Unit 2: Origins and Introduction to Evolution

The idea that species go extinct and are replaced by new species migrating in, but it doesn't account for the increasing complexity of species over time.

Structures in different species that share a similar underlying structure but have different functions.

Structures that are present in an organism but have no known function, often remnants of structures that were useful in ancestors.

A statement based on repeated experimental observations that describe only some aspects of the natural world.

An explanation of some aspects of the natural world that is supported by evidence, observations, and experimentation.

A theory explaining how species evolve over time, emphasizing that modern species are the result of changes from earlier generations, ultimately stemming from a single or a few common ancestors.

The process by which organisms better adapted to their environment are more likely to survive and reproduce, leading to a gradual change in the population over generations.

Factors that influence the survival and reproduction rates of individuals within a population.

A change in the genetic code that can be passed down to offspring.

Mutations with no immediate effect on an individual's ability to survive and reproduce.

Mutations that reduce an individual's ability to survive and reproduce.

Mutations that increase an individual's ability to survive and reproduce.

Functional, structural, or physiological differences between individuals in a population.

A trait that helps an organism survive and reproduce in its environment.

The ability of an organism to survive and reproduce, measured by the number of offspring that survive to reproduce.

The theory that geological processes operate at the same rate today as they did in the past.

The idea that acquired traits can be passed down to offspring.

The theory that evolution occurs in bursts of rapid change followed by long periods of stability.

Fossils that show traits of both ancestral and modern species.

A change in the frequency of alleles in a population due to random chance.

The process of breeding organisms for desired traits.

Two or more species become increasingly different due to differing selective pressures or genetic drift. Occurs when closely related species diversify into new habitats. This process is responsible for the wide diversity of life on Earth, starting from early living cells. It also explains the evolution of humans and apes from a common primate ancestor.

Two or more species become similar in phenotype, even though they have different ancestry. This happens because they are subjected to similar selective pressures. Species share analogous structures, which have similar appearances but different evolutionary origins.

The reciprocal influence of two or more species on each other's evolution. This occurs when species have close ecological interactions, such as predator-prey relationships, competition, or mutualism. The evolution of one species can directly affect the evolution of another. A classic example is the evolution of plants and their herbivores.

A rapid diversification of species from a common ancestor. It often occurs after mass extinction events, creating a large number of new species in a short time period. The species radiate out into diverse environments, taking advantage of new ecological niches.

Different patterns of evolution observed in populations. These pathways are broader than the mechanisms of microevolution, which describe specific processes like natural selection and genetic drift. Pathways describe general patterns of evolution, like convergent evolution and adaptive radiation.

A state where a population experiences little to no change in size over time.

A small population with limited genetic diversity is more vulnerable to the effects of genetic mutations.

A type of natural selection where one extreme phenotype is favored over others.

A type of natural selection where two extreme phenotypes are favored over the intermediate phenotype.

A type of natural selection where the average phenotype is favored, reducing genetic variation.

The study of the distribution of organisms around the world.

The study of early developmental stages of organisms.

The sum of all gene variations within a population.

A variation of a gene that determines specific traits.

The frequency of a specific allele in a population.

The combination of alleles that make up an organism's genetic makeup.

The physical expression of an organism's genotype.

The gradual change in the allele frequencies of a population over time.

The process by which new species arise from existing ones.

The movement of alleles between populations.

A type of genetic drift that occurs when a small group of individuals starts a new population.

A type of genetic drift that occurs when a population experiences a sudden and drastic reduction in size.

When individuals choose mates based on specific traits.

A type of non-random mating where individuals with similar phenotypes breed together.

A type of natural selection that favors traits that increase an individual's chances of finding a mate.

The separation of populations by a physical barrier.

The separation of populations within the same geographic area.

Mechanisms that prevent mating or fertilization between individuals of different species.

Mechanisms that prevent the development of a viable and fertile hybrid offspring.