IB ESS Topic 2.1

Species

A group of organisms that can interbreed and produce fertile offspring

Habitat

The location in which a community, species, population or organism lives. Includes both geographic and physical locations, as well as ecosystems required to meet all environmental conditions needed

Niche

Particular set of abiotic and biotic conditions and resources upon which an organism or population depends

Fundamental niche

The full range of conditions and resources in which a species could survive/reproduce

Realized niche

The actual conditions and resources in which a species exists due to biotic interactions

S curve

Logistic growth curve that shows how a population grows slowly at first, then accelerates, before leveling off as it approaches carrying capacity

J curve

Growth curve that shows how a population grows exponentially. Only sustained when there no environmental resistance

Carrying capacity

The average size of a population determined by competition for limited resources

Limiting factor

Environmental condition/resource that constrains the growth, distribution or abundance of a population within an ecosystem

Biotic factors

The living components of an ecosystem

Abiotic factors

Non-living physical factors that may influence organisms

Ecosystem

Open systems in which both energy and matter can enter and exit. An ecosystem is a community and the physical environment with which it interacts

Density dependent factors

Factors that become more influential as population density increases, acting like a self-adjusting brake on population growth (ex: predation)

Density independent factors

Factors that can significantly impact population size and include natural disasters, climate change and human activity

Population

Group of organisms of the same species living in the same area at the same time, and which are capable of interbreeding

Community

Collection of interacting populations within the ecosystem

Predator

An animal that naturally preys on others, serving as a natural check on populations, preventing them from exceeding carrying capacity

Prey

Animal that is caught and killed by another for food

Carnivores

Animal that only feeds on other animals

Herbivores

An animal that only feeds on plants

Parasites

Organism that lives in or on a host organism, deriving nutrients from it, often harming the host

Saprotroph

Organism that derives nutrients from decaying organic matter. Do extracellular digestion (enzymes to break down material into simple forms) (ex: bacteria)

Scavengers

An animals that feeds on dead animal, plant or refuse matter (vulture)

Detritivore

Animal that feeds on dead organic matter, especially plant detritus (ex: earthworm)

Decomposer

Ecological role that includes detritivores and saprotrophs

Biosphere

Ecological system composed of individuals, populations, communities and ecosystems. Represents the part of Earth where life exists

Intraspecific competition

Competition between member of the same species

Interspecific competition

Competition between members of different species

Binomial nomenclature

All species have 2 part binomial names. First part is genus (capitalized) and second part is species (not capitalized)

Tools to ID species

Dichotomous key, comparison of specimens with reference to collections by taxonomists, DNA surveys, apps like PlanetNet

How do populations interact in ecosystems?

Herbivory, predation, parasitism, mutualism, disease and competition. All have ecological, behavioral and evolutionary consequences

Ecological niche

The role of a species in an ecosystem. Comprises all biotic and abiotic interactions that influence the growth, survival and reproduction of a population, including how food is obtained

Competition for resources (density dependent factor)

As population grows, competition for limited resources (food, water, shelter) intensifies. Can lead to decreased reproduction and survival rates

Predation risk (density dependent factor)

Dense populations become more conspicuous and easier targets for predators. Reduces population growth. Act as natural check on prey populations

Disease transmission (density dependent factor)

In crowded conditions, diseases spread more easily

R strategist

Species that produces large numbers of offspring so they can colonize new habitats quickly and use short-lived resources. Competitive in young, changeable habitats in early parts of succession. Usually have many eggs/offpspring, give little care to offspring, many die before maturity

K strategist

Species that tends to produce small number of offspring, increasing survival rates and enabling life in long-term climax communities. Give more parental care to offspring, investing more energy in process, so need to be competitive in stable, established environments

Limiting factors on growth of human population have what?

Been increasingly eliminated, resulting in consequences for sustainability of ecosystems. Reduced natural predation, technological advancements, agricultural revolutions, etc. have led to resource depletion, habitat destruction and pollution

Sustainability

Natural property of ecosystems, inputs balanced by outputs in steady-state ecosystem

Keystone species

Species that balances others out (ex: otters eating sea urchins). Have a role in sustainability of ecosystems. Disproportionate impact on community structure of keystone species and risk of ecosystem collapse if they’re removed

Biosphere integrity

Ecosystem damage and loss of species can be slowed by protecting the integrity of ecosystems. Protecting ecosystems ensures the preservation of the niche requirements essential for the ongoing survival of a species

Species classification

Knowing an organism’s taxonomic position tells us about its basic biology and potential vulnerabilities

Temperature changes from climate change

Affect life cycles of plants, which affect life cycles of animals. Life cycles of many species synchronized with those of others and the seasons

Niche requirements

Each species has specific requirements for survival and reproduction. Knowing these requirements (like food source) helps us identify potential threats from human activities that disrupt these needs

Life cycles

A species’ life cycle, from birth to reproduction, reveals critical stages that might be sensitive to human disturbance

Autotrophs vs heterotrophs

Autotrophs make own food, heterotrophs don’t

Balance of nature hypothesis

Nature will always balance itself out

Zone of tolerance

Zones where organisms can go to. Consists of zone of intolerance (can’t survive), zone of psychological stress (few thrive), and optimum range (ideal zone)

Generalist

Organism that can use many resources and eat different things (ex: black bear)

Specialist

Organism that can only use specific resources and eat specific things (ex: panda bears)

Mutualism

2 species rely on each other (ex: oxpeckers and mammals)

Commensalism

One species benefits while other isn’t impacted (ex: remora fish getting transport and food from sharks)

Parasitism

One species benefits while other is negatively affected (ex: tapeworms in humans)

Biome

Group of ecosystems that share similar characteristics. Influenced by latitude. Eath has tropical, temperate and polar zones

Binomial nomenclature categories (big to small)

Domain, kingdom, phylum, class, order, family, genus and species

Competitive Exclusion Principle

No two organisms can occupy a specific niche at the same time