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BIO SCI 94 Midterm: Midterm 1 Study Guide


Department
Biological Sciences
Course Code
BIO SCI 94
Professor
Nancy Aguilar- Roca
Study Guide
Midterm

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BIO 94: Winter 2019
Lesson 1
Ch. 1 (pg 5-14)
Vocabulary Terms
Population
Individuals of the same species that are living in the same area at the
same time
Population thinking
Emphasizes variation among individuals
Fitness
Ability to produce viable offspring
Adaptation
A trait that increases the fitness of an individual in a particular
environment
Speciation
Divergence process in which natural selection has cause populations of
one species to form a new species
Evolution
“Descent with modification” - Darwin
Natural Selection vs Evolution
Natural selection acts on individuals, but evolutionary change occurs in
populations
Evolution occurs when heritable variation leads to differential success in
reproduction
Conditions of natural selection
1. Heritable variation in a population- traits passed onto offspring
2. In certain conditions, some traits lead to survival and increased reproductive
success (fitness)
* as a result species are related through common ancestry
Phylogenetic trees
Shows differences in species related by common ancestry
node= common ancestor
How to test competing hypotheses: giraffe neck length
Sexual selection hypothesis vs food competition hypothesis
Males giraffes with longer necks win battles
Giraffes use their long necks to find food
Both hypotheses may be partially correct
Testing competing hypotheses
Manipulation experiment
Ex. how do desert ants find their way back to the nest?

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Hypothesis: ants count their steps
Test 1: Manipulate leg length
Control group = untreated
Normal leg length
Control variable= keep constant throughout
experiments (ex. temp)
How long the ants legs are
Conclusion: ants keep track of # of strides and stride
length
Lesson 2
Ch. 25 (pg. 446-454, 456-464)
Vocabulary terms
Homology
Similarity that exists in species because they inherited the trait from a
common ancestor
1. Genetic homology
DNA, RNA, amino acid sequences
2. Developmental homology
Embryos
3. Structural homology
Adult morphology
Ex. vertebrate forelimbs have the same number
and arrangement of bones
Homologous
Same origin, different function
Development, anatomy, genetic
Ex. front legs of a mouse and the wings of a bat
Convergent
Different origin, same function
Arose independently
Trade off
When an advantage is ALSO a disadvantage
Ex. turtle shells are good for protection but are heavy and make it
hard to move
Random mutations
Transitional feature
A trait in a fossil species that is intermediate between those of older and
younge species
Vestigial trait
Reduced or incompletely developed structure that has no function or
reduced function
Ex. Ostrich wings: reduced wings= cannot fly
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Ex. goosebumps do nothing to keep us warm
Primitive
Older
Advanced
Newer
Galapagos mockingbirds: descent from a common ancestor
South America→ Galapagos
Wind currents, etc.
Phylogeny → non galapagos outgroup
Node = common ancestor
Darwin’s 4 postulates
Must all be true for natural selection to be happening
1. Variation in the population
2. Heritable
3. Produce excess offspring
4. Subset of survivors is not random
Had some trait that allowed them to survive and reproduce which
was then passed down to the next generation
***heritable variation leads to differential reproductive success
Ex. ground finches beak size increased during and after the drought
Lesson 3
Ch. 26 (pg. 465-472)
Vocabulary Words
Natural selection
Increases the frequency of certain alleles (that contribute to reproductive
success)
Genetic drift
Causes allele frequencies to change randomly
May cause alleles that decrease fitness to increase in frequency
Gene flow
When individuals leave one population, join another and breed
Allele frequencies may change
New individuals bring in new alleles
Departing individuals remove alleles
Mutation
Modifies allele frequencies by continually introducing new alleles
They can be beneficial or detrimental or have no effect
Inbreeding
Mating between relatives
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