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Biodiversity 2 Components of Species Diversity: • Species RichnessNumber of species • Species Evenness Relative abundance of each species. Diversity in Ecosystems • Species richness seems to increase productivity and stability or sustainability. Better able to withstand environmental disturbances. • How much species richness is needed is debatable Ecological Niche vs. Habitat Habitat: the location that a species is found in an ecosystem. Niche: the ___________________ of a species in an ecosystem. includes: • conditions (physical & chemical); • resources (such as nutrients or food); • interactions with biotic & abiotic components of the ecosystem; • role in flow of energy cycling of matter. Habitat is like "address" of an organism. Niche is like "occupation" of an organism. Generalists vs. Specialists Generalists: have __________ niches (for example eat many types of food); Examples: cockroaches, coyotes, humans Specialists: have __________ niches (for example require a specific type of habitat); Examples: giant pandas, which eat primarily bamboo Discuss with your table partner the advantages and disadvantages of being either a specialist or a generalist. Fill in your answers on the next slide. Is it better to be a generalist or a specialist? Specialists may have the advantage when environmental conditions are more constant because may be able to _____________ other species for specific resources; ____________ ___________________________ Generalists may have the advantage when environments are rapidly changing, because ____________ ________________; but __________ _______________________________ Native species: species that normally live in a particular ecosystem. Nonnative species: (also called exotic, alien, or ____________ species) originate in other ecosystems; May enter an ecosystem by migration or by deliberate or accidental introduction by humans; •example: "killer bees" Addressing Invasive Species •Prevention- Customs controls etc. •Containment •Removal •Encouraging _________________ of invasive species Example- promotion of nutria as a fur and meat source. Endemic species: Species that are found nowhere else on Earth (type of native species). Often, there are many endemic species on __________ because they are isolated. Examples: Austrian ghost bat, Galapagos marine iguana, Madagascar lemur Indicator species: species that serve as ________________ that a community or ecosystem is being damaged: Examples: •Decline of migratory songbirds in North America indicates loss/ fragmentation of habitat; • Presence of trout in mountain streams is an indicator of good water quality; • Presence of spotted owls is indicator of healthy old–growth forest. Case of the Vanishing Frogs • Habitat loss and fragmentation • Prolonged drought • Pollution • Increase in UV radiation • Parasites • Viral and fungal diseases • Climate change • Overhunting • Nonnative predators and competitors •https://www.youtube.com/watch?v=_lWQLd5U0g8 Vanishing Frogs Video (2 min.) Keystone species: species that play a critical role in an ecosystem: _____________ and ____________ are often keystone species. Examples: • Sea otters prevent sea urchins from depleting kelp beds; • Dung beetles remove animal waste; "The loss of a keystone species is like a drill accidentally striking a power line. It causes lights to go out all over.“ –– E.O. Wilson Foundation Species: Create or enhance their habitat in a way which benefits other species. Examples: Beaver Elephant Discuss with your table partner: Sea stars eat mussels, and urchins in tide pools. These animals have no other natural predator. The graph below indicates the biodiversity with and without sea stars present. Determine if this demonstrates that the sea star is an endemic species, indicator species or keystone species. _________________________________________ _________________________________________ An experiment by Robert Paine showed that without Pisaster (Sea stars) biodiversity decreased. Types of Species Interactions Biotic Interactions: • Predation: members of one species (predator) feed on another species (prey); • Interspecific competition: when two or more species use the same limited resource and adversely affect each other Example: fire ants and native ants in North America; fire ants are better competitors; sharply reduce populations of native species. Intra = _____________ Inter = ______________ Review with your table partner ___________ ___________ ___________ ___________ ___________ http://www.youtube.com/watch?v=yjqIvKKMGSY Is the video showing inter or intraspecies competition? When gulls chase away an eagle from their territory, is it inter or intraspecies competition? ___________________________________ Interspecific competition results because of niche overlap = overlap in requirements for limited resources. Types of Competition: • Interference competition: one species limits another species' __________ to a resource; e.g., hummingbirds defending feeding territories. • Exploitation competition: competing species both have access to a limited resource, but one exploits the resource more __________ or ____________. Discuss with your table partner: After watching the following two video clips determine whether each type of plant competition for light is exploitation competition or interference competition. Strangler Fig: Private Life of Plants (3:30 minutes) http://www.youtube.com/watch?v=UCUtpmwacoE Giant Water Lilies: Private Life of Plants (to 2 min.) http://www.youtube.com/watch?v=igkjcuw_n_U Principle of Competitive Exclusion G.P. Gausse, in a classical experiment (1934), showed that two species with identical niches can not coexist indefinitely. This is called the principle of competitive exclusion. Note that when grown together, Paramecium aurelia outcompetes Paramecium caudatum. Discuss with your table partner: The graph below shows the seed size consumed by two different species. Predict how this type of interspecific competition might shape the natural selection of each species. How might the distribution of each species for this resource use be affected? Draw new graph for results. Hint: what subset of each species is most likely to survive? •Species 1 might adapt by_____________________. •Species 2 might adapt by_____________________. Resource Partitioning This process of different species _______________ _____________________is called resource petitioning. It can allow species with similar resource requirements can coexist because they use limited resources at different times, in different ways, or in different places. Resource petitioning is an ____________ process. When the niche of two species overlap, organisms in each species may be likely to survive using the resource in a way that is not in direct competition. Examples of Resource Partitioning Sharing the Wealth Competition AND the environment can limit distributions of organisms Types of Species Interactions Symbiosis: a long–lasting relationship in which species live together in intimate association. Mutualism Commensalism Parasitism 3 Types of Symbiosis Mutualism: two species interacting in a way that benefits both. Example: ants live in type of swollen thorn acacia. Tree provides nectar food source and ants defend tree from predators. Symbiosis Cont. Commensalism: one organism benefits from another, but neither helps nor harms that other organism Example: epiphyte growing on a tree (epiphyte benefits & tree not usually affected). Symbiosis cont. Parasitism: one organism (parasite) lives on part of another organism (host), host is harmed, Endoparasite: lives inside host (tapeworm) Ectoparasite: lives outside host (lamprey eel, mistletoe) Succession Succession: gradual & fairly predictable change in ___________________________. •Pioneer species: the first species to colonize •The progression of species that colonize with time are commonly termed early, mid, & late successional species. Discuss with your table partner: Compare the characteristics of two different trees below and predict which would come earlier in the succession process. Predict which type of tree would tend to be more dominant in the later stage of succession. Be able to explain your answers. Primary Succession Primary succession occurs in an area where _________ ____________________. Examples: • newly formed islands • after the retreat of a glacier •Typically lichens & mosses first colonize bare rock; •Latter small herbs & shrubs colonize; •Next faster growing tree species that have high light requirements become established •Finally, trees with lower light requirements establish mature community and are able to ___________ earlier species. Primary Succession on the Galapagos Islands Secondary Succession Secondary succession occurs where an area has been disrupted, but ______ _______________________. Example: abandoned field According to the classic view, succession proceeds until an area is occupied by a climax community (or mature communities). Discuss with your table partner: Through the process of succession, predict what generally happens to each of the following factors over time (from early succession to late succession): o Plant size o Diversity o Number of Ecological Niches o Net Primary Productivity Be able to explain your answers. Discuss with your table partner: Go to the website www.treebenefits.org Enter the school’s zip code (98040) to get growth data for trees in our area. Select the tree type Fir, Douglas and compare the CO2 reduced from the atmosphere from the following three sizes of trees. Douglas Fir Diameter 12 inches 25 inches 45 inches (reaching maximum size) Explain this pattern. lb. of CO2 Reduced in year Ecosystem Changes During Succession Characteristic Plant size Species diversity Trophic structure Early Succession small low mostly producers Ecological niches few, more generalized low Late Succession large high mixture of producers, consumers, & decomposers many, more specialized high low high high low simple low complex high low high Community organization (# links) Biomass Net Primary Productivity Food web Efficiency for nutrient cycling Efficiency of energy use As plants become larger and growth rate slows down, the NPP decreases. Theory of Island Biogeography • Species equilibrium model of island biogeography • Developed by Robert MacArthur & Edward O. Wilson. • Based on the idea that the number of species on an island is determined by the ____________ ___________________________. • This theory is applied not only to islands, but any isolated ecosystem. Example: A wildlife preserve surrounded by pavement. Effect of Island Distance from Mainland on Species Diversity Distant islands typically have lower species diversity because of decreased immigration to island. •Note that the lower immigration rate means the immigration and extinction rates intersect for a lower species diversity equilibrium. Discuss with you table partner: How does a smaller island size affect species diversity. __________ species diversity on smaller island How and WHY does a smaller island size effect both the immigration and emigration rates? _______ rate of immigration because smaller island = ______ ___________ _______ rate of extinction because ___________________ _______________. Stability of Ecosystems Two key aspects of stability: •Inertia (or persistence): the ability of a system to resist being disturbed or altered; •Resilience: the ability of a living system to recover after a disturbance; Discuss with your table partner whether the following ecosystems would have a high or low inertia and high or low resilience. Tropical rainforest (high biodiversity, poor soil) •_______ inertia- _____________________________ ___________________________. •______ resilience- ____________________________ __________________________. Grasslands (low biodiversity, prone to fires, nutrient rich soil and deep rooted plants) •_____ inertia- ____________________________ ________________________. •_____resilience-______________________________ _____________________________. In a rainforest, the biotic matter is quickly decomposed and the nutrients are ______ ________. Most of the nutrients are ___________ ____________________. Rainforest have poor soil. In the grasslands, there is a cold/ or dry season where there is a _________ ______________. This allows for a ___________ ____________in the soil. Grasslands have rich soil.