Introduction to Biodiversity: Unit 2 APES

Species Diversity

Variety of different species present in a community

Population Resilience

The more genetically diverse a population is, the better it can respond to environmental stressors.

Population Bottleneck

A sharp, sudden reduction in the size of a population, and can be caused by environmental disasters, disease or human activity

Species Richness

Refers to the number of different species found in an ecosystem or community.

Ecosystem services

The varied benefits that humans freely gain from the natural environment and from properly functioning ecosystems.

Provisioning services

Food, fresh water, raw materials, and genetic resources.

Regulating services

Climate regulation, food and erosion control, water purification, disease and pest management

Cultural services

Recreational, educational, aesthetic and spiritual value, and eco-tourism

Supporting services

Nutrient cycling, primary production, soil formation, and habitat provision.

Island biogeography

The study of the ecological relationships and distribution of organisms on islands, and of these organisms’ community structures.

Fundamental Principle of Island Biogeography

Islands have been colonized in the past by new species arriving from elsewhere

Specialist species

An animal or plant that can only thrive in a narrow range of environmental conditions or feed on a very limited diet; species specific niche and avoids competitive exclusion.

Generalist species

An organism that can thrive in a wide range of environmental conditions and use a diverse variety of food and habitat resources; Broad resource use, potential for competitive exclusion and high adaptability.

Many island species have evolved to be what kind of species?

Specialist

Ecological tolerance

The specific environmental range where a species thrives before injury or death.

Three types of Ecological Tolerance levels (As you go down the line it’s increasing environmental stress)

The optimum zone (most healthy), the stress zone (exceeding optimal range, reduced health, growth, and reproduction) and the limit zone (death).

Individual v. Species Tolerance

Each species has its own range of physiological limits vs. the cumulative range across a whole species defines is full ecological niche.

Short-term disruptions

Rapid occurrences with immediate, localized impacts

Long-term disruptions

Gradual changes over geological timescales. Defines entire biomes.

Periodic processes (seasons, tides, orbital variations)

Regular, repeating cycles.

Episodic processes (Forest fires, volcanic eruptions, and floods)

Occasional, intense events with varying intervals.

Random processes (meteorite impacts and earthquakes)

Unpredictable occurrences.

Orbital variations

Cyclical orbital shifts alter solar radiation distribution (Milankovitch Cycles)

Tectonics and Volcanism

Continental movement and eruptions impact currents and the atmosphere

Atmospheric Composition

Greenhouse gas fluxes regulate planetary temperature.

Glacial extent and Sea level

During glacial periods, massive ice sheets locked up vast quantities of ocean water, causing significant drops in global sea level and exposing coastal plains.

Elevation shifts

The Earth’s crust responds elastically to the changing distribution of ice and ocean mass, leading to adjustments in relative landmass elevation.

Thermal Expansion

Rising global ocean temperatures increase the physical volume of water through thermal expansion, which is a major driver of modern sea level rise.

Genetic Adaptation

Selection favors fit traits across generations

Migration and Range Shift

Populations move to follow suitable climatic conditions

Acclimation and Immediate adjustments

Rapid, temporary adjustments within an individual’s lifetime.

Local extinction/Decline

Rapid change exceeds a population’s adaptive capacity.

Process of Natural Selection leads to…

Adaptation

Variation in traits

Genetic diversity and diverse phenotypes exist. (Mutation and recombination)

Selective pressure

Environmental factors determine fitness (predators, resources, and climate)

Differential reproduction

Individuals with favorable traits pass them on (successful traits are more common)

Population adaptations

Over generations, the population matches the environment (drives long-term evolutionary change)

Primary Succession

1) Bare rock start, 2) Soil formation 3) Stable community

Bare rock start (first step in primary succession)

Starting point: No existing soil or living community

Soil formation (second step in primary succession)

Lichens break down rock; small organisms begin to build soil.

Stable community (third step in primary succession)

Complex, long-lived forest; stable species composition

Secondary Succession

1) Disturbance and starting soil 2) Rapid re-colonization 3) Mature community

Keystone species

An organism that has a huge impact on its ecosystem relative to its small population size (sea otter and beaver) has dramatic cascading changes throughout ecosystem when they are removed.

Indicator species

Indicator species provide early warnings of environmental change, guiding ecosystem monitoring and management (an organism—such as a plant, animal, or microbe—whose presence, absence, or population size reflects the overall health and specific environmental conditions of an ecosystem) ex. Lichens and amphibians.

Disturbance and starting soil (first part of secondary succession)

Disturbance clears existing community; nutrient rich soil remains.

Rapid re-colonization (secondary part of secondary succession)

Fast-growing species and opportunistic plants take root.

Mature community (third part of secondary succession)

Complex, resilient community re-established in shorter time.