Biological Evolution Comprehensive Lecture Series

This set covers the history of evolutionary thought, evidence for Darwin's theory, mechanisms of speciation, patterns of macroevolution, and modern applications in medicine and conservation.

Scala naturae

Aristotle's 'Scale of Nature' model (384-322 BC) based on logic and philosophy, where each life form was seen as perfect, permanent, and occupying a specific space on a scale of increasing complexity.

Nasīr al-Dīn Tūsī

A 13th-century Persian scholar and polymath who proposed basic evolutionary ideas, such as organisms gaining new features through internal and external interactions, approximately $600 \text{ years}$ before Darwin.

Descent with modification

The central idea of biological evolution stating that all life on Earth shares a common ancestor and species accumulate differences over generations as they adapt to different environments.

Taxonomy

The branch of science founded by Carl von Linne (Linnaeus) that uses a binomial system for naming species and a nested system of classifications (genus, family, orders, etc.).

Catastrophism

A theory developed by George Cuvier (1769-1832) suggesting that successive catastrophes like floods or droughts wiped out most life forms in specific rock strata.

Uniformitarianism

The principle promoted by Charles Lyell (1797-1875) stating that geological features are caused by slow, gradual changes and that the laws of nature have been constant over time.

Jean Baptiste de Lamarck

A French scientist who recognized species change over time but incorrectly proposed that complexity is achieved by 'will' and that acquired characteristics (like a giraffe's neck stretching) are passed to offspring.

Thomas Malthus

A British political economist who wrote 'Essay on the Principle of Population' (1798), observing that plants and animals produce more offspring than can survive, leading to a struggle for survival.

Panspermia hypothesis

The theory that the building blocks of life exist throughout the universe and are distributed to planets by meteorites, asteroids, and space dust.

Stratigraphy

The branch of geology that studies rock layers (strata) and layering, primarily used in recording the fossil record within a framework of geological time.

Half-life

The fixed period of time it takes for 50 \text{%} of a radioactive element to decay into another element, such as Carbon 14 decaying to Nitrogen 14 over $5730 \text{ years}$.

Extant

An adjective used to describe a species that is still in existence or surviving, as opposed to extinct.

Taphonomic Processes

The study of all changes that happen to an organism from the moment of death until its discovery, including decomposition, burial, and fossilization.

Stromatolites

Colonies of cyanobacteria that appear in the fossil record as far back as $3.5 \text{ billion years}$ ago.

Cambrian Explosion

An event approximately $545 \text{ mya}$ characterized by a rapid diversification of body plans where all extant phyla appeared over a period of $5-10 \text{ million years}$.

Monophyletic Clade

A group consisting of an ancestral species and all of its descendant species.

Homology

A broad term for any shared trait inherited from a common ancestor, such as the same basic bone structure in different vertebrate limbs.

Synapomorphy

A specific type of homology that refers to a 'newly derived' shared trait defining a particular subgroup.

Convergent Evolution

The process where different species evolve superficially similar (analogous) features, like bird and bat wings, because they evolved to serve the same function despite separate evolutionary origins.

Vestigial Structures

Remnants of features that served a function in an organism's ancestors but no longer serve a significant purpose, such as the human coccyx or pelvic bones in whales.

Ontogeny Recapitulates Phylogeny

The historical idea that an organism's embryonic development mirrors its evolutionary history, as seen in human embryos possessing pharyngeal pouches and a tail stage.

Archaeopteryx

An intermediate fossil dated to $150 \text{ mya}$ that represents a transitional form between dinosaurs and birds, featuring both teeth and feathers.

Tiktaalik roseae

An intermediate fossil dated to $375 \text{ mya}$ found in the Canadian Arctic, linking lobe-finned fishes and tetrapods.

Biological Species Concept

The definition of a species as a group of individuals that can interbreed in nature to produce viable, fertile offspring.

Allopatric Speciation

The formation of new species that occurs when a population is divided into geographically isolated groups by physical barriers like mountains or rivers.

Sympatric Speciation

The formation of new species within the same geographic area as the ancestral population, often involving chromosomal changes or non-random mating.

Genetic Drift

A mechanism of evolution involving random fluctuations in allele frequencies from generation to generation, which is more drastic in smaller populations.

Founder Effect

A type of genetic drift occurring when a few individuals become isolated from a larger population and establish a new population with a different gene pool.

Bottleneck Effect

A type of genetic drift that occurs when a population's size is drastically reduced by a sudden event, leading to a surviving population that no longer represents the original genetic diversity.

Co-evolution

A process where two or more species reciprocally affect each other's evolution, frequently seen in predator/prey or plant/pollinator relationships.

Sexual Dimorphism

The distinct difference in size, color, or ornamentation between the males and females of the same species, often resulting from sexual selection.

Intrasexual Selection

A form of sexual selection where individuals of one sex (usually males) compete directly with each other for mates of the opposite sex.

Intersexual Selection

Also known as mate choice, this occurs when individuals of one sex (usually females) choose which specific individuals of the opposite sex to mate with.

End-Permian Extinction

The largest mass extinction event ($252 \text{ mya}$) where 96 \text{%} of all marine species and 70 \text{%} of land species went extinct.

K-T Extinction

A mass extinction event $65 \text{ mya}$ involving an asteroid impact at Chicxulub and massive volcanism in the Deccan traps, leading to the demise of dinosaurs and the rise of mammals.

Heterochrony

An evolutionary change in the rate or timing of developmental events, which can lead to significant morphological differences in adults.

Paedomorphosis

A condition where an adult retains juvenile characteristics of its ancestors, such as the axolotl retaining external larval gills while being sexually mature.

Homeotic Genes

Master regulating genes, such as Hox genes in animals and MADS-box genes in plants, that control the placement and spatial organization of body parts during embryonic development.

Irreducible Complexity

A concept used by anti-evolutionists suggesting that certain systems cannot function if any one part is removed; the evolution of the eye is used to disprove this fallacy.

Genetic Rescue

A conservation intervention where immigrants are introduced to an inbred, isolated population to increase genetic variation and improve breeding success, as seen in Scandinavian wolves.