The availability of fruits is critical for tropical forests, where the majority of plant species ... more The availability of fruits is critical for tropical forests, where the majority of plant species rely upon animal vectors for seed dispersal. However, we do not know how fruit production is temporally distributed over species and families. Two plant families are particularly important in floristic inventories of Atlantic rain forests: Arecaceae, a few species of which are highly abundant; and Myrtaceae, which is abundant and displays outstanding species diversity. In this context, we asked whether hyperdominance occurs in fruit production in the Atlantic rain forest, and whether it occurs in the abundant species of Arecaceae and Myrtaceae. We investigated whether the temporal fruit production patterns differ between Myrtaceae, Arecaceae, and the plant community as a whole. We also applied a functional dispersion index to assess the temporal fruit diversity over a 2-yr period, with regard to morphological and phenological traits. We found that the phenomenon of hyperdominance occurs in fruit production: five species accounted for more than half of the pulp biomass. Arecaceae fruit biomass peaked at the end of wet season, overlapping with the community peak; whereas Myrtaceae species fruited throughout the year and were an important resource during periods of food scarcity. Myrtaceae filled more of the fruit morphospace over time because their fruits exhibit a large range of morphologies and phenological strategies. Our results demonstrated the importance of combining phenology and fruit morphology in the evaluation of resource availability, which revealed periods of high fruit diversity that could support a range of frugivore sizes and maintain overall ecosystem functionality.
Most bird-dispersed fruits are green when unripe and become colored and conspicuous when ripe, si... more Most bird-dispersed fruits are green when unripe and become colored and conspicuous when ripe, signaling that fruits are ready to be consumed and dispersed. The color pattern for fruits of Miconia albicans (Melastomataceae), however, is the opposite, with reddish unripe and green ripe fruits. We (1) verified the maintenance over time of its bicolored display, (2) tested the communicative function of unripe fruits, (3) tested the photoprotective role of anthocyanins in unripe fruits, and (4) verified whether green ripe fruits can assimilate carbon. Using a paired experiment, we tested whether detection of ripe fruits was higher on infructescences with unripe and ripe fruits compared with infructescences with only ripe fruits. We also measured and compared gas exchange, chlorophyll a fluorescence, and heat dissipation of covered (to prevent anthocyanin synthesis) and uncovered ripe and unripe fruits. Although the bicolored display was maintained over time, unripe fruits had no influen...
ABSTRACT Was beeinflusst die Effektivität von visuellen Signalen, so dass sie eine Antwort von Em... more ABSTRACT Was beeinflusst die Effektivität von visuellen Signalen, so dass sie eine Antwort von Empfängern auslösen? Experimentelle und theoretische Arbeiten in so unterschiedlichen Feldern wie sexueller Selektion und Pflanze-Tier Interaktionen haben eine Selektion auf höhere Auffälligkeit von Signalen nachgewiesen. Um die Auffälligkeit von Signalen bestimmen zu können, ist es notwendig, die räumliche und zeitliche Heterogenität des Hintergrundes zu quantifizieren. Hier vergleichen wir vier Methoden, die die Heterogenität des Hintergrundes beschreiben. In einer saisonalen Flora haben wir Reflexionsdaten in der Trocken- und Regenzeit gesammelt, die (i) nur von den Blättern der Zielarten stammen, vor denen die Signale zu sehen sind; (ii) von allen häufigen Pflanzen der Busch- und Strauchschicht; (iii) von allen Hintergrundmaterialien, die an Zufallspunkten in der Umgebung von Fruchtständen gefunden wurden; (iv) von Hintergrundobjekten, die entlang von Transekten erhoben wurden. Wir haben saisonale Farbänderungen als Farbton, Sättigung und Helligkeit analysiert und außerdem die Auffälligkeit von Fruchtfarben für das Sehvermögen von Vögeln modelliert. Alle Methoden fanden saisonale Unterschiede in der Farbe des Hintergrundes. Die Farbtöne waren gelblich-grüner in der Trockenzeit und gesättigter in der Regenzeit. Nur die räumlich stark begrenzten Methoden i und iii fanden saisonale Unterschiede in der Fruchtauffälligkeit für Vögel. Für Pflanzensignale, die vor einem konstanten Hintergrund gesehen werden, bietet sich die Methode der Zielarten an. Unsere Studie belegt die Wichtigkeit die saisonale Heterogenität der Hintergründe zu beachten; sie zeigt auch dass eine monatliche Datenaufnahme von Reflexionsdaten nicht notwendig ist, um die Auffälligkeit von Fruchtsignalen zu evaluieren.
Communication contributes to mediate the interactions between plants and the animals that dispers... more Communication contributes to mediate the interactions between plants and the animals that disperse their genes. As yet, seasonal patterns in plant–animal communication are unknown, even though many habitats display pronounced seasonality e.g. when leaves senescence. We thus hypothesized that the contrast between fruit displays and their background vary throughout the year in a seasonal habitat. If this variation is adaptive, we predicted higher contrasts between fruits and foliage during the fruiting season in a cerrado–savanna vegetation, southeastern Brazil. Based on a six-year data base of fruit ripening and a one-year data set of fruit biomass, we used reflectance measurements and contrast analysis to show that fruits with distinct colors differed in the beginning of ripening and the peak of fruit biomass. Black, and particularly red fruits, that have a high contrast against the leaf background, were highly seasonal, peaking in the wet season. Multicolored and yellow fruits were less seasonal, not limited to one season, with a bimodal pattern for yellow ones, represented by two peaks, one in each season. We further supported the hypothesis that seasonal changes in fruit contrasts can be adaptive because fruits contrasted more strongly against their own foliage in the wet season, when most fruits are ripe. Hence, the seasonal variation in fruit colors observed in the cerrado–savanna may be, at least partly, explicable as an adaptation to ensure high conspicuousness to seed dispersers.
1. Several fundamental aspects of communication between plants and their mutualists are poorly un... more 1. Several fundamental aspects of communication between plants and their mutualists are poorly understood. It remains unclear whether plant signals are accurate and reliable, that is, whether they recruit mutualists by informing them about the nutritional rewards provided by flowers and fleshy fruits. 2. We evaluated fruit characteristics of 105 vertebrate-dispersed species from an Atlantic rainforest community to examine the relationship between visual fruit stimuli and fruit quality. We combined morphological, biochemical and spectrophotometric methods and employed comparative analyses to assess the evolutionary association among morphological, biochemical and visual characters. 3. We detected a significant phylogenetic signal in most morphological and nutritional traits but not in colour traits, which suggests that fruit colours are evolutionarily labile. We also found that two properties of fruit coloration (brightness and chroma) explain 24-29% of variation in protein and sugar contents, respectively. High sugar content in fruit is associated with dark colour and low chroma (colour saturation). However, fruit brightness is not strongly correlated to protein content and its signalling role remains unknown. 4. We suggest that the negative relationship between chroma and sugar content in fruit can be explained by the fact that sugars up-regulate the synthesis of anthocyanins, the pigments primarily imparting achromatic coloration in fruits. Biochemical pathways could consequently explain the covariance between visual fruit traits and nutritional fruit traits. In this scenario, information could arise as by-product rather than as an adaptation to signal to seed dispersers. 5. Synthesis. We show that fruit visual traits are evolutionary labile and that fruit chroma and brightness can reliably indicate sugar and protein content, respectively. We propose that shared biochemistry is a likely mechanism inducing the covariance between colour (the stimulus) and nutritional quality (as the unseen quality). We hypothesize that by-product information represents a widespread and so far neglected mechanism leading to reliable visual traits in mutualistic and possibly also antagonistic plant-animal interactions.
... Ao professor José Roberto Trigo por ceder seu laboratório na UNICAMP e pela valiosa ajuda com... more ... Ao professor José Roberto Trigo por ceder seu laboratório na UNICAMP e pela valiosa ajuda com as análises químicas. Ao ... Castro, Rodrigo Anzolin, Rodrigo Goiano, Rafael, Omelete e Saldanha. As minhas amigas-irmãs de república, atuais e antigas, Fá, Malu, Dani, Juli e ...
Human-induced wildfires are increasing in frequency in tropical forests, and their deleterious co... more Human-induced wildfires are increasing in frequency in tropical forests, and their deleterious consequences for biodiversity include decreases in seed rain, which may be affected directly by fire or indirectly by the creation of edges between forest and non-forest environments. Understanding seed rain is key to assess the potential for natural regeneration in plant communities. We assessed the impact of fire and fire-created edges on seed rain species richness, abundance, size, weight, and dispersal syndromes in Atlantic Forest remnants in Bahia, Brazil. We assessed seed rain at monthly intervals for an entire year along seven 300 m-long transects placed perpendicular to the edge. We installed seed traps at the edge and at 20, 40, 60, 80, 100, and 150 m into the burnt area and into the forest from forest edge. We recorded a total of 9,050 seeds belonging to 250 morphospecies. We did not observe edge influence; however, we detected a lower abundance and proportion of animal-dispersed seeds in the burnt than in the unburnt areas. The seed abundance in the burnt areas was lower and seeds were smaller and lighter than those in the unburnt area. Seed rain in the burnt area was not greater near to the forest than far from it. The abundance and richness of seed rain was positively correlated with tree density. Our findings highlight the lack of seed rain in burnt areas and differences in community composition between the burnt and unburnt areas. Collectively, these results indicate negative consequences on natural regeneration, which can lead to permanent secondarization and challenges for early regeneration of burnt areas, which will initially have impoverished forests due to low seed richness.
Anthropogenic land use and cover changes impact biodiversity worldwide. However, ecological group... more Anthropogenic land use and cover changes impact biodiversity worldwide. However, ecological groups are differently affected by landscape composition and configuration. Understanding which groups are negatively affected and which thrive in human-modified landscapes is of paramount importance for conservation management, especially for species such as the frugivorous birds, which play an essential role in seed dispersal. We evaluated the relative importance of landscape composition and configuration, explaining taxonomic and functional diversity and their effects on frugivorous birds in the Brazilian Atlantic Forest. We used a robust dataset encompassing 153 forest fragments in the Atlantic Forest hotspot. We classified species as frugivores based on the percentage of fruits in the diet, and used functional traits related to seed dispersal to measure functional diversity. Our results showed that landscape composition was more important than landscape configuration explaining taxonomic and functional diversity of frugivorous birds. In addition, the interaction between landscape composition and configuration explained the loss of functional traits. We demonstrate a disproportional importance of landscape composition explaining taxonomic and functional diversity of frugivorous birds, whereas the traits related to seed dispersal were explained by both compositional and configurational variables. Thus, we highlighted the need to maintain high habitat amount to increase taxonomic and functional diversity of frugivorous birds. However, the interaction of landscape composition and configuration is of paramount importance to sustain functional traits of frugivores in tropical forest landscapes.
Background and Research Aims: Habitat amount plays an important role in determining the presence ... more Background and Research Aims: Habitat amount plays an important role in determining the presence and abundance of bird species in modified landscapes, whereas habitat fragmentation has shown little effects. Toucans (Ramphastidae) and parrots (Psittacidae) are large-bodied primary consumers and among the most representative birds in Neotropical forests. They are highly sensitive to habitat loss; nevertheless, their response to fragmentation has been poorly assessed leading to contradictory results. Here, we evaluate the influence of landscape structure on toucans and parrots in the tropical forest of Los Tuxtlas, Mexico. Methods: We censused birds in 12 landscapes of Los Tuxtlas and used a multi-scale landscape approach to assess the influence of landscape composition and configuration on the number of individuals of toucans and parrots. Results: We found that the most important and positive predictor of toucans and parrots was the amount of primary forest cover in the landscape. For...
A central problem in ecology is to understand how human impacts affect plant-animal interactions ... more A central problem in ecology is to understand how human impacts affect plant-animal interactions that lead to effective seed dispersal services for plant communities. Seed dispersal services are the outcome of plant-frugivore interactions that often form local networks of interacting species. Recent work has shown that some frugivorous bird species are more critical to network organization than others. Here, we explore how patch size and the potential local extinctions of obligate frugivorous birds affect the reorganization of seed dispersal networks. We examined the structure of 20 empirical seed dispersal networks documented across tropical avian assemblages occupying widely variable habitat patch sizes, a surrogate of the amount of remaining habitat. Networks within small forest patches consistently supported both lower plant and bird species richness. Forest patch size was positively associated with nestedness, indicating that reductions in patch size disrupted the nested organization of seed dispersal networks. Obligate frugivores, especially large-bodied species, were almost entirely absent from small forest patches. Analysis at the species level showed that obligate frugivores formed the core of interacting species, connecting species within a given seed dispersal network. Our combined results revealed that patch size reduction erodes frugivorous bird diversity, thereby affecting the integrity of seed dispersal networks. We highlight the importance of conserving large forest patches to maintain tropical forest functionality.
Global biodiversity is threatened by land-use changes through human activities. This is mainly du... more Global biodiversity is threatened by land-use changes through human activities. This is mainly due to the conversion of continuous forests into forest fragments surrounded by anthropogenic matrices. In general, sensitive species are lost while species adapted to disturbances succeed in altered environments. However, whether the interactions performed by the persisting species are also modified, and how it scales up to the network level throughout the landscape are virtually unknown in most tropical hotspots of biodiversity. Here we evaluated how landscape predictors (forest cover, total core area, edge density, inter-patch isolation) and local characteristics (fruit availability, vegetation complexity) affected understory birds seed-dispersal networks in 19 forest fragments along the hyperdiverse but highly depauperate northeast distribution of the Brazilian Atlantic Forest. Also, our sampled sites were distributed in two regions with contrasting land cover changes. We used mist net...
Seed removal is a key component of seed dispersal and may be influenced by both landscape-scale a... more Seed removal is a key component of seed dispersal and may be influenced by both landscape-scale and local attributes, and it has been used as an indicator of the intensity of interactions between ecosystem components. We examined how the seed removal rates, which integrate the activity of seed dispersers and seed predators, vary with landscape-scale forest cover. We collected data under 34 trees belonging to two zoochoric species (Helicostylis tomentosa (Poepp. and Endl.) J. F. Macbr. and Inga vera Willd.) in 17 remnants in the Brazilian Atlantic forest, with different percentages of forest cover. The seed removal rate was estimated using a fast method based on the abundance of intact fruits and fruit scraps on the ground. The amount of forest cover affected the rate of seed removal in a humpbacked shape, with a maximum seed removal rate at intermediate forest cover. Seed removal rates must be related to the amount of food resources offered and diversity of dispersers and predators ...
The availability of fruits is critical for tropical forests, where the majority of plant species ... more The availability of fruits is critical for tropical forests, where the majority of plant species rely upon animal vectors for seed dispersal. However, we do not know how fruit production is temporally distributed over species and families. Two plant families are particularly important in floristic inventories of Atlantic rain forests: Arecaceae, a few species of which are highly abundant; and Myrtaceae, which is abundant and displays outstanding species diversity. In this context, we asked whether hyperdominance occurs in fruit production in the Atlantic rain forest, and whether it occurs in the abundant species of Arecaceae and Myrtaceae. We investigated whether the temporal fruit production patterns differ between Myrtaceae, Arecaceae, and the plant community as a whole. We also applied a functional dispersion index to assess the temporal fruit diversity over a 2-yr period, with regard to morphological and phenological traits. We found that the phenomenon of hyperdominance occurs in fruit production: five species accounted for more than half of the pulp biomass. Arecaceae fruit biomass peaked at the end of wet season, overlapping with the community peak; whereas Myrtaceae species fruited throughout the year and were an important resource during periods of food scarcity. Myrtaceae filled more of the fruit morphospace over time because their fruits exhibit a large range of morphologies and phenological strategies. Our results demonstrated the importance of combining phenology and fruit morphology in the evaluation of resource availability, which revealed periods of high fruit diversity that could support a range of frugivore sizes and maintain overall ecosystem functionality.
Most bird-dispersed fruits are green when unripe and become colored and conspicuous when ripe, si... more Most bird-dispersed fruits are green when unripe and become colored and conspicuous when ripe, signaling that fruits are ready to be consumed and dispersed. The color pattern for fruits of Miconia albicans (Melastomataceae), however, is the opposite, with reddish unripe and green ripe fruits. We (1) verified the maintenance over time of its bicolored display, (2) tested the communicative function of unripe fruits, (3) tested the photoprotective role of anthocyanins in unripe fruits, and (4) verified whether green ripe fruits can assimilate carbon. Using a paired experiment, we tested whether detection of ripe fruits was higher on infructescences with unripe and ripe fruits compared with infructescences with only ripe fruits. We also measured and compared gas exchange, chlorophyll a fluorescence, and heat dissipation of covered (to prevent anthocyanin synthesis) and uncovered ripe and unripe fruits. Although the bicolored display was maintained over time, unripe fruits had no influen...
ABSTRACT Was beeinflusst die Effektivität von visuellen Signalen, so dass sie eine Antwort von Em... more ABSTRACT Was beeinflusst die Effektivität von visuellen Signalen, so dass sie eine Antwort von Empfängern auslösen? Experimentelle und theoretische Arbeiten in so unterschiedlichen Feldern wie sexueller Selektion und Pflanze-Tier Interaktionen haben eine Selektion auf höhere Auffälligkeit von Signalen nachgewiesen. Um die Auffälligkeit von Signalen bestimmen zu können, ist es notwendig, die räumliche und zeitliche Heterogenität des Hintergrundes zu quantifizieren. Hier vergleichen wir vier Methoden, die die Heterogenität des Hintergrundes beschreiben. In einer saisonalen Flora haben wir Reflexionsdaten in der Trocken- und Regenzeit gesammelt, die (i) nur von den Blättern der Zielarten stammen, vor denen die Signale zu sehen sind; (ii) von allen häufigen Pflanzen der Busch- und Strauchschicht; (iii) von allen Hintergrundmaterialien, die an Zufallspunkten in der Umgebung von Fruchtständen gefunden wurden; (iv) von Hintergrundobjekten, die entlang von Transekten erhoben wurden. Wir haben saisonale Farbänderungen als Farbton, Sättigung und Helligkeit analysiert und außerdem die Auffälligkeit von Fruchtfarben für das Sehvermögen von Vögeln modelliert. Alle Methoden fanden saisonale Unterschiede in der Farbe des Hintergrundes. Die Farbtöne waren gelblich-grüner in der Trockenzeit und gesättigter in der Regenzeit. Nur die räumlich stark begrenzten Methoden i und iii fanden saisonale Unterschiede in der Fruchtauffälligkeit für Vögel. Für Pflanzensignale, die vor einem konstanten Hintergrund gesehen werden, bietet sich die Methode der Zielarten an. Unsere Studie belegt die Wichtigkeit die saisonale Heterogenität der Hintergründe zu beachten; sie zeigt auch dass eine monatliche Datenaufnahme von Reflexionsdaten nicht notwendig ist, um die Auffälligkeit von Fruchtsignalen zu evaluieren.
Communication contributes to mediate the interactions between plants and the animals that dispers... more Communication contributes to mediate the interactions between plants and the animals that disperse their genes. As yet, seasonal patterns in plant–animal communication are unknown, even though many habitats display pronounced seasonality e.g. when leaves senescence. We thus hypothesized that the contrast between fruit displays and their background vary throughout the year in a seasonal habitat. If this variation is adaptive, we predicted higher contrasts between fruits and foliage during the fruiting season in a cerrado–savanna vegetation, southeastern Brazil. Based on a six-year data base of fruit ripening and a one-year data set of fruit biomass, we used reflectance measurements and contrast analysis to show that fruits with distinct colors differed in the beginning of ripening and the peak of fruit biomass. Black, and particularly red fruits, that have a high contrast against the leaf background, were highly seasonal, peaking in the wet season. Multicolored and yellow fruits were less seasonal, not limited to one season, with a bimodal pattern for yellow ones, represented by two peaks, one in each season. We further supported the hypothesis that seasonal changes in fruit contrasts can be adaptive because fruits contrasted more strongly against their own foliage in the wet season, when most fruits are ripe. Hence, the seasonal variation in fruit colors observed in the cerrado–savanna may be, at least partly, explicable as an adaptation to ensure high conspicuousness to seed dispersers.
1. Several fundamental aspects of communication between plants and their mutualists are poorly un... more 1. Several fundamental aspects of communication between plants and their mutualists are poorly understood. It remains unclear whether plant signals are accurate and reliable, that is, whether they recruit mutualists by informing them about the nutritional rewards provided by flowers and fleshy fruits. 2. We evaluated fruit characteristics of 105 vertebrate-dispersed species from an Atlantic rainforest community to examine the relationship between visual fruit stimuli and fruit quality. We combined morphological, biochemical and spectrophotometric methods and employed comparative analyses to assess the evolutionary association among morphological, biochemical and visual characters. 3. We detected a significant phylogenetic signal in most morphological and nutritional traits but not in colour traits, which suggests that fruit colours are evolutionarily labile. We also found that two properties of fruit coloration (brightness and chroma) explain 24-29% of variation in protein and sugar contents, respectively. High sugar content in fruit is associated with dark colour and low chroma (colour saturation). However, fruit brightness is not strongly correlated to protein content and its signalling role remains unknown. 4. We suggest that the negative relationship between chroma and sugar content in fruit can be explained by the fact that sugars up-regulate the synthesis of anthocyanins, the pigments primarily imparting achromatic coloration in fruits. Biochemical pathways could consequently explain the covariance between visual fruit traits and nutritional fruit traits. In this scenario, information could arise as by-product rather than as an adaptation to signal to seed dispersers. 5. Synthesis. We show that fruit visual traits are evolutionary labile and that fruit chroma and brightness can reliably indicate sugar and protein content, respectively. We propose that shared biochemistry is a likely mechanism inducing the covariance between colour (the stimulus) and nutritional quality (as the unseen quality). We hypothesize that by-product information represents a widespread and so far neglected mechanism leading to reliable visual traits in mutualistic and possibly also antagonistic plant-animal interactions.
... Ao professor José Roberto Trigo por ceder seu laboratório na UNICAMP e pela valiosa ajuda com... more ... Ao professor José Roberto Trigo por ceder seu laboratório na UNICAMP e pela valiosa ajuda com as análises químicas. Ao ... Castro, Rodrigo Anzolin, Rodrigo Goiano, Rafael, Omelete e Saldanha. As minhas amigas-irmãs de república, atuais e antigas, Fá, Malu, Dani, Juli e ...
Human-induced wildfires are increasing in frequency in tropical forests, and their deleterious co... more Human-induced wildfires are increasing in frequency in tropical forests, and their deleterious consequences for biodiversity include decreases in seed rain, which may be affected directly by fire or indirectly by the creation of edges between forest and non-forest environments. Understanding seed rain is key to assess the potential for natural regeneration in plant communities. We assessed the impact of fire and fire-created edges on seed rain species richness, abundance, size, weight, and dispersal syndromes in Atlantic Forest remnants in Bahia, Brazil. We assessed seed rain at monthly intervals for an entire year along seven 300 m-long transects placed perpendicular to the edge. We installed seed traps at the edge and at 20, 40, 60, 80, 100, and 150 m into the burnt area and into the forest from forest edge. We recorded a total of 9,050 seeds belonging to 250 morphospecies. We did not observe edge influence; however, we detected a lower abundance and proportion of animal-dispersed seeds in the burnt than in the unburnt areas. The seed abundance in the burnt areas was lower and seeds were smaller and lighter than those in the unburnt area. Seed rain in the burnt area was not greater near to the forest than far from it. The abundance and richness of seed rain was positively correlated with tree density. Our findings highlight the lack of seed rain in burnt areas and differences in community composition between the burnt and unburnt areas. Collectively, these results indicate negative consequences on natural regeneration, which can lead to permanent secondarization and challenges for early regeneration of burnt areas, which will initially have impoverished forests due to low seed richness.
Anthropogenic land use and cover changes impact biodiversity worldwide. However, ecological group... more Anthropogenic land use and cover changes impact biodiversity worldwide. However, ecological groups are differently affected by landscape composition and configuration. Understanding which groups are negatively affected and which thrive in human-modified landscapes is of paramount importance for conservation management, especially for species such as the frugivorous birds, which play an essential role in seed dispersal. We evaluated the relative importance of landscape composition and configuration, explaining taxonomic and functional diversity and their effects on frugivorous birds in the Brazilian Atlantic Forest. We used a robust dataset encompassing 153 forest fragments in the Atlantic Forest hotspot. We classified species as frugivores based on the percentage of fruits in the diet, and used functional traits related to seed dispersal to measure functional diversity. Our results showed that landscape composition was more important than landscape configuration explaining taxonomic and functional diversity of frugivorous birds. In addition, the interaction between landscape composition and configuration explained the loss of functional traits. We demonstrate a disproportional importance of landscape composition explaining taxonomic and functional diversity of frugivorous birds, whereas the traits related to seed dispersal were explained by both compositional and configurational variables. Thus, we highlighted the need to maintain high habitat amount to increase taxonomic and functional diversity of frugivorous birds. However, the interaction of landscape composition and configuration is of paramount importance to sustain functional traits of frugivores in tropical forest landscapes.
Background and Research Aims: Habitat amount plays an important role in determining the presence ... more Background and Research Aims: Habitat amount plays an important role in determining the presence and abundance of bird species in modified landscapes, whereas habitat fragmentation has shown little effects. Toucans (Ramphastidae) and parrots (Psittacidae) are large-bodied primary consumers and among the most representative birds in Neotropical forests. They are highly sensitive to habitat loss; nevertheless, their response to fragmentation has been poorly assessed leading to contradictory results. Here, we evaluate the influence of landscape structure on toucans and parrots in the tropical forest of Los Tuxtlas, Mexico. Methods: We censused birds in 12 landscapes of Los Tuxtlas and used a multi-scale landscape approach to assess the influence of landscape composition and configuration on the number of individuals of toucans and parrots. Results: We found that the most important and positive predictor of toucans and parrots was the amount of primary forest cover in the landscape. For...
A central problem in ecology is to understand how human impacts affect plant-animal interactions ... more A central problem in ecology is to understand how human impacts affect plant-animal interactions that lead to effective seed dispersal services for plant communities. Seed dispersal services are the outcome of plant-frugivore interactions that often form local networks of interacting species. Recent work has shown that some frugivorous bird species are more critical to network organization than others. Here, we explore how patch size and the potential local extinctions of obligate frugivorous birds affect the reorganization of seed dispersal networks. We examined the structure of 20 empirical seed dispersal networks documented across tropical avian assemblages occupying widely variable habitat patch sizes, a surrogate of the amount of remaining habitat. Networks within small forest patches consistently supported both lower plant and bird species richness. Forest patch size was positively associated with nestedness, indicating that reductions in patch size disrupted the nested organization of seed dispersal networks. Obligate frugivores, especially large-bodied species, were almost entirely absent from small forest patches. Analysis at the species level showed that obligate frugivores formed the core of interacting species, connecting species within a given seed dispersal network. Our combined results revealed that patch size reduction erodes frugivorous bird diversity, thereby affecting the integrity of seed dispersal networks. We highlight the importance of conserving large forest patches to maintain tropical forest functionality.
Global biodiversity is threatened by land-use changes through human activities. This is mainly du... more Global biodiversity is threatened by land-use changes through human activities. This is mainly due to the conversion of continuous forests into forest fragments surrounded by anthropogenic matrices. In general, sensitive species are lost while species adapted to disturbances succeed in altered environments. However, whether the interactions performed by the persisting species are also modified, and how it scales up to the network level throughout the landscape are virtually unknown in most tropical hotspots of biodiversity. Here we evaluated how landscape predictors (forest cover, total core area, edge density, inter-patch isolation) and local characteristics (fruit availability, vegetation complexity) affected understory birds seed-dispersal networks in 19 forest fragments along the hyperdiverse but highly depauperate northeast distribution of the Brazilian Atlantic Forest. Also, our sampled sites were distributed in two regions with contrasting land cover changes. We used mist net...
Seed removal is a key component of seed dispersal and may be influenced by both landscape-scale a... more Seed removal is a key component of seed dispersal and may be influenced by both landscape-scale and local attributes, and it has been used as an indicator of the intensity of interactions between ecosystem components. We examined how the seed removal rates, which integrate the activity of seed dispersers and seed predators, vary with landscape-scale forest cover. We collected data under 34 trees belonging to two zoochoric species (Helicostylis tomentosa (Poepp. and Endl.) J. F. Macbr. and Inga vera Willd.) in 17 remnants in the Brazilian Atlantic forest, with different percentages of forest cover. The seed removal rate was estimated using a fast method based on the abundance of intact fruits and fruit scraps on the ground. The amount of forest cover affected the rate of seed removal in a humpbacked shape, with a maximum seed removal rate at intermediate forest cover. Seed removal rates must be related to the amount of food resources offered and diversity of dispersers and predators ...
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