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BI1051 - genetics and evolution > Taxonomy and phylogenetics > Flashcards

Taxonomy and phylogenetics Flashcards

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1
Q

Why does taxonomy matter?

A

Underlies all other disciplines like medicine, genetics, biochemistry, ecology, ethology, botany, zoology.

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2
Q

How can misidentification be costly?

A

Economically, food security - nutrition, health.

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3
Q

Give examples of why taxonomic identification is important.

A

Vectores - are they malaria carries?, pathogens - which strain?, food production - pest species or not?

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4
Q

Why was taxonomic identification important for agriculture pests - cassava killers?

A

Mealybug, introduced to Africa, misidentified from s. America, delay to control programme.

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5
Q

How was taxonomic identification useful for covid-19 variants and origins?

A

Find out if vaccines were effective, welsh border policy was based on taxonomy of viral genomes.

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6
Q

What other two principals link directly and all together with taxonomy?

A

Taxonomy (theory and practice of classification) + systematics (process to classify organisms on phylogeny) + phylogenetics (study of tree of life, evolutionary history).

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7
Q

What is taxonomy?

A

Establishing the identity of organisms, describing organisms (recognition of differences), preserving organisms collections, classifying.

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8
Q

What was early classification of indigenous populations?

A

E.g. Inuit, aborigines, native americans, independently developed rudimentary classifications, humans have innate ability to classify, survival value (edible vs poisonous).

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9
Q

What is classification?

A

Making sense of the world’s biological diversity.

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10
Q

What was Aristotle’s classification of living organisms and when?

A

Animals - red blood (land, water, air dwellers) or no red blood - hard bodies (insects) or salt bodies - shell (shellfish) or no shell (jellyfish).

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11
Q

What is the living diversity of life in terms of spp for different organisms?

A

All kind = 10.9mil, animals = 9.8mil, plants = 0.3mil, fungi = 0.6mil, pros = >0.1mil.

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12
Q

Are we nearly there for completely cataloguing life?

A

Out of 10.9mil spp estimated 1.4mil catalogued, 360-2000yrs to complete, majority probably insects, fungi major group of uncatalogued.

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13
Q

What does classification involve?

A

Arranging pops and species into groups, based on shared characteristics/ traits.

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14
Q

What is delimitation?

A

Recognition of different groups of pops and species.

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15
Q

What is arranging?

A

Ordering pops and species.

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16
Q

What is conferring status?

A

Ranking of pops and species.

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17
Q

What is the first step of classification?

A

Delimitation of pops and species.

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18
Q

Who is Carolus Linnaeus 1707-1778?

A

Father of modern taxonomy, Swedish naturalist, revolutionised how life’s described.

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19
Q

What was Linnaeus taxonomic hierarchy?

A

Kingdom, series, phylum, class, division, cohort, order, family, tribe, genus, species.

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20
Q

What happens to categories as you move down the hierarchy?

A

Become less inclusive.

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21
Q

What is the current understood taxonomic hierarchy?

A

Domain, kingdom, phylum, class, order, family, genus, species.

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22
Q

What does binomial nomenclature provide?

A

Scientific names that are universal - understood by scientists worldwide.

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23
Q

How does the binomial nomenclature work?

A

Genus and species, always in italics, do not italicise families orders or class, must capitalise those three, genus THEN species e.g. Homo sapiens.

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24
Q

What were some scientific advances towards Darwin’s theories?

A

Geology - fossilisation, age of earth, anatomy - homology, vestigial structures, evolution and extinction - early concepts, evolutionary forces.

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25
What did Jean-Baptiste Lamarck (1774-1829) propose?
Organs within organisms gain increasing complexity, environment impacts on evolutionary change, conflict between simplicity and complexity.
26
What do we now know about Jean-Baptiste’s proposals?
Fundamentally wrong, some key concepts along correct lines, causation of change misunderstood (not positive).
27
How did Darwin’s finches theory begin?
Post-voyage helped by ornithologist friend John Gould, begin to think about diversity and relationship.
28
What was the theory of common descent?
Component of Darwin’s theory of evolution, other theory of natural selection.
29
What did the theory of common descent explain?
Why members of taxonomic group are more similar to one another than to member of equivalent groups, tells us to seek natural groupings that reflect evolutionary history.
30
What was Alfred russel wallaces sarawak law 1855?
Two or three distinct species may have had a common antitype and each of these may again have become antitypes from which other closely allied species were created.
31
What did John Hunter do 1728-1793?
Arrived at idea of common ancestry earlier than wallace or darwin, couldn't get published, too radical for C18th.
32
What is a natural classification?
One based on evolutionary history - can be constructed only if the species are correctly discriminated.
33
What is the typological species concept?
Typology based on morphology/ phenotype, stems from plato's forms and used by linnaeus, applied in museum research were single specimen is basis for defining species.
34
What is a type method and a type specimen?
Method applied in museum research, the single specimen used for basis.
35
What is a problem of typological species?
Ignores intraspecific variation - all individuals of a species are assumed to conform to a type.
36
What factors make organisms appear different but do not make them different species?
Sexual dimorphism, life stages, geographic and other variants.
37
What is the biological species concept?
Population genetics concept, based on medelian and post-mendelain genetics.
38
What are criteria for the biological species concept?
Interbreeding and reproductive isolation, gene pools and coadaptation of genes within pools, reproductive isolation via intrinsic mechanisms.
39
What are reproductive isolation mechanisms?
Expected when gene pools significantly diverge, no hybrid vigour, interbreeding between populations within a species, pre-zygotic and post-zygotic, hybrid inviabiltiy.
40
What are bio species?
Reproductive isolation - ultimate criterion for distinguishing species.
41
What are morphospecies?
Taxonomists have used indirect evidence of reproductive isolation, usually evidence has been morphological.
42
What largely controls morphology?
Genetics.
43
What can happen if two coexisting populations are morphologically distinct?
Usually can be taken to represent intrinsically isolated gene pools, are shown to be valid biological species.
44
What are cryptic species?
Diverged genetically and behaviourally not morphologically.
45
Why are asexually reproducing organisms a problem of biological species concept?
Do not fulfil criterion of interbreeding, are clonal, e.g. some aphids, all prokaryotes.
46
Why is evolutionary intermediary a problem of biological species concept?
Populations in process of becoming separate species, ring species, anagenesis in paleo species.
47
How are allopathic populations a problem of biological species concept?
Not actually or potentially interbreeding, no intermediate form.
48
Why are sympatric populations good biological species?
No intermediate forms in overlap zone.
49
What is an example of an allopatric population which is a problem?
Rosella parrots, western forms are allopatric, if massive morphological differences should be separate species, may interbreed.
50
What’s an example of something that can be classed as a subspecies?
Ruddy and WH ducks as fully interbreed.
51
What is a subspecies?
Aggregates of local populations of an individual species, inhabit different geographic subdivisions, differ taxonomically, cannot be sympatric.
52
What applies to subspecies even tho they’re taxonomic not genetic?
Reduced gene flow from isolation from physical barriers, subspecies becoming biological species through selection (incipient species).
53
What is a polytypic species?
Species with several subspecies, each denoted by a trinomen.
54
What is the recognition species concept and an advantage/disadvantage?
Allopatric pops not interbreeding, recognise as mates, removes uncertainty, excludes asexually reproducing organisms.
55
What is the phylogenetic species concept?
Species is tip of phylogeny, smallest inclusive monophyletic grouping, relies on common ancestry, recognises role of history, subdivision of lineages into species can be arbitrary.
56
What is the genetic species concept?
Geneticists equivalent of morphospecies concept, measures genetic similarity or distance, can provide evidence for morphological and biological species, relies on human judgment.
57
What are the purposes of classification?
Index of stored information, enables predictions/generalisations to be made.
58
What is an example of how delimitation works?
Indian rhino more features common with each other so forms distinct group.
59
What is an example of ordering?
Indian rhino and Javan rhino not identical but similar so one group, all rhinos share certain features so larger group, rhinos tapirs and horses also similar so even larger group.
60
Who created the tree of life?
Ernst Haeckel 1866.
61
What's a danger of the tree concept?
Tips of tree are not more evolved or better.
62
What are dendrograms?
Used to express classifications instead of trees, each large groups contains smaller with patterns of groups.
63
What does ranking involve?
Conferring status on supraspecific groups.
64
What is topology?
Arrangement of tree branches and stems.
65
What are the three main methods of classifications?
Phenetics, cladistics, orthodox approach.
66
What is phenetics?
Based on overall phenotypic similarity, all characters equal weighting, genealogy ignored, evolutionary history ignored, objective, fixed criteria, phonograms used.
67
What are problems with phenetics?
Does not control for confounding effects of phenotypic similarity that is due to convergent evolution, due to similar selection pressure or mimicry, cannot be depended on to reflect history, homologous vs analogous characters, mimicry.
68
What is covergent evolution due to?
Phenotypic convergence due to selection pressure.
69
What is cladistics?
Based on inferred genealogy, trees are cladograms, shared derived homologous characters, weighting, objective, reflects on history.
70
Who created cladistics and what’s required?
Willi Hennig 1950, all supraspecific groupings monophyletic, paraphyletic and poly are invalid.
71
How are monophyletic taxa recognised?
Traits provide different kinds of info on genealogy, infer whether changed occurred early or late, groupings based on new traits arising in nearest common ancestor.
72
What are the three reasons for why taxa resemble each other?
Character arose early in taxa before occurrence of nearest common ancestor (shared primitive character), character originated in nearest common ancestor (shared derived character), character originated independently by convergence.
73
What’s homoplasy?
Similarity due to convergence.
74
What is the definition of a taxon?
Presence of characters acquired by and restricted to a phyletic line after it branched off from sister group - unshared derived characters.
75
What methods are there for assessing character polarity?
Outgroup comparison (most common, frogs, ovi vs viviparous), embryology (ancestral characters appear early), fossil record (appeared earliest in ancestral state).
76
What are problem with cladistics?
Considers only cladogenesis, sister taxa same rank.
77
What is orthodox classification?
Based on genealogy and divergence, weighting of homologous characters, non-DNA/RNA orthodox classifications criticised, phylogenies or phylograms.
78
Why orthodox?
Classifications on molecular genetic data, recognises clades and grades, more objective, more accurately reflect genetic relationships.
79
Why is there a key advantage of DNA?
Much unaffected by natural selection so evidence, junk DNA mutation highly informative.
80
What is wrong with non-molecular classifications?
Involve far too much subjectivity.
81
Why are all classifications provisional and perpetually modified?
Improvement in methodologies, new species are discovered, organism continue to evolve.
82
How are molecular techniques rapidly improving?
Most classification based on DNA/RNA, humans shown to be closer to chimpanzee than morphology (98.4% similar).

BI1051 - genetics and evolution (15 decks)

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