Bio 2 Chap 1 Exam

Chap 22-26,28,34

Taxon

(taxa) taxonomic unit at any level of hierarchy

Phylogenetic tree

represents evolutionary history of organism

sister taxa

share immediate common ancestor

basal taxa

lineage that diverged early in group history

What phylogenetic trees can (1) and cannot (3) tell us?

CAN: illustrate pattern of descent
CANNOT: does not explain phenotypic similarity, doesn't necessarily indicate absolute age of species, can't assume taxon on tree evolved from taxon next to it

What are used to construct phylogenetic trees?

shared characters

Homologies

phenotypic and genotypic similarities due to a shared common ancestor

Analogous structures

result from convergent evolution, NOT a common ancestor,
Similar in function but not structure

Cladistics

groups organisms by common descent

clade

group of species that includes an ancestral species and all its descendants, smaller clades can be nested in larger clades

Monophyletic group

valid clade that consists of ancestor species and all its descendants

A cladogram is constructed by what?

observable characters

How do you construct a cladogram?

for each character, determine which state is "ancestral" (primitive) and which is "derived" (new), use distantly related organisms as "outgroup" to make determination, group taxa together into character table by shared derived character state

Taxa are grouped by what character state?

shared derived

Phylogenetic tree branches are proportional to what?

to change over geologic time

Maximum parsimony

simplest explanation consistent with facts (Occam's Razor)

Maximum likelihood

tree that reflects most likely sequence of evolutionary events

The 5 Kingdom system

monera, protista, plantae, fungi, animalia

The 3 Kingdom sysstem

Bacteria, archaea, eukarya

bacteria

prokaryotes

archaea

prokaryotes in extreme environments

eukarya

all organisms with eukaryotic cell organisms XCEPT fungi, animalia and plantae

macroevolution

history of life on earth

What are the 4 stages that produced very simple cells?

1. Abiotic synthesis of simple organic molecules
2. Joining of simple molecules into macromolecules
3. Macromolecules "packaged" into protocols (membrane bound droplets with different chemistry than surroundings)
4. Origin of self-replicating Molecules (RNA) that made inheritance possible

Earth's age

4.5 B years

Oparin-Haldane Hypothesis

Organic molecules synthesized in reducing environment with lightening/UV radiation as energy source

Urey and Miller Experiments

1953 experiment simulated early Earth atmosphere, produced amino acids from precursors , accumulated in "primitive soup" of early oceans

Name and describe 3 other possible explanations for the beginning of life on Earth

1. Volcanic sources: produced more amino acids, 2008
2. Deep-sea hydrothermal vents: 300-400 Celsius -\> organic molecules formed may be unstable
3. Deep-sea alkaline vents: 40-90 Celsius -\> organic molecules formed may be more suitable for early life

Simplest definition of evolution

descent w/ modification

What does evolution help you explain?

helps explain the differences and similarities and adaptations among life

What are the major points of evolution?

1. populations are the units of evolution
2. natural selection increases or decreases heritable traits that vary in population
3. descent w/ modification: accumulation of small changes over long periods of time

What are the assumptions of natural selection and why are they important?

individuals do not evolve, can amplify or diminish a trait, based on environment thus always working

What does descent with modification by natural selection explain?

it explains the adaptations of organisms and unity and diversity of life

What ideas pre-dated Darwin's theory?

1. Aristotle- "Great Chain of Being" , (scala nature), linear system, species fixed and unchanging
2. Traditional Judeo-Christian- species designed by God and therefore perfect
3. Carlos Linnaeus: Systema Naturae, binomial nomenclature, described life in a nested system grouped by similarities, classifying life revealed unchanging order of life created by the creator, adaptations evidence that creator designed each species for specific purposes

Who influenced Darwin's thought processes as he developed his theory? What were their ideas?

Malthus: "An Essay on the Principle of Population", population will outgrow food source
Lyell: uniformitarianism, processes operating in the past are still working today

What factors promote selection in populations?

inherited characteristics that enhance survival and reproduction in specific environments

How do we synthesize evolution today? What evidence do we have for its occurrence?

Evidence: Direct observation (antibiotic resistance), Homology, fossil record, biogeography

Aristotle

"Great chain of being", linear system

Linnaeus

showed nested groups to explain how God created each species for a specific purpose, system naturae, binomial nomenclature

fossil record

transitional fossil forms consistent with major branches of descent in tree of life, fossils in layers of sedimentary rock (strata)

strata

represent time

Cuvier

Catastrophism

Catastrophism

catastrophic events altered landscape and killed off life, repopulated by immigration from other areas

Lamarck

1st real theory on how life changes over time:
1. use and disuse
2. inheritance of acquired traits

uniformitarianism

processes operating in the past are happening now

Hutton

gradualism, changes occur through cumulative effect of slow but continuous processes

convergent evolution

unrelated species have similar structures

Wallace

came up with same ideas as Darwin

homologies

1. Homologous structures: similar structures in related organisms
2. Vestigial structures:remnant structures that were of some value to ancestors
3. Molecular homologies: similarity in amino acids among vertebrate hemoglobin
4. Analogous structures: similar structures in unrelated organisms (convergent evolution)

What is a population and how does it relate to evolution?

group of individuals in the same species that can interbreed and produce fertile offspring, population is the smallest unit of evolution

What is natural selection and how does it relate to evolution, populations, individuals in populations?

natural selection acts on phenotypes, indirectly adapts population by maintaining favorable genotypes in gene pool

What does heterozygous mean, homozygous mean? How do these words relate to the concepts of dominant and recessive alleles?

two different alleles (Ab), two same alleles (AA), can be dominant homozygous or recessive homozygous

What is the Hardy-Weinberg Equilibrium (conceptually) and what do its assumptions tell us about populations?

describes genetic makeup expected for a population that is not evolving at a particular locus, if population differs from assumptions they it may mean that the population is evolving, very rare

How does genetic variation manifest itself in populations and how might this impact evolution?

new genetic variations arise by chance, fitness, sexual selection, different modes of natural selection, beneficial alleles are sorted and favored, genetic drift and gene flow

Explain adaptive evolution.

evolution that results in the better match between organisms and their environment

What ensures genetic variation within populations?

sexual reproduction, shuffling via crossing over, independent assortment and fertilization

Why are there no perfect organisms?

environments are always changing, thus the traits are always changing to adapt best to each different environment

genetic drift

rand0m changes in gene frequencies of small populations from generation to generation, tends to reduce genetic variation through losses of alleles, ex. founders effect and bottleneck effect

Hardy-weinberg assumptions

no mutations
natural selection is not occurring
population is infinitely large
random mating
no gene flow

intersexual selection

mate choise, usually females are choosy selecting their mates

gene flow

migration, populations gain or lose alleles which reduce differences overtime, can increase fitness of a population

modes of selection

depends on which phenotypes are favored in a population
direction selection: favors single phenotype
disruptive selection: favors extremes
stabilizing selection: favors intermediates

heterozygous advantage

greater reproductive success of heterozygous individuals compared with homozygotes , tends to preserve variation in a gene pool

sexual selection

natural selection for mating success, may result in sexual dimorphism between males and females, intra and inter sexual selection

neutral variation

no adaptive value for one genotype over another

founder effect

a few individuals are isolated from a larger population

bottleneck effect

population undergoes drastic size reduction as a result of chance events

intrasexual selection

competition among individuals of one sex (usually males) for mates of opposite sex

Microevolution vs. Macroevolution

Micro: change of allele frequencies, driven by natural selection, gene flow and genetic drift
Macro: evolutionary change at or above species level over long periods of time

Explain the biological species concept. Correlate this with explanations of pre and post-zygotic barriers.

population or group populations whose members have potential to interbreed and produce fertile offspring, similarity b/w different species, diversity within a species (pre zygotic & post zygotic barriers)

What is speciation? Why does it occur? What factors are factors that are considered favorable and why?

origin of new species, can occur through allopatric speciation or sympatric speciation, factors are: abundant topographic features, bottlenecks, low dispersal rates, vacant niches and successful specialization

Explain the differences between allopatric speciation and sympatric speciation.

A/S: most common type, gene flow interrupted or reduced when population divided into geographically isolated subpopulations, reproductive isolation must occur
S/S: very rare, occurs in geographically overlapping populations, may occur by exploiting a new niche that reduces gene flow with individuals in original niche, implies spacial segregation doesn't occur but some type of reproductive barrier eliminates gene flow, gene flow may be reduced by sexual selection and habitat differentiation

What is adaptive radiation and how does it relate to speciation?

rapid and frequent allopatric speciation following geographic and reproductive isolation, creates new species quickly

How fast does speciation occur? Are there different explanations for the rates at which it occurs?

punctuated equilibrium or gradualism.

What are the consequences of speciation? Why are these important?

consequences are: more diversity, birth and extinction of species lineage

pre-zygotic barriers

impede mating or hindering fertilization, may be due to differences in habitat (spatial), temporal, or behavior breeding patterns, mechanical or gamete isolation

post-zygotic barriers

prevent hybrid zygote from developing into a viable fertile adult, reduced hybrid fertility: sterile offspring, hybrid breakdown: 1st generation fertile but subsequent generations fail

hybrid zones outcomes

region where closely related species meet, mate and produce offspring with mixed ancestry, hybrids result from mating between related species with incomplete reproductive barriers, OVERTIME reproductive barriers either then are reinforced (fewer hybrids), fusion (2 species fuse) or stability (continue hybrid reproduction)

reproductive isolation

key factor of speciation, block gene flow and limit hybrid formation, classified by whether factors take place before or after fertilization

similarity

species look identical but are distinct species as behavior prevents interbreeding

punctuated equilibrium

speciation takes place in short period of time followed by a long period of stasis

gradualism

species descended from a common ancestor and gradually diverge as unique adaptations are acquired

Did humans evolve from apes? Why or why not? Explain your answer.

it is possible because both groups share extinct common ancestor

What are some unifying traits of primates? Why are they important? Why might have been selected for?

grapsing hands, binocular vision, brain, rotating forearms,

What are the divisions among primates? How are they interrelated?

prosimians, anthropoids, hominoids,

Explain skeletal trends in hominids. Why are these trends important?

Detail, in order, the most important species in hominid evolution. Why was each one important?

What are the two models explaining the appearance and proliferation of Homo sapiens?

Archonta

diastema

prognathism

Primates

foramen magnum

multi-regional model

primate features

vertebral column

out of africa model

anthropoids

bipedalism

hominids