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• Study Guide: Evolution, Natural Selection, and Antibiotic Resistance

MRSA and Antibiotic Resistance

• Methicillin-Resistant Staphylococcus aureus (MRSA) is difficult to eradicate and prevalent in communal environments, treat with vancomycin instead of methicillin.
• A red halo indicates an inflammatory response and the body's process of differentiating self from non-self.
• Colonization occurs when an individual carries a strain of staph without being infected by it.
• Antibiotics can be evaded by bacteria through mutations or gene transfer, interfering with bacterial cell structures.
• Antibiotic resistance can be caused by ending treatment early because incomplete treatment wipes out the weaker bacteria but not the more resistant bacteria.
• Beta-lactam antibiotics, which target bacteria cell walls, can be rendered ineffective by beta-lactamases (enzymes produced by some bacteria).
• Compared to bacterial evolution, human evolution proceeds at a significantly slower pace.

Principles of Natural Selection

• Traits that increase reproductive success are favored by natural selection, leading the possessors of those characteristics to produce more offspring.
• Natural selection acts on populations, based on existing variability; there is no intentional generation of new characteristics.
• A population is a group of similar individuals inhabiting the same geographical area at the same time.

Three Types of Selection

• Stabilizing Selection favors the average trait, resulting in greater reproductive success within the middle range of traits.
• Directional Selection favors one extreme, pushing the population towards one end of the spectrum.
• Disruptive Selection favors both extremes, potentially leading to speciation, creating a bimodal distribution.
• Survival of the Fittest favors offspring with inheritable traits that enhance survival.
• Biological Fitness encompasses an individual's or group's ability to survive and reproduce under specific environmental conditions.

Genetic Diversity & Evolution

• Genetic diversity arises from mutations each time a cell divides; DNA polymerase errors occur creating more genetic diversity within a population.
• Daughter cells are not identical due to typographical errors; offspring lack an exact copy of parent cells.
• Genetic diversity results from the accumulation of mutations and the reorganization of genetic material.

• Mutations naturally occur and increase diversity.
• Sexual reproduction increases genetic variation.
• Microevolution involves small genetic changes within a population, such as eye color, skin, or hair.
• Macroevolution involves large-scale changes that can lead to new species
• The gene pool is the total collection of genes in a population at any one time.
• Biogeography is the study of how species are distributed across the planet.

Speciation & Reproductive Barriers

• A species is generally defined as a group capable of interbreeding and producing fertile offspring, often distinguished by anatomical or genetic differences.
• Biological species concept defines a species as a group of populations with the potential to interbreed and produce fertile offspring in nature.
• Reproductive barriers prevent interbreeding:
• Temporal Isolation occurs when species breed at different times.
• Behavioral Isolation occurs when species have different mating behaviors.

Hardy-Weinberg & Genetic Drift

• Hardy-Weinberg Principle is used to study population genetics: the genetic variation in a population remains constant from one generation to the next in the absence of disturbing factors.
• The founder effect describes the lack of genetic diversity that can occur when members of a small population leave one location and establish a new location.
• Bottleneck effect occurs when a population is drastically reduced, some alleles are lost, and genetic diversity is lower.

Fossils & Evolutionary Evidence

• Fossils provide evidence of macroevolution.
• Homology: similar structures from a common ancestor.
• Convergent evolution is when different organisms develop similar traits because they live in similar environments or face the same challenges.
• Analogous Traits result due to convergent evolution: traits that are similar even though there is no structural similarity.
• Homologous structures have different functions, but similar structures because they are from a common ancestor.
• Radiometric Dating uses isotope decay to determine the age of fossils/rocks.
• Uranium lead method dates rocks by looking at uranium turning into lead over time.
• Tiktaalik is a transitional fossil showing the shift from fish to land-dwelling vertebrates.

Mass Extinctions & Adaptive Radiation

• Mass extinctions often lead to rapid diversification, major events occurred at the end of the Permian and Cretaceous periods.
• The Cambrian explosion marks a sudden increase in animal life diversity as complex organisms evolved.
• Adaptive radiation occurs when organisms evolve to fill ecological niches, species can turn into multiple different species.
• Occurs in new or vacated place after a mass extinction.

Miller-Urey Experiment

• The Miller-Urey Experiment demonstrated that organic molecules could form from inorganic compounds.
• Inputs were water, ammonia, and methane.
• Outputs included amino acids and biomolecules.

Taxonomy & Evolutionary Relationships

• Phylogeny is the actual evolutionary history of organisms.
• Phylogenetic Trees show evolutionary relationships.
• Branch: when natural selection leads to new species or groups.
• Root: the common ancestor of all organisms on the tree.
• Node: the last common ancestor of the organisms that are above this point in a tree.
• Three Domains of Life: Bacteria, Archaea, Eukarya.
• Five Kingdoms: Animal, plant, fungi, protist, monera.

Darwin and others

• Darwin is associated with evolution, but did not invent it, he did sail on the HMS beagle and write a book.
• Descent of modification is one species transforming over time; all living things are related and that the different species emerged over time as a result of natural selection operating over millions of years.
• Darwin theorized natural selection.
• Thomas Malthus (population growth) and Charles Lyell (geological changes over time) influenced Darwin's thinking.
• Alfred Wallace wrote "On the Origin of Species on the Means of Natural Selection," and called it Darwinism; is also responsible for the modern day definition of species.

Random Textbook Stuff

• Plate Tectonics: continents sit atop earth's mantle and move around to cause heat convection currents.
• Taxonomic ranks go: Domain, supergroup, kingdom, phylum, class, order, family, genus, species.
• Vertebrates: animals with a rigid backbone.
• Mammals: possess mammary glands and a hairy body.
• Continental Drift: describes continent movement.
• Sedimentary rocks: from sand and dust compaction.
• Igneous rocks: formed by volcanic eruptions.
• Solar System Theory: planets spring from a swirling solar nebula.
• Vestigial structures are inherited from ancestors, no longer serve a purpose.

Exam Revision Questions

Populations do not evolve on purpose because it is not linear; trends reflect selection forces.

• Darwin's theory of evolution is the foundation for modern evolution.
• Darwin coined "descent of modification," implying a single species evolves over time into new species.
• Natural versus artificial selection is the difference between traits that provide animals to survive and reproduce versus selection via breeding.
• Fossils show changes over time, extinct species, homologous structures, and dating; thus, evidence that supports evolution. Species distribution is biogeography, body structure comparisons is comparative anatomy, comparing DNA and other molecules is molecular biology
• Natural selection can be witnessed via antibiotic resistance, pesticide resistance, and other lifespan changes. Individuals do not evolve; populations evolve through genetic changes; the future generations favor the better traits.
• Genetic drift occurs when a allele in population change, which will cause genetic diversity.
• Gene flow causes the evolution between one population to another, which will cause genetic disversity.
• Genetic bottlenecks reduce a population's genetic diversity which is key for long term survival and health.
• Physical variation arises from genetics and inherited traits, as well as environmental differences that impact survival and reproduction.
• Evolutionary fitness is the ability to survive and reproduce.
• Natural selection changes stabilizing, directional, or disruptive factors for one population in particular. _ While it would seem that organisms are perfectly adapted for their environment, does natural selection is still random and creates imperfect organisms.
• Speciation occurs when a group can interbreed producing fertile offspring.
• Species is biological versus morphological groupings by potential to interbreed and using physical structure to define species.
• The fossil that showed the relationship between land and water was the Tiktaalik.
• Microevolution is in reference to changes in hair or eye color, but macroevolution refers to large changes creating new species.
• Analogous structures are a result of convergent evolution and happens because of similar environments.
• A strong selection force that shapes the population is sexual selection based on mating success.
• The rate for evolution can occur due to environmental changes, mutations, natural selection, and genetic dirft, it is influenced by the frequency and intensity of selective pressures,.
• Continental drift has affected distributions of plant and animals over time due to the movement of the continents.
• After a mass extinction, species will explode to diversify due to less compettion.