Tropical ecology Tropical biodiversity: species richness, diversity of life strategies

Transcription

1 Tropical ecology Tropical biodiversity: species richness, diversity of life strategies (January Weiner)

2 READINGS J. Weiner, "śycie i ewolucja biosfery", 2nd ed/ PWN (2003) Rozdz. 11

3 Part Two Chapters

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5 Simon & Schuster 1984, 1985 (appr. $10 at Amazon.com)

6 Princeton University Press 1997

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8 2005

9 Journal papers Willig MR, Kaufman DM, Stevens RD (2003): Latitudinal gradients of biodiversity: pattern, process, scale and synthesis. Annu. Rev. Ecol. Evol. Syst. 34: Turner JRG (2004): Explaining the global biodiversity gradient: energy, area, history and natural selection. Basic and Applied Ecology 5: Mittelbach GG et al. (2007): Evolution and the latitudinal diversity gradient: speciation, extinction and biogeography. Ecology Letters, 10:

10 Classic text to read: Joseph H. Connel, 1978: Diversity in Tropical Rain Forests and Coral Reefs Science, V. 199, 4335:

11 Problems: Clinal variation of biotic diversity on Earth Hypotheses explaining species richness in the tropics Adaptive strategies of tropical biota

12 Problems: Clinal variation of biotic diversity on Earth Hypotheses explaining species richness in the tropics Adaptive strategies of tropical biota

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15 Alfred Russel Wallace ( )

16 Darwin, Wallace and others: Adaptations in temperate zone depend on abiotic factors (climate); In the tropics on the interactions between organisms; Fischer (1960): [therefore in the tropics] faster differentiation, more quiet time...

17 Global diversity of vascular plants Kier et al. 2005

18 AVAILABILITY ADN QUALITY OF DATA CONCERNING PLANT DIVERSITY Kier et al. 2005

19 Number of species per km 2 < >5000

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22 Latitudinal diversity gradient of fossil Foraminifera (after Stehli et al. 1969)

23 LATITUDINAL GRADIENT OF FAMILY RICHNESS Vascular plants Amphibians Reptiles Mammals Gaston et al

24 LATITUDINAL GRADIENT OF SPECIES (a) AND GENERIC (b) RICHNESS OF BIVALVES (Flessa & Jablonski 1995)

25 Latitudinal gradient of extant species of corals (Fraser & Currie 1996)

26 Taxonomic diversity of the tropics: Phyla ONLY OCEANIC TERRESTRIAL AND AQUATIC Annelida Arthropoda Chordata Mollusca Nematoda Platyhelminthes Rotifera ONLY TERRESTRIAL Onychophora Acanthocephala Brachiopoda Bryozoa Cnidaria Ctenophora Echinodermata Echiura Ectoprocta Gastrotricha Kinoryncha Loricifera Nemertea Phoronida Pogonophora Porifera Priapulida Sippuncula

27 BIRDS OF POLAND: 227 breeding specoes (Tomiałojć & Stawarczyk 2003)

28 Birds of Venezuela: 1382 species (Hilty, 2003)

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33 CLOUD FOREST IN VENEZUELA (Rancho Grande)

34 Number of plant species in equatorial forests (after Primack i Corlett, 2005) Region Neotropics Africa (land) Madagascar Africa total Malaysia Indochina etc. S. India Sri Lanka Australia Total Asia and Pacific Total Pacific Islands Number of species Area forested (mln ha)

35 Number of tree species per ha in rain forests of different continents Primack i Corlett 2005 Other data Gentry 1988: 580 trees of 283 species/ha (Amazon, border of Venezuela and Brasil)

36 Region West Indies, Mexico, Central and South America North America, North of Mexico USA Europe Africa (sub-saharan) Asia (parts of this region) New Guinea, New Britian and New Ireland Australia New Zealand Polynesia TOTAL No. sp Species diversity of ants in various regions From Holldobler and Wilson (1991) and Groombridge (1992).

37 Number of coral genera in frelation to surface temperature of the see (Fraser & Currie 1996)

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46 DIFFICULTIES WITH BIODIVERSITY MEASUREMENT How to measure species number with regard to area? (ecoregions, latitudinal zones, longitudinal belts, meridian, maps with species density contours) The majority of tropical species are not known yet!

47 Okapi (Okapia johnstoni) Giraffidae discovered in Congo in 1900

48 Pseudoryx nghetinhensis 1992

49 wstawić przyrost l. gat. ptaków (jak w podręczniku) odkrywane ostatnio gatunki (liczby, przykłady, antylopa z Wietnamu, ośmiornice głębinowe Wollemia nobilis Anonymus 1999 (Araukariaceae); discovered in Australia : 1994

50 T.L.Erwin

51 ERWIN S ESTIMATE OF THE TOTAL SPECIES RICHNESS 19 trees Luehea seemani (Panama) fumigated species of beetles collected Assumption 1: Average specifity of beetles = 13.5% ergo: No. of specialised species Assumption 2: tree species in rein forests, on each specialised species of beetles ergo: total No. of species specialised Assumption 3: Beetles make up 40% spesies of arthropods ergo: No. of arthropod species Assumption 4: 2 more species in tree canopies than on forest floor ergo: total No. of species in rain forest mln

52 Problems: Clinal variation of biotic diversity on Earth Hypotheses explaining species richness in the tropics Adaptive strategies of tropical biota

53 LATITUDINAL BIODIVERSITY GRADIENTS ARE UNIVERSAL Hillebrand, 2004: meta-analysys of 600 data sets confirms gradient properties: at regional scale are stronger and steeper than at local one; strength and steepness increases with body size of the group studied; strength increases with trophic level; taxonomic effect (poikilo- vs. homeotherms); in freshwater environments weaker than in marine and terrestrial ones; differs between continents and environments; hemispheres (S or N) do not matter.

54 HISTORY OF THE RESEARCH CONCERNING THE GEOGRAPHY OF SPECIES DIFERSITY Wallace 1878 Dobzhanski 1950 Hutchinson 1959 MacArthur (et all.) 1965, 1969, 1972 Pianka 1966 RECENT REVIEWS (WITH NEW HYPOTHESES) Rosenzweig 1992 Brown 1988 Currie 1991 Rohde 1992 Wright, Currie & Maurer 1993 Turner, Lennon & Greenwood 1996 Fraser & Currie 1996 Rohde 1999 Kaspari et al Willig et al Turner 2004 Mittelbach et al. 2007

55 SPECIATION history = randomness LIMBO SPECIES POOL EXTINCTION evolutionary time scale Continental spatial scale dispersal limitation environmental filtering interactions LOCAL COMMUNITY ASSEMBLY RULES SUCCESSION ecological time scale

56 MAJOR APPROACHES AND CONTROVERSIES Neutral theories (MacArthur & Wilson, Hubbell) Niche-based theories (competition, specialization) Equilibrium vs. Non-equilibrum communities

57 GROUPS OF HYPOTHESES ECOLOGICAL FACTORS (carrying capacity) VARIOUS RATE OF SPECIES DIFFERENTIATION (speciation and extinction) MORE TIME FOR DIFFERENTIATION IN THE TROPICS Mittelbach et al. 2007

58 EVOLUTIONARY HYPOTHESES CONC. BIODIVERSITY GRADIENT Differentiation rate similar, but more time in the tropics: 1. Tropical environments are older, many extant clades originated there 2. Clade dispersal from the tropics is limited and only recent Differentiation rate in the tropics is higher......because speciation is faster 1. Genetic drift in small populations 2. Climatic changes accelerate speciation 3. Higher likeness of para- and sympatric speciation 4. Larger area of the tropics more chances for isolation 5. Narrower physiological tolerance of tropical biota 6. Higher temperature accelerates evolution 7. Stronger interactions narrower specialisation and faster speciation...because extinction rate is lower 1. Stable climate 2. Larger area more numerous populations lower risk of extinction

59 Most important hypotheses explaining geographical biodiversity gradient Geographical area History Productivity Environmental energy Rapoport s rule The rate of evolution Geometric limitation Continuous disturbance

60 Geographical area (Terborgh; Rosenzweig) The geometry of the globe implies that the area of equatorial zone is the largest; This area is thermally most uniform and stable; The number of species increases with area; Large area has more diverse habitats.

61 Rosenzweig 1995

62 SPECIES RICHNESS (S) IN RELATION TO THE SURFACE AREA (A) S = ca z log S = log c + z log A

63 NUMBER OF TREE SPECIES IN RELATION TO ISLAND AREA (AUSTRALIA)

64 LARGER AREAS OF RAIN FORESTS MAINTAINT MORE PRIMATE SPECIES Primack i Corlett 2005)

65 NUMBER OF PRIMATE SPECIES CORRELATES ALSO WITH RAINFALL (EXCEPT FOR ASIA) Primack i Corlett 2005

66 log S THE EFFECT OF LATITUDE UPON species-area RELATION Lyons & Willig 2002 data: marsupials and bats of Americas relation: S = C A z where S = species number, A = area C, z = parameters log A C1 > C2 z2 > z3

67 pasami kwadratami 1. A clear latitudinal gradient of z (Lyons & Willig 2002)

68 1. A clear latitudinal gradient of C (Lyons & Willig 2002)

69 Conclusions: Biotic diversity in the tropics is higher but less dependent on area; This effect should be taken into account at any comparisons; log S tropics other log A

70 HISTORY (Rosenzweig) Tropical area was not subjected to deep climatic changes during a long time; Climatic changes caused fragmentation of typical tropical environments (rain forests) and enhanced speciation; In the tropics the number of species increases with time (many old taxons).

71 The extent of recent glaciation, y. ago

72 CHANGES OF THE RAIN FOREST EXTENT IN SOUTH AMERICA DURING PEISTOCENE RECENTLY

73 HISTORY: thermal maximum in eocene, maximum extent of tropical environments Mittelbach et al. 2007

74 Average age of avian taxa in relation to latitude Stebbins: cradle or museum? log (av. age of taxon) latitude Weiner 2003 from Gaston & Blackburne 1996

75 Productivity Higher primary production (Pp) enables to maintain more species populations (S) (Hutchinson 1959, Santa Rozalia ) S correlates (in large spatial scale) with Pp and AET No correlation of Pp i S in small scale No explanation of the mechanism Daniel Simberloff: Santa Rozalia was a goat

76 Environmental energy (Turner) Thermal conditions in the tropics are close to thermoneutrum and stable Individual energy budget is less loaded enabling more expensive specialisations Temperature and PET correlate with S

77 Rapoport s rule Species ranges close to equator are smaller Species ranges at low elevations are smaller Mountains in the tropics are higher (Janzen) Mechanism: seasonal climate suports broader adaptations, enabling greater geographical ranges Stronger endemism in tropical climate Critics: contradictory examples, no evidence for the mechanism postulated

78 Trees Sea molluscs Rapoport s rule Fishes Reptiles and amphibians Ranges of the taxons with the centres distant from equator are larger. Mammals from Stevens 1989; Weiner 2003

79 Trees in Costarica Mammals in Colorado Rapoport s rule on elevation gradient Vertical ranges of species are larger if their centre is located at higher elevation a.s.l.; With increasing elevation the diversity decreases. Birds in Venezuela Stevens 1992; Weiner 2003

80 The rate of evolution The rate of speciation is supposed to increase with temperature: shorter generation time, higher mutation rate, stronger selection pressure (Rohde 1992) Critics: The evidence not convincing

81 Geometric limitation Ranges randomly distributed over a large but limited area make up a gradient of local diversities because of purely mechanical reasons.

82 Intermediate Disturbance Hypothesis (Connel) Rain forest: non-equilibrium; Gaps continuously colonized (succesion) Coral reef: non-equilibrium Intermedite disturbances (hurricanes) and continuous succesion

83 Classic text to read: Joseph H. Connel, 1978: Diversity in Tropical Rain Forests and Coral Reefs Science, V. 199, 4335:

84 FUNCTIONAL SIGNIFICANCE OF BIODIVERSITY IN THE TROPICS Global carbon balance Global water circulation Local trophic cascade Local biogeochemical balance

85 Tree biodiveersity efect upon biomass carbon accumulation in equatorial forest (Panama) Bunker et al. 2005; SCIENCE 310: Mid column: average and c.v. Number of tree species: Carbon accumulation: Mg/ha Simulated sequence of spiecies loss: random large-statured first low density high density slow-growing drought sensitive endemic widespread

86 Species richness

87 The effuct of mammals and birds upon herbivores, soil fauna and phosphorus balance (Dunham, 2008) [exclusion experiment] Study area: equatorial rain forest (Ivory Coast, W. Africa) Mammals and birds excluded from study plots; Studied were: plant consumption faunal composotion decomposition rate phosphorus balance

88 Microfaunal sbundance drops, macrofaunal (earthworms) inceases on the plots void of mammale and birds (Dunham, 2008)

89 Percent loss of leaf biomass and morality of seedlings in he plots without mammals and birds (Dunham, 2008)

90 Changes in the amount of the available inorganic phosphorus (P) and nitrogen (N) in the soil depending on the presence of mammals and birds, after 8 month of exclusion. (Dunham, 2008)

91 Trophic cascade in the rain forest positive effects negative efects (Dunham, 2008)

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