15  •  Ecosystems and Communities 609

Organisms and their environments

Ecosystems have living and non-living components. 610

15.1

What are ecosytems? 610

15.2

Biomes are large ecosystems that occur around the world, each determined by temperature and rainfall. 611

Interacting physical forces create weather. 614

15.3

Global air circulation patterns create deserts and rain forests. 614

15.4

Local topography influences the weather. 616

15.5

Ocean currents affect the weather. 618

Energy and chemicals flow within ecosystems 620

15.6

Energy flows from producers to consumers. 620

15.7

Energy pyramids reveal the inefficiency of food chains. 622

15.8

Essential chemicals cycle through ecosystems. 624

Species interactions influence the structure of communities. 628

15.9

Each species’ role in a community is defined as its niche. 628

15.10

Interacting species evolve together. 629

15.11

Competition can be hard to see, yet it influences community structure. 630

15.12

Predation produces adaptation in both predators and their prey. 631

15.13

Parasitism is a form of predation. 634

15.14

Not all species interactions are negative: mutualism and commensalism. 636

15.15

This is how we do it: Investigating ants, plants, and the unintended consequences of environmental intervention. 637

Communities can change or remain stable over time. 639

15.16

Many communities change over time. 639

15.17

Some species are more important than others within a community. 641

StreetBIO: KNOWLEDGE YOU CAN USE

Life in the dead zone: in boosting plant productivity on farms, we’ve created a “dead zone” in the Gulf of Mexico bigger than Connecticut. 642