Sixth Extinction Crisis

Biodiversity

The total number of species in an area and how many different species are found there.

Biodiversity hotspots

Areas covering 2.4% of Earth's surface but containing over 50% of plant and 42% of animal species.

Species

A group of similar organisms that can interbreed and produce viable offspring.

Phylogenetic species concept

Defines species based on evolutionary history and traits relatedness on the phylogenetic tree.

Speciation

The process by which new species evolve over time.

Gradualistic

Model of speciation where small changes accumulate slowly until reproductive isolation occurs.

Punctuated equilibrium

Model of speciation with long periods of stability interrupted by rapid evolutionary changes.

Prezygotic isolating mechanisms

Barriers that prevent mating or fertilization between species.

Postzygotic isolating mechanisms

Barriers that occur after fertilization, reducing offspring viability or fertility.

Phylogenetic tree

Diagram showing evolutionary relationships among species based on traits and ancestry.

extinction

The complete loss of a species from Earth.

Mass extinction

A widespread and rapid decrease in the biodiversity on Earth involving many species.

Prokaryote

-know the structure

Single-celled organism lacking a nucleus and membrane-bound organelles; includes bacteria and archaea.

autotroph

An organism that produces its own food from inorganic substances (e.g., through photosynthesis).

heterotroph

An organism that obtains energy by consuming other organisms.

saprophytic

Organisms that feed on decaying organic matter.

Eukaryote

Organisms whose cells contain a nucleus and membrane-bound organelles.

fungi

Heterotrophic, saprophytic eukaryotes made of hyphae; reproduce via spores; includes mushrooms, molds, yeasts.

Plants

Multicellular, photosynthetic eukaryotes with alternation of generations and vascular tissues.

Animals

Multicellular, heterotrophic eukaryotes that ingest food and typically have specialized tissues.

Vertebrates

Animals with a backbone; includes fish, amphibians, reptiles, birds, and mammals.

Invertebrates

Animals without a backbone; includes insects, mollusks, and others.

Arthropods

Invertebrates with exoskeletons, jointed appendages, segmented bodies (e.g., insects, spiders).

Anthropocene

Current geological epoch marked by human-induced environmental changes.

Habitat destruction

The alteration or elimination of natural environments, primarily due to human activity like agriculture.

Invasive species

Non-native species that outcompete native species, often due to lack of natural predators.

overexploitation

Removing more individuals from a population than can be naturally replaced.

pollution

Introduction of harmful substances into the environment affecting organism health or reproduction.

Wildlife corridors

Protected areas that connect habitats, allowing species movement and reducing inbreeding.

Marine protected areas

Ocean zones where human activity is restricted to conserve marine biodiversity.

Coral bleaching

Loss of symbiotic algae in corals due to stress, often caused by warming waters, leading to coral death.