Your SlideShare is downloading. ×
0
Biodiversity
Biodiversity
Biodiversity
Biodiversity
Biodiversity
Biodiversity
Biodiversity
Biodiversity
Biodiversity
Biodiversity
Biodiversity
Biodiversity
Biodiversity
Biodiversity
Biodiversity
Biodiversity
Biodiversity
Biodiversity
Biodiversity
Biodiversity
Biodiversity
Biodiversity
Biodiversity
Biodiversity
Biodiversity
Biodiversity
Biodiversity
Biodiversity
Biodiversity
Biodiversity
Biodiversity
Biodiversity
Biodiversity
Biodiversity
Biodiversity
Biodiversity
Biodiversity
Biodiversity
Biodiversity
Biodiversity
Biodiversity
Biodiversity
Biodiversity
Biodiversity
Biodiversity
Biodiversity
Biodiversity
Biodiversity
Biodiversity
Biodiversity
Biodiversity
Biodiversity
Biodiversity
Biodiversity
Biodiversity
Biodiversity
Upcoming SlideShare
Loading in...5
×

Thanks for flagging this SlideShare!

Oops! An error has occurred.

×
Saving this for later? Get the SlideShare app to save on your phone or tablet. Read anywhere, anytime – even offline.
Text the download link to your phone
Standard text messaging rates apply

Biodiversity

196

Published on

Published in: Technology
0 Comments
0 Likes
Statistics
Notes
  • Be the first to comment

  • Be the first to like this

No Downloads
Views
Total Views
196
On Slideshare
0
From Embeds
0
Number of Embeds
0
Actions
Shares
0
Downloads
11
Comments
0
Likes
0
Embeds 0
No embeds

Report content
Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
No notes for slide

Transcript

  • 1. Mark McGinley Honors College and Department of Biological Sciences Texas Tech University Biodiversity
  • 2. Diversity <ul><li>Before we tackle “biodiversity” let’s think about the concept of diversity </li></ul><ul><li>In the simplest terms, diversity is influenced by variation within and among groups </li></ul><ul><li>As will hopefully make sense in just a little while, diversity is influenced by </li></ul><ul><ul><li>The type and amount of variation </li></ul></ul><ul><ul><li>How that variation is distributed </li></ul></ul>
  • 3. Below is a group of letters. What “variation” do you see here? <ul><li>A A aa </li></ul><ul><li>Bb bb b b bb </li></ul><ul><li>c c </li></ul><ul><li>D Dd dd </li></ul><ul><li>Ee ee </li></ul><ul><li>f </li></ul>
  • 4. Variation Within a Group <ul><li>Different letters (variation in type of letter) </li></ul><ul><li>Variation within a type of letter </li></ul><ul><ul><li>Capital vs. lower case </li></ul></ul><ul><ul><li>Different sizes </li></ul></ul><ul><ul><li>Different colors </li></ul></ul><ul><li>Different letters are represented different number of times </li></ul>
  • 5. Variation Within a Group <ul><li>Thus, within a group </li></ul><ul><ul><li>Different types (letters) </li></ul></ul><ul><ul><li>Variation of characteristics within a particular type. </li></ul></ul>
  • 6. What about variation between groups?
  • 7. Which Group Contains More Variation? <ul><li>Group 1 </li></ul><ul><ul><li>A </li></ul></ul><ul><ul><li>B </li></ul></ul><ul><ul><li>C </li></ul></ul><ul><ul><li>D </li></ul></ul><ul><ul><li>E </li></ul></ul><ul><li>Group 2 </li></ul><ul><ul><li>A </li></ul></ul><ul><ul><li>A </li></ul></ul><ul><ul><li>A </li></ul></ul><ul><ul><li>A </li></ul></ul><ul><ul><li>A </li></ul></ul>
  • 8. Group 1 is more variable <ul><li>No variation in Group 2 </li></ul><ul><li>-all of the letters are exactly the same </li></ul><ul><li>More different types of letters in Group 1. </li></ul>
  • 9. Variation Between Groups <ul><li>Groups can differ in the number of types they contain </li></ul><ul><li>Therefore we think of a group containing more types of things as being more variable than a group that contains fewer types. </li></ul><ul><ul><li>In this case we would consider groups with more variation to be more diverse. </li></ul></ul>
  • 10. Which Group Contains More Variation? <ul><li>Group 1 </li></ul><ul><ul><li>B </li></ul></ul><ul><ul><li>B </li></ul></ul><ul><ul><li>B </li></ul></ul><ul><ul><li>B </li></ul></ul><ul><ul><li>B </li></ul></ul><ul><li>Group 2 </li></ul><ul><ul><li>B </li></ul></ul><ul><ul><li>B </li></ul></ul><ul><ul><li>B </li></ul></ul><ul><ul><li>B </li></ul></ul><ul><ul><li>B </li></ul></ul>
  • 11. Variation Between Groups <ul><li>The two groups share the same number of types and number of representatives within a type </li></ul><ul><li>However, Group 2 has more variation among representatives within a type </li></ul><ul><li>In this case we would consider the group with more variation with a type to be more diverse. </li></ul>
  • 12. Which group has more variation? <ul><li>Group 1 </li></ul><ul><ul><li>A </li></ul></ul><ul><ul><li>A </li></ul></ul><ul><ul><li>A </li></ul></ul><ul><ul><li>A </li></ul></ul><ul><ul><li>A </li></ul></ul><ul><ul><li>A </li></ul></ul><ul><li>Group 2 </li></ul><ul><ul><li>A </li></ul></ul><ul><ul><li>A </li></ul></ul>
  • 13. Variation Between Groups <ul><li>There is variation between groups in the number of letters. </li></ul><ul><ul><li>Group 1 has more letters in it than Group 2 </li></ul></ul><ul><li>However, </li></ul><ul><ul><li>they are all the same letter </li></ul></ul><ul><ul><li>all are the same format within a letter. </li></ul></ul><ul><li>Thus, variation in numbers of things doesn’t appear to affect diversity. </li></ul>
  • 14. Which group has more variation? <ul><li>Group 1 </li></ul><ul><ul><li>AAA </li></ul></ul><ul><ul><li>BBB </li></ul></ul><ul><ul><li>CCC </li></ul></ul><ul><li>Group 2 </li></ul><ul><ul><li>AAAAAAA </li></ul></ul><ul><ul><li>B </li></ul></ul><ul><ul><li>C </li></ul></ul>
  • 15. Group 1 is more variable <ul><li>Group 1 and Group 2 have </li></ul><ul><li>- the same total number of letters </li></ul><ul><li>- the same number of different types of letter </li></ul><ul><li>Therefore the variation among the two groups might be considered to be the same. </li></ul><ul><li>But almost all of the letters in Group 2 are A. </li></ul><ul><li>- therefore we might consider that Group 1 is more diverse than group 2. </li></ul>
  • 16. Variation Between Groups <ul><li>So differences in the number of individuals within a type can influence diversity in some cases. </li></ul><ul><li>New Term </li></ul><ul><ul><li>Diversity can be influenced by the “evenness” of the distribution of individuals among different types </li></ul></ul>
  • 17. Which Group is Most Even? <ul><li>Group 1 </li></ul><ul><ul><li>AAA </li></ul></ul><ul><ul><li>BBB </li></ul></ul><ul><ul><li>CCC </li></ul></ul><ul><ul><li>DDD </li></ul></ul><ul><li>Group 2 </li></ul><ul><ul><li>AAAA </li></ul></ul><ul><ul><li>BB </li></ul></ul><ul><ul><li>CCC </li></ul></ul><ul><ul><li>D </li></ul></ul>
  • 18. Factors That Influence Diversity <ul><li>Number of different types of things </li></ul><ul><li>Variation of characteristics within a type </li></ul><ul><li>Evenness of number of individuals across different types of things </li></ul>
  • 19. Which Group is More Diverse? <ul><li>Group 1 </li></ul><ul><ul><li>AA </li></ul></ul><ul><ul><li>BB </li></ul></ul><ul><ul><li>CC </li></ul></ul><ul><ul><li>DD </li></ul></ul><ul><ul><li>EE </li></ul></ul><ul><li>Group 2 </li></ul><ul><ul><li>A </li></ul></ul><ul><ul><li>BB </li></ul></ul><ul><ul><li>CCC </li></ul></ul><ul><ul><li>D </li></ul></ul><ul><ul><li>EE </li></ul></ul><ul><ul><li>F </li></ul></ul>
  • 20. This is a Tricky Question!!!!! <ul><li>Group 2 has more types of letters so we might consider it to be more diverse </li></ul><ul><li>Group 1 contains a more even distribution of letters within a type so we might consider it to be more diverse </li></ul><ul><li>Which group we consider to be the most diverse depends on how we rate the relative influence of number of types vs. evenness. </li></ul><ul><ul><li>The World is Complicated!!!!! (but luckily we can use math to help us solve this problem) </li></ul></ul>
  • 21. What is “Biodiversity”? <ul><li>Biodiversity is a contraction of the two words “biological diversity”. </li></ul><ul><li>Because biodiversity is such a broad, all encompassing concept there is not one well agreed on definition. </li></ul><ul><li>However, most definitions are similar. </li></ul>
  • 22. Biodiversity <ul><li>A measure of the variety of organisms within a local area or region, often including genetic variation, taxonomic uniqueness, and endemism. </li></ul><ul><ul><ul><li>Ricklefs, The Economy of Nature </li></ul></ul></ul>
  • 23. Biodiversity <ul><li>The variety of organisms considered at all levels from genetic variants belonging to the same species through arrays of species to arrays of genera, families, and still higher taxonomic levels; includes the variety of ecosystems, which comprise both the communities of organisms within a particular habitat and the physical conditions under which they live. </li></ul><ul><ul><li>E.O Wilson- The Diversity of Life </li></ul></ul>
  • 24. Biodiversity <ul><li>The variability among living organisms from all sources including, inter alia , terrestrial, marine and other aquatic ecosystems and the ecological complexes of which they are a part; this includes diversity within species, between species, and of ecosystems.&quot; </li></ul><ul><ul><li>Convention on Biological Diversity </li></ul></ul>
  • 25. Genetic Diversity <ul><li>Members of the same population or species can vary in which particular alleles they possess at a particular gene locus. </li></ul><ul><li>Population geneticists have a variety of techniques and metrics they use to measure the amount of genetic variation within and among populations. </li></ul><ul><ul><li>To learn more about this take an Evolution, Population Genetics, or Conservation Biology course. </li></ul></ul>
  • 26. Species <ul><li>Species are usually the focus of diversity studies in ecology </li></ul><ul><li>Species- actually many definitions/species concepts </li></ul><ul><li>Biological Species Concept </li></ul><ul><ul><li>- group of potentially interbreeding individuals that are reproductively isolated from other such groups </li></ul></ul>
  • 27. Biological Species Concept <ul><li>Two individuals are considered to be members of the same biological species if they can potentially exchange genes. </li></ul><ul><li>Often difficult to apply this concept </li></ul><ul><ul><li>Asexual species </li></ul></ul><ul><ul><li>Species that are geographically isolated </li></ul></ul><ul><ul><ul><li>How do we know whether a bird found in Europe can interbreed with a bird in North America </li></ul></ul></ul><ul><ul><li>Ring species </li></ul></ul><ul><li>But this is a conceptually pleasing definition of a species </li></ul>
  • 28. Biological Species <ul><li>Species are basic unit of biodiversity </li></ul><ul><ul><li>Species may be subdivided into sub-species </li></ul></ul>
  • 29. Phenotypic Variation Within Species <ul><li>Variation at the genetic, molecular, physiological, morphological, or behavioral levels. </li></ul><ul><ul><li>Conservation biologists can be especially concerned about genetic variation </li></ul></ul><ul><ul><li>Genetic variation influences the potential for natural selection </li></ul></ul>
  • 30. Species Diversity <ul><li>Species diversity is a characteristic of a community </li></ul><ul><li>Two components of species diversity </li></ul><ul><ul><li>The number of species in a community </li></ul></ul><ul><ul><ul><li>Species richness </li></ul></ul></ul><ul><ul><li>evenness </li></ul></ul>
  • 31. Diversity Indices <ul><li>Ecologists have developed several metrics to quantify species diversity </li></ul><ul><li>These indices differ in how they weight the two critical components of species diversity </li></ul><ul><ul><li>Species richness </li></ul></ul><ul><ul><li>Evenness </li></ul></ul>
  • 32. Species Richness <ul><li>Species richness simply counts the number of species found in a community </li></ul>
  • 33. Diversity Example <ul><li>Species number of individuals </li></ul><ul><li>1 10 </li></ul><ul><li>2 20 </li></ul><ul><li>3 15 </li></ul>
  • 34. Species Richness <ul><li>Because there are three species found in this community </li></ul><ul><li>Species Richness = 3 </li></ul>
  • 35. Species Richness <ul><li>Strengths </li></ul><ul><ul><li>We are often interested in knowing about the numbers of species in a community </li></ul></ul><ul><ul><li>Easy number to calculate </li></ul></ul><ul><ul><ul><li>All we have to do is count the number of species </li></ul></ul></ul><ul><ul><li>This is an easily understandable metric </li></ul></ul><ul><li>Weakness </li></ul><ul><ul><li>Ignores the evenness component of diversity </li></ul></ul>
  • 36. Shannon Diversity Index <ul><li>s </li></ul><ul><li>H = - ∑ (p i * ln p i ) </li></ul><ul><li>i=1 </li></ul><ul><li>where: </li></ul><ul><li>H = the Shannon diversity index </li></ul><ul><li>Pi = proportion of the population made up of species i </li></ul><ul><li>S = numbers of species in sample </li></ul>
  • 37. Let’s Try an Example <ul><li>Species # individuals </li></ul><ul><li>1 10 </li></ul><ul><li>2 20 </li></ul><ul><li>3 30 </li></ul>
  • 38. Shannon Index Example <ul><li>First calculate the p i for each of the S species in the sample (S = 3 species) </li></ul><ul><li>1. determine the total number of individuals sampled in the community </li></ul><ul><li># sp.1 = 10 </li></ul><ul><li># sp.2 = 20 </li></ul><ul><li># sp.3 = 30 </li></ul><ul><li>Total # = 60 ind </li></ul>
  • 39. Shannon Index Example <ul><li>2. For each of the S species </li></ul><ul><li>p i = # ind species i/total # ind </li></ul><ul><li>p i </li></ul><ul><li>sp 1- 10/60 = 0.17 </li></ul><ul><li>sp 2- 20/60 = 0.33 </li></ul><ul><li>sp 3- 30/60 = 0.50 </li></ul>
  • 40. Shannon Index Example <ul><li>Next calculate H </li></ul><ul><li> s </li></ul><ul><li>H = - ∑ (p i * ln p i ) </li></ul><ul><li>i=1 </li></ul>
  • 41. Shannon Index Example <ul><li>H =- ((0.17*ln0.17 + 0.33*ln0.33 + 0.50*ln0.50)) </li></ul><ul><li>H = - (0.17*-1.77 + 0.33*-1.11 + 0.50*-0.69) </li></ul><ul><li>H = - (-0.30 – 0.37 – 0.35) </li></ul><ul><li>H = - (-1.01) </li></ul><ul><li>H = 1.01 </li></ul>
  • 42. Shannon Index <ul><li>The Shannon Index was designed such that </li></ul><ul><ul><li>H gets larger when there are more species </li></ul></ul><ul><ul><ul><li>Not surprising because H should get larger when there are more species in the sample (larger S) </li></ul></ul></ul>
  • 43. Shannon Index <ul><li>The Shannon Index was designed such that </li></ul><ul><ul><li>H gets larger when evenness is greater </li></ul></ul>
  • 44. Shannon Index Pi 0.1 ln pi -2.30259 Pi * ln pi -0.23026 0.2 -1.60944 -0.32189 0.3 -1.20397 -0.36119 0.4 -0.91629 -0.36652 0.5 -0.69315 -0.34657 0.6 -0.51083 -0.3065 0.7 -0.35667 -0.24967 0.8 -0.22314 -0.17851 0.9 -0.10536 -0.09482 1 0 0
  • 45. Shannon Index <ul><li>The value of H gets larger whe </li></ul><ul><ul><li>There are more species </li></ul></ul><ul><ul><li>There is greater evenness </li></ul></ul><ul><li>Thus, diversity of a community increases as the value of H increases </li></ul>
  • 46. Shannon Index <ul><li>Advantages </li></ul><ul><ul><li>The value of H changes in a way that is consistent with our view of how changing species richness and evenness should affect species diversity </li></ul></ul><ul><ul><li>It is relatively easy to calculate </li></ul></ul><ul><li>Disadvantage </li></ul><ul><ul><li>The value of H doesn’t have a direct biological meaning </li></ul></ul><ul><ul><ul><li>What do you know if someone tells you that H = 2.3? </li></ul></ul></ul><ul><ul><ul><li>Useful only for comparison </li></ul></ul></ul>
  • 47. Pielou’s Evenness Index - based on Shannon Index <ul><ul><li>E = H/H max </li></ul></ul><ul><ul><li>H is the value of the Shannon Diversity Index for a particular population </li></ul></ul><ul><ul><li>H max is the maximum value for the Shannon Diversity Index in a population with the same number of species and total number of individuals sampled </li></ul></ul>
  • 48. H max <ul><li>For a particular community the maximum value of H would occur if all species were equally abundant. </li></ul><ul><li>After doing the algebra, H max can be calculated as follow- </li></ul><ul><ul><li>H max = lnS </li></ul></ul>
  • 49. Evenness Index Example <ul><li>E = H/H max </li></ul><ul><li>E = 1.01/ln3 </li></ul><ul><li>E = 1.01/1.098 </li></ul><ul><li>E = 0.919 </li></ul>
  • 50. Simpson’s Index <ul><ul><li>D = ∑ p i 2 </li></ul></ul><ul><ul><li>D measures the probability that two randomly selected individuals in a population belong to the same species </li></ul></ul><ul><ul><li>D ranges from 0 – 1 </li></ul></ul><ul><ul><li>D will be largest when all individuals in a population are members of the same population </li></ul></ul><ul><ul><li>Thus, as D gets larger diversity decreases </li></ul></ul>
  • 51. Simpson’s Index <ul><li>Species # individuals </li></ul><ul><li>1 10 </li></ul><ul><li>2 20 </li></ul><ul><li>3 30 </li></ul>
  • 52. Example <ul><li>D = ∑ p i 2 </li></ul><ul><li>D = (0.17 2 + 0.33 2 + 0.50 2 ) </li></ul><ul><li>D = (0.0289 + 0.109 + 0.25) </li></ul><ul><li>D = 0.388 </li></ul>
  • 53. Simpson’s Index of Diversity <ul><ul><li>Simpson's index of diversity = 1 - D </li></ul></ul><ul><ul><li>The probability that two randomly selected individuals in a community belong to different species. </li></ul></ul><ul><ul><li>Thus, as the Simpson’s Index of Diversity increases the species diversity of the population increases. </li></ul></ul>
  • 54. Simpson’s Index of Diversity <ul><ul><li>Simpson's index of diversity = 1 - D </li></ul></ul><ul><ul><li>The probability that two randomly selected individuals in a community belong to different species. </li></ul></ul><ul><ul><li>Thus, as the Simpson’s Index of Diversity increases the species diversity of the population increases. </li></ul></ul>
  • 55. Diversity Indices <ul><li>Shannon Index is more sensitive to changes in species richness </li></ul><ul><li>Simpson’s Index is more sensitive to changes in evenness </li></ul>
  • 56. Diversity Indices <ul><li>Which diversity index should you choose to use? </li></ul><ul><ul><li>It might depend on whether you were more concerned about rare species </li></ul></ul><ul><ul><ul><li>E.g., changes in the number of rare species has a much greater effect on Shannon’s Index than it does on the Simpson Index </li></ul></ul></ul><ul><ul><li>Many researchers choose to use a number of different diversity indices because they provide different information. </li></ul></ul>

×