Taxonomy and Classification

• Taxonomy originally relied on physical and behavioral characteristics to group organisms.
• Modern classification uses DNA and biochemistry to classify organisms based on evolutionary relatedness.
• Classifying organisms based on evolutionary relatedness can help determine the last time they shared a common ancestor.

Characteristics Scientists Evaluate

• Genetic (DNA)
• Biochemical (proteins and other molecules)
• Cytological (cell types like prokaryote or eukaryote, single vs multicellular)
• Embryological
• Behavioral
• Physical/Structural (Morphology)

Binomial Nomenclature

• An organism's full Binomial name is made up of the Genus name and the species.
• Scientific names are written in italics.
• In handwriting they are cursive or underlined.
• The Genus name is capitalized
• The species is lower-case.
• Human's scientific name is Homo sapiens.

Taxonomic Hierarchy

• Domain is the broadest and most inclusive classification.
• Species is the most specific and least inclusive classification.
• The order of classification is: Domain → Kingdom → Phylum → Class → Order → Family → Genus → Species.
• Organisms in the same species share the most characteristics.
• Organisms in the same domain share the least characteristics.

Key Points

• Eubacteria and Archaebacteria are prokaryotic and unicellular.
• Organisms in all other kingdoms are made of eukaryotic cells and are in Domain Eukarya.
• Protists are mostly single-celled organisms.

Cladograms

• A derived character is one that evolved directly from the ancestor, that will be passed on through all descendants
• Cladograms show when species shared common ancestors and relative time passed since they evolved.
• Comparing DNA is the most accurate way to construct a cladogram.
• Each branch represents an evolutionary lineage of organisms.
• A node represents the ancestral organism that existed before the split into different lines.
• Example: Four walking limbs are present in the salamander, turtle and leopard, while hair present only in mammals.

Darwin's Influences

• Malthus: Populations have more individuals than can survive.
• Lamarck: Traits acquired during an individual's lifetime are passed to offspring (incorrect).
• Lyell and Hutton: Earth changes over time and is much older than 6000 years.
• Alfred Wallace was also ready to publish his own writings about Natural Selection.

Genetics

• Darwin did not know about genetics or Mendel's work.
• Traits are caused by genes (DNA) and are inherited, contradicting Lamarck.
• Giraffes with longer necks survived and reproduced more, shifting the population over time.

Darwin's Observations

• Species vary temporally, sharing traits with present-day organisms, implying relatedness.
• Species vary globally, with similar adaptations in similar environments, indicating unique organisms.
• Species vary locally on island groups, originating from a common species and adapting to different niches: living close doesnt mean same species.

Principles of Natural Selection

• More individuals are born than can survive due to competition.
• Individuals in a population have different trait versions (alleles).
• Traits must be controlled by genes/DNA to be passed on.
• Fitness depends on trait versions, allowing individuals to survive and reproduce.

Key Notes

• Variation must be present and heritable.
• Populations evolve, individuals do not adapt
• Reproduction is essential for fitness.

Adaptations

• Adaptations are heritable traits increasing an organism's fitness in its environment.
• DNA determines traits, with different alleles determining different versions.
• Genetic diversity arises from mutations, chromosomal changes, and sexual reproduction.

Adaptations

• Camouflage helps organisms hide from predators by blending in.
• Mimicry involves pretending to be something dangerous for defense.
• Beak shape in Galapagos finches is an adaptation for specific food source.

Species and Adaptations

• Variation is critical for survival; if no variation, there may be no favorable adaptations.
• Random DNA mutations, gene duplication, and chromosomal translocations.
• Random events during meiosis result in genetic variation between gametes.

Genetic Definitions

• "Selected against" traits are not surviving and reproduction.
• "Selected for" traits are beneficial for survival and reproduction.
• Diversity in alleles is caused by variations in DNA sequences.
• Allele frequency is the proportion of one allele compared to the total number of alleles in a population.

Hardy-Weinberg Equations

• Used to determine allele or genotype frequency.
• Genetic equilibrium means no change in allele frequency over time.
• Opposite of evolution is to look at the 5 mechanisms of evolution.

Genetic Drift

• Random events change allele frequencies, impacting small populations more.
• Genetic drift leads to loss of alleles and/or fixation.
• Bottleneck and Founder effects reduce population size, altering allele frequencies by chance.

Evolution Mechanisms

• There are five things that can cause evolution to occur
• If ANY of these are occuring then evolution is happening
• If NONE of these are happening, the population is in genetic equilibrium.

Speciation

• Can occur when gene pools separate and genetic changes occur differently.
• If enough changes accumulate, two separate species may emerge.

Steps of Speciation

• Reproductive isolation divides gene pools
• No interbreeding occurs in the seperate gene pools
• Genetic drift causes divergence
• Over time two different species can emerge

Reproductive Isolation

• Reproductive isolation can be geographic, temporal, behavioral, anatomical/mechanical, or genetic.
• Allopatric speciation involves geographic isolation.
• Sympatric speciation does not involve geographic isolation.

Divergent Evolution (adaptive radiation)

• Many species evolve from a common ancestor.
• Adaptive radiation can cause species to become stronger.

Convergent Evolution

• When separate species evolve to have similar traits
• Traits were not present in their common ancestors and evolved later

Coevolution

• When species interact with each other, they evolve together
• Examples are: Plant pollinators, birds, and seeds

Concepts of Evolution

• Homologous structures are built similarly among different species but have different functions and indicates a common ancestor.
• Analogous structures have similar functions but are not built the same way and evolved independently.
• Vestigial structuresresult from a common ancestor but no longer used for much in that organism.

DNA Evidence and Evolution

• DNA sequences can determine relatedness; more similar sequences indicate more recent common ancestor.
• When comparing DNA sequences it will be seen that humans are more genetically similar to chimpanzees and more distantly related to gorillas.

Endosymbiotic Theory

• Symbiosis evolved between eukaryotic cells and prokaryotic cells.
• Mitochondria and chloroplasts have DNA similar to bacteria, double membranes, and divide by fission.

Evidences

• Homologous/vestigial structures and fossil records suggest how species evolved.
• Similar embryos indicate similar genes and molecular comparisons show relatedness through DNA.

General Order of Life Forms

• Anaerobic prokaryotes.
• Aerobic photosynthetic prokaryotes.
• Single-celled eukaryotes.
• Multicellular eukaryotic life.

Directional Evolution

• Evolution is not predetermined.
• Bacteria evolving antibiotic resistance.
• Pests evolving pesticide resistance.
• Loss of species due to lack of genetic diversity.

Populations

• Populations evolve, individuals do not.
• In regards to genetic adaptation it is the population, in general, that adapts over time and not the individuals.