Apesunit 2

Three levels of biodiversity

1. Genetic diversity 2. Species diversity 3. Ecosystem diversity

Genetic diversity and environmental disruptions

Genetic diversity increases the likelihood of species survival during environmental changes because different genes can provide advantages in changing conditions.

Species richness

The number of different species represented in an ecological community, landscape, or region.

Species richness and ecosystem resilience

Greater species richness leads to higher ecosystem resilience because the variety of species can support ecosystem functions better when conditions change.

Impact of habitat loss on species

Generalist species may thrive as they can adapt to a wide range of environments, while specialist species may decline or face extinction due to their dependency on specific habitats.

Four categories of ecosystem services

1. Provisioning services 2. Regulating services 3. Cultural services 4. Supporting services

Provisioning services

Provisioning services provide resources such as food, water, and raw materials. Example: Fisheries providing fish for food.

Regulating services

Regulating services control natural processes, such as climate regulation and flood control. Example: Wetlands filtering water and controlling floods.

Cultural services

Cultural services provide non-material benefits, such as recreational, aesthetic, and spiritual benefits. Example: National parks offering recreational opportunities.

Supporting services

Supporting services are essential for the production of all other ecosystem services, such as nutrient cycling and soil formation. Example: Pollination of crops by bees.

Anthropogenic activity and provisioning services

Overfishing can deplete fish stocks, disrupting the provisioning service of fisheries.

Theory of island biogeography

The theory explains that the number of species on an island is determined by its size and distance from the mainland; larger and closer islands tend to have more species.

Species richness on islands

Islands that are further away have lower immigration rates of species, which leads to less diversity.

Colonization in island biogeography

Colonization is the process by which species establish a population in a new habitat, such as an island.

Specialist vs. generalist species on islands

Islands often have unique ecological niches and limited resources, which favors species that are adapted to specific conditions.

Conditions for range of tolerance

1. Temperature 2. Salinity 3. pH 4. Moisture levels

Genetic diversity and ecological range of tolerance

Higher genetic diversity within a population allows for a broader range of tolerance to environmental conditions.

Ecological tolerance

Ecological tolerance refers to the range of conditions that an organism can withstand before suffering harm.

Zones of ecological tolerance

1. Zone of optimal tolerance 2. Zone of physiological stress 3. Zone of intolerance

Organism response in ecological tolerance zones

In the optimal zone, organisms thrive; in the stress zone, they experience reduced growth and reproduction; in the intolerant zone, they may die.

Physiological stressor example

A fish experiencing hypoxia (low oxygen levels) in water could face stress leading to mortality.

Natural ecosystem disruptions

1. Wildfires 2. Hurricanes 3. Earthquakes

Periodic, episodic, and random events

Periodic events occur at regular intervals; episodic events occur irregularly but are predictable; random events happen unexpectedly.

Reasons for Earth's climate change

1. Volcanic activity 2. Changes in solar radiation 3. Plate tectonics

Sea level variation factors

Sea level changes are influenced by glacial cycles, tectonic activity, and thermal expansion of water.

Migration in ecological terms

Migration is the movement of organisms from one region to another, often in search of better resources or conditions.

Reasons for population migration

1. Seasonal changes (food availability) 2. Climate change 3. Breeding opportunities

Adaptation

Adaptation is a trait that enhances the survival and reproductive success of an organism in its environment.

How adaptations arise

Adaptations arise through natural selection, where beneficial traits become more common over generations.

Natural selection

Natural selection is the process by which organisms better adapted to their environment tend to survive and produce more offspring.

Selective force

A selective force is an environmental factor that influences which traits are advantageous. Example: Predation can select for faster prey.

Environmental change and evolution/extinction

If a species cannot adapt to rapid environmental changes, it may evolve new traits to survive or face extinction.

Primary succession

Primary succession is the establishment of a biological community in an area where no soil exists, such as after a volcanic eruption.

Secondary succession

Secondary succession occurs in areas where a disturbance has destroyed a community but left the soil intact, such as after a forest fire.

Keystone species

A keystone species is one that has a disproportionately large impact on its ecosystem relative to its abundance.

Example of a keystone species

Example: Sea otters; they control sea urchin populations, which helps maintain kelp forest ecosystems.

Indicator species

An indicator species is one that reflects the health of an ecosystem, as its presence or absence can indicate environmental conditions.

Pioneer species

Pioneer species are the first organisms to colonize previously disrupted or damaged ecosystems.

Example of a pioneer species

Example: Lichens, which can grow on bare rock and contribute to soil formation.

Climax community

A climax community is a stable and mature ecological community that undergoes little change in species composition.

Example of a climax species

Example: Oak trees in temperate forests.