The following letter, from a network of women zoologists, is a reply to the article of AlShebli e... more The following letter, from a network of women zoologists, is a reply to the article of AlShebli et al. (2020), which suggests that female protégés reap more benefits when mentored by men and concludes that female mentors hinder the success of their female protégés and the quality of their impact. This contribution has two parts. First, we highlight the most relevant methodological flaws which, in our opinion, may have impacted the conclusions of AlShebli et al. (2020). Second, we discuss issues pertaining to women in science, bring a perspective of Women in Zoology and discuss how current diversity policies are positively changing our field.
Some species of the fungal genus Ophiocordyceps that parasitize ants have evolved some degree of ... more Some species of the fungal genus Ophiocordyceps that parasitize ants have evolved some degree of behavioral manipulation to increase their own transmission. Carpenter ants (Camponotus spp.) infected by Ophiocordyceps unilateralis species climb vegetation and bite leaves or other plant parts before death, while other ants infected by other Ophiocordyceps species die buried within or on the leaf-litter, attached to stems and tree trunks. The microenvironment of the host's death location is important for fungal development and dispersal to new hosts, being an interesting example of an extended phenotype. This study investigated the effect of humidity variation in space (15 km 2) and time (14 months) on the occurrence and expression of the extended Ophiocordyceps phenotype parasitizing ants in Central Amazonia. We found O. unilateralis s.l., O. kniphofioides s.l. and O. australis s.l. parasitizing 30 ant species, but O. unilateralis s.l. was by far the most abundant fungus. Parasitized Camponotus atriceps and C. bispinosus were more abundant and died in higher places in periods with greater air humidity. Otherwise, the abundance and height of C. senex cadavers were higher in drier plots. These results provide insights on how the spatial and temporal variation in air humidity may shape the occurrence and behavioral manipulation of ants infected by entomopathogenic fungi at larger scales.
Variation in partner species and frequency of interaction between species pairs are potential dri... more Variation in partner species and frequency of interaction between species pairs are potential drivers of the net outcome of generalized mutualisms. In ant-plant mutualisms, the quality of defence provided by ants is related to ant aggressiveness. Hence, we hypothesize that the performance of plants bearing extrafloral nectaries will be higher when they interact more frequently with more aggressive ant species. We estimated ant aggressiveness in the field by observing their behaviour towards soil baits. Afterwards, we observed the frequency with which individuals from these ant species visited plants through an entire reproductive cycle. We measured the production and persistence of plants reproductive structures through this period and the total seed production. Increasing in the interaction frequency with highly aggressive ants reduced the number of floral buds and seeds produced. Increased visitation frequency by less aggressive ants increased the number of floral buds and seeds p...
:Ant gardens (AGs) are specialized ant-plant associations where arboreal ants build their carton ... more :Ant gardens (AGs) are specialized ant-plant associations where arboreal ants build their carton nests in association with epiphytes that use the carton as a substrate. Most of the epiphytes are planted by ants; therefore, seed selection by ants is a key driver of the epiphyte composition of AGs. However, deterministic post-dispersal factors, such as the surrounding environmental conditions and plant succession, may also influence epiphyte composition. Here we ask whether epiphyte composition on a local scale is associated with dispersal constraints, local environmental conditions (light availability, number of branches and nest height) or AG successional stage. We sampled all epiphyte species in 18 AGs formed byCamponotus femoratusandCrematogaster leviorin Central Amazon, Brazil. AGs were located within a range of 1 km and at a maximum of 20 m from the edges of a dirt road within a primary forest. Epiphytic composition showed strong spatial structure, decreasing in similarity with increasing distance. Environmental conditions and AG successional stage were not related to AG floristic composition, suggesting a key role of stochastic processes related to seed dispersal. A combination of seed abundance and attractiveness in neighbouring AGs seems to drive the higher similarity in epiphyte composition among closer AGs.
ABSTRACT Myrmecochory, or seed dispersal by ants, occurs widely in angiosperms, and particularly ... more ABSTRACT Myrmecochory, or seed dispersal by ants, occurs widely in angiosperms, and particularly in temperate forest herbs in the northern Hemisphere and sclerophyll shrubs in Mediterranean-climate landscapes. The lipid-rich elaiosome on the seed provides nutrition to the ants; however, how the plant benefits from myrmecochory remains unclear. Here, we provide the first comprehensive analysis of the Euphorbiaceae species in the semi-arid Caatinga vegetation region of northeastern Brazil, and show that myrmecochory strongly associates with small plant stature, even after controlling for seed size. The association of myrmecochory with small stature suggests that the primary benefit to plants concerns distance of dispersal, which reduces parental and sibling competition.ResumoA mirmecocoria é um modo de dispersão de sementes comum e amplamente disseminado, ocorrendo em pelo menos 11.000 espécies de angiospermas. Contudo, os benefícios de terem suas sementes dispersas pelas formigas permanecem desconhecidos para a maioria das espécies. Um atributo notável da mirmecocoria é sua ocorrência quase que exclusivamente entre plantas de baixa estatura como ervas em florestas temperadas do hemisfério Norte e arbustos esclerófitos de regiões com clima mediterrâneo na África do Sul, sul da Austrália e sul da Europa. Nós mostramos pela primeira vez neste ensaio a que a mirmecocoria na Caatinga do Nordeste do Brasil é fortemente associada a plantas com baixa estatura, mesmo controlando o tamanho da semente. Essa limitação da mirmecocoria a plantas de baixa estatura sugere que o beneficio primário para as plantas é relacionado à remoção da semente para fora da copa da planta-parental, principalmente para evitar a competição com o adulto.
Anthropogenic disturbance can have important indirect effects on ecosystems by disrupting species... more Anthropogenic disturbance can have important indirect effects on ecosystems by disrupting species interactions. Here we examine the effects of anthropogenic disturbance on distance dispersal by ants for the diaspores of myrmecochorous Euphorbiaceae in Brazilian Caatinga. Rates of diaspore removal and distances removed of Croton sonderianus and Jatropha mollissima were observed at 24 sites ranging from low to very high disturbance (primarily grazing by livestock, hunting and firewood collection). Despite a large number of seed-disperser ant species, there were only two species providing high-quality distance-dispersal services, Dinoponera quadriceps (40% of all observed seed removals) and Ectatomma muticum (33%). D. quadriceps was responsible for 97% of all removals >2 m, and 100% of all removals >5 m. Removal rates did not vary with disturbance for C. sonderianus (small elaiosome), but declined with increasing disturbance for J. mollissima (large elaiosome). The number of removals by Ectatomma was highest at intermediate levels of disturbance, whereas those by Dinoponera decreased systematically with increasing levels of disturbance. Mean dispersal distance was four times higher at sites experiencing low disturbance, where removals >5 m represented a third of all removal events, compared with very highly disturbed sites, where no removals >5 m were observed. Despite high overall diversity there is very limited functional redundancy in disperser ant species, resulting in low disperser resilience in relation to disturbance. This is likely to have important implications for recruitment by myrmecochorous plants, and therefore on vegetation composition and structure, at sites subject to high anthropogenic disturbance.
Recent evidence suggests that the traditional view of myrmecochory as a highly diffuse interactio... more Recent evidence suggests that the traditional view of myrmecochory as a highly diffuse interaction between diaspores and a wide range of ant species attracted to their elaiosomes may not be correct. The effectiveness of dispersal varies markedly among ant species, and combined with differential attractiveness of diaspores due to elaiosome size and composition, this raises the potential for myrmecochorous plants to target ant species that offer the highest quality dispersal services. We ask the question: Do particular physical and chemical traits of elaiosomes result in disproportionate removal of Euphorbiaceae diaspores by high-quality disperser ants in Caatinga vegetation of north-eastern Brazil? We offered seeds of five euphorb species that varied in morphological and chemical traits of elaiosomes to seed-dispersing ants. High-quality seed-disperser ants (species of Dinoponera, Ectatomma and Camponotus) were identified as those that rapidly collected and transported diaspores to their nests, often over substantial distances, whereas low-quality disperser ants (primarily species of Pheidole and Solenopsis) typically fed on elaiosomes in situ, and only ever transported diaspores very short distances. Low-quality disperser ants were equally attracted to the elaiosomes of all study species. However, high-quality dispersers showed a strong preference for diaspores with the highest elaiosome mass (and especially proportional mass). As far as we are aware, this is the first study to identify a mechanism of diaspore selection by high-quality ant dispersers based on elaiosome traits under field conditions. Our findings suggest that myrmecochorous plants can preferentially target high-quality seed-disperser ants through the evolution of particular elaiosome traits.
Life history traits are considered key indicators of plant invasibility. Among them, the germinat... more Life history traits are considered key indicators of plant invasibility. Among them, the germination behavior of seeds is of major relevance because it is influenced by environmental factors of invaded ecosystem. Here, we investigated how seed traits and seed tolerance to environmental factors on seed germination of Calotropis procera vary depending on the invaded ecosystems in northeastern Brazil. We have tested seeds from two vegetation types – Caatinga and Restinga – to different levels of light intensity, salinity, and water stress. Previous to those experiments, seed-set and morphometric analysis were carried out for both studied populations. We have observed a higher seed-set in Caatinga. Seeds produced in this ecosystem had lower seed moisture content. Seeds from Restinga showed lower germination time when light intensity decreased. We observed a reduction in both the germinability and the synchronization index with decreasing osmotic potential and increasing salinity. Nevert...
The following letter, from a network of women zoologists, is a reply to the article of AlShebli e... more The following letter, from a network of women zoologists, is a reply to the article of AlShebli et al. (2020), which suggests that female protégés reap more benefits when mentored by men and concludes that female mentors hinder the success of their female protégés and the quality of their impact. This contribution has two parts. First, we highlight the most relevant methodological flaws which, in our opinion, may have impacted the conclusions of AlShebli et al. (2020). Second, we discuss issues pertaining to women in science, bring a perspective of Women in Zoology and discuss how current diversity policies are positively changing our field.
Some species of the fungal genus Ophiocordyceps that parasitize ants have evolved some degree of ... more Some species of the fungal genus Ophiocordyceps that parasitize ants have evolved some degree of behavioral manipulation to increase their own transmission. Carpenter ants (Camponotus spp.) infected by Ophiocordyceps unilateralis species climb vegetation and bite leaves or other plant parts before death, while other ants infected by other Ophiocordyceps species die buried within or on the leaf-litter, attached to stems and tree trunks. The microenvironment of the host's death location is important for fungal development and dispersal to new hosts, being an interesting example of an extended phenotype. This study investigated the effect of humidity variation in space (15 km 2) and time (14 months) on the occurrence and expression of the extended Ophiocordyceps phenotype parasitizing ants in Central Amazonia. We found O. unilateralis s.l., O. kniphofioides s.l. and O. australis s.l. parasitizing 30 ant species, but O. unilateralis s.l. was by far the most abundant fungus. Parasitized Camponotus atriceps and C. bispinosus were more abundant and died in higher places in periods with greater air humidity. Otherwise, the abundance and height of C. senex cadavers were higher in drier plots. These results provide insights on how the spatial and temporal variation in air humidity may shape the occurrence and behavioral manipulation of ants infected by entomopathogenic fungi at larger scales.
Variation in partner species and frequency of interaction between species pairs are potential dri... more Variation in partner species and frequency of interaction between species pairs are potential drivers of the net outcome of generalized mutualisms. In ant-plant mutualisms, the quality of defence provided by ants is related to ant aggressiveness. Hence, we hypothesize that the performance of plants bearing extrafloral nectaries will be higher when they interact more frequently with more aggressive ant species. We estimated ant aggressiveness in the field by observing their behaviour towards soil baits. Afterwards, we observed the frequency with which individuals from these ant species visited plants through an entire reproductive cycle. We measured the production and persistence of plants reproductive structures through this period and the total seed production. Increasing in the interaction frequency with highly aggressive ants reduced the number of floral buds and seeds produced. Increased visitation frequency by less aggressive ants increased the number of floral buds and seeds p...
:Ant gardens (AGs) are specialized ant-plant associations where arboreal ants build their carton ... more :Ant gardens (AGs) are specialized ant-plant associations where arboreal ants build their carton nests in association with epiphytes that use the carton as a substrate. Most of the epiphytes are planted by ants; therefore, seed selection by ants is a key driver of the epiphyte composition of AGs. However, deterministic post-dispersal factors, such as the surrounding environmental conditions and plant succession, may also influence epiphyte composition. Here we ask whether epiphyte composition on a local scale is associated with dispersal constraints, local environmental conditions (light availability, number of branches and nest height) or AG successional stage. We sampled all epiphyte species in 18 AGs formed byCamponotus femoratusandCrematogaster leviorin Central Amazon, Brazil. AGs were located within a range of 1 km and at a maximum of 20 m from the edges of a dirt road within a primary forest. Epiphytic composition showed strong spatial structure, decreasing in similarity with increasing distance. Environmental conditions and AG successional stage were not related to AG floristic composition, suggesting a key role of stochastic processes related to seed dispersal. A combination of seed abundance and attractiveness in neighbouring AGs seems to drive the higher similarity in epiphyte composition among closer AGs.
ABSTRACT Myrmecochory, or seed dispersal by ants, occurs widely in angiosperms, and particularly ... more ABSTRACT Myrmecochory, or seed dispersal by ants, occurs widely in angiosperms, and particularly in temperate forest herbs in the northern Hemisphere and sclerophyll shrubs in Mediterranean-climate landscapes. The lipid-rich elaiosome on the seed provides nutrition to the ants; however, how the plant benefits from myrmecochory remains unclear. Here, we provide the first comprehensive analysis of the Euphorbiaceae species in the semi-arid Caatinga vegetation region of northeastern Brazil, and show that myrmecochory strongly associates with small plant stature, even after controlling for seed size. The association of myrmecochory with small stature suggests that the primary benefit to plants concerns distance of dispersal, which reduces parental and sibling competition.ResumoA mirmecocoria é um modo de dispersão de sementes comum e amplamente disseminado, ocorrendo em pelo menos 11.000 espécies de angiospermas. Contudo, os benefícios de terem suas sementes dispersas pelas formigas permanecem desconhecidos para a maioria das espécies. Um atributo notável da mirmecocoria é sua ocorrência quase que exclusivamente entre plantas de baixa estatura como ervas em florestas temperadas do hemisfério Norte e arbustos esclerófitos de regiões com clima mediterrâneo na África do Sul, sul da Austrália e sul da Europa. Nós mostramos pela primeira vez neste ensaio a que a mirmecocoria na Caatinga do Nordeste do Brasil é fortemente associada a plantas com baixa estatura, mesmo controlando o tamanho da semente. Essa limitação da mirmecocoria a plantas de baixa estatura sugere que o beneficio primário para as plantas é relacionado à remoção da semente para fora da copa da planta-parental, principalmente para evitar a competição com o adulto.
Anthropogenic disturbance can have important indirect effects on ecosystems by disrupting species... more Anthropogenic disturbance can have important indirect effects on ecosystems by disrupting species interactions. Here we examine the effects of anthropogenic disturbance on distance dispersal by ants for the diaspores of myrmecochorous Euphorbiaceae in Brazilian Caatinga. Rates of diaspore removal and distances removed of Croton sonderianus and Jatropha mollissima were observed at 24 sites ranging from low to very high disturbance (primarily grazing by livestock, hunting and firewood collection). Despite a large number of seed-disperser ant species, there were only two species providing high-quality distance-dispersal services, Dinoponera quadriceps (40% of all observed seed removals) and Ectatomma muticum (33%). D. quadriceps was responsible for 97% of all removals >2 m, and 100% of all removals >5 m. Removal rates did not vary with disturbance for C. sonderianus (small elaiosome), but declined with increasing disturbance for J. mollissima (large elaiosome). The number of removals by Ectatomma was highest at intermediate levels of disturbance, whereas those by Dinoponera decreased systematically with increasing levels of disturbance. Mean dispersal distance was four times higher at sites experiencing low disturbance, where removals >5 m represented a third of all removal events, compared with very highly disturbed sites, where no removals >5 m were observed. Despite high overall diversity there is very limited functional redundancy in disperser ant species, resulting in low disperser resilience in relation to disturbance. This is likely to have important implications for recruitment by myrmecochorous plants, and therefore on vegetation composition and structure, at sites subject to high anthropogenic disturbance.
Recent evidence suggests that the traditional view of myrmecochory as a highly diffuse interactio... more Recent evidence suggests that the traditional view of myrmecochory as a highly diffuse interaction between diaspores and a wide range of ant species attracted to their elaiosomes may not be correct. The effectiveness of dispersal varies markedly among ant species, and combined with differential attractiveness of diaspores due to elaiosome size and composition, this raises the potential for myrmecochorous plants to target ant species that offer the highest quality dispersal services. We ask the question: Do particular physical and chemical traits of elaiosomes result in disproportionate removal of Euphorbiaceae diaspores by high-quality disperser ants in Caatinga vegetation of north-eastern Brazil? We offered seeds of five euphorb species that varied in morphological and chemical traits of elaiosomes to seed-dispersing ants. High-quality seed-disperser ants (species of Dinoponera, Ectatomma and Camponotus) were identified as those that rapidly collected and transported diaspores to their nests, often over substantial distances, whereas low-quality disperser ants (primarily species of Pheidole and Solenopsis) typically fed on elaiosomes in situ, and only ever transported diaspores very short distances. Low-quality disperser ants were equally attracted to the elaiosomes of all study species. However, high-quality dispersers showed a strong preference for diaspores with the highest elaiosome mass (and especially proportional mass). As far as we are aware, this is the first study to identify a mechanism of diaspore selection by high-quality ant dispersers based on elaiosome traits under field conditions. Our findings suggest that myrmecochorous plants can preferentially target high-quality seed-disperser ants through the evolution of particular elaiosome traits.
Life history traits are considered key indicators of plant invasibility. Among them, the germinat... more Life history traits are considered key indicators of plant invasibility. Among them, the germination behavior of seeds is of major relevance because it is influenced by environmental factors of invaded ecosystem. Here, we investigated how seed traits and seed tolerance to environmental factors on seed germination of Calotropis procera vary depending on the invaded ecosystems in northeastern Brazil. We have tested seeds from two vegetation types – Caatinga and Restinga – to different levels of light intensity, salinity, and water stress. Previous to those experiments, seed-set and morphometric analysis were carried out for both studied populations. We have observed a higher seed-set in Caatinga. Seeds produced in this ecosystem had lower seed moisture content. Seeds from Restinga showed lower germination time when light intensity decreased. We observed a reduction in both the germinability and the synchronization index with decreasing osmotic potential and increasing salinity. Nevert...
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