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Eco and Evo > History and Tree of Life > Flashcards

History and Tree of Life Flashcards

1
Q

fossils

A

how it is documented how species change over time

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2
Q

homology

A

species are related by common ancestry

“same-source”

opposite of homoplasy

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3
Q

tree of life

A

a single phylogeny that can be hypothesized that shows relationships among all species

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4
Q

when were there great advances in evolutionary theory?

A

17-1800s

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5
Q

branch

A

a line representing a population through time

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6
Q

root

A

the most ancestral branch in the tree

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7
Q

tip (terminal node)

A

endpoint of a branch

represents a living or extinct group of genes, species, families, phyla, or other taxa

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8
Q

outgroup

A

a taxon that diverged prior to the taxa that are split into two or more branches

represents the most recent common ancestor of the descendant groups

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9
Q

polytomy

A

a node that depicts an ancestral branch dividing into three or more (rather than two) descendant branches

usually indicates that insufficient data were available to resolve which taxa are more closely related

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10
Q

characters

A

a feature

e.g. wing color

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11
Q

character states

A

what the different conditions are called when taxa differentiations with respect to a character

e.g. brown, black, red, gray
(wing color)

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12
Q

pleisomorphic

A

ancestral (primitive) trait

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13
Q

apomorphic

A

changed (derived) trait

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14
Q

synapomorphy

A

shared derived trait found in two or more taxa and their common ancestor, but missing in more distantly related ancestors

e.g. hair/lactating is a synapomorphy for humans and dogs

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15
Q

what factors are used to hypothesize relationships between taxa?

A

character states and synapomorphies

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16
Q

homoplasy

A

a state inherited due to a convergent evolution

“same-form”

opposite of homology

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17
Q

branch lengths

A

branch lengths are arbitrary

emphasis is on the branching pattern which estimates evolutionary relationships among populations

branch lengths show the extent of genetic difference (mutation) among populations

branch lengths show the extent of evolutionary time between nodes

scale bars are included

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18
Q

Precambrian Eon

A

4.6 bya to 542 mya

evidence of both bacteria and archaea

includes:

  • the oldest evidence of life
  • oldest cyanobacteria (oxygenic photosynthesis)
  • origin of eukaryotes
  • multicellular eukaryotes
  • sponges (first animals)
  • cnidarians

stromatolites in Shark Bay, Australia- rocks from this time period that have layers

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19
Q

oldest cyanobacteria (oxygenic photosynthesis)

A

2.6 bya

rise in atmospheric oxygen at 2.3-2.1 bya

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20
Q

origin of Eukaryotes

A

1.8 bya

single-celled and small

21
Q

multicellular eukaryotes

22
Q

sponges

A

635 mya

first animals

were filter species that lived in water

23
Q

cnidarians

A

580 mya

like jellyfish and *

24
Q

Phanerozoic Eon

A

542 mya to present

includes:

  • Cambrian Explosion
  • land plants
  • fungi
  • insects
  • Tiktaalik (earliest tetrapod)
  • end-Permian mass extinction
25
Cambrian Explosion
542-488 mya "explosion" of animals in the fossil record new diversity Cambrian fossils
26
Ediacara fossils
565-542 mya soft-bodied; likely filtered or absorbed food from water not considered animals do not know where to put them in the tree of life
27
Cambrian fossils
541-500 mya big increase in morphological complexity large animals of movement oldest fossils of most animal groups (arthropods, mollusks, echinoderms, chordates) everything is confined in the oceans at this point not sure what caused diversification; multiple non-mutually exclusive hypotheses: - higher oxygen levels - evolution of predation - niches beget niches - new genes
28
higher oxygen levels (potential Cambrian explosion cause)
needed for increased aerobic respiration, large bodies, active movement
29
evolution of predation (potential Cambrian explosion cause)
novel selection pressure lead to co-evolutionary arms races which leads too new traits e.g. evolution of the eyes
30
niches beget niches (potential Cambrian explosion cause)
movement off benthic floor fostered diversification
31
new genes (potential Cambrian explosion cause)
evolution of Hox genes -important in body development allowed for greater diversity
32
land plants
475 mya may have needed fungi in order to be on land
33
fungi
440 mya may have facilitated the transition of plants to land
34
insects
400 mya largest group of animals extant today
35
Tiktaalik
375 mya earliest tetrapod has some fish-like qualities and some tetrapod-like qualities shows the transition between water and land
36
End-Permian mass extinction
252 mya the largest mass extinction >50% of all families and >80% of all genera up to 96% of all marine species and 70% of terrestrial species causes are unclear: - massive changes in temperature, atmosphere, and oceans - flood basalts -- added heat, CO2, and sulfur dioxide
37
Mass extinction
rapid extinction of a large number of lineages throughout the tree of life surviving lineages experience reduced competition creates ecological opportunity for diversification there have been 5 in history end-Permian is the largest
38
dinosaurs
240 mya
39
End-Cretaceous mass extinction
65 mya niche space is clearers out; especially for mammals due to the loss of dinos therefore, it is followed by high diversification rates in mammals and birds impact hypothesis: caused by the impact of 10 km wide asteroid off the coast of Yucatan Peninsula many lineages of modern birds, mammals, and fish date back to this time
40
Impact hypothesis of the end-Cretaceous mass extinction
caused by the impact of 10 km wide asteroid off the coast of Yucatan Peninsula crater at impact site rocks from this time period are rich in rare minerals known from meteorites
41
adaptive radiation
rapid evolutionary diversification within one lineage, producing descendant species with a wide range of adaptive forms major characteristics: - monophyletic group - rapid speciation - ecological diversity- use of a variety of resources and/or occupy a variety of niches mass extinctions provide ecological opportunity for adaptive radiations e.g. hawaiian silversword phylogeny; Galapagos finches; honeycreepers; anolis
42
Ecological opportunity
availability of new or novel resources over time, populations in different niches can become reproductively isolated and form new species e. g. islands: - colonists of islands are often "freed" of competition and can evolve to expand realized niche
43
Morphological innovation
evolution of a new or novel morphological trait could allow descendants to exploit new niches e.g. flowers and pharyngeal jaws
44
flowers (morphological innovation example)
unique reproductive structure important in te diversification of today's > 250,000 angiosperms allows them to cater to specific pollinators leads to quick speciation
45
pharyngeal jaws (morphological innovation example)
second pair of jaws in the throat in some fish highly modified in cichlid fish: - evolved many different forms, each specializing on different food types - has evolved to specialize in different types of prey
46
sister groups
closely related species that share a recent common ancestor at the node where their branches meet
47
ancestral trait
a character that existed in an ancestor
48
derived trait
a character that is a modified form of the ancestral trait found in a descendant originate via mutation, selection, and genetic drift
49
cladistic approach
based on the principle that relationships among species can be reconstructed by identifying sharing derived traits, called synapomorphies

Eco and Evo (15 decks)

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