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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

A

1.6 bya

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
Q

Cambrian Explosion

A

542-488 mya

“explosion” of animals in the fossil record

new diversity

Cambrian fossils

26
Q

Ediacara fossils

A

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
Q

Cambrian fossils

A

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
Q

higher oxygen levels (potential Cambrian explosion cause)

A

needed for increased aerobic respiration, large bodies, active movement

29
Q

evolution of predation (potential Cambrian explosion cause)

A

novel selection pressure

lead to co-evolutionary arms races

which leads too new traits
e.g. evolution of the eyes

30
Q

niches beget niches (potential Cambrian explosion cause)

A

movement off benthic floor fostered diversification

31
Q

new genes (potential Cambrian explosion cause)

A

evolution of Hox genes
-important in body development

allowed for greater diversity

32
Q

land plants

A

475 mya

may have needed fungi in order to be on land

33
Q

fungi

A

440 mya

may have facilitated the transition of plants to land

34
Q

insects

A

400 mya

largest group of animals extant today

35
Q

Tiktaalik

A

375 mya

earliest tetrapod

has some fish-like qualities and some tetrapod-like qualities

shows the transition between water and land

36
Q

End-Permian mass extinction

A

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
Q

Mass extinction

A

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
Q

dinosaurs

A

240 mya

39
Q

End-Cretaceous mass extinction

A

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
Q

Impact hypothesis of the end-Cretaceous mass extinction

A

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
Q

adaptive radiation

A

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
Q

Ecological opportunity

A

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
Q

Morphological innovation

A

evolution of a new or novel morphological trait could allow descendants to exploit new niches

e.g. flowers and pharyngeal jaws

44
Q

flowers (morphological innovation example)

A

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
Q

pharyngeal jaws (morphological innovation example)

A

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
Q

sister groups

A

closely related species that share a recent common ancestor at the node where their branches meet

47
Q

ancestral trait

A

a character that existed in an ancestor

48
Q

derived trait

A

a character that is a modified form of the ancestral trait found in a descendant

originate via mutation, selection, and genetic drift

49
Q

cladistic approach

A

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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