxa are classification groups. From left to right is the flow of time (continual timeline). Each point at which two new species occur called a Node. These nodes indicate a common ancestor for the taxa evolved from that point.

23
Q

What is biogeography?

A

refers to the evidence from geographical distributions of species. Origins and dispersal of modern life is explained through drifting tectonic plates.

24
Q

What is Gondwana?

A

Gondwana was the southern supercontinent that, from 180-150 mya, began splitting.

25
Q

How does Gondwana relate to gene flow?

A

Once the supercontinent split apart into separate land masses, seas and oceans became a physicals barrier stopping gene flow. these populations became isolated from the ancestral species and started to evolve in isolation.

26
Q

What is Gondwana distribution?

A

the indication that organisms evolved in isolation when populations were separated by the drifting apart of three continents.

27
Q

Why do Gondwana distribution species an example of vicariance?

A

Gondwana distribution species show vicariance as they are geographically split by a physical barrier over a geographical range.

28
Q

What is natural selection and what does it work on?

A

natural selection is the process in which inheritable traits that make an individual more likely to survive longer and reproduce, become more common in the gene pool over successive generations. Natural selection works on phenotypes.

29
Q

what is fitness

A

a measure of reproductive success

30
Q

Stabilising selection pressure is…

A

the most common mode of selection in populations where extreme phenotypes are selected against and average phenotypes are selected for

31
Q

Disruptive Selection pressure is…

A

extreme phenotpes are selected for with average phenotypes at a disadvantage

32
Q

Directional selection pressure is…

A

selection of one phenotype at the expense of all other phenotypes; commonly seen in selective breeding

33
Q

How is sexual selection special?

A

It’s a special type of natrual selection in which males compete for females for mating typically through forms of displays. The female selects the “best” partner to mate in - increasing the frequency of these alleles in the gene pool

34
Q

Genetic drift is…

A

the random change in allele frequency in a gene pool - occurs only by chance.

Affects smaller populations more such as founder populations and during bottleneck effect.

35
Q

Founder effect and genetic drift relationship

A

The founder population is not representative of the ancestral population, thus lacks certain alleles. the limited gene pool/ inbreeding/ genetic drift all result in limited gene variation in the population

36
Q

Mutations are…

A

sudden, radon changes in the genetic material that occur by chance

37
Q

Evolution depends on the “…” Genetic variation is determined by “…” and new alleles from a mutation will “…”

A

“Presence of genetic variation in the gene pool of a population”
“the range of different alleles in the gene pool.”
“enter the gene pool and be subject to natural selection.”

38
Q

Gene flow; when it happens and impacts.

A

occurs during migration between populations.
Impacts; genetic diversity of BOTH populations as alleles are removed or added to gene pools. Strongly affects smaller populations.

39
Q

Allopatric speciation occurs…

A

through geographical isolation - the result of a barrier that seperates the population and blocks gene flow. If the two populations were to come together again, RIMs such as behavioural and structureal would prevent mating.

macroevolution

40
Q

Sympatric speciation occurs…

A

WITHOUT geographical isolation. In animals, it may result from distruptive selection. Populations diverged and ecological niches become different on the basis of selection pressue. This niche differentiation is typically the driving force of animal sympatric speciation. In plants, polyploidy is the most common sympatric speciation. This is instant speciation due to different sets of chromosomes .

macroevolution

41
Q

Name all RIMs

A

Geographical
Ecological
Temporal
Behavioural
Invalible hybrid (post)
Gametic incompatability
Structural
Polyploidy
Zygotic (sterility & breakdown)

42
Q

Hybrid inviability
Hybrid sterility
Hybrid breakdown

A
  • does not survive during fertilisation
  • when mature, hybrid is infertle
  • reaches maturity and is able to breed, but second generations are infertile
43
Q

Gradualism is…

A

slow constant rate of change in species over time

44
Q

Evolution proceeds by…

A

gradualism or punctuated equilibrium, or a combination of both

45
Q

Adaptive radiation is…

A

a type of divergent evolution, occurring when there is rapid evolution of a large number of species from a common ancestor to occupy a variety of ecological niches that have become suddenly available

46
Q

Ecological equivalents are…

A

species that occupy similar niches in a similar manner due to similar selection pressures and evolved similar adaptations through convergent evolution.

47
Q

Co-evolution is…

A

reciprocal evolutionary change occuring when a change in a trait in one species acts as a selection pressure for a change in a trait in another unrelated species.

48
Q

What is divergent evolution?

A

populations derived from a common ancestor that are reporudvtively isolated from ancestral species and have adapted to their difference environments and niches. Typically show vestigial organs or homologous structures

“Vestigal organs and homologous structures provide evidence for divergent evolution (common ancestor).”

49
Q

What is convergent evolution?

A

populations not derived from a common ancestor that are reproductively isolated and have adapted to similar environments nad niches. Typically show analogous structure

“Analogous structure provides evidence for convergent evolution (no common ancestor).”

50
Q

What is vicarience?

A

the process where the geographical rnage of a group of organisms is split by a physical barrier (such as a body of water or mountain range) resultign in a lack of gene flow.

division happens naturally as the formation of a river

allopatric speciation is dependent on population movement, not natural seperation by geography.

Bio Speciation (5 decks)

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