conservation biology (1990) - fapesp · phylogeny of species of birds that eat euterpe edulis...
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Conservation Biology (1990)
Selective defaunation creates a new
selective force for evolution: a sequel to
Rodolfo DirzoMauro Galetti
Departamento de Ecologia
São Paulo State University - Rio Claro, São Paulo,
Brazil
We live in a zoologically
impoverished world, from which
all the hugest, and fiercest, and
strangest forms have recently
disappeared…
Alfred Russell Wallace (1876)
World diversity of mammals
40 species
11 species
19 species
14 species
653
199 evaluated (35% in risk)
World= 21% of species at risk
Schipper et al. 2008
8 species
DD= 110 species
Chiarello et al. 2008
Relative importance, in rank order, of ecological predictors of mammalian extinction risk.
Davidson A D et al. PNAS 2009;106:10702-10705
©2009 by National Academy of Sciences
Major Threats
% S
pecie
s
Chiarello et al. 2008
Habitat lossFragmentation Poaching Persecution
The scale of defaunation
Killed animals/yearPeres, 2000, Fa et al. 2002
Hunting affects selectively the game
species
Nobre, 2007
Pro
po
rtio
n
Abundance of mammals in the
continuous Serra do Mar
Nobre & Galetti, unpubl. data
30 x
De
nsid
ade
(In
d/k
m2
)
1
34
2
5
6
7
8 910
111213
>4.000 km sampling
13 Continuous Protected Areas
What’s the status of large mammals in
the largest continuous Atlantic Forest?
Density of mammals: Amazon x Atlantic forest
278,78
75,04
63,96 62,4056,56
19,68 18,6514,33
11,12 10,89 8,925,69 3,66
270
229
200
164
142 140
126
111106,00
0
50
100
150
200
250
300
1 2 3 4 5 6 7 8 9 10 11 12 13
Mam
mal de
nsity (
Ind
/km
2)
Galetti et al. 2009,
Haugaasen & Peres 2005
3x 9.5x
Amazon
Atlantic forest
The role of mammals in promoting diversity
Pollination
Seed dispersal
Seed predation
Herbivory
Trampling
30% of trees
in the
Atlantic
forest
Predation
Competition or Interference
Non defaunated forest
Predation
Predation
Highly Defaunated forests
None Moderate High
Perturbation intensity
Ab
un
da
nce
/Eco
log
ica
l R
ol
Expected changes in mammal communities
in relation to perturbation
Wright, 2003
Trade-offs between rodent and
large mammal abundance in Africa
Saccostomus mearnsi
McCauley et al. 2006
Parque Estadual Serra do Mar
Núcleo Santa Virgínia
2 sites= 15 km
Neves, 2010
30 25 20 15 10 5 0 5 10 15 20 25 30 35 40 45
Canis lupus familiaris
Hydrochoerus hydrochaeris
Eira barbara
Didelphis aurita
Tamandua tetradactyla
Dasypus novemcinctus
Leopardus tigrinus
Cerdocyon thous
Dasyprocta leporina (aff.)
Puma yagouaroundi
Pecari tajacu
Leopardus pardalis
Leopardus wiedii
Cuniculus paca
Puma concolor
Nasua nasua
Alouatta guariba
Tapirus terrestris
Sciurus aestuans
Cebus nigritus
Callithrix aurita
Tayassu pecari
Número de registros
Base Itamambuca Base Vargem Grande
Número de registro por espécie de mamíferos (transectos lineares + armadilhas fotográficas) para as bases Itamambuca e Vargem Grande, bases de pesquisa do Núcleo Santa Virgínia – Parque Estadual da Serra do Mar.
Rocha-Mendes & Galetti, unpubl.
Mammal abundance
Sampling Small Mammals
Live-trap
2700 live-traps/night/site
Pitfall
720 pitfall-traps/night/site
Marsupials
Abundance o
f m
ars
upia
ls
livetrap pitfall
0
1
2
3
4
5
6No-defaunated
Defaunated
Rodents
Abundance o
f ro
dents
livetrap pitfall
0
5
10
15
20
25No-defaunated
Defaunated
Alternative hypothesis
• Snake abundance – Rejected
• Mesopredator abundance – Rejected
• Resource limitation (fruits/insects) – Rejected
• Microhabitat limitation - Rejected
A forest with too many
rodents, may have high
seed predation
Palmito, Euterpe edulis
Dominant and keystone species in the AF
Fruits consumed by more than 47 bird
species
Harvested for palm heart
1
34
2
5
4 defaunated sites
X
3 non-defaunated sites
Richness of Seed Predators in Non-
defaunated forests
Richness of Seed Predators in
Defaunated forests
Defaunated Non-defaunated
0.0
0.5
1.0
1.5
2.0
2.5
3.0
Number of Predations per day
GLM ~ Poisson distribution
F value=10.59; P= 0.0014 **
Df= 1,138
Effect magnitude: 6.33 higher
Nu
mbe
r o
f se
eds p
red
ate
d/d
ay
Higher seed predation in defaunated forests
Proportion of predated
Pro
po
rtio
n
0.0
0.2
0.4
0.6
0.8
1.0
Defaunated Non-defaunated
BirdsLarge rodents
Small rodentsUngulates
Rodents were the major seed predator in defaunated forests
Conclusion 1
• Peccaries exerts a top down effects on
rodent populations
• Peccaries-free forest have higher seed
predation due to rodent overabundance
What about seed
dispersal?
• We collected about 1400 hours of focal
observation in 15 populations of Euterpe
edulis.
• Each area was classified as “defaunated” if
toucans were absent.
15 populations (6 defaunated x 9 non defaunated)
-Frugivory and seed dispersal
-Seed size variation
-Demography and spatial distribution
The extinction of
palmito dispersers
affects more large-
gaped birds
Regurgitate
Regurgitate
Regurgitate
Defecate
Predate
Drop
12 Regurgitate
3 Defecate
4 Predate
10 Drop
Phylogeny of species of birds that eat Euterpe edulis fruits in non-
defaunated forests
Regurgitate
Defecate
Drop
1 Regurgitate
1 Defecate
0 Predate
10 Drop
Phylogeny of species of birds that eat Euterpe edulis fruits in
defaunated forests
Impact of losing large
birdsPollination Seed dispersal
Non-defaunated area
Defaunated area
Long distance dispersal
Dispersal effectiveness
Fruit choice
Defaunation selects for small gaped birds
GLM, F1,10=5.5, P=0.041
380 g 55 g7x
2.5x
Larger seed disperser
in non-defaunated
site
Larger seed
disperser in
defaunated site
Rottweiler Pug
50 kg 7 kg
Large-gaped birds eat
larger seeds than
small-gaped birds
Seed size eaten by different frugivores
GLM, F6,390=25.5, P<0.0001
Seed size eaten by different frugivores
GLM, F6,390=25.5, P<0.0001
Palmito seeds need to
be dispersed by birds
that regurgitate them
Probability of seed germination per disperser type
Survival analysis, F1,3=65.64, P=0.0001
Therefore, large seeds
are not dispersed in
defaunated forests
Regurgitated
(dispersed)
Pecked by birds
(not dispersed)
Defaunated
Non-
defaunate
d
Binary GLM, Site/Size: 2[4] =
153.6, df = 5, P < 0.001
Probability of seed dispersal in defaunated sites decline
with seed size
The populations of
defaunated sites have
smaller seeds
Fragments
Continuous
Comparing seed size among populations with
same soil, climate, forest type
Nested GLM, F2,1594=211, P<0.0001
Comparison of seed size between pair populations
1
1
2
3
4
5
6
7
8
9
10
11
12
13
23
45
136
7 8
9
11
12
8418 seeds
13
populations
Alternative hypothesis
Geographical distance (Rejected)
Tree age (size and DBH) (Rejected)
Rainfall (Rejected)
Latitude (Rejected)
Soils (Rejected)
Trade-off between fruit crop and seed
size (Rejected)
Founder effect (Rejected)
Rapid phenotypic
changes can explain
seed shrinkage in
palmitos
Response to selection (Rt)
Heritability 0.2
0.3
Mean seed size in defaunated sites
(Selected by small frugivores)
Mean seed size in
non-defaunated
population
Generation time in Euterpe = 18.7 years
Rt1 h2(d f dt )
h2=0.3h2=0.2
Continuous forests
Fragmented forests
Predicted seed size after bird defaunation
h2=0.3
h2=0.2
How old are these
fragments?
Fragments
~190 years
(10 generations)
“Between 1821 e 1824, several sugar cane and coffee farms were established.” Rio Claro: The Plantation System. Warren Dean.
Long term consequences
of defaunation under a
Global change scenario
The importance of having larger
seeds
• Larger seeds means more
reserve
• Bigger seedlings (vigor)
• Can be partially predated
• Can have less predators
• May be able to cope with global
change scenarios
Take home messages
1.Defaunation will create new ecological constraints to
plant populations (increasing seed predation, seed
limitation).
2.Defaunation will create new selective force for
evolution
3.Defaunation can drive rapid evolutionary changes on
key phenotypic traits in plants
It is not the strongest of
the species that survives,
nor the most intelligent
that survives. It is the
one that is the most
adaptable to change.
Charles Darwin
Palmito gang