prac 1

Scientific Method

1. Ask a question

2. Background research

3. Formulate a hypothesis

4. Test hypothesis

5. Analyze results and draw conclusions

6. Publish results

Hypothesis

Educated guesses, can be tested, data can support or not support the hypothesis

Independent variable

Variable tested/manipulated

Dependent variable

Measurable outcome/responding variable

Lines of evidence for macroevolution

1. Fossil record

2. Molecular sequence data

3. Structure homology

4. Developmental similarities

5. Vestigial structures

6. Convergent evolution

7. Patterns of distribution

Fossil types

1. Impression (no organic matter preserved)

2. Compression (some organic matter preserved)

3. Petrification (plant tissue replaced with minerals)

4. Amber (preservation with fossilize plant sap)

Three domains of life

Eukarya, bacteria, archaea

Where are fossils located?

Sedimentary rocks

How old is Earth?

4.6 billion years old

Synapomorphy

Shared-derived-shape

How is the time scale broken down?

Eons, Eras, Periods, and Epochs

What causes a new Era to start?

A major extinction event

What era are we currently in?

The Cenozoic Era

What epoch are we in?

The Holocene epoch

What happened during the Permian Period?

A major extinction event 251 MYA

What happened during the Cretaceous Period?

All the dinosaurs died 65.5 MYA

What era did the dinosaurs live in?

Mesozoic

What are the eras in order of time?

Haden, Archaen, Proterozoic, Paleozoic, Mesozoic, Cenozoic

What is the new epoch humans are considered to be in?

Anthropocene

When did cyanobacteria appear on Earth?

3.5 billion years ago

When did earthworms appear on Earth?

200 million - 145 million years ago

When did coral appear on Earth?

488 million years ago

When did trees appear on Earth?

416 - 354 million years ago

When did the switch from gymnosperms to angiosperms occur?

135 million years ago

Cladogram/Phylogenic Tree

Depicts evolutionary relationships among different taxa, evolutionary hypothesis

Taxa

A group of one or more populations of an organism, species, genus, order, etc.

Synapomorphies

Shared derived characteristics present in ancestral species, shared exclusively

Character matrix

Chart to show different taxa and different synapomorphies (characters), use information to build a cladogram

Parsimony

Simplest scientific explanation that fits data is the BEST explanation

Monophyletic group

Common ancestor and ALL descendants

Paraphyletic group

Common ancestor and SOME descendants; not evolutionary meaningful

What does a branch on a cladogram signify?

It signifies each taxon as they branch off from the node

What does a node signify?

A common ancestor

Hierarchical classification system?

Domain, kingdom, phylum, class, order, family, genus, species

When did Homo Sapiens first appear?

0.16 mya

When did Homo Neanderthalensis first appear?

600,000 years ago

When did Homo Ergaster/Erectus first appear?

2 mya

When did Lucy first appear?

3.2 mya

Early evolving homonid traits

Had features such as prominent brow ridge, sagittal crest, forehead slopes back, facial prognathism (facial bones project forward), foramen magnum in rear of skull, small cranial capacity

Modern hominid traits

No brow ridge, no sagittal crest, vertical forehead, no prognathism, central foramen magnum, large cranial capacity

Gene

Structural unit of hereditary information in the form of DNA nucleotide sequences

Allele

Alternative forms of a gene

Locus

Specific place along a chromosome where a given gene is located

Autosomal allele

Allele located on a non-sex chromosome

Genotype

An individual's inheritable genetic makeup

Heterozygous

Possessing two different alleles for a given biallelic gene

Homozygous

Possessing two of the same alleles for a given biallelic gene

Phenotype

The observed characteristics and traits, influenced by the genotype and the environment

Incomplete Dominance

When the phenotype of the heterozygous is an intermediate between the homozygous dominant and homozygous recessive (AA = red, aa = white, Aa = pink)

Complete dominance

When the homozygous dominant and heterozygous genotype produce the same phenotype; from complete dominance from dominant allele (AA = red, aa = white, Aa = red)

19th Century Evolution Scientist

Charles Darwin

Evolution

Changes in relative frequencies of alleles in a population's gene pool over time

Gene pool

Collection in relative frequencies of alleles in a population's gene pool over time

What is the Hardy-Weinberg Principle?

Makes 5 assumptions when NO evolution occurs in a population; NO evolution means genotype and allele frequencies are maintained in a population over time

Hardy-Weinberg assumptions?

1. No mutation

2. No migration

3. No natural selection

4. No impact from genetic drift (large population size)

5. Random mating

**Under these conditions, allele and genotype frequencies will remain constant across generations aka maintaining an equilibrium

Why is Hardy-Weinberg important?

It is how we detect change

What happens when the conditions of the HW Principle are not met?

Evolution has occurred

Allele frequency calculations

Frequency of A (dominant) allele = p

Frequency of a (recessive) allele = q

p + q = 1

Genotype frequency calculations

use p and q (allele frequencies)

Frequency of AA genotype = p^2

Frequency of Aa genotype = 2pq

Frequency of aa genotype = q^2

p^2 + 2pq + q^2 = 1

If population is in HW equilibrium, no evolution is occurring, so you can calculate the _________

expected genotype for the next generation

Mutations

Biochemical changes in the genetic material of the organism

Gene flow

The emigration or immigration of genes out of or into the population

Genetic drift

When unpredictable variations change the structure of the gene pool

Natural selection

When a particular phenotype has a greater (or lesser) reproductive success than an alternative phenotype.

Allelic frequencies are impacted by _____, ______, and _______

Natural selection, genetic drift, and migration

If a population is in HW equilibrium, genotype frequencies depend on _____________

Allele frequencies

Populations that are endangered should be worried about ____________

Genetic drift (due to small pop. size)

On an island, a new predator is introduced. Prey on the island should be worried about ____________

Natural selection

How to calculate total magnification

Ocular (10x) x Objective Lens