Measuring Biodiversity Silk moth (Rothschildia orizaba). Michael Branstetter © Michael Branstetter See the associated lesson plan at nature.ca/education/cls/lp/lpmb_e.cfm Page 1 Teacher Zone nature.ca/education

What Is Biodiversity? The term biodiversity comes from the words biological and diversity. It refers to the variety of life, and includes all living things (plants, animals and micro-organisms) and their unique characteristics. Snail. Michael Branstetter © Michael Branstetter Page 2 Teacher Zone nature.ca/education

What Is Biodiversity? It can mean the variety of habitats, living communities and ecological processes in an ecosystem. It can mean the diversity of genetic characteristics within a species. It can mean the variety of species in a given area. Page 3 Teacher Zone nature.ca/education

Why Is Biodiversity Important? Ecosystems depend on the combined contributions of the individual organisms within them. The loss of any species can prevent that ecosystem from operating the way it should. An ecosystem with a high level of biodiversity is more resistant to environmental change. Page 4 Teacher Zone nature.ca/education

What Is Biodiversity? What does biodiversity mean to you? Let’s draw a mind map! Page 5 Teacher Zone nature.ca/education

Biodiversity Index A biodiversity index is a way of measuring biodiversity. Scientists use different biodiversity indices to measure diversity, and no single one will always be appropriate for the question being posed. In fact, for some conservation questions, more than one measure may have to be used. Page 6 Teacher Zone nature.ca/education

Biodiversity Index Species Richness The total number of species in an area (add them up!) Species Evenness How evenly the species are represented in the area. E.g., Do most of the individuals belong to one species? Weevil (Rhodobaenus sp.). Michael Branstetter © Michael Branstetter Page 7 Teacher Zone nature.ca/education

Species Richness The most common type of biodiversity index is species richness, which refers to the number of species in a particular place. This measure is commonly used because most people have an idea what “species” means. It is also commonly used because species keep their genes more or less to themselves, and to that extent have their own unique history. Page 8 Teacher Zone nature.ca/education

Simpson’s Index Many diversity indices have been developed that combine different measures of biodiversity. One is called the Simpson’s Index. The Simpson’s Index includes BOTH species richness and species evenness in a single number. Ocean sunfish (Mola mola). © iStockphoto.com/Todd Winner Page 9 Teacher Zone nature.ca/education

How to Calculate Simpson’s Index D is the Simpson’s Index n is the total number of organisms of a particular species N is the total number of organisms of all species ∑ means “add up”! ∑ n(n - 1) D = N(N - 1) Page 10 Teacher Zone nature.ca/education

Let’s Try an Example n You have studied a specific site, and have counted the individuals of five different species. n is the total number of organisms of a particular species. Species A 12 Species B 3 Species C 7 Species D 4 Species E 9 Page 11 Teacher Zone nature.ca/education

Simpson’s Index n n - 1 n(n - 1) ∑ n(n - 1) = 264 ∑ n(n - 1) = D Species A 12 11 132 Species B 3 2 6 Species C 7 42 Species D 4 Species E 9 8 72 ∑ n(n - 1) 264 ∑ n(n - 1) D = N(N - 1) ∑ n(n - 1) = 264 Page 12 Teacher Zone nature.ca/education

N = total number of all individuals = 35 Simpson’s Index ∑ n(n - 1) 264 D = = N(N - 1) N(N - 1) N = total number of all individuals = 35 N - 1 = 34 N(N - 1) = 1190 264 D = = 0.22184 1190 This area would score 0.22184 on the Simpson’s Index. The scale ranges from 0–1, with 1 representing the lowest biodiversity. Therefore, the score for this area indicates a high level of biodiversity. Page 13 Teacher Zone nature.ca/education

Biodiversity at Sites in Honduras The following calculations are based on sampling conducted in Honduras by Canadian Museum of Nature research scientist Bob Anderson. Site N N(N - 1) ∑ n(n - 1) D Species Richness Cerro Montecristo 2996 7 120 892 1 600 002 0.2247 61 El Pital 2050 m 233 54 056 6856 0.1268 22 El Pital 2650 m 5411 29 273 510 12 873 694 0.4398 46 Cerro Puca 311 96 410 19 126 0.1984 27 Santa Barbara 839 703 082 55 514 0.0789 44 Page 14 Teacher Zone nature.ca/education

Biodiversity at Sites in Honduras Which site has the highest species richness? Which site is the most diverse according to the Simpson’s Index? (HINT: Has the lowest D). Do any sites have both a low Simpson’s Index and high species richness? Which one(s)? Page 15 Teacher Zone nature.ca/education

Biodiversity and Conservation Which measure—species richness or species evenness— is more important to conservation? Should we incorporate both? Canadian Museum of Nature scientist Bob Anderson identifying new species in the lab. John Longino © John Longino Page 16 Teacher Zone nature.ca/education

Biodiversity and Conservation Why should we preserve biodiversity? What is conservation? What does it take to conserve areas? How is conservation related to biodiversity? Pit viper (Cerrophidion godmani). José Monzon © José Monzon Page 17 Teacher Zone nature.ca/education

Biodiversity and Conservation Some species are rare in nature, or in some areas. How is this important to conservation studies? Is there a chance that scientists might not even find the rare species? Are rare species more important to conserve than common ones? Canadian Museum of Nature scientist Bob Anderson conducting a biodiversity assessment. Michael Branstetter © Michael Branstetter Page 18 Teacher Zone nature.ca/education