Chapter 14, 15, and 17
Download
Report
Transcript Chapter 14, 15, and 17
You are responsible for reading these chapters…we will be
discussing these slides in class, however, we will not be going
slow enough for students to copy word-for-word
This PowerPoint combines Darwin information from
both texts
It provides a lot of background information that should
better help you understand the development of Darwin’s
theories as well as give you a more thorough foundation
of the history of Earth.
Complete the Chapter 15 WebQuest:
ContinentalDriftQuest (located on the Biology:
Exploring Life site
Try to explain how Plate Tectonics and Continental
Drift influenced evolution and biodiversity
You will need to read "On the Move...Continental Drift
and Plate Tectonics." –this is linked on that site =
VERY USEFUL!
Fossils/Their Dating
Fossil Record/Geologic
Time Scale
Continental
Drift/Macroevolution
Mass Extinctions
Formed from remains of organisms buried by
sediments, dust, or volcanic ash
Soft body parts – usually decay rapidly
Hard body parts (shells, bones, or teeth) – may become
preserved; long-lasting
Hard body parts are hardened more
Minerals dissolve in groundwater
Seep into tissues of dead organisms and replace its
organic material
Plant/animal becomes petrified
Some rare fossils contain
organic material
Found as thin films
Pressed between layers of
sand stone or shale
Ex. Idaho – plant leaves
millions of years old that are
still green with chlorophyll
Other Fossils: footprints,
animal burrows, sediment
impressions
Sometimes an
organism happens to
die in a place where
bacteria and fungi
cannot decompose the
corpse
Ice
Plant sap
Fossil record is a “rich storehouse of information”
about macroevolution
Geologic Time Scale
Precambrian
Paleozoic
Mesozoic
Cenozoic
Periods are divided into epochs
Boundaries between eras are marked by a major
change in forms of life and possibly mass extinctions
Know age of fossils based on location in sediment
Relative Ages = reflect the order in which groups of
species existed compared to one another
Absolute Ages = Actual ages in years
Measurement of certain radioactive isotopes in objects
Every isotope has a fixed rate of decay
Number of years for 50% of original sample to decay =
half-life
Unaffected by temperature, pressure and other
environmental conditions
Used to date rocks
Fossils can sometimes be dated as well
Could contain isotopes of elements that accumulated
in the organisms when they were alive
When organism dies, intake of isotopes stops, but
radioactive decay continues
Dinner and a movie usually works! Just kidding.
Can only be used to find the age of recent fossils due to
half-life of C-14 = 5,600 yrs
Any fossil older than 50,000 must be estimated using
the surrounding rocks that contain Uranium-238 and
other radioactive isotopes that have longer half-lives
Continents aren’t locked into place
Landmasses on different plates change position
relative to each other as a result of continental drift
Solution to many biological puzzles
Matching fossils in totally different locations
Differing plants in locations that became isolated
1. 250 million years ago, near end of Paleozoic Era
Plates moved = 1 supercontinent = Pangea
Variety of changes
Shoreline reduced
Sea levels dropped
Shallow coastal seas were drained, destroying shallow water
environments and inhabiting species
Continental interiors influenced as well
Isolated, evolving species came together and competed = cause
mass extinctions
2. 180 Million years ago = Continental Drift
Pangea broke up
Each continent became isolated
Species on each continent diverged in their evolution
and adapted and diversified based on new, separate
continents
Long periods of relative stability broken by brief
periods of great species loss
Extinction of dinosaurs (end of Cretaceous Period
– 65 million years ago)
Climate was cooling
Shallow seas receding
Large meteor hit Yucatan Peninsula in Mexico during
same time, sending dust into the atmosphere
Blocked sunlight
Reduced food production by photosynthesis
Adaptive radiation of
survivors
In aftermath, biological
diversity increased again
Gives surviving organisms
new opportunities
Rise of mammals may have
resulted from the void left by
the extinction of dinosaurs
Identification, naming, and classification of species
Common names cause confusion
Common name can refer to many different species
Doesn’t reflect organism
Universal scientific name needed for all scientists to
clearly communicate
Binomial Nomenclature = two-part Latin naming
system for naming each species
Also a hierarchy of species into broader and broader
groups
Genus + species (Ex. Panthera pardus)
Closely related species are grouped into same genus
Phylogenetic Tree reflects the hypotheses of
evolutionary relationships
Homologous structures
Basic underlying similarities if evolved from single
structure in a common ancestor
Greater number of homologous structures = more
closely the species are thought to be related
Not all structures are inherited from common ancestor
Unrelated species from similar environments have
adaptations that seem very similar = analogous
structures
Wings of insects and birds = evolved independently
despite both are flight equipment and built from
entirely different structures
Early 1800’s
Jean Baptiste Lamarck attempted to explain Buffon’s
observations
Proposed that life evolves/changes
Species are not permanent
Evolution is a process of adaptation
Today – unfairly remembered for mistaken explanation
of how adaptations evolve (make sure you know what
these are – pg. 293)
Voyage of the Beagle
December 1831
Mission – chart poorly known stretches of the S.
American coastline for the British navy
Charles Darwin, 22, was on the ship
Interested in studying geology, plants, animals encountered
on voyage
Pivotal trip in that it changed the thinking of many
Darwin’s Observations
Darwin spent a lot of time on shore while ship’s crew
surveyed
Collected many species of plants and animals
Documented everything in extensive journals
(observations, studies, personal thoughts)
Journals documented Darwin’s thoughts from before
the journey until he returned to port in England
Darwin’s Observations (cont.)
Noticed that plants and animals all had definite S.
Am. Character
Distinct from species in Europe
Deduced that species in S. Am. descended from
ancestral species on that continent
Intrigued by life on Galápagos Island
Species were similar to plants and animals on nearest
mainland (not exactly same)
Allowed Darwin to suggest that species that left the
mainland adapted to new lives on islands
Ideas from Geology
Darwin read a lot despite puking
Read from Lyell’s writings
Proposed that gradual and observable geologic processes
(erosion) could explain the physical features of today’s Earth
River erosion = deep, river-carved canyon
Mountain range rises = earthquakes
Ideas from Geology (cont.)
Darwin personally experienced an earthquake in Andes
Mountains
He collected fossils of ocean organisms high in the Andes
Concluded that (based on Lyell’s work) that the earthquakes
gradually lifted the rock.
2 conclusions:
1. Slow processes of mountain building and erosion suggested an
Earth that must be very cold
2. These slow and gradual processes occurring over vast spans of
time could cause enormous change on Earth
Darwin was at sea for 5 years
Over this time he sent letters and specimens back to
England
This established his reputation with other scientists
Left as young graduate
Returned as a famous naturalist
After analysis of his data, he became convinced that Earth
was ancient and that species change through time.
Thomas Malthus (wrote essay few decades before
Darwin)
Contended that much of human suffering was due to the
human population’s potential to grow
Populations grow IF food supplies and other resources can be
produced
If this does not happen = it is a struggle for existence
This helped Darwin to propose a mechanism of evolutionary
change.
Darwin’s essay (1844)
200 pages
Didn’t release it to the public
Colleagues urged Darwin to publish before someone else
did
Alfred Wallace (1858) came to same conclusion and
wrote to Darwin explaining his findings
Within a month, both had findings presented to public
together
Darwin published The Origin of Species about a year
later
Darwin made 2 main points in his book
1. He argued from evidence that the species of organisms
living on Earth today descended from ancestral species
1. Life has a history of change
2. Descendants of the earliest organisms spread into various
habitats over millions of years
1. Accumulated different modifications = “Descent with
Modification”
2. Accounts for diversity of life
Darwin’s 2nd point
His argument for natural selection was the mechanism
for evolution
Natural selection can cause a population to change over
time
Result = adaptation
Homologous vs. Analogous Structures (evidence of
evolution)
Homologous = similar features that originated in a
shared ancestor (see page 289 in your text)-orcomplete online activity 14.2 in Exploring Life
Look different but have similar skeletal structure
Derive from same structures in embryo
Analogous = serve identical functions and look
somewhat alike
Very different embryological development
Just keeping you on your toes!!!!!
Vestigial Structures – features seem to serve no useful
function now (human’s tailbone) but may have done
so historically
Similarities in Embryology – See page 291, Figure 15-9
Ernst Haeckel – embryological development repeats
evolutionary history! (slightly exaggerated; similarities
fade as development proceeds)
Similarities in Macromolecules - homologous
proteins; RNA and DNA; amino acid sequence is
similar between different species
Coevolution – change of 2 or more species in close
association with each other
Predators and their prey; parasites and hosts; plant-
eating animals and their chosen plant
Convergent Evolution – Organisms appear to be
similar but are not closely related at all –
analogous structures are similar adaptations that
result from this
Divergent Evolution – 2 or more related
populations become more and more dissimilar
Adaptive radiation
Artificial selection
Page 321…differences between human and ape
Anthropoid Primate
Prosimian Primate
Marmosets
Lemurs
Monkeys
Lorises
Apes
Tarsiers
Humans
Movable fingers and toes
Most have flattened nails rather than claws
Some have prehensile hands (grasping)
Color vision (due to activity during day)
Anthropoids
Ex. Gibbon
Well-developed
collarbone
Rotating shoulder joints
Partially rotating elbow
Opposable thumb
Similar dental formula
Large brains
Humans
Specific anthropoid
Bipedal
Cup-shaped pelvis
S-shaped spine
Larger brain
Bipedalism defines first hominid line
1974 Donald Johanson found “Lucy” in the Afar Valley
region of Africa…very well preserved
Cranial capacity size of chimpanzee
Originally thought that bipedalism and large
brain evolved at same time, but the “Lucy”
find proved that upright walking…
• “Lucy” was given this name
• Means “southern ape of Afar Valley”
• About 3.2 million years old
•
•
•
•
Dates from about 2.3 – 3 million years ago
Probably descended from A. afarensis
Taller and heavier than “Lucy”
Had a slightly larger cranial capacity
Australopithecus
robustus
Australopithecus boisei
May have descended
May have descended
from “Lucy” but were
probably not ancestral to
modern humans
from “Lucy” but were
probably not ancestral to
modern humans
• In 1995, Tim White discovered fossils
that may
Predate earliest known
australopithecines by
200,000 years
• Unsure whether it is ancestral to
australopithecines
Found with stone tools
“Handy Human”
Between 1.6-2.5 million years old
Region of the brain essential to speech
may have existed
• Tool marks on animal bones found
near fossils suggest H. habilis ate
meat
•
•
•
•
“Upright human”
1.8 million – 50,000 years ago
Thick skull
Large brow ridges
Low forehead
Large, protruding teeth
Average brain size 2/3 that of modern humans
Adults could easily have been as tall as modern
humans
• Charred bones found near fossils indicate H.
erectus were hunters who used fire (cooking and
heat)
• In colder climates, may have lived in caves
•
•
•
•
•
•
•
•
Neanderthals
230,000 – 30,000 years ago
Heavy bones, thick brow ridges,
protruding teeth
Cranial capacity slightly larger than
modern humans
Stone tools led scientists to believe
that they wore animal skins
Not ancestral to modern humans
Disappeared approximately same
time as modern H. sapiens arrived
(killed off Neanderthals or killed by
disease)
Modern Homo sapiens
Fossils about 35,000 years old
Found in southwestern France
Cro-Magnons
Cranial capacity equal to that of modern humans
High forehead
Lack of protruding brow ridge and teeth
Taller than Neanderthals
Oldest are 100,000 years old
Parallel populations of H. sapiens evolved from different
H. erectus populations around the world
Modern H. sapiens evolved in Africa and spread
throughout the world, replacing populations of H.
erectus and early H. sapiens
RNA molecules can take on a great variety of shapes (t-
shaped tRNA)…dictated by H bonds between particular
nucleotides
Much like the shape of the protein depends on the H
bonds between particular a.a.
Speculation that some RNA molecules might actually
behave like proteins and catalyze chem. rxns.
Thomas Cech
Ribozyme…act as an enzyme
Early Earth had little or no O, so first cells must have
been anaerobic; fossils indicated that they were
prokaryotes and probably heterotrophs
Chemosynthesis…CO2 serves as C source for assembly of
organic molecules…many archaebacteria (live in extreme
and harsh conditions) obtain E this way
Photosynthesis and Aerobic Respiration
O was damaging to some unicellular organism
Early function of aerobic may have been to prevent the
destruction of essential organic compounds by O
Believed that between 2.0 and 1.5 billion years ago a type
of small aerobic prokaryote entered (endosymbiosis)
and began to live and reproduce inside larger, anaerobic
prokaryotes
Lynn Margulis proposed that “invasion” turned mutually
beneficial = giving way to mitochondria
Second invasion may have been related to
cyanobacteria…eventually gave rise to chloroplasts