Diversity: alpha – beta – gamma
0
20
40
60
80
100
120
0 1 2 3 4 5 6 7
Area
Sp
ec
ies
ALPHA
BETA GAMMA
Beta diversity is a concept that helps us to cope with the fact that not every species lives everywhere
= avg +
= avg
Whittaker 1972
Lande 1996
Koleff et al. 2003 J anim Ecol 72:367
Beta diversity indices
Sorensen
Lennon et al.
Koleff et al. 2003 J anim Ecol 72:367
Jaccard"Broad sense" measuresincorporate differences in species richness as well as differences in composition
"Narrow sense" measuresindependent of differences in species richness
Example 1a = 10, b = 10, c = 100Jaccard = 10/120 = 0.08Sorensen = 20/130 = 0.15Lennon = 1- 10/20 = 0.5
1-
Example 2a = 10, b = 10, c = 1000Jaccard = 10/1020 = 0.010Sorensen = 20/1030 = 0.019Lennon = 1- 10/20 = 0.5
ßAB
A
FE
DC
B
ßBD
ßDF
ßAC
ßCE
ßEF
ßCDLa
titu
de
tem
pe
rate
tro
pic
al
Altitudelowland montane
Beta diversity along e.g. latitudinal gradient:• change in community composition measured by beta diversity• change in beta diversity
Latitudinal gradient in alpha diversity – owls
Koleff et al. 2003
focal area
Koleff et al. 2003
Latitudinal gradient in A, B, C parameters – owls
for adjacent pairs of quadrats
A
B C
Beta diversity A/(A+B+C) of owls along latitudinal gradient
Koleff et al. 2003
Amphibians
Birds
Mammals
Beta diversity of vertebrates
decrease in species overlap over 500 km
Reyers et al. 2000
Beta diversity and optimum selection of protected areas
1. select the most species rich plot2. add the plot bringing the highest
number of new species
1. select the plot with the rarest species 2. add the plot with the rarest
unrepresented species
richness-based algorithm rarity-based algorithm
Causes of species turnover in space
Speciation and dispersal limitation: species migration ability vs. barriers
Biological interactions: competitive exclusion from suitable habitats
Habitat availability: biotic and abiotic resources and limiting factors
Apparent species turnover:species too rare to be sampled
Speciation and dispersal limitation: the Hubbell’s (2001) neutral model
- all species ecologically identical - species turnover generated by dispersal limitation
The probability F(r) that 2 trees r km apart are conspecific is modelled as depending on: speciation rate , mean dispersal distance and population density is predicted to decrease linearly with log r
Habitat availability: altitudinal gradient, the mother of all environmental gradients
Ficus copiosa in New Guinea raingorest: 2 samples of 200 caterpillars 150 km apart
0
15
30
45
lowland x lowland lowland x montane
% o
f s
ha
red
sp
ec
ies
0
2
4
6
8
10
low high
Altitude
No.
of s
peci
es
0.0
0.2
0.4
0.6
0.8
1.0
low high
Altitude
Bet
a di
vers
ity [1
-Jac
card
] .
Two modes of altitudinal species turnover:with complete nestedness and zero nestedness
Identical altitudinal trends in species richness meandifferent trends in mean altitudinal range of species and beta diversity between adjacent altitudes
Species turnover along altitudinal gradients: Rhododendron spp. on Mt. Kinabalu
Rhododendrones: 900 spp. worldwide, 300 spp. in SE Asia, 50 spp. in Borneo, 25 spp. on Mt. Kinabalu, incl. 5 endemic spp.
Altitudinal distribution of 454 bird species in Papua New Guinea
0 m asl.
4500 m asl.
K. Tvardikova, unpubl. data
each row is 100 m elevation belt, each column a bird species
Biological interactions: “checkerboard” distributions
Altitudinal segregation of competing parrots in New Guinea:
Language distribution among tribal societies:
0
500
1000
1500
2000
2500
Mt. Niba SepikMts.
Mt.Karimui
KarkarIs.
Tolokiwa NewBritain
Alti
tude
(m
)
Charmosyna placentalis C. rubronotata C. rubrigularis
Diamond, J.M. (1975) Community Ecology
“Checkeboard distribution” - not predicted by island biogeography
Cockoo-dove Macropygia mackinlayi and M. nigrirostris
M. nigrirostris
M. mackinlayi
Checkerboard distribution: Zosterops birds in New Guinea
Zosterops chloris
Zosterops atriceps
Herpetofauna on British Virgin Islands:a nested pattern of species distribution
(a) a maximally cold matrix, (b) actual data, small mammals in Rocky Mts., (c), (d) matrices randomly filled under successively relaxed constraints [Patterson & Atmar 1986].
spec
ies
islands
Nestedness can be used to determine
extinction probabilities
U = 1/(mn) i j uij
T = U/Umax * 100
Matrix temperature T