BIOLOGY CONCEPTS & CONNECTIONS Fourth Edition Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Neil A. Campbell Jane B. Reece Lawrence G. Mitchell Martha R. Taylor From PowerPoint ® Lectures for Biology: Concepts & Connections CHAPTER 36 Communities and Ecosystems Modules 36.1 – 36.4

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Wasps and Pieris caterpillars form an unusual three-step food chain The 4-mm-long wasp Apanteles glomeratus stabs through the skin of a Pieris rapae caterpillar and lays her eggs –The caterpillar will be destroyed from within as the wasp larvae hatch and nourish themselves on its internal organs Dining In

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Ichneumon wasps can detect when a Pieris caterpillar contains Apanteles larvae –A female ichneumon will pierce the caterpillar and deposit her own eggs inside of the Apanteles larvae

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Finally, yet another wasp, a chalcid, may lay its eggs inside the ichneumon larvae Usually, only the chalcids will emerge from the dead husk of the caterpillar

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings A biological community derives its structure from the interactions and interdependence of the organisms living within it Ecosystem functioning depends on the complex interactions between its community of organisms and the physical environment

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings All the organisms in a particular area make up a community A number of factors characterize every community –Biodiversity –The prevalent form of vegetation –Response to disturbances –Trophic structure (feeding relationships) 36.1 A community is all the organisms inhabiting a particular area Figure 36.1

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Biodiversity is the variety of different kinds of organisms that make up a community Biodiversity has two components –Species richness, or the total number of different species in the community –The relative abundance of different species

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Interspecific competition occurs between two populations if they both require the same limited resource A population's niche is its role in the community –The sum total of its use of the biotic and abiotic resources of its habitat 36.2 Competition may occur when a shared resource is limited STRUCTURAL FEATURES OF COMMUNITIES

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings The competitive exclusion principle –Populations of two species cannot coexist in a community if their niches are nearly identical Figure 36.2 High tide Chthamalus Balanus Low tide Ocean

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Competition between species with identical niches has two possible outcomes –One of the populations, using resources more efficiently and having a reproductive advantage, will eventually eliminate the other –Natural selection may lead to resource partitioning

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Predation is an interaction where one species eats another –The consumer is called the predator and the food species is known as the prey Parasitism can be considered a form of predation 36.3 Predation leads to diverse adaptations in both predator and prey

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings As predators adapt to prey, sometimes natural selection also shapes the prey's defenses This process of reciprocal adaptation is known as coevolution –Example: Heliconius and the passionflower vine Figure 36.3A Eggs Sugar deposits

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Prey gain protection against predators through a variety of defense mechanisms –Mechanical defenses, such as the quills of a porcupine

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Chemical defenses are widespread and very effective –Animals with effective chemical defenses are often brightly colored to warn predators –Example: the poison-arrow frog Figure 36.3B

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Camouflage is a very common defense in the animal kingdom –Example: the gray tree frog Figure 36.3C

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Batesian mimicry occurs when a palatable or harmless species mimics an unpalatable or harmful one –The mimicry can even involve behavior –This hawkmoth larva puffs up its head to mimic the head of a snake Figure 36.3D

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Müllerian mimicry is when two unpalatable species that inhabit the same community mimic each other –Example: the cuckoo bee and the yellow jacket Figure 36.3E

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings A keystone species exerts strong control on community structure because of its ecological role A keystone predator may maintain community diversity by reducing the numbers of the strongest competitors in a community –This sea star is a keystone predator 36.4 Predation can maintain diversity in a community Figure 36.4A

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Predation by killer whales on sea otters, allowing sea urchins to overgraze on kelp –Sea otters represent the keystone species Figure 36.4B