Transcript Evolution Evidence and Theory
Evolution Evidence and Theory
Chapter 15 Lab Biology
Vocabulary
• • • • • • • • • • Absolute age Stratum Fossil Acquired trait Relative age Natural selection Vestigial Artificial selection Coevolution Adaptive radiation cast mold extinct law of superposition adapt analogous convergent evolution divergent evolution homologous fitness
Evolution
•
A genetic change within a population over time!
Fossils
•
Fossil is a trace of a long-dead organism.
–
Found:
• 1.
Sedimentary rock
- formed by dust, sand, or mud deposited by wind or water over dead organism – Usually formed by
hard body parts
shell, bones, teeth, or woody stems of an organism — –
Hard minerals replace the tissue of the organism leaving rocklike structures
Sedimentary Rock
Continue Fossils
2.
mold
– imprint in rock in the shape of an organsim -
limestone
3.
cast
– forms when molds are filled with hard minerals
Limestone
–
Limestone
is the most abundant of the non-classic sedimentary rocks. Limestone is produced from the mineral calcite (calcium carbonate) and sediment. The main source of limestone is the limy ooze formed in the ocean. The calcium carbonate can be precipitated from ocean water or it can be formed from sea creatures that secrete lime such as algae and coral. – Chalk is another type of limestone that is made up of very small single celled organisms. Chalk is usually white or gray in color.
• !
Cast
Robert Hooke 1635-1703 • • He concluded that fossils are remains of plants and animals He mostly studied “
petrified wood
” with the aid of the microscope • He hypothesized that living organisms had somehow been turned to rock
Petrified Wood Wood that has turned to stone!
How is Petrified Wood Formed?
• The mud that covered the logs contained volcanic ash, a key ingredient in the petrification process. When the volcanic ash began to decompose it released chemicals into the water and mud. As the water seeped into the wood the chemicals from the volcanic ash reacted to the wood and formed into quartz crystals. As the crystals grew over time, the wood became encased in the crystals which, over millions of years, turned the wood into stone.
Distribution of Fossils
• Nicolaus Steno (1638-1686) – “
law of superpositon
” – states that the top layers of stratum contain the youngest fossils while the lower ones are older • This technique helps scientists to determine the “
relative age
” of a fossil • “
absolute age
” - age in years determined by radiological evidence
Succession of Forms
•
Mass extinctions
– brief periods during which large numbers of species disappears.
– Some of these life forms were unlike any organisms alive today – Probably resulted from drastic changes in the environment, volcanic activity or collisions with asteroids (may have blocked sunlight for long periods of time and decreased temp.)
Biogeography
•
Biogeography
– is the study of the geographical distribution of fossils and of living organisms.
– A comparison of recently formed fossil types with types of living organisms in the same geographic area shows that
lived.
new organisms arise in areas where similar forms already
• Ex: armadillos in North & South America where glyptodonts lived in the past.
Armadillos
Glyptodonts
Scaphognathus crassirostris Lab Fossil
Theories of Evolution
• I.
Lamarck
’
s Explanation
: – French scientist (1744-1829) – Proposed that similar species descended from a common ancestor (fossil records) – He hypothesized that
acquired traits
were passed on to offspring.
Acquired Trait
• • It ’ s not determined by genes!
Instead, it arises during an organism ’ s lifetime as a result of the organism ’ s experience or behavior.
– Ex: 1.
webbed foot on water birds
resulted from repeated stretching of the membrane between the toes – 2.
tails
– if you don ’ t use it you loose it!
Beginning of Modern Evolutionary Theory • II. Charles Darwin (1809-1882) & Alfred Wallace (1823-1913) – “
natural selection
” -hypothesis that organisms best suited to their environment reproduced more successfully than other organisms – Darwin & Wallace announced their hypotheses at the same time – Darwin ’ s name became more associated with evolution The Origin of Species published
Darwin
’
s Voyage on the Beagle
• Sailed in 1831 for
five years
• Collected specimens and kept careful records of his observations • Sailed to South America (Galapagos Islands) and the South Pacific
Darwin
’
s Findings
• • 1. returned to England in October 1836 • 2. collected
13 similar but separate species of finches.
• 3. Each finch species had a
distinctive bill
for specialized food source.
Implied that the finches shared a recent common ancestor
Darwin ’ s Finches
Darwin
’
s Findings
• !
A GRUB!!!!!!!
Darwin
’
s Theories
• TWO THEORIES; – 1.
DESCENT WITH MODIFICATION
– The newer forms appearing in the fossil record are actually the modified descendants of older species • Organisms similar to each other come from a recent
common ancestor
, organisms that are more dissimilar such as finches and armadillos share a more
remote ancestor
Continue…
• 2.
MODIFICATION BY NATURAL SELECTION
– states HOW evolution occurs.
– Organisms having
traits that make them better suited for survival
tend to leave more offspring than organisms with fewer beneficial traits. Darwin called the different degrees of successful reproduction among organisms in a population
NATURAL SELECTION
Evidence of Evolution
• 1.
HOMOLOGOUS STRUCTURES
: similar features that originated in a shared ancestor – Similar in structure BUT differ in function!!
– Ex: penguin, bat, alligator, & human (all derive from the same embryological structures) – These examples i.e. share a fairly recent common ancestor
Homologous Structures
Continue…
• 2.
ANALOGOUS STRUCTURES
: Similar functions BUT differ in structure and embryological development – Ex: wings of a hummingbird and humming moth – both can hover to feed
Analogous Structures
Continue…
• 3.
Vestigial Structure
: them. Features that were useful to an ancestor, but they are not useful to the modern organism that has – Ex:
tailbone
in humans,
appendix
, some snakes have
tiny pelvic bones
and
limb bones
, some whales have
pelvic bones
along with
four chambered stomach
like a cow!
Vestigial Structures
Continue…
• 4.
Similarities in Embryology
– Ex: all vertebrate embryos are similar, but those similarities fade as development proceeds – evidence that indicates that vertebrates share a common ancestor
Vertebrate Embryos
Continue…
• 5.
Similarities in Macromolecules
: The more similar homologous proteins are in different species, the more closely related the species are thought to be.
– Ex: the
amino acid sequence hemoglobin
and in human
gorilla hemoglobin
differ by
ONE
amino acid – While the
Hb
of
humans 67
amino acids!!
and
frogs
differ by
Patterns of Evolution
• 1.
Coevolution
: the change of two or more species in close association with each other is called coevolution – Predators and their prey sometimes co-evolve • Ex: “ tropical region ” bats feed on nectar – Bats have slender muzzle and long tongue that help them to feed,flowers are light in color which helps bats to see them at night and have a fruity odor that is attractive to the bats.
Tropical Bats!
Baby Bats!!
• COOL!
CLOSE UP!!!!
Flowers with Nectar!
Continue…
• 2.
Convergent Evolution
: occurs when the environment selects similar phenotypes, even though the ancestral types were quite different from each other.
– Analogous structures, such as similiar fins in very different animals, are associated with convergent evolution • Ex: sharks and porpoises
Porpoises
Sharks
Continue…
• 3.
Divergent Evolution
: two or more related populations or species become more and more dissimilar. Divergence is nearly always a response to differing habitats and can result in new species – A)
adaptive radiation
Galapagos finches : many related species evolve from a single ancestral species ex: – B)
artificial selection
: all domestic dogs are the same species “ Canis familiaris ”
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