Chapter 19 Lecture Outline See separate PowerPoint slides for all figures and tables pre-inserted into PowerPoint without notes. Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
19.10 Coevolution and Symbiosis In a symbiosis, two or more kinds of organisms live together in often elaborate and more or less permanent relationships there are three major kinds of symbiotic relationships mutualism commensalism parasitism
19.10 Coevolution and Symbiosis Mutualism is a symbiotic relationship in which both species benefit Figure 19.24 The pistol shrimp defends the coral, which he calls home an example of mutualism
19.10 Coevolution and Symbiosis Commensalism is a symbiotic relationship that benefits one species but neither hurts nor helps the other Figure 19.25 Oxpeckers eat insects off an impala an example of commensalism http://www.youtube.com/watch? v=qqa0opbdvjw
19.10 Coevolution and Symbiosis Parasitism is a symbiotic relationship in which one species benefits while the other is harmed Figure 19.26 The head louse, shown here with its egg, feeds on its host and is an example of parasitism http://www.youtube.com/watch?v=vmg- LWyNcAs
19.11 Predation Predation is the consuming of one organism by another in nature, predators often have large effects on prey populations population cycles may be, in some situations, stimulated by predators a classic example is the 10-year cycle of the snowshoe hare, Lepus americanus, that appears to be under the influence of food plants and predators under laboratory conditions, predators may exhaust their prey species and then starve http://www.youtube.com/watch?v=e5nfvszcjdc
Figure 19.29 A predator-prey cycle
Figure 19.28 Predator-prey in the microscopic world
19.11 Predation Predator-prey interactions are an essential factor in the maintenance of communities that are rich and diverse in species predators prevent or greatly reduce competitive exclusion by reducing the number of individuals of competing species
Figure 19.30 Predation reduces competition Sea stars prevent bivalves to monopolize the habitat, when the number of sea stars fall down the number of species occupying the same habitat decreases
19.12 Plant and Animal Defenses Plants have evolved many mechanisms to defend themselves against predators Physical defenses: spines, thorns, prickles Chemical defenses: chemicals that make the plants toxic to herbivores (e.g. mustard) some herbivores have, as a result, evolved a tolerance to these chemicals and may use them for their own defense
Figure 19.31 Insect herbivores are well suited to their hosts Although mustard oil is toxic to many insects, caterpillars of cabbage butterfly are able to break down the mustard oil compounds
Figure 19.32 Warning coloration serves as a defense mechanism in Dendrobatidae many animals have defensive coloration aposematic coloration is a warning coloration that is characteristic of animals that use poisons cryptic coloration is color that blends in with surroundings
Figure 19.33 Cryptic coloration
19.12 Plant and Animal Defenses Predation can exert strong selective pressures on prey populations a coevolutionary arms race between predators and prey is likely because any feature that acts to decrease the probability of capture should thus be strongly favored by selection in prey natural selection would also favor counteradaptations in predators
19.13 Mimicry Batesian mimicry is when a palatable species resembles a poisonous one there may also be nonvisual cues, such as olfaction, involved
Figure 19.35 Müllerian mimics Müllerian mimicry is when several unrelated, but protected, species come to resemble one another for example, the colors black, yellow, and red are used often in aposematic coloration
19.13 Mimicry Self mimicry is a special case of mimicry in which one animal body part comes to resemble another body part this occurs in both prey and predators prey might use this form of mimicry to startle a predator or to provide a false target for attack predators might use this mimicry to simulate bait to lure prey in
Figure 19.36 Self mimicry
WEEK 8 IN WEEK 8, We watched a documentary called: an inconvenient truth. There are no slides for this week