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Chapter 13 Flashcards

Evidence of Evolution (57 cards)

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1
Q

Life of earth arose 3.8 billion years ago

A

-scientists use the geologic timescale to divide the history of earth into eons and eras, based on evidence of biological and geographical events

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2
Q

Evolution is linked to geological events

A

-changes in the environment select for changes in both structures and molecules
-these slowly accumulated over time, producing a variety of organisms today

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3
Q

Evidence of evolution is easy to find

A

-researchers analyze fossils, anatomy and molecular sequences to learn how species are related to one another
-the events of evolution are studied in context with the geologic time scale

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4
Q

Plants and animals of the past left plenty of evidence

A

-paleontology is the study of fossil remains or other clues to past life
-fossils, the remains of ancient organisms, provided the original evidence for evolution

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5
Q

Early evidence for evolution came from comparing organisms

A

-even though the events that led to today’s diversity of life occurred in the past, many clues suggest that all organisms derived from a common ancestor

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6
Q

Define geologic timescale

A

-a division of earth’s history into eons, eras, periods, and epochs defined by major geological or biological events

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7
Q

Fossils record evolution

A

-a fossil is evidence of an organism more than 10,000 years ago (end of Pleistocene epoch). The oldest are over 3 billion years old
-fossils document the history of life on earth
-fossils also allow researchers to test predictions about evolution

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8
Q

Define MYA

A

-million years ago

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9
Q

Define compression (fossils)

A

-leaf sinks
-fine sediment covers leaf
-sediment compresses, forming sedimentary rock

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10
Q

Define petrification (fossils)

A

-animal dies, decays, and is buried
-water containing dissolved minerals seeps through
-organic matter replaced by minerals “turns to stone”

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11
Q

Define impression (fossils)

A

-animal dies, making impression in mud
-animal decays away
-mud hardens to rock

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12
Q

Define casting (fossils)

A

-animal dies and sinks into soft sediment
-animal decays away
-imprint fills with mud
-mud hardens to rock

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13
Q

Define intact preservation

A

-rarely, intact organisms are preserved by being buried suddenly in the absence of oxygen
-these condition minimize decomposition and prevent scavenging

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14
Q

Why are fossils often incomplete?

A

-soft bodied organisms are less likely to be preserved than those with teeth, bones, or shells
-organisms that decompose or are eaten after death are less likely to fossilize
-erosion or movement of earth’s plates destroy fossils that did form
-scientists are unlikely to discover many fossils that must be buried deep in earth or submerged in water

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15
Q

Fossils’ age can be determined

A

-dating fossils yields clues about the timeline of life’s history
-researchers use several different methods to determine the age of fossils

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16
Q

Define relative dating

A

-dates fossils according to the layer of rock
-it assumes that lower rock layer have older fossils than new rock layers
-it’s indirect, simple, and less precise, but still provides valuable information

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17
Q

Define absolute dating

A

-dates fossils using chemistry
-a more direct method is to date the fossil itself
-one way to do this is radiometric dating

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18
Q

Define radiometric dating

A

-measuring the amount of 14C in a fossils to calculate how long ago an organism died

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19
Q

Living organisms use carbon isotopes 12C and 14C

A

-throughout life, organisms accumulate 14C, a radioactive isotope, along with the stable 12C isotope. After the organism dies, no more carbon is added

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20
Q

14C decays over time (to the more stable Nitrogen 14)

A

-living organisms have a constant amount of 14C in their tissues
-after death, half the 14C is lost every 5,730 years
-in other words, the half life of 14C is 5,730 years

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21
Q

Define half life

A

-the time it takes for half the atoms in a sample of radioactive substance to decay 50%, 25%…..

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22
Q

Fossils are dating by measuring 14C

A

-since the amount of 14C decreases at a known rate, scientists can measure the proportion to 14C to 12C in this fossilized wooly mammoth to calculate how long ago it died

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23
Q

Define biogeography

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A

-the study of distribution patterns of species across the planet

24
Q

Biogeography considers species’ geographical locations

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A

-earth’s geography has changed drastically over the last 200 million years

25
Plate tectonics theory explains why continents move
-according to the theory of plate tectonics, forces acting deep within the planer move earth's land masses (plates)
26
Continents are still moving today
-continental movements are a strong force that shapes evolution -earthquakes and volcanoes are evidence that earth's plates continue to move today
27
Species distribution reveal evolutionary events
-the location of various fossil species around 200 MYA tells geographers that earth's continents at that time were arranged into 1 large landmass called Pangea
28
Biogeography sheds light on evolutionary events
-animals on either side of Wallace's line have been separated for millions of years, evolving independently -the result is a unique variety of organisms on each side of the line
29
Anatomical relationships reveal common descent
-investigators often look for anatomical features to determine the evolutionary relationships of two organisms
30
Homologous structures are inherited from a common ancestor
-they are similar in structure because of their common ancestry -all of these animals have similar bones in their forelimbs -these similarities suggest that their common ancestor had this bone configuration
31
Homology demonstrates evolutionary relationships
-homologous structures can develop differently over time -different selective pressures among species lead to changes from the ancestor's bone structure
32
Vestigial structures have lost their function
-a vestigial structure is homologous to a structure in another species -vestigial eyes in blind moles, hindlimbs in some snake species, and pelvises in whales are evidence of these organism's ancestors
33
Analogous structures evolved independently
-similar because of convergent evolution, not common ancestry -anatomical structures are analogous if they are superficially similar but did not derive from a common ancestor -both winds are used for the same function, flight. However, wing structures in birds and in insects are very different
34
Analogous structures result from convergent evolution
-these similarities arose by convergent evolution, which produces similar structures in organisms that don't share the same lineage (arose independently in each lineage)
35
Structures reveal evolution
-species 1 and 2 are derived from a common ancestor -species 2 and 6 have analogous wings that evolved independently -species 7 has vestigial wings that are homologous to species 6 but no longer function
36
Define vestigial
-having no apparent function in one organisms but homologous to a functional structure in another species (like moles eyes)
37
Define convergent evolution
-the evolution of similar adaptation in organisms that do not share the same evolutionary lineage
38
Embryotic development patterns provide evolutionary clues
-evo devo for short -anatomical similarities are often most obvious in embryos -notice how much more similar human and chimpanzee skull structure is in fetuses compared to in adults
39
Early vertebrate embryos appear alike
-adult birds, mice, and humans have very different bodies -their evolutionary relationships are more obvious in embryos
40
Homeotic genes control embryonic development
-homeotic genes are needed for body structures to develop normally -small differences in gene expression might make the difference between a limbed and limbless organism
41
Mutations in homeotic genes produce dramatic body structure changes
-homeotic genes help explain how a few key mutations might produce new species -this fruit fly has a mutation in a homeotic gene that controls where legs develop
42
Noncoding DNA mutation can produce new phenotypes
-gene promoter sequences control where and when genes are expressed
43
Define homeotic gene
-any gene that, when mutated, leads to organisms with structures in the wrong places (like legs where they eyes should be)
44
Molecules reveal relatedness
-comparing DNA and protein sequences determines evolutionary relationships in unprecedented detail
45
DNA and proteins are used to study molecular evolution
-comparing DNA and protein sequences determines evolutionary relationships in unprecedented detail
46
Sequence similarities are inherited from common ancestors
-it is highly unlikely that 2 unrelated species would evolve precisely the same DAN and protein sequence by chance
47
DNA changes explain how evolution works
-in this example, the amylase gene was duplicated -the duplication was selected for eating a high starch diet
48
Homologous protein sequences demonstrate common descent
-cytochrome C is a mitochondrial protein that is expressed in all eukaryotes -the more amino acid differences between species, the more distance the common ancestor
49
Molecular clocks are based on random DNA mutations
-DNA accumulates random mutations are a regular rate, as long as there is no selection for or against the mutation -over time, there are more and more random mutations
50
Molecular clocks predict the number of mutation in a species
-if a gene is estimated to mutate once every 25 million years, then the 2 differences from an ancestor might arise in 50 million years
51
molecular clocks assign dates to evolutionary events
-two species that derived from the same common ancestor 50 MYA might have 4 differences in the nucleotide sequence of the gene
52
Define molecular clock
-application of the rate at which DNA mutates to estimate when two types of organisms derived from a shared ancestor
53
How fast do substitutions occur
-substitutions occur at an estimated rate of 1% per 1 million years
54
Investigating life: limbs lost and limbs gained
-in 2006, researchers discovered fossils of an intermediate form between fish and terrestrial vertebrates -transitional fossils, like those of a Tiktaalik, are evidence for gradual evolutionary change
55
Investigating life: Tikaalik was predicted
-researchers were searching for a fossil representing the transition from fish to amphibians -they knew when and where vertebrates moved onto land, and they found a fossil with a mix of fish and terrestrial features
56
Investigating life: how did snakes evolve?
-snakes are adapted to a burrowing lifestyle -did they evolve on land or from marine reptiles
57
Investigating life: Najash is the most ancient known snake
-Najash lived 90 million years ago, well before snakes evolved -its features, particularly the hindlimbs and pelvis bones, are terrestrial

Principles of biology (12 decks)

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