exam4 bio2 ch 54

Explain how species diversity varies with latitude

Species richness generally declines from the tropics to the poles. This is due to factors like evolutionary history and climate. Tropical regions are older and have had more time for speciation, while temperate and polar regions have been reset by glaciations. The climate in the tropics, with high sunlight and precipitation, supports higher evapotranspiration rates, correlating with greater species richness

Super simple summary:

• Near the equator → lots of species

• Near the poles → fewer species

Explain how species diversity varies with area

Larger geographic areas tend to support more species due to a wider variety of habitats and resources available. This principle is formalized in the species-area curve

Explain how species diversity varies with disturbance patterns

According to the intermediate disturbance hypothesis, moderate levels of disturbance can foster higher diversity than low or high levels. Disturbances create opportunities for different species through ecological succession.

Super simple summary:

• Too calm → a few species take over

• Too chaotic → nothing survives well

• Just right → the most species can live there 🌱

No single factor explains all global diversity patterns; instead…

it's a combination of these elements that shapes biodiversity across different regions

primary succession

Occurs in lifeless areas, such as new volcanic islands or glacial moraines. Initial colonizers are prokaryotes and protists, followed by lichens and mosses. Soil develops gradually, allowing grasses, shrubs, and trees to establish over hundreds or thousands of years.

Super simple summary:

• No life → tiny life → soil → bigger plants → full ecosystem

secondary succession

Happens after disturbances like fires remove most organisms but leave soil intact. Herbaceous plants recolonize first, followed by woody shrubs and forest trees if conditions allow.

Processes in Succession Patterns

Facilitation, Inhibition, Tolerance

Explain the processes of facilitation in succession patterns

Early species improve conditions for later arrivals (e.g., increasing soil fertility).

Explain the processes of inhibition in succession patterns

Early species hinder later species' establishment; later species succeed despite early ones

Super simple summary:

• Early species block others → later species take over when early ones are removed

Explain the processes of tolerance in succession patterns

Later species tolerate conditions without being affected by early arrivals.

Larger Islands: Apply the equilibrium model of island biogeography to make predictions about an island's diversity based on its size

Tend to have higher species diversity due to more available resources, diverse habitats, and larger population sizes, which reduce extinction rates.

Smaller Islands: Apply the equilibrium model of island biogeography to make predictions about an island's diversity based on its size

Experience lower immigration rates and higher extinction rates, leading to fewer species.

Closer Islands: Apply the equilibrium model of island biogeography to make predictions about an island's diversity based on its distance from the mainland

Have higher immigration rates because species can more easily reach them, which also helps maintain lower extinction rates

Farther Islands: Apply the equilibrium model of island biogeography to make predictions about an island's diversity based on its distance from the mainland

Experience lower immigration rates and higher extinction rates, resulting in fewer species

According to MacArthur and Wilson's model, an equilibrium is reached where…

the rate of species immigration equals the rate of species extinction. This equilibrium number of species is influenced by the island's size and proximity to the mainland. Larger and closer islands generally support more species, as demonstrated in experiments with mangrove islands in the Florida Keys.

community

A biological community consists of all the species that inhabit a particular area and interact with each other.

interspecific interaction

These are interactions between individuals of different species, affecting their survival and reproduction. They include competition, exploitation (like predation), and positive interactions (such as mutualism).

competition

This occurs when individuals of different species use a limited resource, reducing the survival or reproduction of both. For example, weeds compete with garden plants for nutrients.

competitive exclusion

The principle stating that two species competing for the same resources cannot coexist permanently in the same place; one will outcompete the other.

ecological niche

The role and position a species has in its environment, including how it obtains resources and interacts with other organisms.

resource partitioning

Differentiation of niches that allows similar species to coexist by utilizing different resources or environments.

predation

An interaction where one organism, the predator, kills and eats another organism, the prey.

aposematic coloration

Bright coloration in animals that serves as a warning to predators about their toxicity or unpalatability.

cryptic coloration

a defense mechanism where animals match their surroundings' colors, patterns, and textures to avoid detection by predators or prey

mimicry

Batesian mimicry involves a palatable species mimicking an unpalatable one for protection

herbivory

An interaction where an herbivore eats part of a plant or alga, benefiting the herbivore and harming the plant.

symbiosis

A broad term encompassing interactions like mutualism, commensalism, and parasitism

parasitism

The parasite benefits by deriving nourishment from its host, which is harmed in the process.

mutualism

Both species involved benefit from the interaction.

commensalism

One species benefits while the other is neither helped nor harmed.

facilitation

colonizing species changed the environment so that it becomes more suitable

for the next species

species richness

Species richness refers to the number of different species in a community

species diversity

Species diversity includes both richness and relative abundance of each species. More diverse communities often produce more biomass and are more stable.

biomass

The total mass of all living organisms in a given area or ecosystem at a certain time.

keystone species

A less abundant species that has a disproportionately large effect on its environment relative to its abundance. They play a critical role in maintaining the structure of an ecological community.