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Ecology: Human Impact & Conservation

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1 Ecology: Human Impact & Conservation
IB Biology G3 & G4

2 Numbers of individuals
Biological Diversity Biological Diversity: Evenness and Richness Richness: the number of different organisms in a particular area (kinds of species) Evenness: how the quantity of each different organism compares to the others (abundance of kinds of species) Numbers of individuals Flower Species Sample 1 Sample 2 Daisy 300 20 Dandelion 335 49 Buttercup 365 931 Total 1000 Is a community diverse if it is dominated by a single species? Why/why not?

3 Simpson Diversity Index
A measure that takes into account richness and evenness Formula: D = Where: D = diversity index N = total number of organisms in the ecosystem n = number of individuals of each species N (N-1) sum of n (n-1)

4 Simpson Diversity Index Example
Species Number (n) n(n-1) Woodrush 2 Holly (seedlings) 8 56 Bramble 1 Yorkshire Fog Sedge 3 6 Total (N) 15 64 Σ n(n-1) D = 15 (14) 64 D = 3.3 What does this number represent? How can it be used?

5 Reasons for Conserving Biodiversity
Economic Examples: rainforest soils for crops; pharmaceuticals; ecotourism Ecological Loss of diversity could collapse the ecosystem; diversity makes ecosystems less susceptible to invasive alien species; diversity of plant species buffers the effects of increasing greenhouse gasses Ethical “We do not inherit the earth from our ancestors, we borrow it from our children” Native American Proverb Aesthetic Nature’s beauty inspires art, gives us awe, and is connected to human cultures in countless ways

6 Biological Control The use of an organism (introduced) to control another organism Risks: introduced organism may not behave as expected (Cane Toads) Benefits: introduced organism may be the only control mechanism flexible enough to be effective against another invasive with no predators Examples Purple loosestrife (invasive in US and Canada) – controlled by 2 species of beetles (Gallerucella) Red Invasive Fire Ants (RIFA) (invasive on many continents) – controlled by Phorid flies red fire ants and phorid flies video on

7 Biomagnification The process by which chemical substances become more concentrated at each trophic level. [Increase]: 10 million times

8 CFCs and Ozone In the atmosphere, CFCs (used in refrigerator coolants, propellants, and foam packaging) release chloride ions. The chloride ions react with ozone (O3) and produce ClO and oxygen gas (O2) The ClO molecules react with atoms of O to form more O2 and free up the Cl In this way the CFCs behave like a catalyst that doesn’t get used up and is free to destroy ozone for a century Depleted ozone layer permits more UV radiation through the atmosphere UV radiation causes: Skin cancer, DNA mutation, sunburn, cataracts, reduced biological productivity, and may be related to loss of amphibian biodiversity globally

9 Indicator Species AKA “the canary in the coal mine”
Organisms sensitive to environmental conditions Examples: Lichen (air pollutions like lead/mercury), macroinvertebrates (water quality)

10 http://www. people. virginia. edu/~sos-iwla/Stream-Study/Methods/Form
Biotic Index

11 Biodiversity in a Nature Reserve
Size of the Reserve Single large or several small sites? Single large better because small sites = small populations (greater chance for extinctions from disease/lack of genetic diversity). Small sites also have more edges (see next). Some organisms have require large territories that can’t overlap. Edge Effect Ecology at the edge of an ecosystem is different from the center. Edges can have more sunlight, more wind, less moisture, and fewer trees. Edge organisms may have more competition/fewer resources. Edges are more susceptible to invasive species. Corridors Smaller, otherwise isolated habitats, connected by corridors allow organisms to travel between them. Problems include exposure in narrow corridors, invasives, and human/animal interactions around corridors.

12 Management in Conservation Areas
Restoration: attempt to return the land to it’s natural state through various active management techniques Recovery of threatened species: usually through habitat restoration (which helps all species ,declared threatened or not, who occupy the habitat) Removal of introduced species: active removal of invasives such as kudzu from the US southern states or leafy spurge in the US western states Legal protection against development/pollution/hunting Funding and prioritizing: limited funding creates the need to make choices: Restore the habitats of all threatened species or just the ones that make the greatest overall impact? Remove all introduced species, or just invasives?

13 In Situ Conservation Conservation of species within their natural habitat (where they belong), such as wildlife reserves, national parks, etc… Includes planning for improvement of biotic and abiotic factors of that habitat Maintaining habitat (space); defense of target species from predation; removal of invasives; maintaining large populations; maintaining genetic diversity Allows threatened species to adapt to environment with minimal interference from humans or invasives Terrestrial reserves are common for in situ conservation, but marine aquatic reserves lag far behind

14 Ex Situ Conservation Conservation of a species outside of their natural habitat Necessary if species is unsafe in the natural habitat, has a population too small to make a come-back, or if social/political/economic reasons make habitat protection impossible Examples: Captive Breeding Facilities Botanical Gardens Seed Banks

15 Captive Breeding Zoos are the most common, most have large sections dedicated to captive breeding programs, animal husbandry experts, and money from tourism Techniques Artificial insemination (when necessary) Embryo transfer to surrogate mothers Cryogenics Human-raised young (when necessary) Pedigrees (to reduce inbreeding) Disadvantages: Captivity-bred organisms can spread disease to wild ones after re-introduction Captivity-bred organisms lack the in situ learning and survival strategies

16 Botanical Gardens and Seed Banks
80,000 plant species kept in private gardens, arboretums and botanical gardens all over the world to protect and breed them Far easier to care for plants than to breed animals Problem: wild relatives of commercial crops are under-represented. Genes from these plants could infuse longevity into traditionally inbred crop plants (i.e. bananas) Seed banks are keeping 10,000 to 20,000 plant species seeds in cold, dark conditions to prevent germination (for decades).

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