Evolution Flashcards

1
Q

3 groups of living mammals distinguished by their reproductive biology

A
  • monotremes
  • marsupials
  • eutherians
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2
Q

who are the closest living relatives of humans?

A

chimpanzees and bonobos

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3
Q

who are the hominids?

A

evolutionary lineage leading to modern humans

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4
Q

what is the only homonin thats not extinct?

A

homo sapiens

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5
Q

a key trait that evolved in the common ancestor of hominins is:

A

bipedal locomotion

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6
Q

advantages to bipedal locomotion

A
  • forelimbs free to manipulate and carry objects
  • eyes elevated, look for prey/ watch for predators more effectively
  • move over long distances more energetically efficiently than close relatives with quadrupedal locomotion
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7
Q

early hominins: Australopithecus

A
  • “lucy” most complete australopith skeleton, found in Ethiopia
  • had relatively small brains, elongate faces, and a bipedal gait
  • 2 lines of evidence
    • pelvis and foot morphology
    • laetoli footprints
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8
Q

homo

A
  • homo clade diverged from an australopithecine ancestor

- genus homo have larger brains, less elongated faces than earlier hominin ancestors and a bipedal gait

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9
Q

earliest known species of homo clade

A

homo habilis

-first evidence of tool manufacture

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10
Q

habilis

A

handy man

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11
Q

homo erectus

A
  • large skull, relatively long legs and short and straight fingers
    • traits suggest they were bipedal and primarily terrestrial (not in trees)
  • made more complex tools than homo habilis
  • able to control fire
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12
Q

who was the first hominid to leave africa?

A

homo erectus

-fossils found in europe, india, china, and indonesia

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13
Q

homo neanderthalensis

A

-common ancestor had increased brain size, decreased jaw muscles
-indicating a shift in diet from herbivory to omnivory
-increased brain size may reflect increasingly complex social interactions and cultural traditions
-stocky with a large skull/brain
-advanced tool technology
hunters of large animals, cave dwelling

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14
Q

who was the hominin not found in Africa?

A
  • homo neandethalensis

- widespread in asia and Europe

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15
Q

how do we know that neanderthalensis practiced symbolically?

A

-flower burial at Shanidar cave, Iraq

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16
Q

homo sapiens

A
  • evolved in Africa
  • large brain, slighter build
  • early humans overlapped with heir sister species neanderthalensis
  • made sophisticated tools and art
    • paintings and sculpture
  • homo spies spread across all of asia reaching north america
17
Q

did early humans and neanderthalensis interbreed?

A
  • yes
  • descendants of eruopeans, asians, other non africans inherited 2% of their genes from neanderthals
  • genetic analysis also suggests blonde/ red hair, fair skin and thick body hair may be inherited from neanderthals
18
Q

biological evolution

A

theory that all organisms on earth are related and have changed over time from an original ancestral form

19
Q

what is modified?

A

the frequency of particular genes (alleles) within a population

20
Q

Where are genes located?

A

on chromosomes

21
Q

different versions of a gene are called

A

alleles

22
Q

the result from evolution

A

genomes of species differ from those of their ancestors

23
Q

how do populations evolve?

A

populations evolve when the environment favors some treats over others, then alleles that code for those traits increase in frequency over time

24
Q

human example of evolution

the red blood cell production in tibet

A
  • tibetans who live at very high altitude, derived from chinese ancestors who lived at low altitude
  • most humans respond to low oxygen at altitude by making more red blood cells to carry more oxygen
  • good in short term
  • tibetans have big frequency of an allele leading to production of fewer red blood cells in response to low oxygen
  • results in more optimal balance of anaerobic vs aerobic metabolism in cells at high altitude
25
Q

is evolution a theory or a fact?

A

both!

  • theory of evolution deals with how evolution happens
  • its also a fact as there is a huge amount of indisputable evidence for its occurrence
26
Q

creationism and the idea of “fixed species”

A
  • many believed in some form of creationism where species were created by a supernatural being
  • as special creations, species were considered to be fixed for all time
27
Q

fossils and cuvier

A
  • george cuvier made 2 observations from his studies of fossils
    • younger fossils, found near surface, more similar to living species than older fossils found deeper
    • between layers of rock, some species disappeared, while new ones appeared
28
Q

catastrophism

A

belief that boundaries between layers correspond with catastrophes throughout time that wiped out entire species
-evidence of extinction

29
Q

transmutation and lamarck

A
  • jean lamarck proposed that if an animal acquired a trait during its lifetime, it could pass it to its offspring
    • giraffe’s neck
30
Q

acquired trait

A

developed over a single lifetime

31
Q

charles darwin

A
  • first to make a strong convincing argument that species change through time
  • ideas were influence by the
    • voyage on the beagle
    • experience with selective breeding
    • thomas malthus (political economist, demographer)
32
Q

voyage on the beagle

A
  • noticed great variabilities with the shape of beaks among species of finches.
  • concluded that small changes accumulating over time were the only plausible explanation for his observations
33
Q

selective breeding

A
  • enhanced desrired characteristics in future generations
  • a few generations of selective breeding could produce populations of pigeons that differed dramatically in appearance (artificial selection)
34
Q

thomas malthus

A
  • malthu’s essay on the principles of population, which discussed effects of individuals competing for limited food resources
  • darwin noted: species typically produce more offspring than needed- some survive and reproduce, others die without reproducing (survival of the fittest)
  • these observations led darwin to propose that populations of species change over time
35
Q

alfred wallace

A
  • proposed a hypothesis almost identical to darwin’s
  • both him and darwin presented a paper to linnaean society of london describing biological evolution by natural selection
36
Q

darwin theory of evolution by natural selection includes 5 observations

A
  • any species, population sizes would increase exponentially if all individuals survived and reproduced successfully
  • populations tend to b stable in size, except for seasonal fluctuations
  • resources are limited (freshwater)
  • members of a population vary in their characteristics; no 2 are exactly the same..
  • much of the variation is heritable
37
Q

darwin’s inferences

A
  • more individuals are produced than the environment can support
  • survival depends in part on inherited traits
38
Q

darwinian evolution

A
  • origins of biological diversity can be explained by purely physical processes
  • evolutionary change occurs in groups of organisms (populations) rather than individuals
  • evolution is a multistage process occurring across generations
  • evolution occurs because some organisms perform better than others in a particular environment