Species Concepts, Microevolution, and Macroevolutionary Patterns

Flashcards covering species concepts, microevolutionary mechanisms, fossilization processes, extinction types, and ecological succession based on the Week 10 to 15 lecture notes.

Morphological species concept

A concept stating that if organisms physically look similar, they are in the same species.

Biological species concept

A concept identifying a species as a group that can mate and produce viable fertile offspring.

Ecological species concept

A concept that defines species based on their ecological niche, including the ecological role or the conditions needed to survive.

Phylogenetic species concept

The smallest set of organisms that share an ancestor and can be distinguished from other such sets.

Chronospecies

Different stages in the same evolving lineage that existed at different points in time.

Ring species

Species with a geographic distribution that forms a ring and overlaps at the ends, where neighbors interbreed but the ends of the chain may not.

Phenotypic plasticity

The ability of a single genotype to produce different phenotypes (observable traits, behaviors, or physiology) in response to environmental conditions.

Sexual dimorphism

The systematic difference in form, size, color, or behavior between males and females of the same species, excluding genitalia.

Mutation

A permanent change in the DNA sequence of an organism that increases genetic diversity.

Migration

The movement of individuals into a new population, leading to a change in gene frequency and increasing variation.

Natural selection

The primary mechanism of evolution where organisms better adapted to their environment survive and reproduce more often, passing on advantageous, heritable traits.

Genetic drift

A purely chance-driven change in the frequency of gene variants (alleles) within a population from generation to generation, most powerful in small populations.

Fitness

A measure of an organism's ability to survive, reproduce, and pass its genes to the next generation relative to others in the same population.

Permineralization

A common fossilization process where mineral-rich groundwater seeps into porous organic tissues, depositing minerals like calcium carbonate or silica to create a stony replica.

Compression

A fossilization method where remains are pressed at depth, producing a dark imprint due to high-pressure forces from overlying sediments.

Molds and Casts

Fossils formed when original material dissolves leaving a space (mold) which is later filled by sediments to create a matching positive impression (cast).

Preserved remains

The rarest form of fossilization where original skeletons and soft body parts are kept intact, such as insects trapped in amber.

Background extinction

The regular rate at which species normally go extinct without major changes to the Earth occurring.

Mass extinction event

A period with dramatically higher rates of extinction, reaching $10$ times the background rate or more, often killing $50\,\%$ or more of a taxonomic group.

Hitchhiking

The survival of traits during mass extinctions not because they are useful, but because they belong to organisms with broad geographic ranges or generalist diets.

Adaptive radiation

A rapid evolutionary process where a single ancestral species diversifies into a multitude of new forms, often triggered by vacant niches or new resources.

Oviparity

A reproductive method where animals lay eggs that develop and hatch outside the mother's body, with the embryo receiving nutrients from the yolk.

Viviparity

The development of the embryo inside the mother's body with metabolic needs provided by maternal circulation until birth.

Polytomy

A node on a phylogeny where more than two lineages descend from a single ancestral lineage, creating a pitchfork-like branching pattern.

Punctuated equilibrium

The idea that evolution occurs in quick bursts followed by long periods of stasis.

Phyletic gradualism

The idea that evolution is a gradual process that happens steadily over time.

Key innovation

A novel genetic, structural, or physiological trait that allows a specific group of organisms to rapidly diversify and exploit new ecological niches.

Exoskeleton

A hard, external covering found in invertebrates like insects that provides armor, muscle attachment, and prevents dehydration.

Endoskeleton

An internal supporting framework, typically composed of bone and cartilage, that protects organs and supports larger body sizes.

Ecological opportunity

Environmental conditions providing abundant underutilized resources, acting as a primary engine for adaptive radiation.

Ectothermic species

Animals that rely on external environmental sources to regulate their body temperature and have lower food energy requirements.

Endothermic species

Animals that maintain a stable, high body temperature using heat generated internally through metabolism, such as birds and mammals.

Amniotic egg

An air-breathing egg with a shell and extra-embryonic membranes that allows for development away from water.

Primary succession

Ecological development in entirely new, barren habitats that lack soil, such as lava flows or retreating glaciers.

Secondary succession

Ecological recovery following a disturbance that removes vegetation but leaves soil, nutrients, and seed banks intact.

Facilitation

A process where pioneer species modify the environment to make it more suitable for later-arriving species.

Inhibition

A process where early colonizing species hinder the establishment of later species by monopolizing resources.

Rank abundance curve

A chart used to visualize biodiversity by displaying both species richness and species evenness simultaneously.

Species accumulation curve

A graph plotting the cumulative number of species discovered as a function of sampling effort.

Community

All the interacting populations of different species that live in the same geographic area, excluding non-living elements.

Evenness

A measure of the relative abundance of different species, indicating how close in numbers each species in an environment is.