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bio120 > Lec 10 slides > Flashcards

Lec 10 slides Flashcards

1
Q

adaptive radiation

A

the evolution of ecological and phenotypic diversity within a rapidly multiplying lineage

-originates from single common ancestor
-process results in an array of many species
-the species differ in traits allowing
exploitation of a range of habitats and
resources

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2
Q

4 features commonly identify an adaptive radiation:

A

-recent common ancestry from a single species
-phenotype-environment correlation
-trait utility
-rapid speciation

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3
Q

causes of adaptive radiation

A

-ecological opportunity
-high tendency for speciation

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4
Q

ecological opportunity- the absence(or reduction) of competition for resources

A

colonization of competition-free regions (e.g. islands, lakes, continents)
-galapagos finches, east african cichlids

extinction (eliminates competitors)
-mammals radiated after mass extinction of dinosaurs

key innovation (evolution of a trait that provides access to new resources)
-anole lizards radiated after evolving toepads

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5
Q

high tendency for speciation

A

reproductive isolation evolves more readily in some clades than others
-e.g. finches vs. mockingbirds

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6
Q

what can hybridization lead to

A

speciation

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7
Q

hybridization

A

the exchange of genes b/w species as a result of occasional inter-species mating
-sometimes can reverse speciation process to merge 2 groups into 1

varies across tree of life

can result in complex patterns of variation
-can be evolutionary significant for speciation, especially by polyploidy

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8
Q

polyploidy

A

describes an organism, tissue or cell with more than 2 complete sets of homologous chromosomes

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9
Q

allopolyploidy

A

-more than 2 sets of chromosomes from DIFFERENT species
-arises from duplicated karyotype following hybridization b/w species
-most common type of polyploidy
-results in TETRAPLOID gametes

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10
Q

autopolyploidy

A

-more than 2 sets of chromosomes from SAME species
-arises from duplicated karyotype
-e.g. non-disjunction
-results in TETRAPLOID gametes

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11
Q

hybridization to form an allopolyploid

A

-2 DIFFERENT species mate and produce f1 hybrid offspring (AA)
-f1 hybrid offspring produces unreduced diploid gametes (AA) due to meiotic non-disjunction
-diploid gametes combine to produce tetraploid f2 offspring
-tetraploid is fertile, but is reproductively isolated from parental species

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12
Q

evolutionary significance of polyploidy

A

polyploids are reproductively isolated from their diploid parents
-form of SYMPATRIC speciation

polyploids exhibit novel phenotypes
-allows exploitation of new habitats

polyploids often show hybrid strength due to heterozygosity, particularly in allopolyploids

polyploid origin for 50% of flowering plants
-many crop plants and invasive species

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13
Q

true or false: in lineages f1 hybrids form readily

A

false

in lineages, f1 hybrids can no longer form

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14
Q

taxonomy

A

the theory and practice of classification and naming

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15
Q

systematics

A

the study of biodiversity and the evolutionary relationships among organisms

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16
Q

taxon

A

a single named taxonomic unit at any level (plural taxa)

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17
Q

carolus linnaeus

A

-father of taxonomy
-binomial nomenclature
-hierarchical system of classification

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18
Q

7 taxon groups

A

kingdom
phylum
class
order
family
genus
species

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19
Q

purpose of biological classification

A

-name is a key to shared info on an organism
-has predictive power
-enables interpretation of origins and evolutionary history

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20
Q

species made of many pop, linked by…

A

gene flow

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21
Q

nodes

A

(common ancestor b/w 2 taxon)
-correspond to historical lineage splitting events, when one lineage splits into 2

22
Q

branches(aka edges)

A

(taxa lines)
-correspond to single ancestor-descendant lineages
-all branches are connected by nodes

23
Q

tips (aka leaves, terminals, OTUs)

A

(tips of taxa)
-do not have represented descendants
-can be:
-individuals, species, clades

24
Q

internal branches

A

connect 2 nodes

25
Q

external branches

A

connect a tip and a node

26
Q

root

A

(common ancestor)
-node representing earliest time point in the diagram
-often represented by an unlabeled branch
-don’t always have roots

27
Q

sister groups

A

(2 taxon groups sharing common ancestor)
-immediate descendants of same ancestor
-sister taxa are those that are the immediate descendants of the same ancestor

28
Q

parent branch

A

connects to main common ancestor
-give rise to ‘daughters’

29
Q

daughter branch

A

connects taxon to immediate descendant

30
Q

ingroup on phylogenetic tree

A

consists of the focal species in a phylogenetic study

(everything except species closest to common ancestor and CA)

31
Q

outgroup

A

more distant relative of the ingroup taxa
-can help to root the phylogeny and help determine what character states are ancestral
-helps determine and position root

(species closest to common ancestor and CA)

32
Q

most recent common ancestor (MRCA)

A

-youngest node that’s ancestral to all lineages in a given group of taxa
-different mrca for diff taxa groups

33
Q

clade

A

any piece of a phylogeny that includes an MRCA and all of its descendants
-i.e. any piece of a phylogeny that exhibits monophyly

34
Q

monophyly

A

property of having a mrca and descendants
-describes a group made up of an ancestor and all its descendants (clade)
-can separate group with one cut

35
Q

how many clades can a phylogenetic tree contain

A

n-1

36
Q

paraphyly

A

-describes a group made up of an ancestor and some (but not all) of its descendants
e.g. grade
-doesn’t pass scissor test

37
Q

polyphyly

A

describes a group that DOESN’T contain the most recent common ancestor of all members

38
Q

ancestral trait

A

terms refer to the inheritance of traits for a given group of species
-do NOT describe species themselves
-for the species in a clade, a trait is ‘ancestral’ if it was inherited in its presents form from the mrca of the clade

39
Q

derived trait

A

a trait is derived for that clade if it originated within the clade
(i.e. in a descendant of the clade’s mrca)

40
Q

true or false: the same trait can be ancestral for a clade but derived within a larger clade

A

true

41
Q

synapomorphy

A

shared, derived trait for a clade
-a trait that all species in the clade share, and that evolved on the branch leading to the clade
(i.e. it’s derived within the context of more inclusive clades)

42
Q

homology

A

when structures observed in different taxa can be traced to a single structure present in a shared evolutionary ancestor

43
Q

homoplasy

A

-when diff species develop traits independently due to environ. pressures
-type of convergent evolution

44
Q

why conduct a phylogenetic analysis

A

-understand history of life
-understand large-scale patterns of evolution
-understand how many times traits have evolved, how fast, under what conditions
-practical:
-where/when did parasites spread
-which flu strain was the most successful last year

45
Q

notes about phylogenetic reconstruction

A

-phylogenetic relatedness is inferred from homologous traits
-homoplasy (e.g. convergent trait evolution) can mislead phylogenetic inference

46
Q

2 principal sources of macroevolutionary insights

A

paleontology, phylogenetics

47
Q

paleontology

A

-provides a direct record of past evolutionary change
-inference is strongest for groups that fossilize well

48
Q

phylogenetics

A

-provides an indirect record of past evolutionary change
-inference is strongest for groups that have living representatives

49
Q

fossil record

A

-provides only evidence for completely extinct clades
-documents long-term patterns of global biodiversity
-provides evidence for catastrophic extinctions during earth’s history

50
Q

phylogenetics

A

provides evidence for explosive diversification following mass extinctions

51
Q

diversification rate

A

speciation rate - extinction rate

52
Q

other features associated with increased diversification

A

-herbivory
-species with more sexual selection
-animal pollination in plants
-increased dispersal
-increased range size

bio120 (42 decks)

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