Lesson 2: Evidence of Evolution (sir ppt) Flashcards
Two theories
- Theory of special creation
- Theory of evolution: descent with modification
- species are immutable (do not change)
- variation among individuals is limited
- lineages do not split
- species are created seperately and independently -> genealogically unrelated
- earth and its living creatures are young (~6,000 years old)
- John Ray (1686): “one species never springs from the seed of another”
Theory of special creation
species do not change
immutable
variation of individuals in theory of special creation
limited
theory of special creation:
lineages __ __ __
do not split
theory of special creation:
species are created separately and independently
genealogically unrelated
theory of special creation:
age of earth
~6,000 years old
“one species never springs from the seed of another”
John Ray (1686)
- species are not immutable -> change over time
- lineages split and diverge = speciation
- over long periods of time, novel forms of life an derive from earlier forms = macroevolution
- species are derived not independently but from common (shared) ancestors (genealogically related) = common ancestry
- earth and life are considerably more than 6,000 years old
Theory of Evolution: Descent with Modification
Theory of Evolution: Descent with Modification:
species change over time
not immutable
average beak size may change from one generation to the next
microevolution
Theory of Evolution: Descent with Modification:
lineages split and diverge
speciation
speciation
lineages may split and diverge
Theory of Evolution: Descent with Modification:
over long periods of time, novel forms of life can be derived from earlier forms
macroevolution
Theory of Evolution: Descent with Modification:
species are dervied not independently but from common (shared) ancestors
genealogically related = common ancestry
Theory of Evolution: Descent with Modification:
age of Earth
more than 6,000 years old
Evidence of Evolution
- microevolution
- speciation
- macroevolution
- common ancestry
change in gene frequency within a population and can be observed over short periods of time
microevolution
microevolution
change in gene frequency within a population and can be observed over short periods of time
example of microevolution
evolution of antibiotic resistance
Evidence of microevolution
- selective breeding
- direct obervation of natural populations
- anatomy of living species
- also known as artificial selection
- the practice of mating individuals with desired traits as a means of increasing the frequency of those traits in a population
Selective breeding
artificial selection
breeders chooses only individuals with the most desirable traits
- small herb tht depends on a rainy season that runs from winter to spring
- individuals germinate, grow, flower, set seed, and die within a single year
- evolved flowering time
field mustard, Brassica rapa
In mid-1990s, seasonal rains lasted into late spring
long growing season
In early 2000s, seasonal rains ended early
short growing season
useless of rudementary version of a body part that has an important function in other, closely allied, species
vestigial structure
example of animals with vestigial structures
- brown kiwi, wings
- royal python, spur
small fish that lives in coastal ocean waters throughout the Northern Hemisphere and readily invades freshwater
threespine stickleback
carry heaby body armor
marine sticklebacks
bony plates protecting their sides and pelvic fins modified into spines
heavy body armor
carry light armor
freshwater sticklebacks
fewer bony plats, and reduced (vestigial) pelvic structures
light armor
populations, or goups of populations, within and among which individuals actually or potentially interbreed and outside of which they do not interbreed
species
species are population within and among which individuals actually or potentially interbreed
Biological Species Concept
who wrote the biological species concept
Ernst Mayr, 1942
different species
- disinclined to mate
- fail to produce healthy, fertile offspring
evidence of speciation
- evidence from laboraory experiments
- evidence from natural populations
Evidence of speciation from lab experiments
- The case of bacteriophage Φ6
- The case of Drosophila pseudoobscura
RNA virus that infects Pseudomonas syringae
Φ6
what does Φ6 infect
Pseudomonas syringae
can infect four different varieties of P. syringae
Φ6WT
has a mutation in the P3 gene, which enables it to attach and infect another P. syringae variety and P. pseudoalcaligenes
Φ6broad
mutation of Φ6broad
P3 gene
what can Φ6broad infect
- another P. syringae variety
- P. pseudoalcaligenes
strain that could no longer infect P. syringae but can infect P. pseudoalcaligenes
Φ6E1narrow
Evidence of speciation from natural populations
The case of threespine stickleback
4 stages of speciation
- speciation starts with a single population in which there is variation among individuals
- population divided into readily distinguishable subpopulations that still interbreed
- distinct populations with limited interbreeding
- distinct populations whose reproductive isolation is irreversible
example of human diseases that originated in other animals
- diphtheria from domesticated herbivores
- measles from cattle
- smallpox from virus of rodents or camels
generally refers to evolution above the species level
macroevolution
Evidence of macroevolution
- fossil record - transitional forms
- a living transitional form
any trace of an organism that lived in the past
fossil
worldwide collection of fossils
fossil record
- published a list of 23 species known only from fossils to challenge the hypothesis that unusual forms in the fossil record would eventually be found alive
- argued that it’s impossible for these enormous creatures to still live but escape detection –> extinction
George Cuvier
fossil and living organisms in the same geographic region resemble each other, but are distinct from organisms found in other areas
succession
shows a mix of traits typical of ancestral populations and novel traits seen later in descendants
transitional species
occurs in species level wherein one species change into another by the process of evolution
transmutation
all life-forms are related
common ancestry
the theory of descent with modification ultimately connects all organisms to a single __ __
common ancestor
Evidence of common ancestry
Homology
- fundamental similarities underlying the obvious physical differences among species
- study of likeness
homology
“homology is the same organ in different animals under every variety of form and function”
Richard Owen
inherited fundamental design from a common lineage/ancestor
structural homology
similarities between species on the molecular level
Molecular homologies
novel traits are shared in a __ __
nested pattern
the theory of descent with modification from common ancestor predicts that __ __ should share __ __ of novel traits
- extant organisms
- nested sets
can predict the order in which the traits should appear in the fossil record
nesting of shared traits
molecular homology - ?
the case of shared flaws
- theory that Earth’s features are mostly accounted for by violent, large-scale events that occurred in a relatively short amount of time.
- species that went extinct was probably killed off by a giant natural disaster.
Catastrophism
idea that Earth has always changed in uniform ways and that the present is the key to the past
uniformitarianism
divides up the history of the earth based on life-forms that have existed during specific times since the creation of the planet
geologic time scale
calculates an age in years for geologic materials by measuring the presence of a short-life radioactive
Radiometric dating
