Study Guide 2_ Exam 2

Law of Superposition

The principle that in a series of sedimentary rock layers, the oldest layers are at the bottom and the youngest layers are at the top.

Stratigraphy

The study of rock layers (strata) and their chronological relation to geological time periods.

Assemblage

A group or collection of fossils that are consistently found together within a particular rock layer, indicating species that existed at the same time.

Uniformitarianism

The theory that processes that shape the earth's surface today have been occurring in the same manner throughout Earth's history.

Catastrophism

The theory that Earth's geology has been shaped by sudden, violent events such as earthquakes and floods.

Natural Selection

The process by which organisms better adapted to their environment tend to survive and produce more offspring.

Fitness

The ability of an organism to survive, reproduce, and pass its genes to the next generation.

Macroevolution

Large-scale evolutionary changes that result in the emergence of new species over long periods of time.

Microevolution

Small-scale evolutionary changes within a species over shorter time periods.

Divergent Evolution

When two species evolve in diverse directions from a common ancestor.

Convergent Evolution

When unrelated species independently evolve similar traits as a result of adapting to similar environments.

Homologous Structures

Anatomical features in different species that share a common ancestor, but may perform different functions.

Analogous Structures

Structures in different species that serve similar functions but evolved independently, without a common ancestor.

Transitional Form

Fossils or organisms that show the intermediate evolutionary forms between different species.

Gene Linkage

The tendency of genes located close to each other on the same chromosome to be inherited together.

Crossing Over

The exchange of genetic material between homologous chromosomes during meiosis, impacting gene linkage.

Rh Factor

A protein present on red blood cells that can affect pregnancy if an Rh-negative mother carries an Rh-positive fetus.

Lamarck’s Evolution Mechanism

The idea that organisms can pass on traits acquired during their lifetime to their offspring.

Malthus’ Theory

The idea that populations grow exponentially, leading to competition for limited resources, which influences natural selection.

Adaptive Radiation

The rapid evolution of diversely adapted species from a common ancestor to fill various ecological niches.

Endosymbiotic Theory

The theory that eukaryotic cells evolved through symbiotic relationships between different prokaryotic cells.

Embryology in Evolution

The study of embryonic development to understand evolutionary relationships among species.

Polymorphism

The occurrence of two or more different alleles at a locus in a population.

Incomplete Dominance

A genetic situation in which one allele does not completely dominate another allele, resulting in a new phenotype.

Codominance

A genetic scenario where both alleles in a heterozygote produce their phenotypes simultaneously.

Polygenic Trait

A trait that is controlled by multiple genes, resulting in a continuous range of phenotypes.