Ecosystems, Population Dynamics, and Adaptations

Vocabulary flashcards covering key concepts from ecology, biomes, species interactions, nutrition types, population dynamics, hominid evolution, and ecosystem energy/nutrient cycles.

Endemic

Organisms that are naturally restricted or isolated to a specific geographical area.

Transpiration

The evaporation of water from internal plant surfaces and its diffusion to the atmosphere through the stomata.

Photoperiod

The duration of daily light exposure that triggers physiological responses in plants, such as flowering.

Calcicole

A plant species adapted to grow in lime-rich soils with high soil $\text{pH}$, such as Alfalfa and Junipers.

Calcifuges

Plant species adapted to acidic soils with a $\text{pH} < 4$, such as Azaleas.

Ectothermic

Describing animals whose body temperature is governed by the surrounding environment because they cannot regulate it through metabolic pathways.

Endothermic

Describing animals that can regulate and maintain their body temperature through metabolic pathways.

Pneumatophores

Vertical root branches in mangrove trees that grow upward into the air to absorb oxygen in waterlogged anaerobic soils.

Aerenchyma

Spongy tissue in mangrove roots containing air passages that allow oxygen to move downward through the root system.

Lenticels

Small pores on mangrove roots that absorb oxygen and transport it into spongy tissue while preventing salty water from entering.

Range of Tolerance

The range of an environmental factor within which an organism can survive, bounded by zones of stress and zones of intolerance.

Biome

A major type of ecosystem characterized by specific climatic conditions, plant communities, and animal adaptations.

Biosphere

The sum of all the biomes and ecosystems on Earth where life exists.

Ecological Niche

The specific role, position, and multidimensional space occupied by a species within its environment, including resource use, biotic interactions, and required abiotic conditions.

Fundamental Niche

The full range of abiotic conditions and biotic resources a species can potentially tolerate and utilize in the absence of competition.

Realized Niche

The actual portion of the fundamental niche that a species occupies as a result of limiting factors such as competition.

Competitive Exclusion

The principle stating that two closely related species requiring identical ecological resources cannot occupy the same niche indefinitely, leading to the exclusion or extinction of one species.

Obligate Aerobes

Organisms that strictly require oxygen for survival and metabolic respiration, such as Micrococcus luteus.

Obligate Anaerobes

Organisms that can only live in anoxic conditions because oxygen kills or inhibits them, such as Clostridium tetani.

Facultative Anaerobes

Organisms that use oxygen for respiration when available but can tolerate and grow under anoxic conditions, such as Escherichia coli.

Holozoic Nutrition

A form of heterotrophic nutrition where whole pieces of food are swallowed and subsequently digested and absorbed internally.

Mixotrophic Nutrition

A nutritional mode in which organisms, such as Euglena, utilize both autotrophic and heterotrophic pathways to obtain carbon and energy.

Chemoheterotrophs

Organisms that obtain energy for ATP production from the oxidation of carbon compounds obtained from other organisms, and derive carbon compounds from other organisms.

Photoheterotrophs

Organisms that obtain energy for ATP production by absorbing light using pigments (not chlorophyll in Archaea) and derive carbon compounds from other organisms.

Chemoautotrophs

Organisms that obtain energy for ATP production by oxidizing inorganic chemicals (e.g., $\text{Fe}^{2+}$ to $\text{Fe}^{3+}$) and synthesize organic carbon compounds from carbon dioxide.

Saprotrophic Nutrition

A mode of nutrition where organisms feed on dead organic matter by secreting digestive enzymes externally and absorbing the resulting soluble products across their cell walls.

Dental Arcade

The structural arrangement of the row of teeth in the jaw, evolving from a U-shape with a diastema in chimpanzees to a parabolic shape without a diastema in modern humans.

Secondary Metabolite

An organic compound produced by metabolic pathways present in only certain taxonomic groups, which is non-essential for basic cellular growth but functions in defense or ecological competition.

Antibiotics

Secondary metabolites secreted by microorganisms, such as penicillin from Penicillium, to kill or inhibit the growth of competing microbial species.

Allelopathic Agents

Secondary metabolites secreted into the soil by plants, such as ailanthone from Ailanthus altissima, to inhibit seed germination, growth, and survival of neighboring plants.

Ecosystem

A system comprising a biological community of interacting organisms together with their non-living physical (abiotic) environment.

Closed Ecosystem

An ecosystem in which energy can enter or exit, but matter and chemical substances cannot be exchanged across its boundaries.

Open Ecosystem

An ecosystem that freely exchanges both energy and matter (chemical substances) with its external surroundings.

Community

A group of populations of different species living and interacting with one another in a specific geographic area.

Population

A group of organisms belonging to the same species that live in the same area at the same time.

Carrying Capacity

The maximum population size of a species that a specific environment can sustainably support based on available resources.

Density-Independent Factors

Environmental influences, such as fires or frosts, that affect population mortality and size equally regardless of population density.

Density-Dependent Factors

Biotic or abiotic influences, such as disease, competition, and predation, whose impacts on population size intensify as population density increases, operating via negative feedback.

Patterns of Dispersion

The spatial distribution of individuals within a population's range, categorized into clumped, uniform, or random arrangements.

Keystone Species

A species that exerts a strong, disproportionate impact on the structure, diversity, and balance of an ecological community relative to its abundance.

Predation

A $(+,-)$ species interaction where a consumer organism hunts, kills, and feeds upon another consumer organism (prey).

Parasitism

A $(+,-)$ symbiotic interaction where one organism (the parasite) lives on or inside another organism (the host) to derive nutrients, causing harm but usually not immediate death.

Herbivory

A $(+,-)$ feeding interaction where a primary consumer feeds on all or part of a plant species (producer).

Mutualism

A $(+,+)$ interspecific relationship in which both participating species derive a fitness benefit from the interaction.

Commensalism

A $(+,0)$ ecological relationship where one species benefits from the interaction while the other species remains unaffected.

Pathogenicity

A $(+,-)$ relationship in which a pathogen species lives inside a host organism and causes disease.

Detritivore

An organism, such as an earthworm or dung beetle, that ingests non-living organic matter and digests it internally.

Top-down Control

Ecological regulation where higher trophic levels (predators) depress or control the population densities of lower trophic levels (herbivores and producers).

Bottom-up Control

Ecological regulation where the availability of mineral nutrients and primary producers limits the abundance and energy flow to higher trophic levels.

Biomass

The total dry mass of organic matter in individual organisms, trophic levels, or ecosystems.

Gross Production

The total amount of organic matter or chemical energy fixed by autotrophs (primary producers) in an ecosystem per unit time.

Net Production

The amount of organic matter remaining in an ecosystem after subtracting energy expended by producers in cellular respiration, calculated as $NP = GP - R$.

Secondary Productivity

The rate at which consumers accumulate carbon compounds into biomass through assimilation and growth across higher trophic levels.

Carbon Sink

An ecosystem where the rate of photosynthetic carbon fixation exceeds the total rate of cellular respiration, leading to a net accumulation of carbon.

Carbon Source

An ecosystem where total cellular respiration exceeds photosynthetic carbon fixation, resulting in a net release of carbon dioxide to the environment.

Keeling Curve

A long-term graph recording atmospheric carbon dioxide concentrations at the Mauna Loa Observatory in Hawaii since 1959, demonstrating seasonal oscillations and an ongoing upward trend.