Intermediate disturbance hypothesis communities that

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Biology: The Unity and Diversity of Life
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Chapter 45 / Exercise 15
Biology: The Unity and Diversity of Life
Starr/Taggart
Expert Verified
INTERMEDIATE DISTURBANCE HYPOTHESISCommunities that experience intermediatelevels of disturbance will contain highest possible species richness because more species can coexist within community.If disturbance is:1.FREQUENT – favours good colonizers.2.RARE – favours good competitors.3.INTERMEDIATE – neither is favoured, both types persistSpecies richnessDisturbance frequency
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Biology: The Unity and Diversity of Life
The document you are viewing contains questions related to this textbook.
Chapter 45 / Exercise 15
Biology: The Unity and Diversity of Life
Starr/Taggart
Expert Verified
DISTURBANCE INTENSITY ALSO MATTERS!Intensity (severity) – death toll / destruction Frequency – how often disturbance occurs
Q2: THINK-PAIR-SHAREBased on what you know about predator- mediated coexistence, and now the impacts of disturbance on an area, how might these factors influence the biodiversity of an area?
EX. ALGAL SUCCESSION ON ROCKY SHORESousa(1979)Studied effects of wave action on community succession on rocky shore of southern CaliforniaWave action = disturbanceSubstrate: bouldersWave action is highest on small boulders (45%), intermediate on medium boulders (9%) and lowest on large ones (0.1%)
EX. ALGAL SUCCESSION ON ROCKY SHOREAlgalSuccessionUlva speciesGelidium coulteri Gigartina leptorhynchos Rhodoglosom affine
EX. ALGAL SUCCESSION ON ROCKY SHOREResults:Small boulders – dominated by Ulva species (green algae)Medium-sized boulders – mix of patches at all stages of succession, with 3-5 species per rock on average (highest species richness)Large boulders – monoculture of G. canaliculata(lowest species richness of all three rock sizes)
3) ENVIRONMENTAL AGE: EVOLUTIONARY TIMECommunities with recent large-scale disturbancesLower species diversity due to disturbanceEx) volcanic eruptions, glaciation eventsYounger communitiesNot all species have reached community yetSpecies present may not have had time to adapt to fill all available niches
Q3: THINK-PAIR-SHAREThe tropics are often described as both a cradle and a museum with respect to the level of biodiversity found there.Why do you think we apply the terms cradle and museum to the tropics?
BIODIVERSITY HOTSPOTSBiodiversity hotspot – an area with high biodiversity (contains many endemic species) that is threatened with habitat loss (generally due to human actions)
Reefs provide many importantfunctions:Natural barrier that protects shorelines from storm surges and erosion due to regular wave actionAre integral element of many aquatic ecosystemsFood and shelter for many aquatic organismsOnly cover 1% of earth’s surface but house 25% of marine fish speciesYield compounds that have been used to treat cancer, HIV, cardiovascular disease, etc.CORAL REEFS ARE MARINE HOTSPOTS
CORAL REEF ECOSYSTEMS IN SERIOUS DANGERReefs are in seriousdangerOverfishingSedimentationNutrient pollutionGlobal warming (temperature, ocean acidification)
GREAT BARRIER REEF BLEACHING EVENTShttp://-change/bleaching-is-a-real-bitch-great-barrier-reef- tourism-headed-for-tough-times-20170317-gv0y2v.html
NOT ALL SPECIES HAVE EQUAL EFFECT ON COMMUNITY

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