Diversity: alpha

1
Diversity alpha beta gamma
2
Beta diversity is a concept that helps us to cope
with the fact that not every species lives
everywhere
Whittaker 1972
? ? ?avg
Lande 1996
? ?avg ?
3
(No Transcript)
4
Beta diversity indices
Koleff et al. 2003 J anim Ecol 72367
5
"Broad sense" measures incorporate differences in
species richness as well as differences in
composition
Lennon et al.
"Narrow sense" measures independent of
differences in species richness
Example 1 a 10, b 10, c 100 Jaccard
10/120 0.08 Sorensen 20/130 0.15 Lennon
1- 10/20 0.5
Example 2 a 10, b 10, c 1000 Jaccard
10/1020 0.010 Sorensen 20/1030 0.019 Lennon
1- 10/20 0.5
Koleff et al. 2003 J anim Ecol 72367
6

• Beta diversity along e.g. latitudinal gradient
• change in community composition measured by beta
  diversity
• change in beta diversity

7
Latitudinal gradient in alpha diversity owls
Koleff et al. 2003
8
Latitudinal gradient in A, B, C parameters
owls for adjacent pairs of quadrats
A
focal area
C
B
Koleff et al. 2003
9

Beta diversity A/(ABC) of owls along
latitudinal gradient
Koleff et al. 2003
10
Beta diversity of vertebrates
Birds
Mammals
Amphibians
decrease in species overlap over 500 km
11
Beta diversity and optimum selection of protected
areas
richness-based algorithm
rarity-based algorithm
Reyers et al. 2000

1. select the most species rich plot
2. 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

12
Causes of species turnover in space
Speciation and dispersal limitation species
migration ability vs. barriers
Habitat availability biotic and abiotic
resources and limiting factors
Biological interactions competitive exclusion
from suitable habitats
Apparent species turnover species too rare to be
sampled
13
Speciation and dispersal limitation the
Hubbells (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
14
Habitat availability altitudinal gradient, the
mother of all environmental gradients


15
Two modes of altitudinal species turnover with
complete nestedness and zero nestedness
Identical altitudinal trends in species richness
mean different trends in mean altitudinal range
of species and beta diversity between adjacent
altitudes
16
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.
17
Altitudinal distribution of 454 bird species in
Papua New Guinea
0 m asl.
4500 m asl.
each row is 100 m elevation belt, each column a
bird species
K. Tvardikova, unpubl. data
18
Biological interactions checkerboard
distributions
Altitudinal segregation of competing parrots in
New Guinea
Language distribution among tribal societies
19
Checkeboard distribution - not predicted by
island biogeography
M. nigrirostris
M. mackinlayi
Cockoo-dove Macropygia mackinlayi and M.
nigrirostris
Diamond, J.M. (1975) Community Ecology
20
Checkerboard distribution Zosterops birds in New
Guinea
21
Zosterops chloris
Zosterops atriceps
22
Herpetofauna on British Virgin Islands a nested
pattern of species distribution
23
Nestedness can be used to determine extinction
probabilities
species
islands
(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.
24
Matrix temperature T
U 1/(mn) ?i ? j uij T U/Umax 100