Diversity
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Diversity. What is Diversity?. Diversity is often considered as a function of two components: A) the number of different species and B) the relative numbers of individuals of each species. There are 3 main types of Diversity we need to know about: Species Diversity, Genetic Diversity,

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Diversity

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Diversity


What is Diversity?

  • Diversity is often considered as a function of two components:

    A) the number of different species and

    B) the relative numbers of individuals of each species.


There are 3 main types of Diversity we need to know about:

SpeciesDiversity,

Genetic Diversity,

Habitat Diversity

We can measure diversity so that we can quantify and compare different ecosystems using a Diversity index.


Species Diversity

  • The variety of species per unit area. This includes both the number of species present and their relative abundance.


Genetic Diversity

  • The range of genetic material present in a gene pool or population of a species.


Habitat Diversity

  • The range of different habitats or number of ecological niches per unit area in an ecosystem, community or biome.


How did this diversity of species come about?

First we need to know about how organisms can change……. Lets use a giraffe as an example


How Natural Selection works…..

We have to start with 2 main ideas and look at their consequences:

  • Populations tend to produce more offspring than an environment can support.

  • There is variation in members of a species.


1. Populations tend to produce more offspring than an environment can support.

http://www.senescence.info/overpopulation.jpg


We can remember this from our look at rabbits in Australia, and human population.

http://www.cartoonstock.com/directory/o/over_population_gifts.asp


2. There is variation in members of a species.

Just look around you……

But you need to note that:

Variation within our species is the result of different selection pressures operating in different parts of the world, yet this variation is not so vast to justify a construct such as race having a biological or scientific basis.

http://news.softpedia.com/images/news2/12-of-the-DNA-Differs-Amongst-Human-Races-and-Populations-2.jpg


  • This leads to a struggle for existence…….

Who is struggling here?

http://www.wildlifeart.org/artImages/large/struggle_for_existence.jpg


Some organisms within the population have characteristics that make them better at overcoming these struggles

  • The prize for winning is that they get to pass on more of their genes (that gave them those characteristics) to the next generation.


Each habitat has different conditions so different organisms succeed. So does each Biome and Niche.

So how come biomes in different areas of the world have different species?

How do different species come about?

In order to answer these questions we need to consider speciation.


Speciation or how do new species appear?

  • 1. In a space there are some organisms.

  • 2. There is natural variety within the species.

  • 3. The space gets divided. So does the population.

  • 4. Conditions on either side of the divide are different.

  • 6. …Eventually enough change builds up that the 2 groups can’t interbreed…..a new species has been formed.

  • 5. …so different varieties survive on either side of the divide.


Different ways that populations can get separated……

This is called continental drift.

Pick a continent. What impact will the land movements shown affect:

Geology?

Movement of animals and trees?

Climate?

Isolation?

Biodiversity?


Go back to your succession work….

  • What happened to Biodiversity through the stages of succession? Why?

  • What impact will ecosystem stability have on biodiversity? Are more diverse habitats more resilient to change? Why?

  • What will happen to Biodiversity if humans keep interfering with succession? (Eg Logging, grazing, farming, burning.)

  • What happens to Biodiversity with Fragmentation of habitats?


Discussion

  • Conservation of habitat diversity usually leads to the conservation of species and genetic diversity.

  • Why should we conserve habitats?

  • If we are going to conserve them which ones should we prioritize and why?


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