1. Corrections to class handout: on the spatial dispersion indices handout the hypotheses should read H0: Id=1 vs. H1: Id =! 1 (=! means not equal)
Homework assignment (due March 13 in class):
Lab Assignment: Ecological measures
IMPORTANT: Read all of this handout before starting!!!
Goals:
1) Calculating diversity indices
2) Calculating similarity coefficients
3) Calculating spatial dispersion indices
Assignment: implement the following procedures using MINITAB and answers questions at the end of each section.
A. Calculating diversity indices
1. Calculate Shannon-Wiener diversity indices (H’) and evenness (J) for the following data set.
Two 50 x 6 m transects were surveyed at each of three depths at Puako, Hawaii in 1992 and the total number of fish observed were tabulated:
SPECIES 15 ‘ 25’ 40’
Parupeneus bifasciatus 5 0 20
Parupeneus multifasciatus 14 19 16
Paracirrhites arcatus 11 4 2
Chaetodon multicinctus 3 33 30
Forcipiger flavissimus 6 19 21
Chromis hanui 0 0 3
Dascyllus albisella 0 0 9
Plectroglyphidodon imparipennis 2 2 0
Thallosoma duperrey 66 14 14
Acanthurus nigrofuscus 78 78 1
Ctenochaetus strigosus 34 130 130
Zanclus cornutus 3 3 8
Zebrasoma flavescens 3 115 115
Melichthys niger 44 46 46
Gomphosus varius 42 42 4
Stegastes fasciolatus 33 33 8
Chromis vanderbiliti 13 13 0
Questions: How do the three sites compare with respect to diversity and evenness? Do diversity and evenness patterns correspond? What does this tell you about the fish communities at Puako?
B. Calculating similarity indices
1. Using the data listed above calculate percent similarity between the three sampling locations.
Questions: Which sites are most similar? Why? How does similarity compare to the two measures of diversity? Is diversity an important component of similarity?
D. Calculating spatial dispersion indices
1. Open the data file using Retrieve 'M:\MR350\BSTARS2.MTW' or the FILE Þ OPEN WORKSHEET command. The data are the number of brittle stars (Ophiocoma spp.) in 120-0.25 m2 quadrats at Onekahakaha.
Download brittlestar data file (BSTARS2.MTW)
2. Using the data set calculate the variance-to-mean ratio, Greens’ index and Morisita’s index of spatial dispersion for these data.
Questions: What spatial dispersion patterns do brittlestars display using 0.25 m2 quadrats? Why do you think they display this pattern? How do the three indices compare?
THIS ASSIGNMENT IS DUE WED. MARCH 13 IN CLASS
List of references:
Ludwig, J. A. and J. F. Reynolds. 1988. Statistical Ecology: a primer on methods and computing. John Wiley & Sons, New York.
Magurran, A. E. 1988. Ecological diversity and its measurement. Princeton Univ. Press, Princeton, NJ. 179 pp.
Southwood, T. R. E. 1966. Ecological Methods, with particular reference to the study of insect populations. Chapman and Hall, London. 524 pp.
Zar, J. H. 1984. Biostatistical Analysis. Prentice Hall, Inc. Englewood Cliffs, NJ.