Lecture Exam 3 Flashcards
when was life first seen on earth
3.8 billion years ago
who were the first two people to establish evolution as a powerful scientific theory
Charles Robert Darwin,
and
Alfred Russel Wallace
founders of evolution by natural selection are
- Charles Robert Darwin (1809 - 1882)
- Alfred Russel Wallace (1823 - 1913)
Pre-Darwinian Evolutionary ideas,
Early Greek philosophers; Xenophanes, Empedocles, and Aristotle all developed ideas
on evolutionary change and recognized fossils as evidence of former life 2500 years ago!
what is the key to understanding evolution
fossils
post Greek philosophers (who were starting to understand evolution via fossils), evolutionary thinking became restricted almost 2000 years ago due to
- multiple view about the age of the Earth, mostly due to religious beliefs
- James Ussher - began on 4004 BCE
- George Louis Buffon - Earth is 70,000 years old (what and idiot)
who was Jean Baptiste de Lamarck (1744 to 1829)
Authored the 1st complete explanation of evolution in 1809 before Darwin
was mocked and shunned from society for his ideas
who authored the 1st complete explanation of evolution in 1809 before Darwin
Jean Babtiste de Lamarck (1744 - 1829)
- made convincing case that fossils were the remains of extinct animals
- proposed the mechanism - inheritance of acquired characteristics
Inheritance of acquired Characteristics
define Lamarckism
organisms strive to meet demands of the environment
- acquire adaptations individually and then pass them on to offspring
- individual organisms transform their characteristics to produce evolution
Lamarckism is NOT accepted now due to genetic studies showing that acquired traits of an organism are NOT passed on to offspring (example of giraffes and their long necks)
Darwinism VS Lamarckism
Darwin’s evolutionary theory differs from Lamarck’s
- it is a variational, not a transformational theory
- evolution occurs in a population and not an organism level
- evolutionary change is caused by differential survival and reproduction among organisms with advantageous traits
- Desirable traits slowly accumulate and get passed down through generations
who was Sir Charles Lyell (1797 - 1875)
- Geologist who established the principle of uniformitarianism (changes in the Earth’s crust over time from continues processes)
- His book, Principles of Geology, greatly influenced Darwins thoughts
- Showed that natural forces acting over long periods of time can explain fossil bearing rocks
- English geologist and friend of Darwin
define Lyell’s Uniformitarianism
Sir Charles Lyell (1797 - 1875)
Uniformitarianism encompasses two important principles that guide scientific study of the history of nature
- Laws of physics and chemistry have not changed throughout Earth’s history
- Past geological events occurred by natural process similar to those observed today
importance of Darwin’s Great Voyage of Discovery
Charles Robert Darwin (1809 - 1882)
- presented the first credible explanation of evolutionary change
- made extensive collections and observations on a 5 year voyage (1831 to 1836) aboard the H.M.S Beagle
Darwins journal - The Voyage of the Beagle - published 3 years after the Beagle’s return was significant in the way
- it was an instant success and required two additional printings within the first year
- Unearthed numerous fossils long extinct and noted the resemblance between Souther American fossils and the known fossils of North America
overall, The Voyage of the Beagle enabled Darwin to formulate his major ideas about the evolution of life
in 1858, Darwin received a manuscript from Alfred Russel Wallace (1823 to 1913), and English naturalist in Malaya that summarized
the main points of the natural selection theory on which Darwin had been working for two decades
- Darwin published Wallace’s manuscript along with a statement of his own
- Darwin followed by publishing On the Origin of Species by Means of Natural Selection in 1859
Darwins main premise of evolution is
perpetual change
- the world is neither constant nor perpetually cycling, but always changing with hereditary continuity from past to present
- evidence by fossils - remnants of past life uncovered from the crust of the earth
many organisms leave no _________, so the _________ record is incomplete
fossils
fossil
the fossil record is biased because preservation is _________
selective
___________ skeletons and ____________ with shells provide more fossil records, unlike soft-bodied animals leave fossils only in _____________ conditions like the Burgess Shale of British Columbia
vertebrate,
invertebrates
exceptional conditions
vertebrates - humans
invertebrates - spiders, snails, butterflies, worms
fossils form in _________ layers, new deposits are on top of older material
stratified layers
in rare situations, the age of fossils is directly proportional to depth of the layers
animals of the _________ period, approximately _____ million years ago,
as reconstructed from fossils preserved in the Burgess Shale
Cambrian period
505 million years ago
________ or _______ fossils serve as indicators of specific geological periods and events
index or guide
layers of fossils often tilt and crack, and can erode or be covered with new deposits from a different layer. Under heat and pressure, the rock becomes
metamorphic and the fossils are therefor destroyed
oil comes from
foraminiferans
Sedimentary rock layers form the basis of the law of
stratigraphy
- dates oldest layers at the bottom and youngest at the top
time is divided into:
eons, eras, period, and epochs
radiometric dating methods for determining rocks’ age developed in the late
1940s
radioactive decay of naturally occurring elements is independent of heat and pressure, commonly called -
radioactive clocks
what are the two methods of radiometric dating
Potassium-Argon Dating
and
Rate of decay of uranium into lead
explain how Potassium-Argon Dating works
Potassium-40 decays to argon-40 and calcium-40
half life of potassium-4- is 1.3 billion years
calculating the ratio of remaining potassium-40 to amount originally there provides close mathematical estimate of the age of rock deposit
explain Rate of decay of Uranium into lead
- one of the most useful radioactive clocks
- can date age of rock layers on Earth
- error is less than 1% over 2 billion year
Sinosauropteryx is the first known
feathered dinosaur
- it lived in China around 130 million years ago
Caudipteryx had feathers just like
modern birds, even though it was not a bird
what is the name of this organism and why is it special
Cassowary bird, one of the only living dinosaurs
(among other bird species)
what did Darwin say about Common Descent
Darwin proposed that all plants and animals descended from a common ancestor
life’s history forms a branching tree called a
phylogeny
- all forms of life, including extinct branches, connect to this tree
- the genealogies of all modern species can trace backward until they converge on ancestral lineages shared with other species, both living and extinct
- phylogenetic research is successful at reconstructing the history of life
What did Darwin think about homology
Darwin saw homology as major evidence for common descent
Richard Owen described homology as:
“the same organ in different organisms under every variety of form and function”.
vertebrate limbs show the same basic structures modified
for different functions
Every time a new feature arises on an evolving lineage, a new
homology forms
homology - (the state of having the same or similar relation, relative position, or structure.)
homology gets transmitted to all descendant lineages, unless
it is subsequently lost
Darwin devoted an entire book to the idea that humans share common descent with _____ called -
with apes,
called The Descent of Man and Selection in Relation to Sex
Darwins central idea that apes and humans have a common ancestor was explained by
anatomical homologies
Darwins idea that apes and humans have a close resemblance from a common descent was initially accepted by many people at the time, true or false
false
phylogenetic reconstruction is defined as the pattern
formed by the sharing of homologies among species providing evidence for common descent and allows us to reconstruct the branching evolutionary history of life
Phylogenetic Reconstruction
branches of the tree combine species into ___________ ____________ of smaller groups within larger groups
nested hierarchies
Phylogenetic Reconstruction
Structural, Molecular, and chromosomal homologies are all combined to reconstruct ____________ _________
Evolutionary trees
Ontogeny is the development of
an organism through its entire life
Recapitulation (the biogenetic law) by ___________________ proposed that ontogeny recapitulates phylogeny
Later revised by
Ernest Haeckel
Later revised by K.E. von Baer who argued that early development were more widely shared among animal groups than later ones and can be affected by divergence
