Chapter 53 Reading Quiz

2. Chapter 53 Reading Quiz • A bunch of populations living close together and possibly interacting is called a ____. • Which type of interspecific interaction is beneficial to both species? • “Cryptic coloration” is also known as… • The links in a food chain are also called ____ levels. • The sum weight of all individuals in a population is known as the …

3. 1. Explain the relationship between species richness, relative abundance, and diversity. • Species diversity  the number and relative abundance of species in a biological community • Species richness  the number of species in a community • Relative abundance  a measure of the proportion of a species in the community as a whole 

4. 2. Distinguish between the “individualistic hypothesis” and the “interactive hypothesis”. • The individualistic hypothesis depicted a community as a chance assemblage of species found in an area because they have similar abiotic requirements • The interactive hypothesis saw each community as an assemblage of closely linked species having mandatory biotic interactions that cause the community to function as an integrated unit 

6. 3. Explain how interspecific competition may affect community structure. • Interspecific interactions are those that occur between populations of different species living together within a community • Competition will result in one species being dominant over the other • “Niches” come into play, and only one species may occupy a niche; the other must adapt to a different niche or not survive 

8. 4. What is coevolution? • Coevolution  a change in one species that acts as a selective force on another species - counteradaptation of the second species, in turn, affects selection of individuals in the first species 

9. 5. Describe the variations of predation and parasitism. • Can have positive, negative, or neutral effects on the species involved • Predation and parasitism are both (+/-) interactions • Predation • Parasitism • Parasitoidism • Herbivory 

10. 6. What are some defenses that animals and plants have against being eaten? • Plants: - thorns, spines, hooks - chemicals, hormone analogues • Animals: - passive, active, mechanical, or chemical - cryptic coloration, shape - aposematic coloration (bright warning) - mimicry 

12. 7. Describe the competitive exclusion principle, what niches are, and the evidence that competition exists in nature. • The competitive exclusion principle predicts that two different species competing for the same limiting resources cannot coexist in the same community - one will use resources more efficiently, thus reproducing more rapidly and eliminating the inferior competitor • An ecological niche is the sum total of an organism’s use of biotic and abiotic resources in it’s environment - how it “fits into” an ecosystem • The weaker organism will become extinct OR • One of the species will evolve to the point of using a different set of resources 

13. 8. Distinguish between commensalism and mutualism. • Commensalism is a (+/0) interaction in which the symbiont benefits and the host is unaffected ex: cowbirds & cattle; sharks & remoras • Mutualism is a (+/+) interaction requiring the evolution of adaptations in both species ex: flowers & insects; lichen 

15. 9. How do predators, mutualism, and parasitism alter community structure? • Predators can alter community structure by moderating competition among prey species (Ex: zebras & lions) • Mutualism can have community-wide effects (Ex: mycorrhizae fungi) • Parasitic diseases that reduce populations of one species also impact other species 

16. 10. Explain how disturbance is one of the most prominent features of most communities. • Disturbances are events that disrupt communities - they change resource availability and create opportunities for new species - the impact depends on the size, frequency, and severity of the disturbance - can be caused by natural disasters, overgrazing by animals, alteration on natural ecosystems 

17. 11. Why do we consider humans to be the most widespread agents of disturbance? • Logging and clearing for farmland has reduced and disconnected forests • Agricultural development disrupts grasslands • Centuries of overgrazing by animals has contributed to the famine in parts of Africa • Human disturbances usually reduce biodiversity 

18. 12. Describe the stages of succession. • Primary succession  when life begins in areas essentially barren due to lack of formed soil - volcanoes, retreated glaciers • Secondary succession  if an existing community has already been cleared by some disturbance that leaves the soil intact 

21. 13. What accounts for the geographical ranges of species? • Biogeography  the study of the past and present distribution of individual species and entire communities • Limitation of a species to a particular range may be due to: - failure of the species to disperse beyond its current range - failure of pioneer individuals that spread beyond the observed range - the species having retracted from a once larger range to its current boundaries 

22. 14. Describe island biogeography. • Islands provide opportunities to study factors affecting species diversity of communities due to their isolation and limited size • # of species determined by immigration and emigration, which are determined by island size and distance from mainland • Smaller islands have higher extinction rates • The farther away an island is from mainland, the less species, relative to island size 