AP Bio Unit 7

Aristotle

Recognized variety in organism and inheritance

Great chain of being

Carolus Linnaeus

Swedish naturalist and father of taxonomy

Developed a classification system that was for “tree like” than a ladder

Thomas Malthus

British economist and demographer

“Struggle for existence”

Human population increases at a faster rate than out agriculture, therefore out food supply can run out

Darwin realized that same could be said for every species

Carrying Capacity

The population that an environment can support

When resources are plentiful, population can grow fast.. less competition

George Cuvier

Paleontologist

Helped prove extinction through his studies of fossils

Charles Lyell and James Hutton

Geologists

Theory of Uniformitarianism (Earth has always changed in uniform ways and that the present is the key to the past.)

Jean Baptiste de Lamarck

Developed a theory of evolution

1. Use and disuse

   1. The more the body part was used, the larger it got

2. Acquired Characteristics'

   1. Characteristics acquired during an organisms lifetime can be passed to their offspring

Charles Darwin

British naturalist

Traveled and collected data on the HMS Beagle for almost 5 years

Noticed “Artifical selection” in dogs, asked if it could be applied to nature

Alfred Russel Wallace

Sent an essay that aligned with Darwins work, about the theory of natural selection

Darwin’s Idea

Descent with modification

1. Members of a population often vary in their inherited traits

2. All species can produce more offspring than the environment can support, this creating competition

Survival of the fittest

Who is the ‘strongest’

the ones who produce the most sucessful offspring

Natural Selection

Process in which individuals that have certain heritable traits survive and reproduce at a higher rate than do other individuals because of those traits

Fossils

Only form under ideal conditions

Used to estimate age or organisms

Homologous structures

Structures that are structurally similar but serve different purposes

Indicates common ancestry

Ex: Human hand and bat wing

Vestigial Structures

Body part not used anymore but still remains in the organism

Ex: appendix

Analogous structures

Serve the same purpose but built differently

Do not indicate common ancestry

ex: wings of birds and insects

Embryological evidence

Similar structure on the embryos of all vertebrates

Some disappear

Ex. tail, gill slits

Biochemical evidence

Similarities in DNA sequences and amino acid sequences

Convergent evolution

Organisms evolve similar structures or similar adaptations to meet the same environmental challenges but do not share recent common ancestry

Instead they share analogous structures

Phylogeny

Evolutionary history of a species or group of species

ex. the evolutionary history of birds

A thing, not something you do

Systematics

The process of classifying things and figuring out their evolutionary history

Uses actual data, constantly changes based on new information

Taxonomy

Naming things and classifying things based on a set of characteristics

Binomial Nomenclature

Using a 2 part scientific name for every species

First part is the genus name

Second is the specific epithet

ex. Homo sapien

Hierarchical Classification

Domain

Kingdom

Phylum

Class

Order

Family

Genus

Species

Dumb King Phillip came over for great spaghetti

Taxon

Any named group at any level

ex. Kingdom - Animalia

Phylogenetic Trees

Branching diagram that:

Shows common ancestry

Displays differences

Matches taxonomy

New info may alter things

Branch point

Term used in phylogenetic trees

Common Ancestor

Sister taxa

Terms used in phylogenetic trees

Groups that share an immediate ancestor not shared by other groups

Basal taxon

Terms used in phylogenetic trees

Lineage that diverages from all the other groups early on

Data used to make phylogentic trees

Fossil records - youngest species are in the upper strata

Molecular homologies - compare amino acid and DNA sequences

Morphological homologies - homologous and vestigial structures

Cladistics

Way of determining phylogeny by looking at homologous structures

Based on: Common ancestry and shared characteristics

Clades

Includes a common ancestor and things descended from it

Like taxons, but a clade is monophyletic, not paraphyletic or polyphyletic

Monophyletic

An ancestral species and all of its descendants

Matches

Paraphyletic

Ancestral species and some descendants

Doesn’t match

Polyphyletic

Has several species but not the ancestor

Doesn’t match

Shared primitive character

A character that extends beyond the taxon you are defining

Shared derived character

Evolutionary novelty unique to a clade

Branch length

The longer the branch, the longer the species has been around

Molecular Clocks

Trying to measure the absolute time of evolutionary change

Microevolution

A change in the genetic makeup of a population from generation to generation

What causes variation?

Mutations - most nucleotide changes do not have an effect on phenotype

Sexual reproduction

Chromosomal changes

The environment

Population

Localized group of individuals that are capable of interbreeding and production fertile offspring

Species

Groups of populations whose members have the potential to interbreed and produce fertile offspring but are unable to do so with other populations

Gene pool

The total of all alleles of all the genes in a population at a given time

Fixed allele

Only one allele for a gene

No variation among members of a population with that gene

Hardy-Weinberg Equilibrium

If the frequencies of alleles and genotypes doesn’t change from generation to generation, then it is in equilibrium and is not evolving

If it does change, then the population is evolving

Hardy-Weinburg Conditions that must be met

Large population

No gene flow

No mutations

Random Mating

No natural selection

Genetic drift

Change in gene pool due to luck or chance

Bottleneck effect

When lots of members die and the surviving population is no longer representative of original population

Founders effect

When some individuals become isolated from the larger population

Leads to inbreeding

Genetic Drift

More likely in smaller populations

Can cause allelic frequency to change randomly

Loss of variation

Gene flow

The transfer of alleles into or out of a population

Usually reduces differences between populations

Natural selection

Some members of a population have more reproductive success than others

Because genes better match the environment

Relative fitness

Contribution of a genotype to the next generation compared to another genotype

Sterile organisms - zero relative fitness

Directional Selection

Favors one extreme for a phenotype

Usually occurs when environment changes or populations move

Distruptive selection

When conditions favor both extremes

Usually leads to new species

Stabilizing selection

Acts against extremes and favors the average individual

Balancing selection

When natural selection maintains stable frequencies for 2 or more phenotypic forms in a population

Macroevolution

Changes above the species level

Speciation

Formation of a new species

Morphological Species concept

Characterizes species by body characteristics

Con: Analogous structures and convergent evolution

Paleontological Species concept

Focuses on fossil record

Con: They’re all dead

Ecological Species concept

Focuses on a species niche

Niche - the role or job a species has in a community

Cons: Assumptions get made, difficult to define a species niche

Phylogenetic Species approach

Each species has a unique genetic history by comparing physical and molecular differences

Cons: Genetic differences are a difficult way to separate species

Biological Species approach

Members of the same species have to be able to interbreed and produce fertile offspring

Cons: extinct species

Reproductive Isolation

Produces new species

Many types that fall into one of two categories

Prezygotic Reproductive Isolation

Keeps two things from mating

Postzygotic Reproductive Isolation

Keeps offspring from mating

Habitat Isolation

Two different species occupy different geographical areas

Temporal Isolation

Species breed at different times

ex. day, year, dif plants bloom at dif times of the year

Behavioral Isolation

Courtship rituals are unique to a species

ex. bird mating calls

Mechanical Isolation

Morpholgical differences prevents mating

ex. plants with different pollinators

Gametic Isolation

Sperm cannot fertilize egg

Reduced hybrid viability

Genes of different parent species may interact and impair hybrid’s development

Hybrids are sterile

Meiosis fails becuase of different chromosome structure or number

Hybrid Breakdown

Hybrids are fertile but when they reproduce their offspring are weak

Allopatric Speciation

When population is divided into geographically isolated populations

Sympatric Speciation

Speciation that occurs when populations overlap

Due to chromosomal changes and non-random mating

Hybrid zone

Two species interbreed and produce fertile offspring

Gradualism

Gradual changes lead to new species at regular intervals

Punctuated Equilibrium

Period of stasis interrupted by periods of rapid change

Majority of changes occur at the start

Stage 1

Where did the first cells come from

Abiotic synthesis of organic molecules

Amino acids and nucleotides

Stage 2

Where did the first cells come from

The building of polymers from monomers

Polymers have been produced by dropping monomers onto hot clay, sand, rock

Stage 3

Where did the first cells come from

Protocells - packaging polymers into membrane bound structures that maintain internal chemistry

Stage 4

Where did the first cells come from

Origin of self-replicating molecules, making inheritance possible

Early earth’s atmosphere

Electron adding

Water vapor, CO2, nitrogen, methane, ammonia

Oceans were a ‘primitive soup’ of organic molecules

Stanley Miller and Harold Urey Expirement

Proved that energy could create monomers

Other hypothesis on how monomers were created

Volcanic eruptions

From Space - meteorites

Thermal vents and submerged volcanoes

Started in ice - eutectic freezing made it possible

Protocells

Aggregates of abiotically produced molecules surrounded by a membrane or

membrane-like structure

Ribozymes

RNA molecules with catalytic capabilities

Self-splicing and replication

Transports molecules

Relative dating

Fossils buried deeper are older

Can compare strata across continents

3.5 - 3.9 Billion Years ago (BYA)

Life begins

3.5 - 2.0 BYA

Prokaryotes dominated Earth

2.7 BYA

oxygen accumulates

Indicates photosynthesis

2.1 BYA

Eukaryotes

Endosymbiant

A cell that lives inside a host cell

1.2 BYA

Multicellularity - the first multicellular organisms began as colonies

543 MYA

The Cambrain Explosion

Huge diversification of animals

500 MYA

Colozination of land

Needed to prevent dehydration

Adaptive Radiation

Periods of change in which many new species form from one species

Molecular changes

Small changes in DNA may lead to big changes