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© Getty Images/Taxis BIOL 3240 Plant and Animal Ecology Communities: Biodiversity What is biodiversity? By definition it is the various forms of life How.

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Presentation on theme: "© Getty Images/Taxis BIOL 3240 Plant and Animal Ecology Communities: Biodiversity What is biodiversity? By definition it is the various forms of life How."— Presentation transcript:

1 © Getty Images/Taxis BIOL 3240 Plant and Animal Ecology Communities: Biodiversity What is biodiversity? By definition it is the various forms of life How many species are there anyway? Estimated 1.4 million already described… perhaps up to 100 million waiting

2 How can we measure it? An example from La Selva Field Station (OTS) Studied ant species in leaf litter http://www.esf.edu/resorg/rooseveltwildlife/Research/soilbiodivers/soilbiodivers.htm

3 How can we measure it? Species accumulation curves provide estimates of what remains as well as directs decision about sample size.

4 Is species richness even across the globe? If not… where would you expect the greatest diversity (i.e. what are the two most diverse ecosystems on the planet)? Primary productivity likely influences richness (rate of biomass accumulation per unit area as a result of photosynthesis). Regional stability likely influences richness (what areas have been subjected to glaciation events?) Climatic stability may influence richness (what areas are the most stable across months, years and longer?)

5 Is species richness even across taxonomic groups? Name your favorite organism…

6 Why are some taxa richer? Size limitations… Adaptive radiation can occur when a novel form is introduced to an established environment (or vice versa).

7 Why should we be concerned about biodiversity? Habitat loss is the major cause of extinctions/declines Other anthropogenic causes Examples for amphibian extinctions Consequently, we need to know what exists where so that we can best be prepared to protect/save as many species as possible!!! Hotspots… http://www.biodiversityhotspots.org/xp/Hotspots/ http://www.biodiversityhotspots.org/xp/Hotspots/

8 Why should we be concerned about biodiversity? Habitat loss is the major cause of extinctions/declines Other anthropogenic causes

9 How can we measure it? # of species (Richness) Relative distribution of species abundance (Evenness) Type of BirdCampus A Campus B Pigeon9620 Robin120 Starling120 Purple grackle120 House Sparrow120

10 How can we measure it? Indexes measure both # of species and evenness (alpha and gamma) Simpson’s index Between 0 and 1… 0 infinite div. and 1 no diversity Simpson's Index of diversity 1 – D Simpson's Reciprocal Index 1 / D FlowerIndividuals # 1Individuals # 2 Daisy30020 Dandelion33549 Buttercup365931 Total1000 D = (n / N) 2 n = the total number of organisms of a particular species N = the total number of organisms of all species

11 SpeciesSample OneSample 2 Woodrush22 Holly (seedlings)856 Bramble10 Yorkshire Fog10 Sedge36 Total (N)1564 Use the following data to calculate A) Simpson’s Index B) Simpson’s Index of Diversity C) Simpson’s Reciprocal Index D = (n / N) 2

12 How can we measure it? Another popular Index is the Shannon – (Weaver/Wiener) index H = Σ – (P i * lnP i ) H = Shannon Index P i = Fraction of entire population made up of species i S = Number of species encountered Σ = Indicates the sum from species 1 to species S s i = 1

13 Calculate the Shannon Index for the data below... H = Σ – (P i * lnP i ) H = Shannon Index P i = Fraction of entire population made up of species i S = Number of species encountered Σ = Indicates the sum from species 1 to species S s i = 1 Type of BirdCampus A Campus B Pigeon9620 Robin120 Starling120 Purple grackle120 House Sparrow120

14 Calculate the Shannon Index for the data below... H = Σ – (P i * lnP i ) H = Shannon Index P i = Fraction of entire population made up of species i S = Number of species encountered Σ = Indicates the sum from species 1 to species S s i = 1 Type of Bird Campus A NiPilnP i -(P i *lnP i ) Pigeon96 Robin11 Starling11 Grackle11 House Sparrow 11


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