EEMB 3 midterm 1 terms

Biodiversity

The variety of life across different levels, including genes, species, ecosystems, and ecological roles

Ecology

The study of how organisms interact with one another and with their environments

Evolution

Change in populations over time, and the process that gives rise to the diversity of life.

Ecosystem

A community of organisms and the physical environment they interact with.

Lineage

A sequence of ancestors and descendants through evolutionary time.

Microbe

A microscopic organism, including many bacteria, archaea, protists, fungi, and some other forms of life.

Organism

An indivdual thing.

Phylogeny

A hypothesis about the evolutionary relationships among organisms.

Species

A group of organisms often defined by shared evolutionary history and, in many cases, the ability to interbreed.

Tree of life

A representation of the evolutionary relationships among all living organisms.

Biodiversity Index

A numerical way of comparing biodiversity across communities, often using information about species and abundance.

Climate stability

The relative consistency of environmental conditions over time, which may support specialization and diversification.

Contour Plot

A type of map that uses lines or color gradients to show changes in a variable across space.

Ecological pattern

A repeated or observable distribution in nature, such as how biodiversity changes across latitude.

Functional Diversity

The roles species play in an ecosystem differ. If the same number of species perform similar functions (redundancy), it is less diverse than if those species fill a wide range of ecological niches.

Genetic Diversity

Even if species are the same, the genetic variation within those species populations can differ, indicating different levels of adaptability and biodiversity.

Hypothesis

A testable explanation for an observed pattern or process.

Latitudinal Diversity Gradient

The global pattern in which biodiversity tends to be highest near the equator and lower toward the poles.

Niche Specialization

A driver of biodiversity where species evolve to specific resources and habitats, reducing competition and allowing coexistence. 

Primary Productivity

The rate at which producers, such as plants and algae, convert energy into organic matter.

Species Composition (identity)

The specific species present matter. An ecosystem with unique, specialized, or endemic species possesses higher conservation value and functional diversity than one with widely distributed generalist species.

Species Evenness

The degree to which individuals are distributed evenly among species in a community.

Species Richness

The number of different species present in a given area or community.

Tropics

The region of Earth near the equator that recieves relatively direct sunlight year round

Archaea

one of the three domains of life, made up of single-celled organisms that are distinct from Bacteria and are more closely related to Eukarya.

Bacteria

one of the three domains of life, consisting of single-celled organisms with no nucleus and cell walls that usually contain peptidoglycan.

Cell envelope

the outer layers surrounding a cell, including the membrane and, in many microbes, the cell wall.

Cell wall

a protective outer structure found outside the cell membrane in many organisms, helping provide shape and support.

Domain

the broadest major category of life, above kingdom, used to classify organisms into Bacteria, Archaea, and Eukarya.

Eukarya

one of the three domains of life, including organisms whose cells contain a nucleus and other membrane-bound organelles.

Evolutionary relationship

the pattern of shared ancestry that connects different organisms through evolutionary time.

Flagella

long whip-like structures that help some cells move through their environment.

Homology

similarity between traits or molecules because they were inherited from a common ancestor.

Molecular evidence

information from DNA, RNA, proteins, or other molecules that helps scientists study evolutionary relationships.

Molecular phylogeny

the use of molecular data, such as gene or RNA sequences, to reconstruct evolutionary relationships.

Peptidoglycan

a strong mesh-like molecule found in the cell walls of most bacteria but not in Archaea.

Phylogeny

the evolutionary history and relationships among organisms.

Prokaryote

a cell without a nucleus; historically used to group Bacteria and Archaea together, though they are now recognized as separate domains.

Ribosomal RNA (rRNA)

a molecule found in ribosomes that is present in all cellular life and is especially useful for comparing deep evolutionary relationships.

Three-domain system

the modern classification of life into Bacteria, Archaea, and Eukarya based on evolutionary relationships.

Tree of life

a branching representation of the evolutionary relationships among all organisms on Earth.

Woese, Carl

the scientist whose work comparing ribosomal RNA helped reveal Archaea and transform the tree of life.

Cyanobacteria

photosynthetic bacteria that use sunlight to make energy and release oxygen.

Early earth

the planet during its earliest history, when conditions were very different from today.

Faint young sun paradox

the puzzle that the early Sun was dimmer than it is today, yet Earth still seems to have had liquid water.

Fossil evidence

preserved remains, traces, or structures that provide evidence of ancient life.

Geological evidence

clues preserved in rocks and minerals that help scientists reconstruct ancient Earth.

Greenhouse gases

gases such as carbon dioxide and methane that trap heat in the atmosphere.

Habitability

the conditions that make it possible for life to survive and persist.

Hypothesis

a scientific explanation proposed to account for observations when direct evidence is limited.

Isua rocks

ancient rocks from Greenland that help scientists infer conditions on early Earth.

Microbe

a microscopic organism, such as a bacterium or archaeon

Microbial world

a world in which life is dominated by microscopic organisms.

Miller-Urey experiment

an experiment showing that organic building blocks can form from simple chemicals under simulated early Earth conditions.

Origin of life

the question of how the first living systems arose from nonliving matter.

Panspermia

the idea that some ingredients for life may have arrived on Earth from space.

Radiometric dating

a method used to determine the age of rocks and fossils using radioactive decay

RNA world hypothesis

the idea that RNA may have been an early molecule of life because it can both store information and catalyze reactions.

Stromatolite

layered rock structures formed by microbial communities and among the oldest evidence of life on Earth.

Ubiquitous

in the context of microbes, this means found everywhere.

Hydrothermal vents

are the results of seawater percolating down through openings in the oceans crust; typically these occur near spreading centers or subduction zones.

Chemotroph

organism that uses chemicals as its primary source of energy.

Phototroph

organism that uses light as its primary source of energy.

Lithotroph

organism that obtains electrons from inorganic substrates.

Organotroph

organism that obtains electrons from organic substrates.

Heterotroph

organism that consumes already fixed carbons.

Autotroph

organism that can fix its own carbon.

Archaea

single-celled microbes, distinct from bacteria, found in nearly every environment, from hot springs and oceans to soils and animal guts.

Asgard archaea

a group of archaea, named after Norse gods, whose genomes carry genes once thought unique to eukaryotes; the closest known relatives of eukaryotes.

Endosymbiosis

a relationship in which one organism lives inside another, how an archaea host gained the bacterium that became the mitochondrion.

Ether-linked lipids

archaeal membrane lipids whose chains attach to glycerol through ether bonds , which are more chemically stable than the ester bonds in bacterial and eukaryotic membranes.

Extremophile

an organism that thrives in extreme conditions, such as high heat, acidity, or salt.

Lipid divide

the puzzle that eukaryotes descend from archaea yet build their membranes with bacterial-type lipids.

Metagenomics

sequencing DNA directly from an environmental sample, which lets scientists study organisms that have never been grown in the lab.

Methane (CH4)

a potent greenhouse gas produced by methanogens.

Methanogen

an archaean that produces methane as a byproduct of its metabolism

Methanogenesis

the production of methane by microbes, a metabolism found only in archaea.

Mitochondrion

the energy-producing organelle of eukaryotic cells, descended from a bacterium taken in by an archaeal host

Nitrification

the conversion of ammonia to nitrite and then nitrate, an important step in the nitrogen cycle