Chps 7, 8, 14 APES
Terms
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- Biological diversity (biodiversity)
- Refers to the variety of life-forms, commonly expressed as the number of species in an area, or the number of genetic types in an area.
- Genetic diversity
- The total amount of genetic variability within a population or species
- Habitat diversity
- The different kinds of habitat in a given area
- Species diversity
- The different kinds of species in an area
- Species richness
- The total number of species
- Species evenness
- The relative abundance (population density) of each species
- Evolution
- The heritable changes that shape the appearance and function of organisms over time
- Natural Selection
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Charles Darwin
Some individuals may be better suited to the environment than others. Change is not always for the better. - Species
- A group of individuals that share a common gene pool and can/do reproduce
- Mutation results in...
- genetic variation. Natural selection uses beneficial mutations to increase chances of survival
- Genetic drift
- When there is a change in gene frequency that is not caused by natural selection. ex. seperating two sheep populations by a valley
- Evolution of life on Earth (3)
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The original atmosphere was not hospitable to life, it had little or no oxygen and consisted of N2, CO2, and CH4. The earth's atmosphere has changed radically as organisms evolved and populated the planet.
Major and sudden climate change has happened due to catastrophic meteor impacts, driving species extinctions (dinosaurs).
Environmental change drives the process of natural selection which ensures that organisms will adapt to their environment. - Number of species on Earth (2)
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1.4 million species on earth; could be up to 100 million total
So many species because natural selection forces specialization, the successful species is not the only one that out-competes its neighbors, it is the species that avoids competition from its neighbors. With increasing specialization comes greater diversity - Niche
- A species' place in the ecosystem: where it lives, where it breeds, what it eats, tolerance limits of various abiotic conditions, optimal conditions. The breadth of the niche determines if the species is rare or common.
- Cosmopolitan species
- One that has a broad niche
- Principle of competitive exclusion
- No two species can coexist in the same habitat and occupy the same niche
- Symbiosis
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"living together"
A relationship between two organisms that is beneficial to both and enhances each organism's chance of persisting - Mutualism
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Symbiosis
"living together"
A relationship between two organisms that is beneficial to both and enhances each organism's chance of persisting - Factors that influence species diversity (2)
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Tropical regions have higher species diversity because of stable climate (favors specialists)
Humans have a negative impact on species diversity - Genetic engineering (2)
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Modify species by inserting the genes from other organisms.
Impact it will have on biodiversity is the capacity to preserve the genetic material of endangered species and the potential to clone extinct species from preserved genetic material. - Realms
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Six biogeographic regions divided on the basis of fundamental features of animals found in those areas.
Nearctic (North America), Neotropical (Central and South America), Palaearctic (Europe, northern Asia, and northern Africa), Ethiopian (central and southern Africa), Oriental (the Indian subcontinent and Malaysia), and Australian. - Wallace's realms
- Recognition of the worldwide regions and patterns in animal species was the first step to understanding biogeography.
- Biotic provinces
- Region inhabited by a characteristic set of taxa (species, families, orders), bounded by barriers that prevent the spread of those distinctive kinds of life to other regions.
- Biome
- Major ecosystem usually defined by dominant vegetation and climate. The same biome can be found in different biogeographic provinces when the climates are similar, because similar environments select for similar traits.
- Different types of Biomes (9)
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Arctic Tundra
Subarctic Northern coniferous forest
Temperate Forest
Temperate Grassland
Temperate Mediterranean scrub
Desert Rainforest
Desert Monsoon forest
Desert Savanna
Desert - Convergent Evolution
- Similar environmental constraints force similar adaptations
- Divergent Evolution
- Species become separated by barriers and is a major cause of speciation
- Island Biogeography (3)
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Species diversity is proportional to the size of the island and to the distance from the nearest continent.
1. Two sources of new species are migration from the mainland and evolution of new species
2. Have fewer species than continents - Adaptive radiation
- The process that occurs when a species enters a new habitat that has unoccupied niches and evolves into a group of new species, each adapted to one of these niches that give it competitive advantage.
- Biogeography and people (4)
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Biogeography affects biological diversity, and changes in diversity in turn affect people and their living resources.
People have altered biodiversity by hunting, habitat alteration, and introducing exotics ex. Snakes to Hawaii.
Moving a species within its own biotic province is not likely to be harmful.
Moving a species into the same biome from a different biotic province is likely to be harmful, and local moves are likely to be less harmful than global moves. - Traditional Single Species Management
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Assumed that a population can be characterized by its population size, that undisturbed, the population would stabilize at its carrying capacity
Approach failed
- Logistic growth curve
- The S-shaped growth curve that shows a small population growing rapidly, but the growth rate slows down, and the population eventually reaches a constant size.
- Maximum sustainable yield (MSY)
- A rate of harvest that theoretically sustains the population size (harvesting 1/2 the carrying capacity) but never been demonstrated in nature
- Why are Grizzly Bears difficult to manage? (3)
- Little historical data on previous population sizes, difficult to estimate current population size, requires large amount of habitat that overlays with humans
- American Bison Management (2)
- Decreased primarily from hunting pressure, based on historical data, numbers were 50-70 million in the U.S. west
- Minimum viable population
- Estimated smallest population that can maintain itself and its genetic variability indefinitely.
- Improved wildlife management approaches
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1. Allow for a margin of error in setting a target population size
2. Have concern for the entire biological community and all renewable resources
3. Maintain the ecosystem upon which the species depends
4. Continuously monitor, analyze and assess - Historical range of variation in population sizes
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Critical to estimating chances of extinction
ex. American Whooping Crane has historically low population numbers, so it has a low chance of extinction - Age structure in a population
- A decrease in older individuals in the population signifies a decrease in survival and overexploitation ex. Salmon
- Harvest records
- Helps estimate previous populations ex. bowhead whale and ship logs
- Can commercial fishing ever be sustainable?
- Predatory fish populations appear to be 10% of pre-industrial levels
- Chesapeake Bay
- Problems have arisen in species despite intensive management efforts that have failed because they are based on the logistic growth curve and because fisheries are an open resource subject to the 'tragedy of the commons'
- U.S. Endangered Species Act of 1973
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Endangered species- any species which is in danger of extinction throughout all or a significant portion of its range
Threatened species- any species which is likely to become an endangered species within the foreseeable future throughout all or a significant portion of its range - Extinction is... (4)
- the rule of nature and the ultimate fate of all species. Humans cause extinctions by over hunting or harvesting, modifying or eliminating habitats, introducing exotic species and by polluting.
- Kirtland's Warbler
- Many endangered species are adapted to natural environmental change and require it. When human actions eliminate that change, a species can become threatened with extinction. ex. Fire control