Ecology Week 10, Lecture 17

Ecology - Week 10, Lecture 17

• Competition is the use or defense of a resource by one individual that reduces that resource for others.
• There are two main types of competition: interference and exploitative.
• Interference competition involves direct interaction, such as physical aggression or territorial fights.
• Exploitative competition means depleting shared resources, such as bats, hummingbirds, and nectar.

Ecological Niche

• A realized niche is the range of abiotic and biotic conditions a species can tolerate and the ways of life it pursues.
• A realized niche is often conceived as a multidimensional space.
• A realized niche can be subdivided into components, like feeding niche or roosting niche.
• Niche axes can include variables such as water depth, prey size, salinity, predator density, nesting sites, hiding sites, activity patterns (diurnal?), and temperature.

Adaptive Radiation

• Adaptive radiation is the recent, rapid diversification of a clade in response to the opening of new niche space.
• Examples include African cichlids and Darwin's finches.
• Specific examples of African cichlids and their diets are provided, such as Genyochromis mento (eats fish scales and fins), Caprichromis orthognathus (eats baby fish and eggs), Trematocranus placodon (eats mollusks) and others.
• Specific examples of Darwin's finches and their dietary adaptations are provided, such as the small ground finch which crushes seeds.

Darwin's Finches

• Darwin's finches, located in the Galapagos Islands, exhibit beak variations correlated to specific diet types.
• Finch beaks are categorized as crushing, probing, sharp, and grasping.
• Different finch species have different beak shapes and thus different dietary specializations.

Hawaiian Honeycreepers

• Hawaiian honeycreepers are an example of adaptive radiation.
• Diversification occurred in response to the opening of new habitats and food resources.

Species Diversity in Streams

• Species diversity increases as the stream size increases.
• The species diversity increases due to increased habitat and food diversity.
• Several examples are provided, such as Xiphophorus variatus, Poecilia mexicana, Gambusia regani, Cichlasoma cyanoguttatum, etc.

Competition and Resource Use

• Resource partitioning is when co-occurring species use different resources.
• Examples include fish size eaten by co-occurring seabirds or foraging heights of warblers.
• Processes that could cause resource partitioning include Species Sorting (process that determines community composition based on species ability to invade, given biotic and abiotic conditions) and Character Displacement (process by which co-occurring species evolve differences to reduce competition)

Competitive Exclusion Principle

• Two species cannot live together indefinitely on the same limiting resource.
• Limiting resource means factors that increase population size when increased.
• Complete competitors cannot coexist.

Resources

• Resources are substances or factors required by an organism for normal growth, maintenance, and reproduction.
• Resources can be depleted.
• Decreased resources lead to decreased population size.
• Plants' resources include nutrients, sunlight, pollinators/seed dispersors, and water.
• Animal resources include food, roosting spaces, nesting sites, water, and mineral licks.
• Variables such as temperature, water salinity, water depth, or activity patterns aren't considered as resources.

Character Displacement

• Character displacement is the process where co-occurring species evolve differences to reduce competition.

• Examples mentioned include beak depth differences in Galapagos finches.

• Different beaks of finches are adapted to feed on different types of seeds.

This quiz covers competition in ecology, specifically the two main types: interference and exploitative competition. Additionally, it addresses ecological niches and adaptive radiation, exploring how species adapt to their environments. Test your understanding of these fundamental ecological concepts.