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 adaptationso 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 categorieso 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 theoryo 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 Species1)

2)

III. DARWIN’S CONCLUSIONS

• Descent with Modificationo 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 Modificationo 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 Observationo Antibiotic/Drug Resistance

o Coloration in GuppiesoEndler’s Experiments

• Fossil Recordo 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 Ex. Forelimbs of humans, cats, whales, bats, etc.

o ___________________ 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

• Biogeographyo Geographical distribution

of specieso 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 non-

evolving 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)

________________________ (think genotype)• p2 = % of AA as a decimal• 2pq = % of Aa as a decimal• q2 = % of aa as a decimal

V. POPULATION GENETICS, contHardy-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):

_________________ _________________ _________________ _________________ _________________

VI. MICROEVOLUTION, cont• Genetic Drift

o Changes in the gene pool due to_______________. o More commonly seen in ____________ population sizes. o Usually reduces genetic variability. o 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

VI. MICROEVOLUTION• Gene Flow

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 POPULATIONTendency 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 speciesAKA….. 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 SpeciationBased 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