Transcript V. POPULATION GENETICS, cont

UNIT VII
POPULATION GENETICS & CLASSIFICATION
I. EVOLUTION VOCABULARY
• Evolution
o Change in the _________________
___________________________ of
organisms over time
o Descent with modification
• Natural Selection
o Populations of organisms can change
over the generations if individuals having
certain _________________
_____________ leave more offspring
than others
o ___________________ reproductive
success
• Evolutionary adaptations
o A prevalence of inherited characteristics
that ______________ organisms’
______________ and
_____________________ in
__________________ environments
November 24, 1859
II. A HISTORY OF EVOLUTIONARY THEORY
• Carolus Linnaeus (1707-1778)
o “Father of __________________”
o Grouped similar species into a hierarchy of increasingly
general categories
o Had no evolutionary reasoning behind this
• James Hutton (1726-1797)
o Theory of ___________________
o Profound change is the cumulative product of slow but
continuous processes
• Jean-Baptiste de Lamarck (1744-1829)
o ________________________
o Body parts used extensively become larger & stronger while
those that aren’t used deteriorate (ex. Blacksmith or Giraffe
neck)
o Inheritance of __________________ Characteristics
II. A HISTORY OF EVOLUTIONARY THEORY, cont
• Thomas Malthus (1776-1834)
o Populations
• Charles Lyell (1792-1875)
o Theory of ______________________________
o Geologic processes have not changed throughout
Earth’s history, so the forces and the rates at which
these forces operate are the same today as in the
past
• Gregor Mendel (1822-1884)
o “Father of ________________”
o Inheritance patterns
• Alfred Wallace (1823-1913)
o Independently developed evolutionary theory
o Not 1st to publish = little to no credit
II. A HISTORY OF EVOLUTIONARY THEORY, cont
II. A HISTORY OF EVOLUTIONARY THEORY, cont
• Charles Darwin (1809-1882)
– Naturalist
– HMS Beagle
– _____________________ Islands
• Darwin’s _______________: New species of finches arose from gradual accumulation of
adaptations due to variations in food supply, terrain
– The Origin of Species
1)
2)
III. DARWIN’S CONCLUSIONS
• Descent with Modification
o Summary of Observations
 Members of a population often _________
greatly in their traits.
 Traits are inherited from parents to offspring.
 All species are capable of producing _______
offspring that their environment can _________.
 Owing to a _________ of food or other
resources, many of these offspring do not
______________.
III. DARWIN’S CONCLUSIONS, cont
• Decent with Modification
o Summary of Inferences
 Individuals whose inherited traits give
them a ________________________
_____________________ of surviving
and reproducing in a given
environment tend to leave _________
offspring than other individuals.
 This unequal ability of individuals to
survive and reproduce will lead to the
accumulation of _______________
____________ in the population over
generations.
IV. EVIDENCE FOR
EVOLUTION
• Direct Observation
o Antibiotic/Drug Resistance
o Coloration in Guppies
o Endler’s Experiments
• Fossil Record
o Succession of forms over time
o Transitional Links
IV. EVIDENCE FOR EVOLUTION, cont
•
Homology
o
____________________ structures – similar in
characteristic resulting from _____________
ancestry (not necessarily the same function)
o
o
Ex. Forelimbs of humans, cats, whales, bats, etc.
___________________ organs - remnants of
structures that had important functions in
ancestors
 Ex. Snake Pelvis & Pharyngeal Pouches (gill slits)
o
Does NOT apply to convergent evolution
 Independent evolution of similar features in different
lineages
 _____________________ structures – similar structure/
function between two species that are not closely related
IV. EVIDENCE FOR
EVOLUTION, cont
• Comparative ________________
o Pharyngeal Pouches (gill slits)
o Post Anal Tail
• Molecular Biology
•
•
Similarities in DNA, proteins, genes, & gene
products
Common genetic code
IV. EVIDENCE FOR EVOLUTION, cont
• Biogeography
o Geographical distribution
of species
o Continental Drift
 Pangaea
o Islands are inhabited by
organisms most closely
resembling nearest land
mass
V. POPULATION GENETICS
• Population Genetics
 The study of genetic changes in populations
• Population

• Species

• Gene pool
 Population’s genetic make-up
V. POPULATION GENETICS, cont
• Hardy-Weinberg Principle
– Predicts ______________________
____________________ in a nonevolving population; that is, a
population in ___________________
– Can be used to determine if a
population is evolving
– States that allele frequencies in a
population will remain constant from
generation to generation if _________
conditions are met
V. POPULATION GENETICS, cont
• Five Conditions for Hardy-Weinberg Equilibrium
1)
2)
3)
4)
5)
• If any of these conditions are not met, evolutionary
change will occur
V. POPULATION GENETICS, cont
• Hardy-Weinberg Equation
________________________
(think phenotype)
• p = dominant phenotype (AA or Aa)
• q = recessive phenotype (aa)
________________________
• p2 = % of AA as a decimal
• 2pq = % of Aa as a decimal
• q2 = % of aa as a decimal
(think genotype)
V. POPULATION GENETICS, cont
Hardy-Weinberg Practice Problems
1. If you know that you have 16% recessive fish (bb), calculate the
frequency of each genotype using Hardy-Weinberg
V. POPULATION GENETICS, cont
• Hardy-Weinberg Practice Problems, cont
2. If in a population of 1,000, 90 show recessive phenotype (aa), use
Hardy-Weinberg to determine frequency of allele combinations.
VI. MICROEVOLUTION
• A change in the ____________________ of a population over a
succession of generations
• Five main causes (opposite
of HWE):
_________________
 _________________
 _________________
 _________________
 _________________
• Genetic Drift
o
o
o
o
VI. MICROEVOLUTION, cont
Changes in the gene pool due to_______________.
More commonly seen in ____________ population sizes.
Usually reduces genetic variability.
There are _________ situations that can drastically reduce population size:
 ___________________________: type of genetic drift resulting from a reduction in
population (natural disaster) such that the surviving population is no longer genetically
representative of the original population
 ___________________________: type of genetic drift attributed to colonization by a
limited number of individuals from a parent population; Gene pool is different than source
population
• Gene Flow
VI. MICROEVOLUTION
 Genetic exchange due to the migration of __________ individuals or gametes
between populations
 Tends to reduce differences between populations
• Natural Selection
 Differential success in _________________________
 Only form of microevolution that adapts a population to its _______________
• Mutations
 A change in an organism’s __________ (gametes; many generations)
 Original source of genetic variation (raw material for natural selection)
• Nonrandom Mating
 Inbreeding and selective mating both can change allele frequencies of different
genotypes
VII. VARIATIONS IN POPULATION
• Polymorphism
 Coexistence of 2 or more distinct forms of individuals _______________ within
the same population
 Applies only to _______________ characters
• Geographical Variation
 Differences in genetic structure between populations
 _____________: graded change in some trait along a geographic axis
 Mutation and Recombination
 Occur by _________ & process of
____________ & fertilization
VII. VARIATIONS IN POPULATION
Tendency of natural selection to reduce variation is countered by mechanisms
that ________________ or ________________ variation
• Diploidy
 2nd set of chromosomes hides variation in the ____________________
• Balanced Polymorphism
 Heterozygote Advantage
○ _______________________________________
_________________________________________
__________________________________________
_________________________________________
 Frequency-Dependent Selection
o _______________________________________
__________________________________________
__________________________________________
__________________________________________
__________________________________________
__________________________________________
o Parasite/host – evolutionary race
VII. VARIATIONS IN POPULATION
• Adaptive Evolution due to
Natural Selection
 _________________________ Contribution an individual makes
to the gene pool of the next
generation
• 3 ways in which natural
selection alters variation
____________________
____________________
____________________
VII. VARIATIONS IN POPULATION
• Sexual Selection
 Can result in ___________________
____________________________ secondary sex characteristic
distinction that does not directly relate
to sex
 Explains why males & females often
look different other than the obvious
reproductive structures
 _____________________ Selection
 “within the same sex”
 Direct competition between
individuals of the same sex
 _____________________ Selection
 Mate choice/female choice
VIII. MACROEVOLUTION
• _____________________- Origin
of new taxonomic groups
• Speciation
______________________ accumulation of heritable
changes transform existing
species into new species
________________ - branching
evolution; budding of new
species from a parent species
that continues to exist
Basis of biological diversity
VIII. MACROEVOLUTION
• Biological Species Concept
 Ernst Mayr - 1942
 ‘Working Definition of a Species’ - population
or group of populations whose members have
the potential to interbreed and produce viable,
fertile offspring, but cannot produce viable
fertile offspring with members of other species
 AKA….. similar organisms that can make
babies that can make babies 
 Can be difficult to apply to certain organisms…
• Reproductive Isolation
o Prevents closely related species from interbreeding when their ranges overlap.
o 2 types
Prezygotic - _______________________________________________
Postzygotic - ______________________________________________
VIII. MACROEVOLUTION
VIII. MACROEVOLUTION
VIII. MACROEVOLUTION
VIII. MACROEVOLUTION
• Speciation
o _______________________________ - Fossil record shows evidence
of bursts of many new species, followed by periods of little change
o _______________________________ - Other species appear to
change more gradually
 Fits model of evolution proposed by Darwin
VIII. MACROEVOLUTION
• Modes of Speciation
 Based on how gene flow is
interrupted
 ____________________________
 Populations segregated by a
geographical barrier; can result
in ________________________
 Ex. island species
 ____________________________
 Reproductively isolated
subpopulation in the midst of its
parent population
 Ex. cichlid fishes