Biological Evolution: Macro and Micro

• Biological evolution involves the mutation of genetic material across generations.
• Evolution is observable when mutations in an organism's genotype are expressed through its phenotype.
• Evolutionary change is occurring today and can be observed in the development of antibiotic resistance in bacteria.
• Evolutionary theory is supported by fossil records, biochemistry, and naturalistic observations.
• Biological evolution helps in understanding the living world and our species and explains patterns in fossils contained in rocks.
• Biological evolution tells us that all life is related and descended from a common ancestor.
• Descent with modification is the central concept of evolution.
• It is understood through adaptation to the environment; traits are inherited through natural processes.

Macroevolution and Microevolution

• Macroevolution is how species evolve over time, evidenced by fossils.
• Microevolution involves changes in gene frequency on a small scale.
• Macroevolution can be considered the accumulation of microevolutionary changes.

Systematics: Organizing Life

• Systematics involves classifying organisms into nested hierarchies, with Kingdoms being the most inclusive category.
• Kingdoms are divided into Phyla, Classes, Orders, Families, Genus, and Species.
• Carl Woese added the Domain as a higher taxonomic rank due to the discovery of three distinct forms of RNA.
• Classification relies on shared characteristics to create descriptive names and organize organisms into groups.
• Carl von Linné simplified and unified taxonomy by introducing the system of binomial nomenclature.

Lamarckism and Evolutionary Foundations

• Jean-Baptiste Lamarck suggested that parents could pass on traits or behaviors acquired during their lifetime through use or disuse.
• Lamarck thought evolution trended from simple to complex forms, believing in spontaneous generation.

Revolutionary Ideas: Darwin and Wallace

• Charles Darwin and Alfred Russel Wallace discovered natural selection, a process where traits give an organism advantages or disadvantages.
• Darwin's observations of finches in the Galapagos Islands, noting different species in similar environments, played an important role in forming the theory of evolution
• Darwin's voyage on the H.M.S. Beagle allowed him to collect diverse specimens and fossils, leading to his theories of natural selection.
• Wallace's field work revealed that closely related species live close to one another and identified the "Wallace Line" that separates Asian and Australasian species in the Sunda Straits.
• Natural Selection is the mechanism that makes survival to the next generation possible, favoring organisms with enough favorable characteristics to pass on their genes.

Mendelian Inheritance and Genetics Take Shape

• Gregor Mendel's work with pea plants established the foundation for understanding inheritance.
• Mendel's work demonstrated how traits are passed down and applied statistics to predict inherited traits, bolstering natural selection with genetics.
• Genes come in two forms called alleles (“Law of Segregation”).
• Alleles can be dominant (expressed in an organism’s appearance) and recessive (not expressed).
• The selection of one allele of a gene over another occurs independently of selection occurring among other genes (“Law of Independent Assortment”).

Mutation, Migration, Drift, and Natural Selection

• Key processes driving evolutionary change are genetic mutation, gene migration, genetic drift, horizontal gene transfer, and natural selection.
• Genetic mutations are changes in DNA sequences caused by errors in replication or repair.
• Gene migration introduces new genetic material into a population through sexually reproducing individuals from separate populations.
• Genetic drift results from chance events, where some individuals leave behind more offspring than others, independent of environmental changes.
• Horizontal gene transfer occurs through viral transfer (transduction), plasmids (transformation), or direct contact between cells (conjugation).
• Natural selection requires genetic variation, heredity, and differential reproduction within a population.

Forms of Natural Selection

• Sexual selection involves species using physical features or prowess to attract mates and pass on their genetic material.
• Artificial selection involves humans selecting favorable attributes in organisms, such as corn, for agriculture.
• Coevolution involves two or more species affecting one another's evolutionary trajectory through ecological relationships.

A Word About “Fitness”

• Fitness depends on being "good enough" for current environmental conditions, not individual will.
• Adaptations are features that improve function in an environment through natural selection.
• Vestigial structures are non-functional adaptations left over from an ancestor.
• Exaptations are features with a former adaptive purpose but are now used differently.
• Maladaptive traits harm a species' fitness.

Modern Evolutionary Theory: “the Modern Synthesis”

• The Modern Synthesis combines Darwinian ideas with Mendel's genetics.
• It integrates macroevolutionary changes seen in the fossil record with microevolutionary changes observed in nature and laboratories.
• Neo-Darwinian evolutionary theory involves integrating new fields and discoveries into a unified model.