Transcript Mission 2
• Succession is a process that involves a series of changes in a community over time. • Ecological disruptions like volcanic eruptions, forest fires, floods, and even mowing a lawn can trigger succession. • When habitats change or niches open, the process of succession can occur – even in a climax community. • The first species to arrive after a disruption tend to be small, hardy, fast growing, and able to live on very few resources are called pioneer species. • These organisms alter the environment, creating new niches for other species to fill. • As new species build the community, succession slows down. • When all available niches are filled, the community stabilizes to become a climax community. Bozeman Science http://www.youtube.com/watch?v=V49IovRSJDs • Mt St helens • http://www.youtube.com/watch?v=4RsMyVavT2 Q • http://www.youtube.com/watch?v=TLpc71YOtcE • Ecological succession • http://www.youtube.com/watch?v=WyqCQq6SZK Q http://www.youtube.com/watch?v=Na 2HYq11yuM • Sometimes a single species can radically change a stable community. • • • • • • • • • • • • • • • • • • American alligator: Alligators use their tails to make burrows to stay warm and when they move on, these burrows fill with water which is used by other species. Alligators are also predators, keeping the numbers of other species in check. Beavers: Beavers are considered habitat engineers because they change the environment by building dams. This dam building provides still water in which many species flourish. Bees: By pollinating plants, bees contribute to their survival. The plants are shelter for insects, which are then eaten by other species, like birds. Elephants: By eating small trees, elephants preserve the grasslands, because the grasses need plenty of sun to survive. If they were not there, the savanna would convert to a forest or scrublands. Gopher tortoise: This tortoise makes large burrows which are used by more than 350 species, including owls, snakes and frogs. Grizzly bears: As predators, bears keep down the numbers of several species, like moose and elk. They also carry and deposit seeds throughout the ecosystem. Bears that eat salmon will leave their dropping and the partially eaten remains that provide nutrients such as sulfur, nitrogen and carbon to the soil. Hummingbirds: Pollination is the reason hummingbirds are a keystone species. In places where the numbers of hummingbirds are low, other species of plants will take over the ecosystem. Ivory tree coral: 300 invertebrate species call this coral home. It is here that fish live, breed and become food for larger fish. Jaguars: Jaguars are predators, as are many keystone species. They have a very diverse diet of about 87 different species, which contributes to their importance by keeping the numbers of these species in balance. Mountain Lions: These predators cover large areas and influence many species. Their prey will alter where they eat and live because of the mountain lion. Scavengers are also affected by the mountain lion’s activity. Pacific salmon: Salmon die after spawning and this brings important nutrients to the place where they were born. Their death provides food for many species in the area. Prairie dogs: By eating grass, prairie dogs keep water in the soil instead of the water evaporating from the leaves of plants. By tunneling, they help channel rainwater into the water table. By burrowing, they mix different layers of soil, combine it with their droppings, and aerate the soil. Red mangrove: This tree grows along the shoreline in the tropics and its roots protect the soil from erosion. The roots also offer protection to small animals, including reef fish. Sea otters: Sea otters are a keystone species in the kelp forests. They eat many invertebrates, but especially sea urchins. If there are too many sea urchins, they will eat too much of the kelp and destroy it. Sea stars: Sea stars eat mussels and keep their numbers in check. Too many mussels will crowd out other species, and since mussels have no other natural predators, sea stars are invaluable for keeping the ecosystem diverse. Snow geese: If there are not enough snow geese in salt marshes, other harmful species will take over. When the geese graze, it leaves open areas for other varieties of plants to take root, thus adding to the diversity of the habitat. Spruce budworm: This is a moth that lives in conifer forests. As the population of budworms increases, more small animals and birds move into the area to eat the larvae. This will cause some trees to die, but they will be replaced by younger trees, and the cycle will begin again. Sugar maple: This tree is a keystone species of the hardwood forest. It brings water from lower levels in the ground that helps • The beaver is called a keystone species and is so important that its removal could cause a chain reaction that might collapse the whole community. • The American beaver uses its forestry, aquatic architecture, and engineering skills to change an area of dry woodlands into a wetlands. • Biodiversity increases as the beaver pond grows. • Populations of aquatic organisms, amphibians, reptiles, and insects increase. • Badgers, skunks, and deer find a niche in this new habitat. • The community that develops in this changed habitat depends a great deal on the activities of the beaver. • http://www.youtube.com/watch?v=Na2HYq11yu M • Trees that can survive the beaver’s devastation, will pass on their survival traits. When one species influences the evolution of another, it is called coevolution. • Symbiosis is the close interaction between two or more organisms of different species, in which one or both benefit from the relationship e.g. coral and photosynthetic algae. Symbiosis • When both partners benefit, the symbiotic relationship is called mutualism. • http://www.youtube.com/watch?v=Xm2qdxV VRm4 • Natgeo http://education.nationalgeographic.com/edu cation/lesson/symbiotic-relationships-marineecosystems/?ar_a=1 Symbiosis • Parasitism is a form of symbiosis in which one organism benefits at the expense of the other e.g. • http://www.youtube.com/watch?v=ydXenL7iu 0w Symbiosis • Another type of symbiotic relationship, in which one organism benefits with no harm to the other, is called commensalism e.g. shark and the remora fish (the remora eat the scraps from the shark’s prey; the remora benefit but the shark is unharmed. Survival Strategies • Organisms use many different Survival Strategies to adapt to their environment, such as mimicry, camouflage, and chemical defenses. Survival Strategies Survival Strategies Survival Strategies Survival Strategies Survival Strategies • http://www.youtube.com/watch?v=DWsN63P RCW8 • http://www.youtube.com/watch?v=AdZVJ2fIso • https://www.youtube.com/watch?v=xxnIrI4LT zQ • https://www.youtube.com/watch?v=__ZvtiRVl pk