ESPM 15 Midterm 1 - Lecture 13: Biodiversity

Alpha vs beta vs gamma diversity?

Alpha = within one habitat; beta = turnover between habitats; gamma = regional total

Where is biodiversity highest, and why are mountains diverse?

Near the equator (latitudinal gradient); mountains have more niches from topographic variation

Extirpation vs extinction?

Extirpation = disappears from part of its range (local); extinction = gone globally

What does HIPPO stand for?

Habitat loss, Introduced species, Pollution, Population growth, Overexploitation

Which is NOT a key threat to biodiversity: co-extinction, natural disasters, pollution?

Natural disasters

What are the 4 dimensions of biodiversity?

Taxonomic, phylogenetic, genetic, functional

Species richness vs evenness?

Richness = number of species; evenness = how evenly individuals are spread among them

Give two explanations for the latitudinal diversity gradient

More solar energy and longer growing seasons near the equator; greater habitat area and longer evolutionary time in the tropics

How do drivers like habitat complexity and disturbance raise biodiversity?

They create more niches and prevent competitive exclusion

How does disturbance raise diversity? (the mechanism)

It knocks back dominant competitors and opens space, so weaker competitors get a foothold instead of being excluded

How do species interactions themselves drive diversity?

Predation, competition, and mutualism force specialization and open new niches

What is phylogenetic diversity?

How evolutionarily distinct the species are — deep, unique branches of the tree of life

Genetic vs functional diversity?

Genetic = variation in genes within and between populations; functional = variety of ecological roles and traits

Why does habitat complexity raise diversity?

More microhabitats mean more niches, so more species can coexist without outcompeting each other