1,721,279 research outputs found
Determining the Minimal Background Area for Species Distribution Models: MinBar PACKAGE
No full text1. One of the crucial choices when modelling species distributions using pseudo-absences approaches is the delineation of the background area to fit the model. We hypothesise that there is a minimum background area around the centre of the species distribution that characterizes well enough the range of environmental conditions needed by the species to survive. Thus, fitting the model within this area should be the optimal solution in terms of both quality of the model and execution time. 2. MinBAR is an R package that calculates the optimal background area. The version 1.0.0 is implemented for MaxEnt and uses Boyce Index as a metric to assess models performance. 3. Two case studies are presented to assess the hypothesis and to illustrate the package. 4. Partial models trained with part of the species distribution often perform better than those fitted on the entire extension. MinBAR is a versatile tool that helps modellers to objectively define the optimal solution.N
Data from: Effects of the control of an invasive tree on the structure of a plant-frugivore network
No full text[Description of the data] These data were generated to evaluate the structure of plant-bird frugivory interaction networks in a plant community invaded by the guava tree (Psidium guajava L.) by comparing network metrics before and after control actions.[Methods] We conducted the study in the Caieira Natural Municipal Park (CNMP), a protected area that covers 1.27 km² (Joinville, state of Santa Catarina, southern Brazil) (26°18’24”S, 48°47’36”W) (Figure 1a). The climate is subtropical, constantly humid, with hot summers and no dry season, and average maximum temperatures between 26.0 and 27.6º C (Cfa type in the Köppen classification; Joinville, 2021). The vegetation cover of the CNMP is represented by two forest types: coastal forest (restinga arbórea, in Portuguese) and mangrove (Joinville, 2021), both in the Atlantic Forest domain, an important global biodiversity hotspot (Myers et al., 2000) (Figure 1a,b). The park grants public access to landscaped areas and trails.
Non-native species were planted in a small orchard in the park between 1970 and 2004. Some of those trees, such as guava (Psidium guajava), avocado (Persea americana), and star fruit (Averrhoa carambola), still bear fruit in the area (Preis, 2020). Several invasive non-native plants have established populations in the park, and are listed in the management plan for control by park managers (Joinville, 2021). An established population of P. guajava trees was present both in landscaped areas and in restinga and mangrove remnants, totaling around 410 individuals per km².
Psidium guajava is a shrub or tree in the Myrtaceae family, up to 12 m in height, with smooth, scaly, reddish-brown bark. Fruits are globular to pyriform, 2–8 cm long, green to yellow, with pink, yellow, or white pulp (Landrum & Mitra, 2021). Psidium guajava can produce fruits throughout the year, especially in the summer months (Landrum & Mitra, 2021), but fruit phenology varies according to the species variety and water availability (Moura, 2001). In the study area, fruiting occurred between late summer to autumn (February to April; BM, personal observation). The main forms of dispersal are zoochory and anthropochory (Arévalo-Marín et al., 2021; Heleno et al., 2013b). The species is an important node in its introduced range both in pollination networks in Galapagos (see Traveset et al., 2015) and plant–frugivore networks in Galápagos, South Africa and Brazil (see Baltzinger et al., 2020; Heleno et al., 2013b; Silva & Pizo, 2020).
The origin of P. guajava is uncertain, but several authors suggest that it originated between northern South America and Central America (Arévalo-Marín et al., 2021). More recent studies indicate that it may have originated in the savannas and semi-deciduous forests of South America (Landrum & Mitra, 2021) or in the humid Chaco and/or Cerrado (Arévalo-Marín et al., 2021). Psidium guajava is widely cultivated in several countries and considered invasive in several tropical and subtropical regions of the world (Landrum & Mitra, 2021; Richardson & Rejmánek, 2011), such as East Africa (Witt & Luke, 2017), North America (Acevedo-Rodríguez & Strong, 2012), Brazil (Sampaio & Schmidt, 2013; Ziller & Dechoum, 2013) and the Galápagos Islands in Ecuador (Guézou et al., 2010; Urquía et al., 2019). Use by human populations very likely increased its distribution in the past (Arévalo-Marín et al., 2021). As an invasive species, it can form dense stands that displace native vegetation (Leão et al., 2011); thus, the balance between valuable fruit production and invasive potential requires careful monitoring (Landrum & Mitra, 2021) and continuous control.
Data collection of frugivory interactions
We collected data in the CNMP between February and April of 2021 and 2022, when P. guajava trees were fruiting in 2021, and in the same timeframe after P. guajava suppression, in 2022. We carried out thirty field surveys each year. In each survey, the same trail was covered by two observers in early morning hours (6:45 am ± 15 min until 10:00 am ± 30 min) or in the afternoon (4:00 pm ± 15 min and 6:30 pm ± 30 min) (Pizo & Galetti, 2010). The trails mainly covered landscaped areas and restinga vegetation (Figure 1a). In addition, we defined three observation areas (Figure 1c), where two observers kept watch together for 20 minutes (Jordano & Schupp, 2000). Each observer recorded all avian frugivory events on fruiting plants with a pair of binoculars (Leitz Wetzlar Trinovid 10x40) and a digital camera (Sony DSC-HX300 and Nikon Coolpix p510). Walking direction along the trail and order of observation areas were alternated on sampling days on each field survey to ensure that all study site areas were observed at different times of day. We carried out data collection at the same period of time over two consecutive years to ensure sampling consistency regarding the presence of migratory birds and fructification of the sampled plant species. We performed a nonparametric Wilcox test to verify whether the hours of observation in each year were different between years. The dependent variable was the duration of observation (in minutes) at every fortnight and the independent variable was sampling year. We used the iNEXT function from the iNEXT package to assess community diversity and build species accumulation curves (Hsieh, Ma, & Chao, 2022), using abundance data to estimate bird and plant diversity based on the Shannon index (q = 1). We conducted the analysis using R 3.6.2 software (R core Team, 2022).
We used the following parameters to record frugivory interactions by birds (feeding bouts): the plant species on whose fruits a bird was feeding, and the respective bird species. A new frugivory event was counted if the bird left the tree, and then returned. The number of fruits/seeds ingested per visit was not counted. Bird foraging flocks were recorded as separate interactions per individual. Bird identification was mostly carried out in the field, but we consulted experts and literature in case of uncertainty. Scientific nomenclature follows the Brazilian Committee of Ornithological Records (Pacheco et al., 2021). Likewise, plants not identified in the field were identified with help from experts who reviewed photographic records. The nomenclature of plant species is based on the “Flora e Funga do Brasil” database (2022).
Psidium guajava control campaigns
We conducted two P. guajava control campaigns in the CNMP. In October 2021, control mainly focused on adults and reproductive individuals, but also included small plants in the surroundings of eliminated adults. We eliminated a total of 435 plants. In May 2022, one month after the sampling period, a follow-up expedition took place, in which we eliminated 85 non-reproductive plants as well as resprouted plants. Altogether, we cut down about 520 P. guajava trees in the area. We cut close to ground level with a chainsaw, followed by immediate spraying of a 6% Garlon 480BR (Triclopyr active ingredient) solution on the stump (Dechoum & Ziller, 2013). Once regrowth was observed, we carried out a re-check with foliar application of a 2% Glyphosate solution. During the second field survey, one fruiting P. guajava tree was found, so we eliminated all fruits, the tree was later cut down, and the stump treated.
Network metrics
We organized the interactions observed during each year into quantitative matrices (i=plant species; j=bird species) based on the frequency of frugivory events observed in the CNMP. Two data matrices were built: the first one, entitled “unmanaged community”, referred to the plant community invaded by P. guajava in 2021, prior to the control intervention; the second one, entitled “managed community”, corresponded to the same community after control, in 2022. Both quantitative networks were built and analyzed using the Bipartite package (Dormann et al., 2009) in software R, version 3.6.2 (R core Team 2022). We calculated sampling completeness of species interactions using Chao1 as a richness estimator and the SCw1 function (Macgregor et al., 2017).
We evaluated the following network-level metrics, then contrasted them with those from null models for significance assessments: quantitative nestedness (weighted NODF; Almeida-Neto & Ulrich, 2011), quantitative modularity (DIRTLPAwb+ algorithm; Beckett, 2016), and interaction strength asymmetry (ISA; Dormann et al., 2008). We used Z-scores to assess significance of nestedness and modularity with null-model functions by comparing the results obtained with the observed values, using the methods vaznull and method r2d, respectively, with 999 randomizations each. We also used the null.t.test with 999 randomizations to obtain the significance of interaction strength asymmetry (Dormann et al., 2008). Interaction strength asymmetry varies between −1 and 1, with positive values indicating high dependence of an animal on a plant species, and negative values indicating the opposite (Blüthgen et al., 2007).
We evaluated the following species-level metrics: plant species degree centrality (Martín-González et al., 2010), plant species nestedness contribution, asymmetry of plant species interactions using the push-pull index (Vázquez et al., 2007) and participation coefficients (c-values), and within-module degree (z-values) for network modules (Olesen et al., 2007). Degree centrality takes the number of links of each node (k) into account. The push-pull index indicates the direction of interaction asymmetry based on dependency; positive values indicate that a species more strongly affects the species of the other level with which it interacts than vice versa (“pusher”), while negative values indicate that a species is, on average, more strongly affected by its interaction partners than it affects them (“being pulled”) (Vázquez et al., 2007). The cz-values were evaluated for both plant and bird species. We calculated the thresholds for participation coefficients and within-module degree for each network level (null models with 95% confidence intervals) and used them to identify the topological role of each species (network hub, module hub, connector, or peripheral; Olesen et al., 2007).Invasive non-native species are one of the main causes of degradation of ecosystems worldwide. The control of invasive species is key to reduce threats to ecosystem viability in the long-term. Observations of structural changes in ecological interaction networks following invasive species suppression can be useful to monitor the success of ecological restoration initiatives. We evaluated the structure of plant-bird frugivory interaction networks in a plant community invaded by the guava tree (Psidium guajava L.) by comparing network metrics before and after control actions. Psidium guajava was relevant in all metrics for the unmanaged network in this study, with high degree centrality and high nestedness contribution. Based on the asymmetry of species interactions, we found that birds were highly dependent on the invasive plant before suppression. Once P. guajava trees were eliminated, bird and plant species richness, total number of interactions, and modularity increased, whereas nestedness and interaction strength asymmetry decreased. The diet of the bird community became more diversified once P. guajava was no longer available and relevant species roles in community structure emerged. Our results corroborate the fact that ecological restoration interventions should include the control of non-native plant species that attract frugivorous animals in order to diversify plant-frugivore interactions and thus maintain biodiversity in natural ecosystems.Funding: Coordenação de Aperfeicoamento de Pessoal de Nível Superior : 001, National Council for Scientific and Technological Development : Universal 14/2012.Peer reviewe
Data from: Effects of the control of an invasive tree on the structure of a plant-frugivore network
No full text[Methods] We conducted the study in the Caieira Natural Municipal Park (CNMP), a protected area that covers 1.27 km² (Joinville, state of Santa Catarina, southern Brazil) (26°18'24"S, 48°47'36"W) (Figure 1a). The climate is subtropical, constantly humid, with hot summers and no dry season, and average maximum temperatures between 26.0 and 27.6º C (Cfa type in the Köppen classification; Joinville, 2021). The vegetation cover of the CNMP is represented by two forest types: coastal forest (restinga arbórea, in Portuguese) and mangrove (Joinville, 2021), both in the Atlantic Forest domain, an important global biodiversity hotspot (Myers et al., 2000) (Figure 1a,b). The park grants public access to landscaped areas and trails.
Non-native species were planted in a small orchard in the park between 1970 and 2004. Some of those trees, such as guava (Psidium guajava), avocado (Persea americana), and star fruit (Averrhoa carambola), still bear fruit in the area (Preis, 2020). Several invasive non-native plants have established populations in the park, and are listed in the management plan for control by park managers (Joinville, 2021). An established population of P. guajava trees was present both in landscaped areas and in restinga and mangrove remnants, totaling around 410 individuals per km².
Psidium guajava is a shrub or tree in the Myrtaceae family, up to 12 m in height, with smooth, scaly, reddish-brown bark. Fruits are globular to pyriform, 2–8 cm long, green to yellow, with pink, yellow, or white pulp (Landrum & Mitra, 2021). Psidium guajava can produce fruits throughout the year, especially in the summer months (Landrum & Mitra, 2021), but fruit phenology varies according to the species variety and water availability (Moura, 2001). In the study area, fruiting occurred between late summer to autumn (February to April; BM, personal observation). The main forms of dispersal are zoochory and anthropochory (Arévalo-Marín et al., 2021; Heleno et al., 2013b). The species is an important node in its introduced range both in pollination networks in Galapagos (see Traveset et al., 2015) and plant–frugivore networks in Galápagos, South Africa and Brazil (see Baltzinger et al., 2020; Heleno et al., 2013b; Silva & Pizo, 2020).
The origin of P. guajava is uncertain, but several authors suggest that it originated between northern South America and Central America (Arévalo-Marín et al., 2021). More recent studies indicate that it may have originated in the savannas and semi-deciduous forests of South America (Landrum & Mitra, 2021) or in the humid Chaco and/or Cerrado (Arévalo-Marín et al., 2021). Psidium guajava is widely cultivated in several countries and considered invasive in several tropical and subtropical regions of the world (Landrum & Mitra, 2021; Richardson & Rejmánek, 2011), such as East Africa (Witt & Luke, 2017), North America (Acevedo-Rodríguez & Strong, 2012), Brazil (Sampaio & Schmidt, 2013; Ziller & Dechoum, 2013) and the Galápagos Islands in Ecuador (Guézou et al., 2010; Urquía et al., 2019). Use by human populations very likely increased its distribution in the past (Arévalo-Marín et al., 2021). As an invasive species, it can form dense stands that displace native vegetation (Leão et al., 2011); thus, the balance between valuable fruit production and invasive potential requires careful monitoring (Landrum & Mitra, 2021) and continuous control.
Data collection of frugivory interactions
We collected data in the CNMP between February and April of 2021 and 2022, when P. guajava trees were fruiting in 2021, and in the same timeframe after P. guajava suppression, in 2022. We carried out thirty field surveys each year. In each survey, the same trail was covered by two observers in early morning hours (6:45 am ± 15 min until 10:00 am ± 30 min) or in the afternoon (4:00 pm ± 15 min and 6:30 pm ± 30 min) (Pizo & Galetti, 2010). The trails mainly covered landscaped areas and restinga vegetation (Figure 1a). In addition, we defined three observation areas (Figure 1c), where two observers kept watch together for 20 minutes (Jordano & Schupp, 2000). Each observer recorded all avian frugivory events on fruiting plants with a pair of binoculars (Leitz Wetzlar Trinovid 10x40) and a digital camera (Sony DSC-HX300 and Nikon Coolpix p510). Walking direction along the trail and order of observation areas were alternated on sampling days on each field survey to ensure that all study site areas were observed at different times of day. We carried out data collection at the same period of time over two consecutive years to ensure sampling consistency regarding the presence of migratory birds and fructification of the sampled plant species. We performed a nonparametric Wilcox test to verify whether the hours of observation in each year were different between years. The dependent variable was the duration of observation (in minutes) at every fortnight and the independent variable was sampling year. We used the iNEXT function from the iNEXT package to assess community diversity and build species accumulation curves (Hsieh, Ma, & Chao, 2022), using abundance data to estimate bird and plant diversity based on the Shannon index (q = 1). We conducted the analysis using R 3.6.2 software (R core Team, 2022).
We used the following parameters to record frugivory interactions by birds (feeding bouts): the plant species on whose fruits a bird was feeding, and the respective bird species. A new frugivory event was counted if the bird left the tree, and then returned. The number of fruits/seeds ingested per visit was not counted. Bird foraging flocks were recorded as separate interactions per individual. Bird identification was mostly carried out in the field, but we consulted experts and literature in case of uncertainty. Scientific nomenclature follows the Brazilian Committee of Ornithological Records (Pacheco et al., 2021). Likewise, plants not identified in the field were identified with help from experts who reviewed photographic records. The nomenclature of plant species is based on the "Flora e Funga do Brasil" database (2022).
Psidium guajava control campaigns
We conducted two P. guajava control campaigns in the CNMP. In October 2021, control mainly focused on adults and reproductive individuals, but also included small plants in the surroundings of eliminated adults. We eliminated a total of 435 plants. In May 2022, one month after the sampling period, a follow-up expedition took place, in which we eliminated 85 non-reproductive plants as well as resprouted plants. Altogether, we cut down about 520 P. guajava trees in the area. We cut close to ground level with a chainsaw, followed by immediate spraying of a 6% Garlon 480BR (Triclopyr active ingredient) solution on the stump (Dechoum & Ziller, 2013). Once regrowth was observed, we carried out a re-check with foliar application of a 2% Glyphosate solution. During the second field survey, one fruiting P. guajava tree was found, so we eliminated all fruits, the tree was later cut down, and the stump treated.
Network metrics
We organized the interactions observed during each year into quantitative matrices (i=plant species; j=bird species) based on the frequency of frugivory events observed in the CNMP. Two data matrices were built: the first one, entitled "unmanaged community", referred to the plant community invaded by P. guajava in 2021, prior to the control intervention; the second one, entitled "managed community", corresponded to the same community after control, in 2022. Both quantitative networks were built and analyzed using the Bipartite package (Dormann et al., 2009) in software R, version 3.6.2 (R core Team 2022). We calculated sampling completeness of species interactions using Chao1 as a richness estimator and the SCw1 function (Macgregor et al., 2017).
We evaluated the following network-level metrics, then contrasted them with those from null models for significance assessments: quantitative nestedness (weighted NODF; Almeida-Neto & Ulrich, 2011), quantitative modularity (DIRTLPAwb+ algorithm; Beckett, 2016), and interaction strength asymmetry (ISA; Dormann et al., 2008). We used Z-scores to assess significance of nestedness and modularity with null-model functions by comparing the results obtained with the observed values, using the methods vaznull and method r2d, respectively, with 999 randomizations each. We also used the null.t.test with 999 randomizations to obtain the significance of interaction strength asymmetry (Dormann et al., 2008). Interaction strength asymmetry varies between −1 and 1, with positive values indicating high dependence of an animal on a plant species, and negative values indicating the opposite (Blüthgen et al., 2007).
We evaluated the following species-level metrics: plant species degree centrality (Martín-González et al., 2010), plant species nestedness contribution, asymmetry of plant species interactions using the push-pull index (Vázquez et al., 2007) and participation coefficients (c-values), and within-module degree (z-values) for network modules (Olesen et al., 2007). Degree centrality takes the number of links of each node (k) into account. The push-pull index indicates the direction of interaction asymmetry based on dependency; positive values indicate that a species more strongly affects the species of the other level with which it interacts than vice versa ("pusher"), while negative values indicate that a species is, on average, more strongly affected by its interaction partners than it affects them ("being pulled") (Vázquez et al., 2007). The cz-values were evaluated for both plant and bird species. We calculated the thresholds for participation coefficients and within-module degree for each network level (null models with 95% confidence intervals) and used them to identify the topological role of each species (network hub, module hub, connector, or peripheral; Olesen et al., 2007).Invasive non-native species are one of the main causes of degradation of ecosystems worldwide. The control of invasive species is key to reduce threats to ecosystem viability in the long-term. Observations of structural changes in ecological interaction networks following invasive species suppression can be useful to monitor the success of ecological restoration initiatives. We evaluated the structure of plant-bird frugivory interaction networks in a plant community invaded by the guava tree (Psidium guajava L.) by comparing network metrics before and after control actions. Psidium guajava was relevant in all metrics for the unmanaged network in this study, with high degree centrality and high nestedness contribution. Based on the asymmetry of species interactions, we found that birds were highly dependent on the invasive plant before suppression. Once P. guajava trees were eliminated, bird and plant species richness, total number of interactions, and modularity increased, whereas nestedness and interaction strength asymmetry decreased. The diet of the bird community became more diversified once P. guajava was no longer available and relevant species roles in community structure emerged. Our results corroborate the fact that ecological restoration interventions should include the control of non-native plant species that attract frugivorous animals in order to diversify plant-frugivore interactions and thus maintain biodiversity in natural ecosystems.Funding provided by: Coordenação de Aperfeicoamento de Pessoal de Nível Superior
ROR ID: https://ror.org/00x0ma614
Award Number: 001
Funding provided by: National Council for Scientific and Technological Development
ROR ID: https://ror.org/03swz6y49
Award Number: Universal 14/2012Peer reviewe
Effects of food availability on butterfly diversity and network specialization across altitudinal levels in a Mediterranean landscape
No full textAltitudinal gradients, which involve diverse biotic and abiotic variables in small-scale spaces, provide a good opportunity to investigate the local and regional patterns that influence species assemblages, including those of pollinators and the plants with which they interact him. Here, we studied the variation in butterfly assemblages and their interactions with flowering plants across different altitudes in a Mediterranean mountain system. Moreover, considering the different vegetation (i.e. grassland, forest, shrubland)at each altitudinal level (i.e. lowland, mid-mountain, high-mountain), we examined the effects of food availability on butterfly assemblages.
We found butterfly richness and number of interactions between butterflies and flowering plants to be mainly influenced by the altitudinal level, with the mid-mountain region exhibiting the highest levels of both variables. Flower abundance positively correlated with butterfly richness on the lowland and high-mountain levels, while vegetation was a key factor impacting both butterfly richness and butterfly-flower interactions. Network modularity was highest at the mid-mountain level, while species specialization increased with the altitudinal levels. Species composition varied significantly across the altitudinal gradient, occurring at each specific altitudinal level and between different habitats, driven primarily by species turnover rather than a nested decline in species as altitude increases.
Our findings suggest that even though topoclimate may shape species composition at a regional scale, resource availability is key to explaining the differences among habitats with similar climatic conditions. This underscores the importance of promoting and maintaining diverse food resources for butterflies, particularly in the challenging environmental conditions found at both high and low altitudinal levels in Mediterranean mountain regions. Furthermore, a multiscale approach to butterfly conservation is imperative, considering the interplay of regional and local factors that influence community composition and diversity.Peer reviewe
Disentangling small island ecological multilayer networks: relationships with ecological and evolutionary island patterns
No full textMultilayer networks facilitate the integration of multiple interaction types by quantifying the per capita effects of species on each other, thereby advancing our understanding of the intrinsic complexity of natural food webs. Using a multilayer network framework, this study provides the first food web data for a small oceanic island (Montaña Clara, Canary Islands) and compares it with available data from another small island of continental origin in the context of island biogeography theory. During the two most contrasting seasons, we collected data on interactions between plants and their pollinators, herbivores, seed dispersers, and saprotrophic, symbiotic and pathogenic root-associated-fungi. Pollination, herbivory and seed dispersal were sampled via flower visitation census, direct observation, and faecal analysis, respectively, while fungi were identified using DNA metabarcoding. We identified 64 animal species and 367 fungal amplicon sequence variants (ASVs) interacting with the 13-plant species sampled. Five plant species (38%) showed the highest values of multilayer versatility (> 0.5), indicating they are the most important for the structure of the ecosystem. A total of 23 modules were detected, more than half of which were restricted to a single type of interaction, and approximately 73% of the species switched modules between pairs of interaction types. Comparing the results with those from the continental island, the oceanic shows a simpler network, higher overall versatility and a less modular structure. These results are consistent with ecological and evolutionary predictions from island biogeography theory. Future studies involving different interaction types and conducted on islands with different traits, such as taxonomical/functional disharmony, density trade-offs, or interaction release, will allow for the assessment of the generality of the observed patterns.Peer reviewe
LIFE4Pollinators' Platform: How Citizen Science Can Help Monitoring Plants and Pollinators
No full textDataset analysed in the article entitled "LIFE 4 Pollinators Platform: How Citizen Science Can Help Monitoring Plants and Pollinators".
The LIFE 4 Pollinators project (LIFE18/GIE/IT/000755) “Involving people to protect wild bees and other pollinators in the Mediterranean” aims to enhance the conservation of pollinating insects and entomophilous plants across the Mediterranean region by fostering a virtuous cycle that promotes progressive changes in anthropogenic practices currently threatening wild pollinators.
As part of this project, a web platform was developed in 2021 to collect photographs of insects visiting flowers (https://www.life4pollinators.eu/en/submission).
This dataset presents data collected between May 2021 and May 2024 through this web-platform, uploaded over 2,000 photographs of plant-pollinator interactions.Peer reviewe
Determining the minimal background area for species distribution models: MinBAR package
No full textOne of the crucial choices when modelling species distributions using pseudo-absences and background approaches is the delineation of the background area to fit the model. We hypothesise that there is a minimum background area around the geographical centre of the species distribution that characterises well enough the range of environmental conditions needed by the species to survive. Thus, fitting the model within this geographical area should be the optimal solution in terms of both quality of the model and execution time. MinBAR is an R package that calculates the optimal background area by means of sequentially fitting several concentric species distribution models (SDMs) until a satisfactory model in terms of the included metrics is reached. The version 1.1.2 is implemented for MaxEnt (using either maxnet or the original java program) and uses Boyce Index as a metric to assess models performance. Three case studies are presented to test the hypothesis and assess package's functionality. We show how partial models trained with part of the species distribution often perform equal or better than those fitted on the entire extent. MinBAR is a versatile tool that helps modellers to objectively define the optimal solution
Changes in the structure of seed dispersal networks when including interaction outcomes from both plant and animal perspectives
No full textInteraction frequency is the most common currency in quantitative ecological networks, although interaction quality can also affect benefits provided by mutualisms. Here, we evaluate if interaction quality can modify network topology, species' role and whether such changes affect community vulnerability to species loss. We use a well-examined study system (bird–lizard and fleshy-fruited plants in the ‘thermophilous' woodland of the Canary Islands) to compare network and species-level metrics from a network based on fruit consumption rates (interaction frequency, IF), against networks reflecting functional outcomes: a seed dispersal effectiveness network (SDE) quantifying recruitment, and a fruit resource provisioning network (FRP), accounting for the nutrient supply of fruits. Nestedness decreased in the FRP and the SDE networks, due to the lack of association between fruit consumption rates and 1) nutrient content and; 2) recruitment at the seed deposition sites, respectively. The FRP network showed lower niche overlap due to resource use complementarity among frugivores. Interaction evenness was lower in the SDE network, in response to a higher dominance of lizards in the recruitment of heliophilous species. Such changes, however, did not result in enhanced vulnerability against extinctions. At the plant species level, strength changed in the FRP network in frequently consumed or highly nutritious species. The number of effective partners decreased for species whose seeds were deposited in unsuitable places for recruitment. In frugivores, strength was consistent across networks (SDE vs IF), showing that consumption rates outweighed differences in dispersal quality. In the case of lizards, the increased importance of nutrient-rich species resulted in a higher number of effective partners. Our work shows that although frequency strongly impacts interaction effects, accounting for quality improves our inferences about interaction assembly and species role. Thus, future studies including interaction outcomes from both partners' perspectives will provide valuable insights about the net effects of mutualistic interactions.This study is framed within projects CGL2007-61165/BOS and CGL2017-88122-P from the Spanish Ministry of Science and supported by FEDER funds from the European Union. We are grateful to Guido Jones, currently funded by the Cabildo de Tenerife under the TFinnova Programme supported by MEDI and FDCAN, for revising the English and making useful recommendations to improve it. We are especially grateful to Airam Rodríguez, David Padilla, Beatriz Rumeu, Daniel González, Benito Pérez, Yurena Gavilán, Patricia Marrero, Elsa Bonnaud and Concepción Nieves, who helped at different stages of the study. AGC benefitted from a JAE-PRE fellowship from the Spanish National Research Council (CSIC) and was funded by the island council, Cabildo de Tenerife, under the identification mark “Tenerife 2030” (P. INNOVA 2016-2021).Peer reviewe
Effects of the control of an invasive tree on the structure of a plant-frugivore network
No full textInvasive non-native species are one of the main causes of degradation of ecosystems worldwide. The control of invasive species is key to reducing threats to ecosystem viability in the long term. Observations of structural changes in ecological interaction networks following invasive species suppression can be useful to monitor the success of ecological restoration initiatives. We evaluated the structure of plant-bird frugivory interaction networks in a plant community invaded by the guava tree (Psidium guajava L.) by comparing network metrics before and after control actions. Psidium guajava was relevant in all metrics for the unmanaged network in this study, with high degree centrality and high nestedness contribution. Based on the asymmetry of species interactions, we found that birds were highly dependent on the invasive plant before suppression. Once P. guajava trees were eliminated, bird and plant species richness, total number of interactions, and modularity increased, whereas nestedness and interaction strength asymmetry decreased. The diet of the bird community became more diversified once P. guajava was no longer available and relevant species roles in community structure emerged. Our results corroborate the fact that ecological restoration interventions should include the control of non-native plant species that attract frugivorous animals in order to diversify plant-frugivore interactions and thus maintain biodiversity in natural ecosystems.This study was funded in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior—Brasil (CAPES)—Finance Code 001, and by the project “Etnobotânica, manejo e domesticação de espécies no sul do Brasil” (CNPq Universal 14/2012).Peer reviewe
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