tropical biodiversity: species richness, diversity of life...
TRANSCRIPT
Tropical ecology
Tropical biodiversity: species richness,
diversity of life strategies(January Weiner)
J. Weiner, "śycie i ewolucja biosfery", 2nd ed/PWN (2003)
Rozdz. 11
READINGS
Part TwoChapters 4 - 7
2009
1992
19992010
Simon & Schuster 1984, 1985
(appr. $10 at Amazon.com)
Princeton University Press1997
2005
Journal papers• Willig MR, Kaufman DM, Stevens RD (2003):
Latitudinal gradients of biodiversity: pattern, process, scale and synthesis . Annu. Rev. Ecol. Evol. Syst. 34: 273-309
• Turner JRG (2004): Explaining the globalbiodiversity gradient: energy, area, history and natural selection . Basic andApplied Ecology 5: 435-445
• Mittelbach GG et al. (2007): Evolution andthe latitudinal diversity gradient: speciation, extinction and biogeography. Ecology Letters, 10: 315–331
Classic text to read:
Joseph H. Connel, 1978:
Diversity in Tropical Rain Forestsand Coral Reefs
Science, V. 199, 4335: 1302-1310
Problems:
• Clinal variation of biotic diversity on Earth• Hypotheses explaining species richness in
the tropics• Adaptive strategies of tropical biota
Problems:
• Clinal variation of biotic diversity on Earth• Hypotheses explaining species richness in
the tropics• Adaptive strategies of tropical biota
Alfred Russel Wallace (1823 – 1913)
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...
Kier et al. 2005
Global diversity of vascular plants
Kier et al. 2005
AVAILABILITY ADN QUALITY OF DATA CONCERNING PLANT DIVERSITY
Number of species per 10000 km2
<100 100-200200-400400-1000
1000-15001600-20002000-30003000-4000
4000-6000>5000
Latitudinal diversity gradient of fossilForaminifera (after Stehli et al. 1969)
Amphibians
Reptiles Mammals
Gaston et al.. 1995
LATITUDINAL GRADIENT OF FAMILY RICHNESS
Vascular plants
LATITUDINAL GRADIENT OF SPECIES (a) AND GENERIC (b) RICHNESS OF BIVALVES
(Flessa & Jablonski 1995)
Latitudinal gradient of extant species of corals(Fraser & Currie 1996)
Taxonomic diversity of the tropics: Phyla
• Annelida• Arthropoda• Chordata• Mollusca• Nematoda• Platyhelminthes• Rotifera
• Acanthocephala• Brachiopoda• Bryozoa• Cnidaria• Ctenophora• Echinodermata• Echiura• Ectoprocta• Gastrotricha• Kinoryncha• Loricifera• Nemertea• Phoronida• Pogonophora• Porifera• Priapulida• Sippuncula
• Onychophora
ONLY OCEANIC
ONLY TERRESTRIAL
TERRESTRIAL AND AQUATIC
BIRDS OF POLAND:
227 breeding specoes(Tomiałojć & Stawarczyk 2003)
Birds of Venezuela:
1382 species(Hilty, 2003)
CLOUD FOREST IN VENEZUELA (Rancho Grande)
Number of plant species in equatorial forests(after Primack i Corlett, 2005)
25061700Total Asia and Pacific
830175200Total
1000Pacific Islands
700Australia
1000Sri Lanka
4000S. India
10000Indochina etc.
45000Malaysia
18020000Africa total
4000Madagascar
16000Africa (land)
40093500Neotropics
Area forested (mln ha)Number ofspecies
Region
Number of tree species per hain rain forests of different continents
Primack i Corlett 2005
Other dataGentry 1988: 580 trees of 283 species/ha(Amazon, border of Venezuela and Brasil)
Speciesdiversity of
ants invariousregions
42Polynesia
23New Zealand
9667TOTAL
1100Australia
275New Guinea, New Britian and New Ireland
2080Asia (parts of this region)
2500Africa (sub-saharan)
429Europe
400USA
585North America, North of Mexico
2233West Indies, Mexico, Central andSouth America
No. sp.Region
From Holldoblerand Wilson (1991) andGroombridge(1992).
Number of coral genera in frelation to surfacetemperature of the see (Fraser & Currie 1996)
DIFFICULTIES WITHBIODIVERSITY MEASUREMENT
• How to measure species number withregard to area? (ecoregions, latitudinalzones, longitudinal belts, meridian, mapswith species density contours)
• The majority of tropical species are not known yet!
Okapi (Okapia johnstoni)Giraffidae
discovered in Congo in 1900
Pseudoryx nghetinhensis
1992
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
T.L.Erwin
19 treesLuehea seemani (Panama) fumigatedspecies of beetles collected .................................1200
Assumption 1: Average specifity of beetles = 13.5%ergo: No. of specialised species .............................163
Assumption 2: 50000 tree species in rein forests, on each specialisedspecies of beetles
ergo: total No. of species specialised .......... 8150000
Assumption 3: Beetles make up 40% spesies of arthropodsergo: No. of arthropod species ................... 20000000
Assumption 4: 2 × more species in tree canopies than on forest floorergo: total No. of species in rain forest ............ 30 mln
ERWIN’S ESTIMATE OF THE TOTAL SPECIES RICHNESS
Problems:
• Clinal variation of biotic diversity on Earth• Hypotheses explaining species richness in
the tropics• Adaptive strategies of tropical biota
Hillebrand, 2004:meta-analysys of 600 data sets confirms gradient properties:
• at regional scale are stronger and steeper than atlocal one;• strength and steepness increases with body size ofthe group studied;• strength increases with trophic level;• taxonomic effect (poikilo- vs. homeotherms);• in freshwater environments weaker than in marineand terrestrial ones;• differs between continents and environments;• hemispheres (S or N) do not matter.
LATITUDINAL BIODIVERSITY GRADIENTSARE UNIVERSAL
HISTORY OF THE RESEARCH CONCERNING THEGEOGRAPHY 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. 2000– Willig et al. 2003– Turner 2004– Mittelbach et al. 2007
LOCALCOMMUNITY
LIMBOSPECIATION EXTINCTION
SPECIESPOOL
evolutionarytime scale
„ASSEMBLYRULES”environmental filtering
dispersal limitation
interactions
ecologicaltime scale
history = randomness
SUCCESSION
Continental spatial scale
MAJOR APPROACHES ANDCONTROVERSIES
• Neutral theories (MacArthur & Wilson, Hubbell)
• Niche-based theories (competition, specialization)
• Equilibrium vs. Non-equilibrum communities
GROUPS OFHYPOTHESES
ECOLOGICAL FACTORS(carrying capacity)
VARIOUS RATE OFSPECIESDIFFERENTIATION(speciation and extinction)
MORE TIME FOR DIFFERENTIATION IN THE TROPICS
Mittelbach et al. 2007
Differentiation rate similar, but more time in the tro pics: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 faster1. Genetic drift in small populations 2. Climatic changes accelerate speciation3. Higher likeness of para- and sympatric speciation4. Larger area of the tropics – more chances for isolation5. Narrower physiological tolerance of tropical biota6. Higher temperature accelerates evolution7. Stronger interactions – narrower specialisation and faster speciation
...because extinction rate is lower1. Stable climate2. Larger area – more numerous populations – lower risk of extinction
EVOLUTIONARY HYPOTHESES CONC. BIODIVERSITY GRADIENT
Most important hypotheses explaininggeographical biodiversity gradient
• Geographical area• History• Productivity• Environmental energy• Rapoport’s rule• The rate of evolution• Geometric limitation• Continuous disturbance
• The geometry of the globe implies that thearea of equatorial zone is the largest;
• This area is thermally most uniform andstable;
• The number of species increases witharea;
• Large area has more diverse habitats.
Geographical area(Terborgh; Rosenzweig)
Rosenzweig 1995
SPECIES RICHNESS (S) IN RELATIONTO THE SURFACE AREA (A)
S = cAz log S = log c + z log A
NUMBER OF TREE SPECIESIN RELATION TO ISLAND AREA (AUSTRALIA)
LARGER AREAS OF RAIN FORESTS MAINTAINT MOREPRIMATE SPECIES
Primack i Corlett 2005)
NUMBER OF PRIMATE SPECIES CORRELATES ALSOWITH RAINFALL (EXCEPT FOR ASIA)
Primack i Corlett 2005
THE EFFECT OF LATITUDE UPON
„species-area” RELATIONLyons & Willig 2002
• data: marsupials and bats of Americas
• relation: S = C Az
where S = species number, A = areaC, z = parameters
log S
log A
1 2 3
C1 > C2z2 > z3
1. A clear latitudinal gradient of z (Lyons & Willig 2002)
pasami
kwadratami
1. A clear latitudinal gradient of C (Lyons & Willig 2002)
Conclusions:• Biotic diversity in the tropics is higher but less dependent on area;• This effect should be taken into account atany comparisons;
log S
log A
tropics
other
HISTORY(Rosenzweig)
• Tropical area was not subjected to deepclimatic changes during a long time;
• Climatic changes caused fragmentation oftypical tropical environments (rain forests) and enhanced speciation;
• In the tropics the number of speciesincreases with time (many old taxons).
The extent of recent glaciation, 18000 y. ago
CHANGES OF THE RAIN FOREST EXTENTIN SOUTH AMERICA
DURING PEISTOCENE RECENTLY
Mittelbach et al. 2007
HISTORY: thermal maximum in eocene,maximum extent of tropical environments
Average age of avian taxain relation to latitude
Weiner 2003 from Gaston & Blackburne 1996
Stebbins: „cradle or museum?”
latitude
log
(av.
age
ofta
xon)
Productivity
• Higher primary production (Pp) enables to maintain more species populations (S) (Hutchinson 1959, „Santa Rozalia”)
• S correlates (in large spatial scale) with Ppand AET
• No correlation of Pp i S in small scale• No explanation of the mechanism
Daniel Simberloff: „Santa Rozalia was a goat”
Environmental energy(Turner)
• Thermal conditions in the tropics are closeto thermoneutrum and stable
• Individual energy budget is less loadedenabling more expensive specialisations
• Temperature and PET correlate with S
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 geographicalranges
• Stronger endemism in tropical climate
• Critics: contradictory examples, no evidence for the mechanism postulated
Rapoport’s rule
Ranges of the taxonswith the centres distantfrom equator are larger.
TreesSea molluscs
Fishes Reptiles and amphibians
Mammals
from Stevens 1989; Weiner 2003
Rapoport’s ruleon elevation gradient
Vertical ranges of species arelarger if their centre is locatedat higher elevation a.s.l.;With increasing elevation thediversity decreases.
Stevens 1992; Weiner 2003
Trees in Costarica
Mammals in Colorado
Birds in Venezuela
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
Geometric limitation
• Ranges randomly distributed over a largebut limited area make up a gradient oflocal diversities because of purely„mechanical” reasons.
Intermediate Disturbance Hypothesis(Connel)
• Rain forest: non-equilibrium; • „Gaps” continuously colonized (succesion)• Coral reef: non-equilibrium• Intermedite disturbances (hurricanes) and
continuous succesion
Classic text to read:
Joseph H. Connel, 1978:
Diversity in Tropical Rain Forestsand Coral Reefs
Science, V. 199, 4335: 1302-1310
FUNCTIONAL SIGNIFICANCE OFBIODIVERSITY
IN THE TROPICS
• Global carbon balance• Global water circulation• Local trophic cascade• Local biogeochemical balance
Tree biodiveersity efect uponbiomass carbon accumulation in
equatorial forest (Panama)Bunker et al. 2005; SCIENCE 310:1029-1031
• Mid column : average and c.v.• Number of tree species: 1 ... 126• Carbon accumulation: Mg/ha• Simulated sequence of spiecies loss:
• random• large-statured first• low density ‘’• high density ‘’• slow-growing ‘’• drought sensitive ‘’• endemic ‘’• widespread ‘’
Species richness
The effuct of mammals and birds uponherbivores, 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
Microfaunal sbundance drops, macrofaunal (earthworms) inceases on the plots void of mammale and birds (Dunham, 2008)
Percent loss of leaf biomass and morality of seedlings in he plotswithout mammals and birds
(Dunham, 2008)
Changes in the amount ofthe available inorganicphosphorus (P) andnitrogen (N) in the soildepending on the presenceof mammals and birds, after 8 month of exclusion.
(Dunham, 2008)
Trophic cascade in the rain forest
positive effects
negative efects
(Dunham, 2008)