DOCSLIB.ORG

A Comparative Test of Phylogenetic Diversity Indices

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
A Comparative Test of Phylogenetic Diversity Indices Oecologia (2008) 157:485–495 DOI 10.1007/s00442-008-1082-2 COMMUNITY ECOLOGY - METHODS PAPER A comparative test of phylogenetic diversity indices Oliver Schweiger · Stefan Klotz · Walter Durka · Ingolf Kühn Received: 5 June 2007 / Accepted: 19 May 2008 / Published online: 20 June 2008 © Springer-Verlag 2008 Abstract Traditional measures of biodiversity, such as distinctiveness values for particular species across the com- species richness, usually treat species as being equal. As munity. It is therefore strongly linked to species richness this is obviously not the case, measuring diversity in terms and reXects phylogeny per se weakly but satisWes set mono- of features accumulated over evolutionary history provides tonicity. We suggest that AvTD and J are best applied to additional value to theoretical and applied ecology. Several studies that compare spatially or temporally rather indepen- phylogenetic diversity indices exist, but their behaviour has dent communities that potentially vary strongly in their not yet been tested in a comparative framework. We pro- phylogenetic composition—i.e. where set monotonicity is a vide a test of ten commonly used phylogenetic diversity more negligible issue, but independence of species richness indices based on 40 simulated phylogenies of varying is desired. In contrast, we suggest that TTD be used in stud- topology. We restrict our analysis to a topological fully ies that compare rather interdependent communities where resolved tree without information on branch lengths and changes occur more gradually by species extinction or species lists with presence–absence data. A total of 38,000 introduction. Calculating AvTD or TTD, depending on the artiWcial communities varying in species richness covering research question, in addition to species richness is strongly 5–95% of the phylogenies were created by random resam- recommended. pling. The indices were evaluated based on their ability to meet a priori deWned requirements. No index meets all Keywords Phylogenetic tree · Pure diversity · requirements, but three indices turned out to be more suit- Quadratic entropy · Taxic weights · Taxonomic distinctness able than others under particular conditions. Average taxo- nomic distinctness (AvTD) and intensive quadratic entropy (J) are calculated by averaging and are, therefore, unbiased Introduction by species richness while reXecting phylogeny per se well. However, averaging leads to the violation of set monotonic- Many ecological studies, especially large-scale ones, rely ity, which requires that species extinction cannot increase on species richness as a measure of biodiversity because the index. Total taxonomic distinctness (TTD) sums up time and money constraints often impede eVorts to obtain more detailed information. However, the use of species richness as the sole reXection of biodiversity may be of lim- Communicated by Wolf Mooij. ited value since it treats all species as being equal and does not take into account phylogenetic relationships (Vane- O. Schweiger (&) · S. Klotz · W. Durka · I. Kühn Wright et al. 1991). The diVerences in the evolutionary his- Department of Community Ecology, UFZ—Helmholtz Centre for Environmental Research, tory of community members result in a diversity of mor- Theodor-Lieser-Street 4, 06210 Halle, Germany phological, physiological, and behavioural characters e-mail: [email protected] (Williams and Humphries 1996) and of their features (Faith 1992), where a feature means a particular state of a charac- O. Schweiger · S. Klotz · I. Kühn Virtual Institute for Macroecology, ter. Many of the characters may represent functional traits Theodor-Lieser-Street 4, 06120 Halle, Germany (e.g. Woodward and Cramer 1996; Lavorel et al. 1997; 123 486 Oecologia (2008) 157:485–495 Diaz and Cabido 2001), and the feature richness of a com- based on morphological or functional diVerences (Izsak and munity may be closely related to its functional diversity Papp 1995), on Linnean taxonomy (Warwick and Clarke (e.g. Tilman et al. 1997; Petchey and Gaston 2002; Petchey 1995), on branch lengths of phylogenies based on molecu- et al. 2004). lar data (Solow et al. 1993; Pavoine et al. 2005) or, if Sechrest et al. (2002) showed that biodiversity hotspots branch lengths are not known, on the number of nodes sep- across the globe harbour even greater amounts of evolu- arating each pair of species (Faith 1992). The values within tionary history than would be expected based on species the distance matrix can be interpreted as the distinctiveness richness. Heard and Mooers (2000) demonstrated that phy- between each pair of species or each particular species and logenetic relationships are one of the most important fac- all other species (Rao 1982; Izsak and Papp 2000; Ricotta tors determining species extinction, and Strauss et al. and Avena 2003). Several summary statistics have been (2006) showed that the degree of phylogenetic distance proposed to obtain an index for the whole community. Rao may determine the invasion success of exotic taxa. Hence, (1982), for example, proposed a diversity index termed phylogenetic information may be a better indicator of con- quadratic entropy (QE) that is based on both relative spe- servation value than species richness alone. cies abundances and a measure of the pairwise distances The application of information obtained by phylogenetic between community species. When information about any relationships therefore represents a promising approach kind of distance measure is lacking, QE reduces to the (Webb et al. 2002). Several authors have proposed a variety Simpson index. When abundance data are lacking (or they of indices other than species richness which also take into are equal), QE will be a function of the species number account phylogenetic diversity; however, these diVer (also called intensive quadratic entropy, J, in Izsak and greatly in their method of calculation (Vane-Wright et al. Papp 2000). A similar index, average taxonomic distinct- 1991; Faith 1992; Solow et al. 1993; Faith 1994; Warwick ness (AvTD), was developed by Warwick and Clarke and Clarke 1998; Izsak and Papp 2000; Clarke and War- (1995), which measures the mean distance between two wick 2001a; Rodrigues and Gaston 2002). These indices randomly chosen species. can be separated in two categories: topology based and dis- Krajewski (1994) investigated the behaviour of some tance based (Krajewski 1994). Vane-Wright et al. (1991) phylogenetic diversity indices using the avian family Grui- were the Wrst to propose the application of topology-based dae. Based on a comparison of the ability of these indices to methods, which reXect the phylogenetic branching order rank species and contribute to phylogenetic diversity, he within a monophyletic group. In this approach, each species reported a serious disagreement between the indices, espe- of a community is weighted by the inverse number of nodes cially at intermediate levels of ranking, and concluded that between that species and the root of the phylogenetic tree, “until some working consensus is reached […], phyloge- in a way that the most distinctive (close-to-root) species netic indices are unlikely to supersede more traditional have the highest weights. Community distinctness (as a measures of biodiversity”. Consequently, as long as the measure of phylogenetic diversity) is then obtained simply mathematical and ecological qualities of these indices are by summing the weights of the species. In this paper, we not suYciently investigated in a comparative way, relying use the terms “distinctiveness” and “distinctness” sensu on species richness, for example, would be preferable since Warwick and Clarke (2001). Following their deWnition, the selection of an index to account for phylogenetic rela- “distinctiveness” describes the relation of a particular spe- tionships, and possibly the results and potential conserva- cies to the rest of the community, whereas “distinctness” tion recommendations, will be quite arbitrary. represents a property of the community as a whole. While Krajewski (1994) investigated the ability of the Distance-based methods use either a minimum spanning indices to identify “phylogenetically unique” species, path or a pairwise distance approach. The minimum span- which was motivated by an individual species-focussed ning path measures the phylogenetic diversity of a commu- conservation context, we focus on their ability to measure nity by summing up the branch lengths of the subtree that phylogenetic diversity at the community level. Community- includes the community’s species (PD in Faith 1992). wide phylogenetic diversity patterns can also be used for Branch lengths indicate the expected number of molecular conservation concerns (e.g. the selection of priority areas; “features” accumulated over evolutionary history. Common Posadas et al. 2001), but they are also highly suited for branches reXect shared molecular information inherited monitoring the eVects of environmental change on overall from common ancestors, while the branch length of a single community structure (e.g. Warwick and Clarke 1995; species not shared by others reXects exclusive information. Knapp et al. 2008). By analogy with studies investigating While the minimum spanning path approach measures the behaviour of evenness indices (Smith and Wilson 1996) overall phylogenetic information of a community, the pair- or functional diversity indices (Mason et al. 2003), we pro- wise distance approach is based on a distance matrix vide a comparison
Load more

Recommended publications
  • Bridging the Gap Between Ecological Diversity Indices and Measures of Biodiversity with Shannon’S Entropy: Comment to Izsa´K and Papp
    Ecological Modelling 152 (2002) 1–3 www.elsevier.com/locate/ecolmodel Bridging the gap between ecological diversity indices and measures of biodiversity with Shannon’s entropy: comment to Izsa´k and Papp Carlo Ricotta * Department of Plant Biology, Uni6ersity of Rome ‘‘La Sapienza’’, Piazzale Aldo Moro 5, 00185 Rome, Italy Received 31 May 2001; accepted 11 October 2001 Abstract Most ecological diversity indices summarize the information about the relative abundances of community species without reflecting taxonomic differences between species. Nevertheless, in the environmental conservation practice, data on species abundances are generally unknown. In such cases, to summarize the conservation value of a given site, so-called ‘biological diversity’ measures need to be used. Most of these measures are based on taxonomic relations among species and ignore species relative abundances. In a recent paper, Izsa´k and Papp suggest that the quadratic entropy index (Q) is the only diversity index used to date in the ecological practice that incorporates both species relative abundances and a measure of the pairwise taxonomic differences between species in the analyzed data set. I show here that a number of traditional ecological diversity measures can be generalized to take into account a taxonomic weighting factor. Since these new indices violate part of the mathematical properties that an index should meet to be termed an ecological diversity index, I defined this new family of indices ‘weak diversity indices’. © 2002 Elsevier Science B.V. All rights reserved. Keywords: Biodiversity measures; Ecological diversity; Quadratic entropy; Shannon’s entropy; Species richness 1. Introduction data on species abundances are generally un- known.
    [Show full text]
  • Species Biodiversity Lab
    SCIENCE IN THE PARK: ROCK POOLS SPECIES BIODIVERSITY LAB Purpose: To understand the importance of biodiversity, calculate the indices of the Simpson’s Index, and quantify the biodiversity of a sample. Developed by E. A. Betts Time: 40 minutes BACKGROUND: Simpson's Diversity Index is a measure of diversity. In ecology, it is often used to quantify the biodiversity of a habitat. It takes into account the number of species present, as well as the abundance of each species. Before looking at Simpson's Diversity Index in more detail, it is important to understand the basic concepts. Biological diversity can be quantified in many different ways. The two main factors taken into account when measuring diversity are richness and evenness. Richness is a measure of the number of different kinds of organisms present in a particular area. For example, species richness is the number of different species present. However, diversity depends not only on richness, but also on evenness. Evenness compares the similarity of the population size of each of the species present. Richness - The number of species per sample is a measure of richness. The more species present in a sample, the 'richer' the sample. Species richness as a measure on its own takes no account of the number of individuals of each species present. It gives as much weight to those species which have very few individuals as to those which have many individuals. Thus, one daisy has as much influence on the richness of an area as 1000 buttercups. Evenness - Evenness is a measure of the relative abundance of the different species that make up the richness of an area.
    [Show full text]
  • Indexes of Group Diversity 1 Some Common Indexes Of
    INDEXES OF GROUP DIVERSITY 1 SOME COMMON INDEXES OF GROUP DIVERSITY: UPPER BOUNDARIES1,2 ANTONIO SOLANAS Department of Behavioral Sciences Methods, Faculty of Psychology, University of Barcelona Institute for Research in Brain, Cognition, and Behavior (IR3C), University of Barcelona REJINA M. SELVAM Department of Behavioral Sciences Methods, Faculty of Psychology, University of Barcelona Institute for Research in Brain, Cognition, and Behavior (IR3C), University of Barcelona JOSÉ NAVARRO Department of Social Psychology, Faculty of Psychology, University of Barcelona DAVID LEIVA Department of Behavioral Sciences Methods, Faculty of Psychology, University of Barcelona Institute for Research in Brain, Cognition, and Behavior (IR3C), University of Barcelona 1 Address correspondence to Antonio Solanas, Departament de Metodologia de les Ciències del Comportament, Facultat de Psicologia, Universitat de Barcelona, Passeig de la Vall d’Hebron, 171, 08035-Barcelona, Spain. Electronic mail may be sent to Antonio Solanas at: ([email protected]) 2This research was supported by the Spanish Ministry of Science and Innovation, grant PSI2009-07076 and by the Generalitat of Catalonia’s Agència de Gestió d’Ajuts Universitaris i de Recerca, grant 2009SGR1492. INDEXES OF GROUP DIVERSITY 2 Summary. —Workgroup diversity can be conceptualized as variety, separation, or disparity. Thus, the proper operationalization of diversity depends on how a diversity dimension has been defined. Analytically, the minimal diversity must be obtained when there are no differences
    [Show full text]
  • Diversity Indices: Shannon and Simpson
    Name: Date: Student Handout 1A: How to Calculate Biodiversity Diversity Indices: A) A diversity index is a mathematical measure of species diversity in a given community. B) Based on the species richness (the number of species present) and species abundance (the number of individuals per species). C) The more species you have, the more diverse the area, right? D) However, there are two types of indices, dominance indices and information statistic indices. E) The equations for the two indices we will study are: s Shannon Index (H) = - ∑ pi ln pi i=1 1 Simpson Index (D) = s 2 ∑ pi i=1 The Shannon index is an information statistic index, which means it assumes all species are represented in a sample and that they are randomly sampled. Can you point out any problems in these assumptions? In the Shannon index, p is the proportion (n/N) of individuals of one particular species found (n) divided by the total number of individuals found (N), ln is the natural log, Σ is the sum of the calculations, and s is the number of species. The Simpson index is a dominance index because it gives more weight to common or dominant species. In this case, a few rare species with only a few representatives will not affect the diversity. Can you point out any problems in these assumptions? In the Simpson index, p is the proportion (n/N) of individuals of one particular species found (n) divided by the total number of individuals found (N), Σ is still the sum of the calculations, and s is the number of species.
    [Show full text]
  • The Shannon-Weiner Species Diversity Index
    This article reprinted from: Nolan, K.A. and J.E. Callahan. 2006. Beachcomber biology: The Shannon-Weiner Species Diversity Index. Pages 334-338, in Tested Studies for Laboratory Teaching, Volume 27 (M.A. O'Donnell, Editor). Proceedings of the 27th Workshop/Conference of the Association for Biology Laboratory Education (ABLE), 383 pages. Compilation copyright © 2006 by the Association for Biology Laboratory Education (ABLE) ISBN 1-890444-09-X All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of the copyright owner. Use solely at one’s own institution with no intent for profit is excluded from the preceding copyright restriction, unless otherwise noted on the copyright notice of the individual chapter in this volume. Proper credit to this publication must be included in your laboratory outline for each use; a sample citation is given above. Upon obtaining permission or with the “sole use at one’s own institution” exclusion, ABLE strongly encourages individuals to use the exercises in this proceedings volume in their teaching program. Although the laboratory exercises in this proceedings volume have been tested and due consideration has been given to safety, individuals performing these exercises must assume all responsibilities for risk. The Association for Biology Laboratory Education (ABLE) disclaims any liability with regards to safety in connection with the use of the exercises in this volume. The focus of ABLE is to improve the undergraduate biology laboratory experience by promoting the development and dissemination of interesting, innovative, and reliable laboratory exercises.
    [Show full text]
  • Spatial Patterns of Bacterial Richness and Evenness in the NW Mediterranean Sea Explored by Pyrosequencing of the 16S Rrna
    Vol. 61: 221–233, 2010 AQUATIC MICROBIAL ECOLOGY Published online December 30 doi: 10.3354/ame01484 Aquat Microb Ecol Contribution to AME Special 4 ‘Progress and perspectives in aquatic microbial ecology’ OPENPEN ACCESSCCESS Spatial patterns of bacterial richness and evenness in the NW Mediterranean Sea explored by pyrosequencing of the 16S rRNA Thomas Pommier1, 2, P. R. Neal3, Josep M. Gasol1, Montserrat Coll1, Silvia G. Acinas1, Carlos Pedrós-Alió1,* 1Departament de Biologia Marina i Oceanografia, Institut de Ciències del Mar, CSIC, 08003 Barcelona, Spain 2Ecologie Microbienne, UMR5557, USC1193 CNRS, INRA, Université Lyon I, 69622 Villeurbanne, France 3Marine Biological Laboratory, Woods Hole, 02543 Massachusetts, USA ABSTRACT: Due to analytical limitations, patterns of richness and evenness of microbes are scarce in the current literature. The newest and powerful pyrosequencing technology may solve this issue by sampling thousands of sequences from the same community. We conducted a study of diversity along a horizontal transect (ca. 120 km) and a depth profile (surface to bottom at ca. 2000 m) in the northwestern Mediterranean Sea, using this technology on the V6 region of the 16S rDNA gene and analyzed patterns of richness and evenness of marine free-living bacterial communities. A total of 201 605 tag sequences were obtained from the 10 samples considered and clustered according to their similarity in 1200 operational taxonomic units (OTUs) per sample on average. We found a par- allel decrease in richness and evenness from coast to offshore and from bottom to surface. We also observed a predominance of a few OTUs in each sample, while ca. 50% of all OTUs were found as singletons, which indicated that the community structures differed dramatically between sites despite the relative proximity and the physical connectivity between the samples.
    [Show full text]
  • The Use of Entropy to Measure Structural Diversity
    The use of entropy to measure structural diversity L. Masisi 1, V. Nelwamondo 2 and T. Marwala 1 1School of Electrical & Information Engineering Witwatersrand University, P/Bag 3, Wits, 2050, South Africa 2Graduate School of Arts and Sciences, Harvard University, GSAS Mail Center Child 412, 26 Everett Street Cambridge, Massachusetts, 02138 USA Abstract — In this paper entropy based methods are accuracy. However this study will only focus on three compared and used to measure structural diversity of an measures of diversity, Shannon, Simpson and Berger ensemble of 21 classifiers. This measure is mostly applied in Parker to quantify structural diversity of the classifiers. ecology, whereby species counts are used as a measure of Shannon entropy has found its fame in information diversity. The measures used were Shannon entropy, theory as it is used to measure the uncertainty of Simpsons and the Berger Parker diversity indexes. As the states[10]. In ecology Shannon is used to measure the diversity indexes increased so did the accuracy of the ensemble. An ensemble dominated by classifiers with the diversity indices of species, however in this study instead same structure produced poor accuracy. Uncertainty rule of the biological species the individual classifiers are from information theory was also used to further define treated as species [11]. For example, if there are three diversity. Genetic algorithms were used to find the optimal species of different kind, two of the same kind and one of ensemble by using the diversity indices as the cost function. another kind, then that would replicate three MLP's of The method of voting was used to aggregate the decisions.
    [Show full text]
  • Measuring Biological Diversity in R
    Measuring biological diversity in R Dan Flynn, Brenda Lin, and Daniel Bunker 18 March 2008 Columbia University Understanding biodiversity and the ecosystem processes that come with said biodiversity can help inform policy toward sustainable development. Land use changes have affected the habitat and feeding resources of many taxa, thereby changing species composition and abundances. This change in land use and species distribution may also lead to changes in ecosystem services and functions that are necessary for human well-being. In this lab, we will look at changes within bird species diversity as land is converted from forest to more intensive coffee agriculture. Coffee is a crop that is grown within a large variation of shade cover. On the one extreme is traditional rustic coffee, which is planted under a forest canopy, and on the other extreme is intensive coffee agriculture, which has little or no shade cover (Figure 1). There is a large range of shade systems in between these two extremes. The conversion of coffee farms from traditional rustic systems to intensive, unshaded monocultures is presumed to have large effects on bird biodiversity because of the loss of vegetation diversity and structure in sun monocultures. This may be especially important for bird migration between North and South America because shade trees within traditional coffee farms have served as potential sources of habitat and food during previous migration, and declines in certain bird species have been blamed on the gradual removal of shade trees in Central American coffee systems. 1 The data you will be using in this lab looks at the bird species found in forest, rustic coffee, polyculture, and shaded monoculture habitats.
    [Show full text]
  • The PD Phylogenetic Diversity Framework: Linking Evolutionary History to Feature Diversity for Biodiversity Conservation
    CORE Metadata, citation and similar papers at core.ac.uk Provided by Springer - Publisher Connector The PD Phylogenetic Diversity Framework: Linking Evolutionary History to Feature Diversity for Biodiversity Conservation Daniel P. Faith Abstract Feature diversity refers to the relative number of different features repre- sented among species or other taxa. As a storehouse of possible future benefi ts to people, it is an important focus for biodiversity conservation. The PD phylogenetic diversity measure provides a way to measure biodiversity at the level of features. PD assumes an evolutionary model in which shared features are explained by shared ancestry. This avoids philosophical and practical weaknesses of the conventional interpretation of biodiversity as based on some measure of pair-wise differences among taxa. The link to features also provides a family of PD-based calculations that can be interpreted as if we are counting-up features of taxa. The range of feature diversity calculations assists comparisons of methods, and helps overcome the cur- rent lack of review and synthesis of the variety of proposed methods for integrating evolutionary history into biodiversity conservation. One family of popular indices is based on the evolutionary distinctiveness (ED) measure. These indices all have the limitation that complementarity, refl ecting degree of phylogenetic overlap among taxa, is not properly taken into account. Related indices provide priorities or other scores for geographic areas, but do not effectively combine complementarity, prob- abilities of extinction, and measures of restricted-range. PD-based measures can overcome these problems. Applications include the identifi cation of key biodiver- sity sites of global signifi cance for biodiversity conservation.
    [Show full text]
  • Biodiversity Accounting
    Biodiversity Accounting November 2018 Outline • Learning objectives • Key concepts • Policy linkages • Exercise • How to compile • Data sources • Country examples SEEA EEA accounts, tools and linkages 3 Biodiversity accounting : key concepts 4 What is biodiversity? Convention on Biological Diversity (CBD), 1992 defines biodiversity as: “Biological diversity means 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 part; this includes diversity within species, between species and of ecosystems” 5 Biodiversity in the SEEA-EEA • Three components to biodiversity: Biodiversity Extent (or species) account account Outside of SEEA EEA • …the measurement of biodiversity is focused on the assessment of diversity of species, although changes in the diversity of ecosystems is also an important output, derived from the measurement of changes in ecosystem extent and condition. (SEEA EEA, p 152). 6 Link to SEEA EEA • In SEEA EEA: biodiversity is a characteristic relevant in measurement of condition of ecosystem assets. > Measures of biodiversity are considered to relate primarily to ecosystem assets in the accounting model. > E.g. birdwatching or fishing not seen as flows of biodiversity services > Consistent with a view that biodiversity can be degraded or enhanced over time, an attribute that applies only to assets in an accounting context. • Measures of biodiversity can be indicators of flows of final ecosystem services (e.g. biodiversity indicators related to value of recreational services from wildlife related activities, where people gain benefit from experiencing the diversity of nature (as distinct from services received from appreciation of individual species) Concepts • Species population: The summation of all the organisms of the same species or species group that live in a particular geographical area and have the capability of interbreeding.
    [Show full text]
  • Biodiversity Indexes: Value and Evaluation Purposes
    E3S Web of Conferences 48, 01001 (2018) https://doi.org/10.1051/e3sconf/20184801001 IWGM 2018 Biodiversity Indexes: Value and Evaluation Purposes Jatna Supriatna1 1Institute for Sustainable Earth and Resources (I-SER) and Dept of Biology, Faculty of Math and Sciences, Universitas Indonesia Abstract. Biodiversity is a word recently introduced by experts in the field of biology. This word became more meaningful after Edward O. Wilson of Harvard University introduced it in a book entitled Biodiversity, an extension of biological diversity, in 1989 [11]. In subsequent developments, it became very popular and used not only by environmental biologists but also by researchers, environmentalists, funders, educators, social experts, economists, policy makers, and many others, although many do not know what that means. Biodiversity includes variations within the biological community, where living species, and ecosystems, where communities are located, as well as interaction between them (Pri. The science of biodiversity has emerged rapidly since then included monitoring and evaluation systems which is measuring the value of biodiversity components, such as the number of species present, the population of species, a habitat or the sum of all such components within a given area or site. Such monitoring and evaluation may be carried out for a variety of reasons, included identification of a given area for biodiversity richness, evenness or healthy ecosystems. The richness is the number of species per sample, the more species present in a sample, the richer the sample. Evenness is a measure of the relative abundance of the different species making up the richness of an area. Two commonly used to measure biodiversity Simpson index Ds and Shannon’s index H’.
    [Show full text]
  • Community Diversity: Controls and Patterns
    Community Diversity: Controls and Patterns Topics • What is biodiversity and why is it important? • What are the major drivers of species richness? • How might the drivers of species richness and hence levels of species richness differ among biomes? Patterns of Biodiversity across Biomes Predicted Species Richness Wet Tropical Temp. Dec. Temp. Con. Boreal Desert Community Diversity Defined Biodiversity Merriam-Webster - the existence of many different kinds of plants and animals in an environment. Wikipedia - is the degree of variation of life forms within a given species, ecosystem, biome, or an entire planet. U.S. Congress Office of Technology Assessment - the variety and variability among living organisms and the ecological complexes in which they occur. Diversity can be defined as the number of different items and their relative frequency. For biological diversity, these items are organized at many levels, ranging from complete ecosystems to the chemical structures that are the molecular basis of heredity. Thus, the term encompasses different ecosystems, species, genes, and their relative abundance." Community Diversity Defined Species richness - Species evenness - Species diversity - Community Diversity Defined Species richness - number of species present in the community (without regard for their abundance). Species evenness - relative abundance of the species that are present. Species diversity - Considers both the number of species (richness) in the community and their relative abundance (evenness or equability). Shannon-Wiener Diversity Index Where: H’ = the value of the Shannon-Wiener diversity index pi = the proportion of the ith species loge = the natural logarithm s = the number of species in the community Community Diversity Defined Community Richness Shannon’s index Abundance Guild – group of species that make their living in a similar way Richness Shannon’s index Abundance Individual species Abundance Copyright © The McGraw-Hill Companies, Inc.
    [Show full text]