darwin Flashcards
what did Plato and Aristotle believe about species?
they were permanent and did not evolve
charles darwin 1859 book
“On the Origin of Species by Means of Natural Selection”
what did darwin’s book challenge?
the scientific views of the time including the belief that the earth was just 6-10,000 years old and populated by unchanging life forms individually made during the 1st week
what was the Judeo-Christian belief supported by?
natural theology - a philosophy dedicated to discovering God’s plan by studying nature
what did Linnaeus sought to discover?
order in the diversity of life and if the founder of taxonomy
what is taxonomy?
concerned with naming and classifying all life forms
what did Linnaeus develop?
2 part naming system - binomial nomenclature - which uses a genus and species
how did linnaeus group species?
grouped similar looking species into general categories, implying no evolutionary kinship
what did Cuvier do?
paleontologist who studied fossils in layers of sedimentary rocks called strata
what did Cuvier document?
the succession of fossil species in the Paris Basin and noted that the deeper/older the stratum, the more dissimilar the flora and fauna life from today’s modern organisms
what did Cuvier notice? what did he form from that?
noticed extinctions had occurred and developed the idea of catastrophism
catastrophism
each stratum corresponded in time to a catastrophe (flood/drought) that destroyed many species of that time and the ravaged region was repopulated by species migrating from other areas
what did geologist Hutton explain?
the various landforms on earth today as having risen by gradualism
what idea did geologist lyell develop?
uniformitarianism - geological processes haven’t changed over time; ex. the forces that eroded mountains in the past are the same ones working today
what did Lamark first suggest?
a model to explain how life evolved
what did lamark compare? what did he find out?
by comparing current living species to fossil forms he could see a chronological series of older to younger fossils leading to modern day species
what was on the lowest rungs of the ladder?
microscopic organisms which Lamark thoght arose spontenously from nonliving materials (false)
what was at the top of the ladder?
complex plants and animals
what is the first idea Lamarck is remembered for?
“use & disuse”
idea that if you use a body part a lot, that bpdy part will become larger and stronger, if you dont use a body part it will deteriorate
2nd idea Lamarck is known for?
his belief of inheritance of acquired characteristics - modifications an organism acquires during its life can be passed onto offspring (not true but he was the first to say life evolves)
after being bored with medical school, what did darwin become?
naturalist
what ship did darwin travel in?
HMS Beagle
what did darwin have to do on the voyage?
collect, record, and observe thousands of exotic faunas and floras
what place was Darwin interested in?
Galapagos - islands of relatively recent volcanic origin west of SA
what are the characteristics of the animals on the Galapagos?
they live no where else in the world, bearing resemblance to species living on the mainland of SA
what did it seem that happened on the islands?
they were colonized by plants and animals that strayed from the mainland and then diversified on the different islands
how many types of finches did Darwin collect? what ws the main difference?
13 types that were similar but different species; beaks and what they ate
different types of beaks and function
large beak adapted to cracking seed
another beak to grasp insects
another used small twig as a probe for wood0boring insects
what did darwin began to view as related processes?
new species and adaptation
what would happen if a geographical barrier like a water channel separated 2 islands which isolated 2 populations of the same species?
the populations would diverge more and more to adapt to local environment conditions and eventually become two different species
what is a species?
defined as sharing similar anatomical characteristics, members can interbed and produce fertile offspring
what made darwin publish his book?
naturalist Wallace developed a similar theory which encouraged darwin to quickly publish his book
what did darwin believe organisms descended from?
a single common ancestor and over millions of years accumulated diverse modifications to fit their environment
what did darwin replace the word evolution with in his book?
“descent with modifications”
tree of life
each branch shows lineage
animals categories
D K P C O F G S
Darwin’s first main point on natural selection regarding number
production of more individuals than the environment can support leads to a struggle for existence
darwin’s second main point on natural selection regarding survival
it is not random, bu depends on variation/genetics as those “bets fit” to the environment survive and reproduce and pass on genes - “survival of the fittest”
darwin’s third main point on natural selection?
the unequal ability of some individuals to survive and reproduce will lead to gradual change in a poulation
when did darwin recognize the struggle for existence on human population?
essay by Maithus spoke of human suffering that would occur as human population increases faster than food supplies and other resources
what is a characteristic all species share?
the capacity to overeproduce
artificial selection
the breeding of domesticated plants and animals for desired traits
what have humans done with artificial selection?
modified many species over generations that now bear no resemblance to their wild ancestors
what did darwin reason about natural selection?
it should bring about gradual change eliminating less favorable variations over 100 to 1000 generations
what is the smallest unit that can evolve?
population
what is a population
a species that can interbred and share a common geographic area
what is evolution measured by?
not measured by individuals, it is variations in populations over many generations
why is natural selection situational?
a favorable adaptation in one situation may be useless or harmful in different circumstances
what is responsible for variations?
the environment does not create variations in a population
mutations and genetic recombination (crossing over and law of independent assortment) are responsible
how did darwin mainly document evolution?
evidence from the geographical distribution of species called biogeography ex. islands have many native species yet resemble mainland species
what did darwin base his observation on?
the fossil record
paleontologists have discovered many transitional/intermediate forms that link older fossils to modern species
what type of structures are used as evidence for evloution?
homologous structures
what is similar between some organisms ?
same anatomical structures
ex. forelimbs of humans (grasp), cats (climb), whales(swim), bats (fly) have many of the same skeletal elements but very different functions
how is similar anatomical structure a sign of relation?
it makes no sense to have similar infrastructure unless they descended from a common ancestor
what other examples of other homologous structures?
vestigial organs – historical remnants of structures that had importance in ancestors ex. coccyx, appendix, wisdom teeth, ear muscles
what are vestigial organs?
reduced versions of organs that would be wasteful to continue providing blook, nutrients, and space to organs that no longer have major functions
closely related species go through similar stages of what?
similar stages of embryonic development ex. all vertebrate embryos, including humans go through a stage where they have gills/pharyngeal pouches/arches
what does molecular biology support the relationship of?
between species reflected in similar DNA and proteins
how related are life forms?
related to some extent through branching descent from the earliest organisms and even humans and bacteria have some proteins in common
the common genetic code shared by most life forms in evidence of?
evidence of the branching of the tree of life ever since the code’s beginning in an early life form
law vs theory
law =describe
theory= explain
why is the idea that darwin’s ideas as “just a theory” flawed?
it fails to separate the idea that modern species did indeed evolve from ancestral forms - there is a lot of evidence
main mechanism for evolution
natural selection
other mechanisms for evolution?
artificial selection
sexual selection
punctuated equilibrium
many more
to biologists, what is evolution?
a fact
what is the theory part of evolution?
the mechanisms of natural selection
what are scientists questioning now about natural selection?
if it alone accounts for evolution
