Earth & Its Biomes
The Evolution Revolution
How Species Split
Deep-Time History
Ecological Science
100

This scientific term refers to all regions of the Earth that are inhabited by life, encompassing both living (biotic) and non-living (abiotic) elements.

The biosphere

100

This random genetic change serves as the ultimate source of all brand-new, heritable alleles within a biological population.

A DNA mutation

100

This widely utilized species concept defines a species based strictly on reproductive compatibility and the potential to produce fertile offspring in nature.

The Biological Species Concept

100

Vesto Slipher and Edwin Hubble photographed this cosmic phenomenon to document that distant galaxies are moving away from us and the universe is expanding.

Redshifting

100

This scientific discipline is defined as the study of the complex, interconnected interactions between living organisms and their physical environment.

 Ecology

200

Located roughly 20 to 30 degrees North and South of the Equator, this parched biome features specialized vegetation adapted to extreme daytime heat and rapid nightly cooling.

Desert

200

These two 19th-century naturalists independently arrived at highly similar theories of evolutionary change driven by natural selection.

Charles Darwin and Alfred Russell Wallace

200

This type of speciation is initiated when a physical geographic barrier (like a canyon or river) splits a population and completely blocks gene flow.

Allopatric speciation

200

What was the first theory of chloroplast being double membraned

endosymbiosis theory

200

This type of species plays a uniquely disproportionate role in maintaining the overall health, diversity, and structural stability of its ecological community.

keystone species

300

This maritime coastal biome, situated 30 to 50 degrees from the Equator, is dominated by dense, tangled, evergreen woody shrubs that rely on periodic fire cycles to regenerate.

The chaparral

300

This major reproductive strategy prevents the accumulation of harmful mutations over generations by shuffling alleles into entirely novel genotypes.

Sexual reproduction

300

This prezygotic barrier keeps closely related species reproductively isolated simply because they mate or release gametes at different times of the day, season, or year.

Temporal isolation

300

These layered, fossilized sedimentary rock structures were built roughly 3.5 billion years ago by ancient colonies of photosynthetic prokaryotes trapping debris.

Stromatolites

300

Widely sprayed in the 1950s for pest control, this persistent chemical insecticide caused severe reproductive damage to top-level birds of prey due to biomagnification in food webs.

DDT

400

Spanning latitudes of 60 to 75 degrees North, this freezing, treeless biome is defined by a permanently frozen subsoil layer known as permafrost.

The tundra

400

This term describes anatomical structures—like a human arm and a whale flipper—that share an underlying skeletal design because they were inherited from a common ancestor.

Homologous structures

400

A donkey and a horse can mate to produce a strong, healthy mule, but the mule is completely sterile—an example of this specific postzygotic reproductive barrier.

Reduced hybrid fertility

400

This term describes anatomical structures that originally evolved to serve one survival function but were later co-opted to serve a completely different purpose (like feathers evolving for insulation and later being used for flight).

Exaptations

400

n community ecology, this specific scale of species diversity measures the rate of species turnover or change when moving from one local site to another.

Beta diversity

500

These three primary physical factors shape global climate zones by dictating solar intensity, dispersing heat, and modifying local rainfall patterns.

Latitude, wind/ocean currents, and topography

500

Under Richard Dawkins' "cake recipe" analogy, this specific copying mistake is compared to accidentally substituting "1 tablespoon" of salt for "1 teaspoon," resulting in a massive change to the final product's expression.

A point mutation (or single base pair change)

500

This hybrid zone outcome occurs when hybrid offspring are less fit than their parents, prompting natural selection to strengthen prezygotic barriers and complete the speciation process.

Reinforcement

500

The evolution of photosynthetic cyanobacteria releasing immense quantities of oxygen gas as a byproduct of metabolic energy use triggered this massive global atmospheric transition.

The Great Oxidation Event

500

Under the "RNA World" hypothesis, these primitive precursors to life formed spontaneously when lipid molecules naturally assembled into double-layered spherical bubbles in water.

Protocells