Understanding Evolution: Key Concepts and Processes
Understanding Evolution: Key Concepts
- Definition of Evolution: Change over time.
- Definition of Biological Evolution: Change in the genetic makeup of a population from generation to generation.
- Darwin’s Theory of Evolution by Natural Selection: Influenced by Wallace, Darwin published On the Origin of Species in 1859, laying out his theory of natural selection and providing significant evidence to support it.
- Definition of Gene Pool: The sum of all of the genetic information of all of the members of a population.
- Definition of Mutation: Change in the DNA sequence.
- Definition of Gene Flow: The movement of genes from one population to another.
- Definition of Genetic Drift: A random process that removes alleles from the population, usually through random deaths.
- Definition of Population Bottleneck: Occurs when a population is drastically reduced in number, resulting in very low genetic diversity.
- Definition of Founder Effect: The reduced genetic diversity that results when a population is descended from a small number of colonizing ancestors.
- How Natural Selection Causes Populations to Evolve (Example): The environment selects which traits will give an individual an advantage, increasing its chance of reproducing. Individuals pass these beneficial traits to the next generation, increasing their chance of reproducing.
- Definition of Adaptation: The population becomes better matched to its environment. Different environments select for different traits.
- Definition of Fitness: If you can survive long enough and gather enough resources to have offspring, then you are fit.
- Directional Selection: Individuals at one extreme of a range of phenotypes have an advantage over all other phenotypes and are more likely to reproduce.
- Stabilizing Selection: Individuals with intermediate phenotypes within the range have an advantage. Individuals not within this intermediate range tend to be selected against.
- Disruptive Selection: Individuals at either end of a phenotypic range have an advantage, while individuals in the middle are selected against.
- Fossils as Evidence for Evolution: Fossils preserve the evidence of change.
- Embryo Development as Evidence for Evolution: Embryology is the study of the developing embryo. Related organisms have similar embryos. The more closely related two organisms are, the longer it takes for their embryos to differ.
- DNA Sequencing as Evidence for Evolution: The sequence of A, T, G, and C can be used like homologous traits to determine how species are related. The more similar these DNA traits are, the more closely related the species.
- Definition of Artificial Selection: Humans choose which traits will increase an individual’s chance for reproducing.
- Definition of Sexual Selection: The members of the opposite sex determine which traits will increase the chance of an individual reproducing.
- Human-Caused Evolution in Other Species: We let individuals with desired traits reproduce and prevent individuals without those traits from reproducing, which can cause large changes over fewer generations. The individuals with undesirable traits have a 0% chance of reproducing.
- Biological Species Concept: One or more populations that can interbreed to produce fertile offspring but are reproductively isolated from other groups. They can make babies with each other, but they can’t make babies with other populations.
- Horse and Donkey Example (Biological Species Concept): A horse and a donkey are different species even though they can have living hybrid offspring (mules) because mules are usually infertile. Donkey + Horse = Mule.
- Ecological Species Concept: A distinct group of organisms with a unique set of adaptations to a particular environment.
- Polar Bear and Grizzly Bear Example (Ecological Species Concept): A polar bear and a grizzly bear are different species even though they can produce viable offspring (grolar bears) because they live in different environments.
- Definition of Speciation: Two populations become different species when they are prevented from producing viable offspring with each other, resulting in no gene flow and reproductive isolation.
- Age of the Earth: 4.6 Billion years old.
- Allopatric vs. Sympatric Speciation:
- Allopatric Speciation: The formation of new species from geographically isolated populations. Geographic isolation occurs when two populations are physically separated by some sort of barrier (mountains, rivers, oceans).
- Sympatric Speciation: Formation of a new species in the absence of geographic isolation. Populations must become isolated in other ways, such as ecological specialization, where different individuals in the population prefer different resources (food, nesting sites, etc.).
- Adaptive Radiation: The rapid speciation of one species into many new species. This only occurs under certain conditions, such as colonization of a new location, mass extinction removing existing species, or the evolution of a novel trait that gives a significant competitive advantage.
- Definition of Homologous Trait: Closely related organisms evolve differently in response to different environments (divergent evolution). They have the same underlying structure, are inherited from a common ancestor, but have different functions and adaptations for different environments.
- Definition of Vestigial Organ: Homologous structures that no longer serve a function and have been reduced.
- Definition of Convergent Evolution: Different underlying structure, not inherited from a common ancestor, but the same function and adaptations for the same environment.
- Linnean Hierarchy: Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species.
Importance of Biodiversity
Explain why biodiversity is important– The variety of life in the world, or in a particular habitat or ecosystem
High biodiversity is a sign of a healthy environment. Low biodiversity makes an ecosystem more prone to collapse when the environment changes
Domains and Kingdoms of Life
- Three Domains of Life: Archaea, Bacteria, Eukarya.
- Four Kingdoms within the Domain Eukarya: Animalia, Fungi, Plantae, Protista.
- Be able to identify the kingdom or phylum of an organism based on its characteristics
- Definition of Autotroph: Produce their own food.
- Definition of Heterotroph: Consume other organisms for food.
- Be able to read a phylogenetic tree
- Which organisms are more closely related
- Where on the tree you would find the common ancestor of two organisms
- Identify which organisms are more closely related and explain what traits they share
- Biodiversity part 2 lecture