ANT 154BN–16 Diversity- Patterns and processes

ANT 154BN–16 Diversity- Patterns and...

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Unformatted text preview: ANT 154B Lecture #16: Diversity: patterns and processes 1 March 2011 Tuesday, March 1, 2011 1 This Thursday: guest lecture Lydia Beaudrot There will be no course notes, but we will post the slides and we plan to make an audio podcast of the lecture (posted later than usual) Tuesday, March 1, 2011 2 Tuesday, March 1, 2011 3 Diversity: patterns & processes 1. Explaining patterns of diversity neutrality vs. niches island biogeography prey switching Tuesday, March 1, 2011 4 Diversity: patterns & processes >1. Explaining patterns of diversity neutrality vs. niches island biogeography prey switching Tuesday, March 1, 2011 5 Neutrality vs. niches Niche models: Non-random • division of resources • effects of various types of ecological variation and interactions Neutral models: • size of the community • rates of species dispersal • rates of speciation and Random extinction Chase 2005 Tuesday, March 1, 2011 6 183 1. A comparison of the neutral and niche models, listing the key assumptions, Table inputs a Forum nd outputs of each. This is not meant to be an exhaustive list, and merely shows some of the key inputs and outputs of each Neutral Key Assumption Inputs No differences among species Metacommunity size Speciation rate Dispersal rate Niche Trade-offs prevalent Spatial heterogeneity Intrinsic Extrinsic Temporal heterogeneity Intrinsic Extrinsic Spatial configuration Interactions in the food web Rank–Abundance Diversity Area Several types of heterogeneity Food web structure Key assumptions and data inputs t c Outputs Rank–Abundance Diversity Area Speciation Dispersal Compositional turnover Space P t r 1 t p 1 f p m s f c Tuesday, March 1, 2011 C Compositional turnover hase 2005 Space 7 d a t c t h e re i s Metacommunity size Spatial heterogeneity prey sp Speciation rate Intrinsic the 183 1. A comparison of therate al and niche Extrinsiclisting the key assumptions, 1970; C Table models, Dispersal neutr inputs a co Forum nd outputs of each. This is not meant to be an exhaustivegeneity merely shows facilitat Temporal hetero list, and some of the key inputs and outputs of each Intrinsic predato Extrinsic Pr much le Spatial configuration Neutral Niche sts (ethe .g. Interactions in the food web Inputs Key outputs Key Assumption Outputs Inputs No differences Rank–Abundance among Diversityspecies Area Metacommunity size Speciation Speciation rate Dispersal Compositional turnover Space Dispersal rate Trade-offs prev Rank–Abundance alent Diversity Area Spatial heterogeneity Several types of heterogeneity Intrinsic Food web structure Extrinsic Compositional turnogeneity Temporal hetero ver Space Intrinsic EnExtrinsic vironment Response to environmental change Spatial configuration Diversity changes Interactions in the food web for rres eso coexist 19 Inter th discuss pr anothe 19 tionsfac an coexist pre (see, e. mu 2002, 2 Outputs Rank–Abundance Diversity Area Speciation Dispersal Compositional turnover Space Composition changes Invasive species Rank–Abundance Effects of and on diversity Diversity Effects of and on composition Area Ecosystemal types of heterogeneity Sever function Effects of diversity e Food web structur Effects of composition sts for co Tuesday, March 1, 2011 Compositional turnover Space Environment Above dis the neu nichan et modtio els Chase 2005 co some p 8 tiple (me s Neutrality vs. niches for primates Niche models: • primate species clearly occupy distinct niches body mass, morphology, physiology, resource use • supported by some biogeographic patterns differences in forest habitats, competitors Tuesday, March 1, 2011 9 Neutrality vs. niches for primates Neutral models: • rates of speciation, dispersal, and extinction poorly characterized for primates fragmentation studies support some predictions • random, historical contingencies clearly have effects potential species pool impacts community Tuesday, March 1, 2011 10 Neutrality vs. niches for primates • very few empirical tests published Tuesday, March 1, 2011 11 Kamilar (2009) Tuesday, March 1, 2011 12 Primate community assembly rules: hypotheses Dispersal limitation (neutral) Ecological partitioning (niche) Chase et al. (2005) Tuesday, March 1, 2011 13 Primate community assembly rules: hypotheses Dispersal limitation (neutral) Ecological partitioning (niche) Community similarity Geographic distance Community similarity Ecological distance Tuesday, March 1, 2011 14 Primate community assembly rules: hypotheses Dispersal limitation (neutral) Ecological partitioning (niche) Community similarity Community similarity Geographic distance Community similarity Community similarity Geographic distance Ecological distance Tuesday, March 1, 2011 Ecological distance 15 Africa South America n=23 n=45 n=28 n=28 Madagascar Tuesday, March 1, 2011 Borneo n=124 16 Regional species pools Table 2. Number per taxa Africa S. America Madagascar Borneo Diurnal species 35 28 13 11 Nocturnal species 9 3 16 2 Genera 17 13 14 8 Common taxa Africa: Pan troglodytes & Perodicticus potto at 70% (16/23) of sites South America: Cebus apella at 93% (42/45) of sites Madagascar: Eulemur fulvus at 86% (24/28) of sites Borneo: Hylobates muelleri at 79% of (22/28) sites Fo rR Tuesday, March 1, 2011 17 e Variables Community Community ssimilarity imilarity j (a + b – j) J= Geographic distance J= a= b= j= Jaccard index of similarity # species at site a # species at site b # species occurring at both sites Ecological distance Vegdist function, Vegan community ecology package, R Tuesday, March 1, 2011 18 Variables Community similarity Geographic Geographic distance distance Ecological distance Pairdist function, Spatstat package, R Tuesday, March 1, 2011 19 Variables Community similarity A composite of 14 ecological variables Net Primary Productivity Geographic distance Elevation Climatic and weather variables Soil variables Ecological distance Mahlanobis distances, R 2.8.1 Tuesday, March 1, 2011 20 Components of ecological distance measure Included variables Transformation Excluded variables Tuesday, March 1, 2011 21 Community similarity Community similarity residuals Geographic distance Ecological distance residuals Ecological distance Geographic distance Tuesday, March 1, 2011 e.g., assessing the effects of ecological distance while controlling for geographic distance 22 r = 0.07, p = 0.03 r = 0.61 Africa r = 0.33 Diurnal primate community similarity residuals (Jaccard index) South America r = 0.28 r = 0.25 Madagascar r = 0.27 Borneo Pearson method ,10,000 permutations solid lines, p-values ≤ 0.001 no line: p > 0.5 Tuesday, March 1, 2011 Ecological distance residuals Geographic distance residuals Beaudrot & Marshall 2011 J. Anim. Ecol. 23 Dispersal limitation for primates? Potential costs of colonization higher predation risk loss of knowledge about local food resources loss of benefits of remaining near kin Geographic barriers to dispersal mountain ranges rivers forest discontinuities Tuesday, March 1, 2011 24 Madagascar r = 0.28 r = 0.25 Diurnal primate community similarity residuals (Jaccard index) Ecological distance residuals Geographic distance residuals Primates greater proportion of competitor community (44% versus 8-12%, Jurnvall & Wright 1998) Tuesday, March 1, 2011 25 F ig u re 3 -1 -2 -3 -4 -5 Canonical 1 Madagascar more variable Madagascar -6 -7 -8 -9 -10 -11 -12 -13 -14 7 South America Africa 8 r Fo 9 10 11 Canonical 2 12 13 14 Borneo ! 99% density ellipses, JMP 8.0.1 26 Tuesday, March 1, 2011 R Nocturnal species Sampling biases? Lower dispersal costs? Africa: 9 / 35 S. America: 3 / 28 Madagascar: 16 / 13 Borneo: 2 / 11 Tuesday, March 1, 2011 27 Primate community structure • dispersal limitation is an important determinant of primate community structure (≥ niche differentiation) • consistent with several models (e.g., patch dynamics, neutral models) • tests of assumptions of neutral theory (e.g., functional equivalence hypothesis) are necessary Tuesday, March 1, 2011 28 Diversity: patterns & processes >1. Explaining patterns of diversity neutrality vs. niches island biogeography prey switching Tuesday, March 1, 2011 29 Equilibrium model of island biogeography MacArthur & Wilson 1963; MacArthur 1972 Tuesday, March 1, 2011 30 Equilibrium model of island biogeography I rate of immigration or extinction of species E 0 MacArthur & Wilson 1963 Tuesday, March 1, 2011 Nequilibrium number of species 31 Island biogeography: effects of island size Ibig rate of immigration or extinction of species Esmall Ismall Ebig 0 MacArthur & Wilson 1963 Tuesday, March 1, 2011 Nsmall Nbig number of species 32 Island biogeography: effects of island size Amphibians & reptiles Freshwater birds Tuesday, March 1, 2011 33 Island biogeography: effects of island size Tuesday, March 1, 2011 34 Island biogeography: distance from mainland Inear rate of immigration or extinction of species E Ifar 0 MacArthur & Wilson 1963 Tuesday, March 1, 2011 Nfar Nnear number of species 35 Island biogeography: distance from mainland Species richness distance from New Guinea (km) Diamond 1972 Tuesday, March 1, 2011 36 Equilibrium model of island biogeography: a test Wilson and Simberloff (1968, 1969) Tuesday, March 1, 2011 37 Equilibrium model of island biogeography Wilson and Simberloff (1968, 1969) Tuesday, March 1, 2011 38 Island biogeography: additional considerations • the shape of curves may differ between different taxa, possibly related to dispersal abilities • observed numbers of species may differ from expected based on habitat and resource diversity • patterns will differ between arbitrary islands and oceanic islands Tuesday, March 1, 2011 39 Island origins: arbitrary islands e.g., peninsular islands Tuesday, March 1, 2011 40 Island origins: oceanic Tuesday, March 1, 2011 41 Species richness patterns species time species time Tuesday, March 1, 2011 42 Island biogeography: key implications • species composition on islands may change, but equilibrium numbers of species are relatively constant (i.e., dynamic equilibrium) • the equilibrium number of species will be positively correlated with island area, and negatively correlated with distance from the mainland Tuesday, March 1, 2011 43 Island biogeography: key implications • species diversity depends on historical contingencies (i.e., the availability of potentially colonizing species) • models can be applied to habitat fragments (e.g., forest patches remaining following logging) Tuesday, March 1, 2011 44 Habitat fragmentation species time Tuesday, March 1, 2011 45 Island biogeography and conservation Tuesday, March 1, 2011 46 Newmark 1995 Tuesday, March 1, 2011 47 Island biogeography and conservation Species turnover Extinctions Newmark 1995 Tuesday, March 1, 2011 48 Island biogeography and conservation species time Tuesday, March 1, 2011 Newmark 1995 49 r2 = 0·39 0·06 – 0·42 0·20 F= 38·2 0·05 – 12·5 11·1 P< 0·0001 NS – 0·01 0·01 Slope 0·15 −0·01 – 0·14 0·20 Intercept 0·81 0·58 – 0·70 0·95 rS = 0·62 −0·06 – 0·67 0·58 P< 0·0001 NS – 0·01 0·01 r S −1 = ( n ) 0·60 (20) – – 0·70 (9) 0·50 (16) P< 0·001 – – 0·05 0·1 Island biogeography: primates in forest fragments coefficients (corr. coeffs) of ent area p er site in the four individual sites; bar, median. e sample size per site so small.) = 0·5 n, P < 0·02. *Individual ts. he fragments at the single Tuesday, March 1, 2011 l at i o n ( i n B r a z i l ) w e r e a l l Fig. 2 Proportional species richness (% of number in nearby main forest block) by fragment area for the globe and the four Harcourt continents (double log10). Globe, P < 0·0001; Africa, NS; Asia, n = 1; Madagascar, P = 0·01; South America, P < 0·01. Statistical detail s in Table 3. Statistics are for arcs ine and Doherty 2005 50 Tuesday, March 1, 2011 51 The matrix matters Tuesday, March 1, 2011 52 The matrix matters Species sensitivity to: Prugh et al. 2008 Tuesday, March 1, 2011 53 Diversity: patterns & processes >1. Explaining patterns of diversity neutrality vs. niches island biogeography prey switching Tuesday, March 1, 2011 54 Prey switching Predator Prey types A B C D E If predators focus on most common prey types (i.e., the most efficient competitors), then rare species may coexist, even if inferior competitors. Tuesday, March 1, 2011 55 Prey switching: two prey species prey switching amount of prey type in diet random foraging 0: 100 50: 50 100: 0 56 relative abundance of two prey types Tuesday, March 1, 2011 Why do predators switch prey species? search image? learning? processing? Tuesday, March 1, 2011 57 Does prey switching determine the diversity of primate communities? con: predation rates on most primate species quite low pro: predator switching common current suite of predators probably reduced observed predation rates may be underestimates Tuesday, March 1, 2011 58 Does prey switching by vertebrates determine the diversity of SouthEast Asian plant communities? Tuesday, March 1, 2011 59 Take home messages 1. Neutral and niche models, which invoke distinct mechanisms, have both been applied to explain patterns of diversity. Niche models are probably more applicable to primate communities, but few formal tests of neutral models for primates have been published to date. 2. Island biogeography theory predicts that the equilibrium number of species on an islands will be positively correlated with island area, and negatively correlated with distance from the mainland. 3. Prey switching may help to maintain species diversity in ecological communities, but is unlikely to be an important factor determining species diversity in most primate communities. Tuesday, March 1, 2011 60 Question to ponder The theory of island biogeography has been very influential on the field of conservation biology, particularly in the context of the design of protected areas. Based on your understanding of island biogeography, in each of the following six pairs of potential reserve designs select the one that would more effectively conserve biodiversity. For each pair, explain briefly why you made your choice, referencing island biogeography theory and other relevant theoretical relationships that you have learned about. Bonus: Are there conflicting factors that make selection difficult in some cases? If so, which, and why? Tuesday, March 1, 2011 61 Reserve design choices or or (assume equal total area) or (assume equal total area) (buffer zone) or or or (assume equal total area) 62 Tuesday, March 1, 2011 ...
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This note was uploaded on 04/05/2011 for the course ANT 154bn taught by Professor Debello during the Winter '10 term at UC Davis.

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