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AP Environmental Science

Mr. Grant

Lesson 28

Evolution, Biodiversity, and

Population Ecology

Levels of Ecological Organization

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Mastery Check

Describe the steps involved in allopatric speciation.

 

When a population is split into two populations that become geographically and reproductively isolated from each other, they may evolve over time, in their different environments and under different selective pressures, into different species. This is called allopatric speciation.

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Objectives:

• Define the terms ecosystems and niche.

• List the levels of ecological organization.

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Ecosystems: All organisms and nonliving entities that occur and interact in a particular area at the same time.

Niche: The functional role of a species in a community.

Define the terms ecosystems and niche.

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List the levels of ecological organization.

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We study ecology at several levels

Ecology and evolution are tightly intertwined

Biosphere = the total of living things on Earth and the areas they inhabit

Community = interacting species that live in the same area

Ecosystem = communities and the nonliving material and forces they interact with

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We study ecology at several levels

Population ecology = investigates the dynamics of population change The factors affecting the distribution and abundance

of members of a population

Why some populations increase and others decrease

Community ecology = focuses on patterns of species diversity and interactions

Ecosystem ecology = studies living and nonliving components of systems to reveal patterns Nutrient and energy flows

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Each organism has habitat needs

Habitat = the environment where an organism lives It includes living and nonliving elements

Habitat use = each organism thrives in certain habitats, but not in others Results in nonrandom patterns of use

Habitat selection = the process by which organisms actively select habitats in which to live Availability and quality of habitat are crucial to an

organism’s well-being

Human developments conflict with this process

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Each organism has habitat needs

Habitats vary with the body size and needs of species A soil mite vs. an elephant

Species have different habitat needs at different times Migratory birds use different habitats during migration,

summer, and winter

Species use different criteria to select habitat Soil, topography, vegetation, other species

Water temperature, salinity, prey

Species survival depends on having suitable habitat

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A specialized frog

• Epiphytes grow on trees for support

- Obtaining water from the air

- They collect pools of rainwater and pockets of leaf litter

- Frogs lay their eggs in these rainwater pools

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Niche and specialization are key concepts in ecology

Niche = summary of everything an organism does Use of resources

Functional role in a community: habitat use, food selection, role in energy and nutrient flow, interactions with other individuals

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Niche and specialization are key concepts in ecology Specialists = species that have narrow niches and specific

needs

Extremely good at what they do

But vulnerable when conditions change

Generalists = species with broad niches

Use a wide array of habitats and resources

Can live in many different places

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TED Video

Nalini Nadkarni: Conserving the Canopy (16:30)

Called "the queen of canopy research," Nalini Nadkarni explores the rich, vital world found in the tops of trees. She communicates what she finds to non-scientists — with the help of poets, preachers and prisoners.

A unique ecosystem of plants, birds and monkeys thrives in the treetops of the rainforest. Nalini Nadkarni explores these canopy worlds — and shares her findings with the world below, through dance, art and bold partnerships.