Bio Final

Who was Jean-Baptiste de Lamarck?

First scientist to propose species change over time with a mechanism

Lamarck’s two principles

• Use and disuse

• Inheritance of acquired characteristics

Why was Lamarck wrong?

Traits acquired during life are NOT genetically inherited

What were early beliefs about species?

• Species are fixed

• Designed for a purpose

Who was Charles Darwin?

Scientist who proposed natural selection

What voyage shaped Darwin’s ideas?

HMS Beagle (5-year journey)

Observations from South America

• Fossils resemble living species

• Marine fossils on mountains

• Species match environment

Why are the Galápagos Islands important?

• Unique (endemic) species

• Similar to mainland species

What did finches demonstrate?

 Adaptation to environment (beak differences)

What is the Tree of Life?

All organisms share a common ancestor

Define evolution

Change in allele frequency over time

Define adaptation

Trait that increases survival & reproduction

Define natural selection

Individuals with beneficial traits reproduce more

Define fitness

Reproductive success

darwin Observations

-Variation
-Overproduction of offspring

darwin Inferences

-Better traits → more survival/reproduction
-Traits accumulate over generations

What is a gene pool?

All alleles in a population

gene

dna

allele

type of gene

Define population

Same species in same area that interbreed

Community

multiple species (living)

ecosystem

living + nonliving

genetic variation

differences in DNA

evolution needs

genetic variation

3 types of variation

• mutation

• gene duplication

• sexual reproduction

microevolution

change in allele frequency in population

Mutation

Random DNA change

Genetic drift

Random allele change

Gene flow

Movement of alleles between populations

Sexual selection

Traits increase mating success

Founder effect

 Small group forms new population

Bottleneck effect

Population shrinks → variation lost

stabilizing selection

• favors average

• lower variation

• mean constant

Directional selection

• favors one extreme

• mean shifts

Disruptive selection

• Favors both extremes

• Variation ↑

Hardy-Weinberg equation

p2+2pq+q2=1

What is 2pq?

Heterozygotes

What does p + q = 1 mean?

Total allele frequency = 100%

5 conditions for equilibrium

• No mutation

• No selection

• Large population

• No gene flow

• Random mating

r-strategy traits

• Many offspring

• Low survival

• Unstable environment 

K-strategy traits

• Few offspring

• High parental care

• Stable environment 

speciation

one species splits into two

macroevolution

evolution above species level

Biological Species Concept (BSC)

interbreed and produce viable, fertile offspring

biological species concept requirement

reproductive isolation/no gene flow

Morphologicla species concept

defined by physical traits

morphological species concept used for:

• fossils

• asexual organisms

Lineage species concept

smallest branch on phylogenetic tree

reproductive isolation

cant interbreed

habitat isolation

species live in diff enviornments; prezygotic

temporal isolation

breed at different times; prezygotic

behavioral isolation

different mating behaviors; prezygotic

mechanical isolation

physical imcompatibility

gametic isolation

gametes cant fuse

reduced hybrid viability

hybrid doesnt form well; postzygotic

reduced hybrid fertility

hybrid sterile; post zygotic

hybrid breakdown

offspring weak; post zygotic

Biological species concept limits

• fossils

• asexual

• hybrids

Allopatric speciation

Geographic separation

1. isolate

2. mutate

3. selection

4. reproductive isolation

Sympatric speciation

Occurs in same geographic area

1. polyploidy

2. habitat differentiation

3. sexual selection

polyploidy

cells contain more than two complete sets of chromosomes; reproductive imcompabibility

habitat differentiation

different resource use

sexual selection

mate preference

Adaptive radiation

Rapid formation of many species

• new niches

• extinction

• new traits

Punctuated equilibrium

rapid evolution then stability continusly

Extinction

All members of species die

radiometric dating

Uses radioactive decay to determine absolute age

Krakatau effect

lowered temp 1.2 Celcius

crataceous extinction

asteroid impact

What caused oxygen buildup?

Photosynthetic prokaryotes

When did life first appear?

3.8 billion years ago

stromatolites

Layered rock structures formed by prokaryotes

when did eukaryotes appear

1.5 billion years ago

endosymbiont theory

chlorophylls engulfed prokaryotes → became organelles

when was multicellularity

1.3 billion years ago

what limited multicellularity

global ice age

Cambrian Explosion

• 535-525 Million years ago

• Rapid diversification of animal phyla

• dinosaurs extinct

65.5 MYBP

basal taxon

Lineage that diverged earliest

polytomy

Unresolved evolutionary relationship

clade

Common ancestor + ALL descendants

systematics

Study/classification of biodiversity

homologous trait

Trait shared due to common ancestry

homology

Similarity from shared ancestry

plesiomorphy

Ancestral trait

apomorphy

Derived trait

synapomorphy

Shared derived trait

autapomorphy

Derived trait unique to one taxon

convergent evolution

Independent evolution of similar traits

Divergent evolution

from one common ancestor diverge

analogous structures

Same function, different origin

homoplasies

Similar traits NOT from common ancestry

evolutionary reversal

Derived trait → ancestral trait

Paraphyletic

Missing some descendants

Principle of parsimony

Simplest explanation is most likely

Order of classification

Domain → Kingdom → Phylum → Class → Order → Family → Genus → Species

symbiosis

Close interaction between different species (“living together”)

Mutualism

+/+ both species benefit

Commensalism

+/0 one benefits, other unaffected