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Ignasi Bartomeuswww.bartomeuslab.com
[email protected]@ibartomeus
An empirical evaluation of the role of network structure for community stability
WHY?
1) nestedness confer stability in mutualistic networks
Thebault and Fontaine 2006. Science, Lever et al. 2014 Ecol. Let.
2) Species contributing most to nestedness are more likely to go extinct
Saavedra et al. 2011 Nature; 2013 Nature comm.
Confront expectations with data!
How?
ES42CH01-Winfree ARI 26 September 2011 12:49
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300 to 3,000 m radius
a
b
Figure 3Schematic showing the two study designs contrasted in this review. (a) Design focused on surroundinglandscape cover. Sampling is generally done within a fixed habitat type. In the most common design, sitesvary in the proportion of surrounding land cover composed of specific habitat types such as forest (dark green)or agriculture ( yellow). The radius at which landscape cover is assessed varies across studies but is typicallybetween 300 and 3,000 m. Other designs, which we include in this category, vary either the linear distance tothe nearest habitat patch or the area of the habitat patch. (b) Design focused on local land-use type. Thesestudies compare pollinator communities among different habitat types. The surrounding landscape coverand the spatial extent of the habitat type where pollinators are sampled are generally not reported.
Figure 4)]. Bees and butterflies both show strong negative responses to land-use change in extremesystems, but more mixed responses in moderate systems (Supplemental Tables 2 and 3). Extremeland use causes a strong decrease in abundance and/or richness (e.g., Aizen & Feinsinger 1994,Koh & Sodhi 2004, Kremen et al. 2002, Ockinger & Smith 2006), whereas studies in moderatelyanthropogenic landscapes find more varied responses (e.g., Bartomeus et al. 2010, Bergman et al.2008).
Study designs that make comparisons across habitat types, rather than across landscape gra-dients, find even fewer negative effects, and responses are predominantly positive for most taxa(Supplemental Table 4). For bees, the ratio of negative-to-positive responses decreases from8.2 for extreme landscape studies to 2.0 for moderate landscape studies, to 0.5 for across-habitatcomparisons. For butterflies, the ratios decrease from 6.0 to 3.0 to 1.1, respectively (Supple-mental Tables 2–4). The responses of syrphid flies and vertebrates are difficult to interpretdue to the limited number of landscape-scale studies that have been conducted (SupplementalTables 2 and 3).
The reason why pollinator abundance and/or richness often decrease with increasing humanland use in the surrounding landscape, but increase with conversion of natural to anthropogenic
8 Winfree · Bartomeus · Cariveau
Ann
u. R
ev. E
col.
Evol
. Sys
t. 20
11.4
2:1-
22. D
ownl
oade
d fr
om w
ww
.ann
ualre
view
s.org
by 6
7.13
9.62
.82
on 1
1/18
/11.
For
per
sona
l use
onl
y.
ES42CH01-Winfree ARI 26 September 2011 12:49
?
? ?
?
?
?
? ?
?
?
300 to 3,000 m radius
a
b
Figure 3Schematic showing the two study designs contrasted in this review. (a) Design focused on surroundinglandscape cover. Sampling is generally done within a fixed habitat type. In the most common design, sitesvary in the proportion of surrounding land cover composed of specific habitat types such as forest (dark green)or agriculture ( yellow). The radius at which landscape cover is assessed varies across studies but is typicallybetween 300 and 3,000 m. Other designs, which we include in this category, vary either the linear distance tothe nearest habitat patch or the area of the habitat patch. (b) Design focused on local land-use type. Thesestudies compare pollinator communities among different habitat types. The surrounding landscape coverand the spatial extent of the habitat type where pollinators are sampled are generally not reported.
Figure 4)]. Bees and butterflies both show strong negative responses to land-use change in extremesystems, but more mixed responses in moderate systems (Supplemental Tables 2 and 3). Extremeland use causes a strong decrease in abundance and/or richness (e.g., Aizen & Feinsinger 1994,Koh & Sodhi 2004, Kremen et al. 2002, Ockinger & Smith 2006), whereas studies in moderatelyanthropogenic landscapes find more varied responses (e.g., Bartomeus et al. 2010, Bergman et al.2008).
Study designs that make comparisons across habitat types, rather than across landscape gra-dients, find even fewer negative effects, and responses are predominantly positive for most taxa(Supplemental Table 4). For bees, the ratio of negative-to-positive responses decreases from8.2 for extreme landscape studies to 2.0 for moderate landscape studies, to 0.5 for across-habitatcomparisons. For butterflies, the ratios decrease from 6.0 to 3.0 to 1.1, respectively (Supple-mental Tables 2–4). The responses of syrphid flies and vertebrates are difficult to interpretdue to the limited number of landscape-scale studies that have been conducted (SupplementalTables 2 and 3).
The reason why pollinator abundance and/or richness often decrease with increasing humanland use in the surrounding landscape, but increase with conversion of natural to anthropogenic
8 Winfree · Bartomeus · Cariveau
Ann
u. R
ev. E
col.
Evol
. Sys
t. 20
11.4
2:1-
22. D
ownl
oade
d fr
om w
ww
.ann
ualre
view
s.org
by 6
7.13
9.62
.82
on 1
1/18
/11.
For
per
sona
l use
onl
y.
Stability measures (e.g. species loss speed)
+ + =
Metaweb
ES42CH01-Winfree ARI 26 September 2011 12:49
?
? ?
?
?
?
? ?
?
?
300 to 3,000 m radius
a
b
Figure 3Schematic showing the two study designs contrasted in this review. (a) Design focused on surroundinglandscape cover. Sampling is generally done within a fixed habitat type. In the most common design, sitesvary in the proportion of surrounding land cover composed of specific habitat types such as forest (dark green)or agriculture ( yellow). The radius at which landscape cover is assessed varies across studies but is typicallybetween 300 and 3,000 m. Other designs, which we include in this category, vary either the linear distance tothe nearest habitat patch or the area of the habitat patch. (b) Design focused on local land-use type. Thesestudies compare pollinator communities among different habitat types. The surrounding landscape coverand the spatial extent of the habitat type where pollinators are sampled are generally not reported.
Figure 4)]. Bees and butterflies both show strong negative responses to land-use change in extremesystems, but more mixed responses in moderate systems (Supplemental Tables 2 and 3). Extremeland use causes a strong decrease in abundance and/or richness (e.g., Aizen & Feinsinger 1994,Koh & Sodhi 2004, Kremen et al. 2002, Ockinger & Smith 2006), whereas studies in moderatelyanthropogenic landscapes find more varied responses (e.g., Bartomeus et al. 2010, Bergman et al.2008).
Study designs that make comparisons across habitat types, rather than across landscape gra-dients, find even fewer negative effects, and responses are predominantly positive for most taxa(Supplemental Table 4). For bees, the ratio of negative-to-positive responses decreases from8.2 for extreme landscape studies to 2.0 for moderate landscape studies, to 0.5 for across-habitatcomparisons. For butterflies, the ratios decrease from 6.0 to 3.0 to 1.1, respectively (Supple-mental Tables 2–4). The responses of syrphid flies and vertebrates are difficult to interpretdue to the limited number of landscape-scale studies that have been conducted (SupplementalTables 2 and 3).
The reason why pollinator abundance and/or richness often decrease with increasing humanland use in the surrounding landscape, but increase with conversion of natural to anthropogenic
8 Winfree · Bartomeus · Cariveau
Ann
u. R
ev. E
col.
Evol
. Sys
t. 20
11.4
2:1-
22. D
ownl
oade
d fr
om w
ww
.ann
ualre
view
s.org
by 6
7.13
9.62
.82
on 1
1/18
/11.
For
per
sona
l use
onl
y.
ES42CH01-Winfree ARI 26 September 2011 12:49
?
? ?
?
?
?
? ?
?
?
300 to 3,000 m radius
a
b
Figure 3Schematic showing the two study designs contrasted in this review. (a) Design focused on surroundinglandscape cover. Sampling is generally done within a fixed habitat type. In the most common design, sitesvary in the proportion of surrounding land cover composed of specific habitat types such as forest (dark green)or agriculture ( yellow). The radius at which landscape cover is assessed varies across studies but is typicallybetween 300 and 3,000 m. Other designs, which we include in this category, vary either the linear distance tothe nearest habitat patch or the area of the habitat patch. (b) Design focused on local land-use type. Thesestudies compare pollinator communities among different habitat types. The surrounding landscape coverand the spatial extent of the habitat type where pollinators are sampled are generally not reported.
Figure 4)]. Bees and butterflies both show strong negative responses to land-use change in extremesystems, but more mixed responses in moderate systems (Supplemental Tables 2 and 3). Extremeland use causes a strong decrease in abundance and/or richness (e.g., Aizen & Feinsinger 1994,Koh & Sodhi 2004, Kremen et al. 2002, Ockinger & Smith 2006), whereas studies in moderatelyanthropogenic landscapes find more varied responses (e.g., Bartomeus et al. 2010, Bergman et al.2008).
Study designs that make comparisons across habitat types, rather than across landscape gra-dients, find even fewer negative effects, and responses are predominantly positive for most taxa(Supplemental Table 4). For bees, the ratio of negative-to-positive responses decreases from8.2 for extreme landscape studies to 2.0 for moderate landscape studies, to 0.5 for across-habitatcomparisons. For butterflies, the ratios decrease from 6.0 to 3.0 to 1.1, respectively (Supple-mental Tables 2–4). The responses of syrphid flies and vertebrates are difficult to interpretdue to the limited number of landscape-scale studies that have been conducted (SupplementalTables 2 and 3).
The reason why pollinator abundance and/or richness often decrease with increasing humanland use in the surrounding landscape, but increase with conversion of natural to anthropogenic
8 Winfree · Bartomeus · Cariveau
Ann
u. R
ev. E
col.
Evol
. Sys
t. 20
11.4
2:1-
22. D
ownl
oade
d fr
om w
ww
.ann
ualre
view
s.org
by 6
7.13
9.62
.82
on 1
1/18
/11.
For
per
sona
l use
onl
y.
Overall structure (e.g. nestedness)
Stability measures (e.g. species loss speed)
Map worldwide.
2) Species contributing most to nestedness are more likely to go extinct
Each node nestedness contribution
Permutation of the node values
Each node nestedness contribution Each node real loss order
Rank of extinctionPermutation of the node values
Sites
Pollinators
ES42CH01-Winfree ARI 26 September 2011 12:49
?
? ?
?
?
?
? ?
?
?
300 to 3,000 m radius
a
b
Figure 3Schematic showing the two study designs contrasted in this review. (a) Design focused on surroundinglandscape cover. Sampling is generally done within a fixed habitat type. In the most common design, sitesvary in the proportion of surrounding land cover composed of specific habitat types such as forest (dark green)or agriculture ( yellow). The radius at which landscape cover is assessed varies across studies but is typicallybetween 300 and 3,000 m. Other designs, which we include in this category, vary either the linear distance tothe nearest habitat patch or the area of the habitat patch. (b) Design focused on local land-use type. Thesestudies compare pollinator communities among different habitat types. The surrounding landscape coverand the spatial extent of the habitat type where pollinators are sampled are generally not reported.
Figure 4)]. Bees and butterflies both show strong negative responses to land-use change in extremesystems, but more mixed responses in moderate systems (Supplemental Tables 2 and 3). Extremeland use causes a strong decrease in abundance and/or richness (e.g., Aizen & Feinsinger 1994,Koh & Sodhi 2004, Kremen et al. 2002, Ockinger & Smith 2006), whereas studies in moderatelyanthropogenic landscapes find more varied responses (e.g., Bartomeus et al. 2010, Bergman et al.2008).
Study designs that make comparisons across habitat types, rather than across landscape gra-dients, find even fewer negative effects, and responses are predominantly positive for most taxa(Supplemental Table 4). For bees, the ratio of negative-to-positive responses decreases from8.2 for extreme landscape studies to 2.0 for moderate landscape studies, to 0.5 for across-habitatcomparisons. For butterflies, the ratios decrease from 6.0 to 3.0 to 1.1, respectively (Supple-mental Tables 2–4). The responses of syrphid flies and vertebrates are difficult to interpretdue to the limited number of landscape-scale studies that have been conducted (SupplementalTables 2 and 3).
The reason why pollinator abundance and/or richness often decrease with increasing humanland use in the surrounding landscape, but increase with conversion of natural to anthropogenic
8 Winfree · Bartomeus · Cariveau
Ann
u. R
ev. E
col.
Evol
. Sys
t. 20
11.4
2:1-
22. D
ownl
oade
d fr
om w
ww
.ann
ualre
view
s.org
by 6
7.13
9.62
.82
on 1
1/18
/11.
For
per
sona
l use
onl
y.
ES42CH01-Winfree ARI 26 September 2011 12:49
?
? ?
?
?
?
? ?
?
?
300 to 3,000 m radius
a
b
Figure 3Schematic showing the two study designs contrasted in this review. (a) Design focused on surroundinglandscape cover. Sampling is generally done within a fixed habitat type. In the most common design, sitesvary in the proportion of surrounding land cover composed of specific habitat types such as forest (dark green)or agriculture ( yellow). The radius at which landscape cover is assessed varies across studies but is typicallybetween 300 and 3,000 m. Other designs, which we include in this category, vary either the linear distance tothe nearest habitat patch or the area of the habitat patch. (b) Design focused on local land-use type. Thesestudies compare pollinator communities among different habitat types. The surrounding landscape coverand the spatial extent of the habitat type where pollinators are sampled are generally not reported.
Figure 4)]. Bees and butterflies both show strong negative responses to land-use change in extremesystems, but more mixed responses in moderate systems (Supplemental Tables 2 and 3). Extremeland use causes a strong decrease in abundance and/or richness (e.g., Aizen & Feinsinger 1994,Koh & Sodhi 2004, Kremen et al. 2002, Ockinger & Smith 2006), whereas studies in moderatelyanthropogenic landscapes find more varied responses (e.g., Bartomeus et al. 2010, Bergman et al.2008).
Study designs that make comparisons across habitat types, rather than across landscape gra-dients, find even fewer negative effects, and responses are predominantly positive for most taxa(Supplemental Table 4). For bees, the ratio of negative-to-positive responses decreases from8.2 for extreme landscape studies to 2.0 for moderate landscape studies, to 0.5 for across-habitatcomparisons. For butterflies, the ratios decrease from 6.0 to 3.0 to 1.1, respectively (Supple-mental Tables 2–4). The responses of syrphid flies and vertebrates are difficult to interpretdue to the limited number of landscape-scale studies that have been conducted (SupplementalTables 2 and 3).
The reason why pollinator abundance and/or richness often decrease with increasing humanland use in the surrounding landscape, but increase with conversion of natural to anthropogenic
8 Winfree · Bartomeus · Cariveau
Ann
u. R
ev. E
col.
Evol
. Sys
t. 20
11.4
2:1-
22. D
ownl
oade
d fr
om w
ww
.ann
ualre
view
s.org
by 6
7.13
9.62
.82
on 1
1/18
/11.
For
per
sona
l use
onl
y.
+ +
For deciduous forests in US:
Rachael Winfree
What drives extinction order then?
What drives extinction order then?
More in Winfree et al. 2014 Am. Nat.
1) nestedness confer stability
Nestedness
Relative nestedness (NODF)
Nestedness % Links lost at 50% habitat destruction
50% habitat loss
% lin
ks lo
ssRelative nestedness (NODF)
+ +
link loss at 50% habitat loss
link loss at 50% habitat loss
?
Thank you @ibartomeuswww.bartomeuslab.com
This project is been possible thanks to...Data providers: Rachael Winfree, Dan Cariveau, Laura Burkle, Marie Winsa, Marcelo Aizen, Jennifer Wickens, Andrea Holzchuh, Juanpe Gonzalez-Varo, …
but also to theory developers.
What models do not take into account: Complexity!
Species have different levels of dependencies on its partners
Species may be regulated by other factors (e.g. nest sites)
…
Not a critique to the models/mechanisms, but to its relevance in real ecosystem.
What empirical data does not takes into account:Sampling artefactsLack of measures of stability…
Not a critique to the observational studies, but to its ability to detect the signal.
(But see Bartomeus 2013 PLoS ONE)
