Biology- Evolution and Natural Selection

Endosymbiotic theory

A biological theory that explains the origin of eukaryotic cells from prokaryotes, positing that certain organelles, like mitochondria and chloroplasts, were once free-living bacteria that were engulfed by ancestral eukaryotic cells.

Punctuated equilibrium

A theory in evolutionary biology suggesting that species remain relatively unchanged for long periods, punctuated by brief episodes of rapid evolution and speciation.

Speciation

The process through which new distinct species arise from a common ancestral species, often due to genetic divergence and reproductive isolation.

Natural selection

A mechanism of evolution where individuals with traits better suited to their environments have higher survival and reproductive rates, leading to those traits becoming more common in a population over generations.

Evolution

The change in the inherited characteristics of biological populations over successive generations, which can lead to the emergence of new species.

Artificial selection

The intentional breeding of organisms by humans for specific traits, leading to changes in species over generations that differ from natural selection.

Mutation

A change in the DNA sequence of an organism's genome, which can lead to new traits and contribute to genetic variation.

Variation

Differences within a population's traits, typically based on genetic differences, which is essential for the process of evolution through natural selection.

Stabilizing selection

A type of natural selection that favors average phenotypes by selecting against extreme variations, leading to a reduction in variation over time.

Vestigial structures

Body parts that have lost their original function through the course of evolution, such as the human appendix or whale pelvis.

Homologous structures

Anatomical features that are similar in different species due to shared ancestry, even if their functions may have diverged.

Analogous structures

Features in different species that serve a similar function but evolved independently, indicating that they do not share a common ancestor.

Directional selection

A type of natural selection that favors one extreme phenotype over others, leading to a shift in the population's phenotypic distribution.

Disruptive selection

A form of natural selection that favors extreme phenotypes over intermediate forms, potentially leading to speciation.

Biogeography

The study of the distribution of species and ecosystems in geographic space and through geological time, providing insights into evolutionary processes.

Gene pool

The total collection of genes and their variations (alleles) within a population, representing the genetic diversity available for evolution.

Overproduction

A principle of evolution where organisms produce more offspring than the environment can support, leading to competition for resources.

Adaptation

A trait that enhances an organism's ability to survive and reproduce in a particular environment, resulting from the process of natural selection.

Descent with modification

A phrase that describes the process of evolution, where descendant species change over time from their ancestors, often adapting to different environments.

Paleontologist

A scientist who studies fossils and ancient life forms to understand Earth's biological history and the processes of evolution.

Geologist

A scientist who studies the Earth's physical structure, its history, and the processes that shape it over time.

Anthropologist

A researcher who studies human societies, cultures, and their development, often including aspects of biology and evolution.

Genetic drift

A random change in allele frequencies in a population, which can lead to significant evolutionary changes over time, especially in small populations.

Extinct

A term used to describe a species that has no living individuals left, having completely disappeared from the planet.

Tectonic plates

Large slabs of Earth's lithosphere that move and interact at their edges, shaping the planet's geology and affecting the distribution of species.

Paleocoicera

A genus of extinct ammonoid cephalopods known from the fossil record, significant for studying the evolution of marine life.

Mesozoic Era

A geological era spanning from about 252 to 66 million years ago, known as the age of dinosaurs and characterized by significant evolutionary developments.

Cenozoic Era

The current geological era, beginning 66 million years ago, marked by the rise of mammals and flowering plants following the extinction of dinosaurs.

Charles Darwin

An English naturalist whose work on the theory of evolution and natural selection, particularly with his book 'On the Origin of Species,' laid the foundation for modern evolutionary biology.

Alfred Russel Wallace

A British naturalist who independently conceived the theory of evolution through natural selection; his writings prompted Darwin to publish his own theory.

Jean Baptiste Lamarck

A French biologist known for his early theory of evolution by inheritance of acquired characteristics, which was later largely discredited in favor of Darwinian evolution.

John Gould

A British ornithologist who studied and classified birds from the Galápagos Islands, contributing to Darwin's understanding of evolution.

Fossil record

The historical sequence of life on Earth created by fossils, providing evidence for evolutionary processes and the history of species.

Fossil

Remains or traces of ancient organisms preserved in rock, which serve as important evidence for understanding past life forms and their evolution.

Radioactive dating

A method used to date materials like rocks or fossils based on the decay rate of radioactive isotopes, providing estimates of age on a geological time scale.

Carbon 12 dating

A form of radiocarbon dating that measures the ratio of carbon isotopes in organic materials, allowing for dating of specimens that are up to about 50,000 years old.