11 research outputs found
Extreme Rainfall Events Alter the Trophic Structure in Bromeliad Tanks Across the Neotropics
Changes in global and regional precipitation regimes are among the most pervasive components of climate change. Intensification of rainfall cycles, ranging from frequent downpours to severe droughts, could cause widespread, but largely unknown, alterations to trophic structure and ecosystem function. We conducted multi-site coordinated experiments to show how variation in the quantity and evenness of rainfall modulates trophic structure in 210 natural freshwater microcosms (tank bromeliads) across Central and South America (18°N to 29°S). The biomass of smaller organisms (detritivores) was higher under more stable hydrological conditions. Conversely, the biomass of predators was highest when rainfall was uneven, resulting in top-heavy biomass pyramids. These results illustrate how extremes of precipitation, resulting in localized droughts or flooding, can erode the base of freshwater food webs, with negative implications for the stability of trophic dynamics
Species niches, not traits, determine abundance and occupancy patterns: A multiâsite synthesis
International audienceAim: Locally abundant species are usually widespread, and this pattern has been related to properties of the niches and traits of species. However, such explanations fail to account for the potential of traits to determine species niches and often overlook statistical artefacts. Here, we examine how trait distinctiveness determines the abilities of species to exploit either common habitats (niche position) or a range of habitats (niche breadth) and how niche position and breadth, in turn, affect abundance and occupancy. We also examine how statistical artefacts moderate these relationships. Location: Sixteen sites in the Neotropics. Time period 1993â2014. Major taxa studied Aquatic invertebrates from tank bromeliads. Methods: We measured the environmental niche position and breadth of each species and calculated its trait distinctiveness as the average trait difference from all other species at each site. Then, we used a combination of structural equation models and a meta-analytical approach to test traitâniche relationships and a null model to control for statistical artefacts. Results: The trait distinctiveness of each species was unrelated to its niche properties, abundance and occupancy. In contrast, niche position was the main predictor of abundance and occupancy; species that used the most common environmental conditions found across bromeliads were locally abundant and widespread. Contributions of niche breadth to such patterns were attributable to statistical artefacts, indicating that effects of niche breadth might have been overestimated in previous studies. Main conclusions: Our study reveals the generality of niche position in explaining one of the most common ecological patterns. The robustness of this result is underscored by the geographical extent of our study and our control of statistical artefacts. We call for a similar examination across other systems, which is an essential task to understand the drivers of commonness across the tree of life
Effects of the precipitation regimen and spatial scale on the invertebrate communities and ecosystem processes in phytotelmata
Understanding the factors that drive community stmcture and ecosystem processes are a relevant goal in ecology. One factor is environmental heterogeneity that alters communities through changes in habitat and available resource for species; however, it is unclear if those effects can change according to the spatial scale. Another factor is climate change, which affects community composition and ecosystem functionality through the loss of particular predator species; although, it is unknown if rainfall variability can alter the community and energy and nutrient flux in temporal ecosystems, such as ponds or phytotelmata. We used the community within two phytotelmata, ecological model system in order to assess effect regime on communities and ecosystem processes. bromeliads and tree holes, as an of spatial scale and hydrological regime on communities and ecosystem processes. First, we studied the invertebrate community associated to Guzmania multiflora (AndrĂ©) AndrĂ© ex Mez. (Bromeliaceae) and their biological traits. We assessed the relation between biological traits and habitat complexity and resource availability. We found that habitat complexity not only alters the taxonomical diversity of invertebrates in bromeliads but also their functional diversity tlnough changes in the abundance and richness of biological traits. In this regard, biological traits provide an approach to ecosystem processes and invertebrate adaptations to environmental conditions. Second, we investigated the effects of spatial scale dependence of habitat and detritus on community and decomposition. We found that species turnover of invertebrates associated with free holes depended on a spatial scale and that there was a scale-dependent effect of habitat and litter on the community and litter decomposition. Third, we assessed the relationship between the amount and frequency of precipitation and bromeliad community and functioning. We found that the magnitude of precipitation rather than rainfall frequency affected invertebrate communities, decomposition, and primary productivity. Finally, we analyzed the energy and nitrogen flux in a bromeliad invertebrate food web and its interaction with the loss of an intraguild predator. We found that the interaction between shifts in the amount of precipitation and the presence/absence of the predator altered the energy and nitrogen flow in the bromeliad food webDoctor en Ciencias - BiologĂaDoctorad
Primer registro del género Systelloderes (Hemiptera: Heteroptera: Enicocephalidae) en Guzmania multiflora (Bromeliaceae) en Colombia.
Se conoce poco sobre la relaciĂłn entre depredadores de la familia Enicocephalidae y plantas. Se reporta la presencia de dos especies de Systelloderes habitando en plantas de Guzmania multiflora (Bromeliaceae) en un bosque de montaña de Colombia. Este estudio se llevĂł a cabo en la Reserva Forestal Protectora de las Cuencas HidrogrĂĄficas de Rio Blanco y Quebrada Olivares Manizales, Caldas, Colombia, donde se recolectaron bromelias entre cero y tres metros de altura. Aunque especies de Systelloderes habĂan sido reportadas con anterioridad en Colombia, este gĂ©nero no habĂa sido encontrado dentro de bromelias
A case of communal egg-laying of Gonatodes albogularis (Sauria, Sphaerodactylidae) in bromeliads (Poales, Bromeliaceae)
The Neotropical Yellow-Headed Gecko Gonatodes albogularis commonly use cavities in the trees as a microhabitat for egg-laying. Here, we present the first record of this species in Colombia using the tank bromeliad Tillandsia elongata as nesting sites, along with the occurrence of communal egg-laying in that microhabitat
A case of communal egg-laying of Gonatodes albogularis (Sauria, Sphaerodactylidae) in bromeliads (Poales, Bromeliaceae)
The Neotropical Yellow-Headed Gecko Gonatodes albogularis commonly use cavities in the trees as a microhabitat for egg-laying. Here, we present the first record of this species in Colombia using the tank bromeliad Tillandsia elongata as nesting sites, along with the occurrence of communal egg-laying in that microhabitat
Climate influences the response of community functional traits to local conditions in bromeliad invertebrate communities
International audienceFunctional traits determine an organism's performance in a given environment and as such determine which organisms will be found where. Species respond to local conditions, but also to larger scale gradients, such as climate. Trait ecology links these responses of species to community composition and species distributions. Yet, we often do not know which environmental gradients are most important in determining community trait composition at either local or biogeographical scales, or their interaction. Here we quantify the relative contribution of local and climatic conditions to the structure and composition of functional traits found within bromeliad invertebrate communities. We conclude that climate explains more variation in invertebrate trait composition within bromeliads than does local conditions. Importantly, climate mediated the response of traits to local conditions; for example, invertebrates with benthic life-history traits increased with bromeliad water volume only under certain precipitation regimes. Our ability to detect this and other patterns hinged on the compilation of multiple fine-grained datasets, allowing us to contrast the effect of climate versus local conditions. We suggest that, in addition to sampling communities at local scales, we need to aggregate studies that span large ranges in climate variation in order to fully understand trait filtering at local, regional and global scales
Constraints on the functional trait space of aquatic invertebrates in bromeliads
International audienceFunctional traits are commonly used in predictive models that link environmental drivers and community structure to ecosystem functioning. A prerequisite is to identify robust sets of continuous axes of trait variation, and to understand the ecological and evolutionary constraints that result in the functional trait space occupied by interacting species. Despite their diversity and role in ecosystem functioning, little is known of the constraints on the functional trait space of invertebrate biotas of entire biogeographic regions.We examined the ecological strategies and constraints underlying the realized trait space of aquatic invertebrates, using data on 12 functional traits of 852 taxa collected in tank bromeliads from Mexico to Argentina. Principal Component Analysis was used to reduce trait dimensionality to significant axes of trait variation, and the proportion of potential trait space that is actually occupied by all taxa was compared to null model expectations. Permutational Analyses of Variance were used to test whether trait combinations were cladeâdependent.The major axes of trait variation represented lifeâhistory strategies optimizing resource use and antipredator adaptations. There was evidence for trophic, habitat, defence and lifeâhistory niche axes. Bromeliad invertebrates only occupied 16%â23% of the potential space within these dimensions, due to greater concentrations than predicted under uniform or normal distributions. Thus, despite high taxonomic diversity, invertebrates only utilized a small number of successful ecological strategies.Empty areas in trait space represented gaps between major phyla that arose from biological innovations, and trait combinations that are unviable in the bromeliad ecosystem. Only a few phylogenetically distant genera were neighbouring in trait space. Trait combinations aggregated taxa by family and then by order, suggesting that niche conservatism was a widespread mechanism in the diversification of ecological strategies
Functional redundancy dampens precipitation change impacts on speciesârich invertebrate communities across the Neotropics
International audienceAnimal community responses to extreme climate events can be predicted from the functional traits represented within communities. However, it is unclear whether geographic variation in the response of functional community structure to climate change is primarily driven by physiological matching to local conditions (local adaptation hypothesis) or by differences between species pools in functional redundancy (insurance hypothesis). We conducted a coordinated experiment to understand how aquatic invertebrate traits mediate the responses of multitrophic communities to changes in the quantity and evenness of rainfall in 180 natural freshwater microcosms (tank bromeliads) distributed across six sites from 18°N in the Caribbean to 29°S in South America. At each site, we manipulated the mean and dispersion of the daily amount of rainfall that entered tank bromeliads over a 2-month period. Manipulations covered a response surface representing 50% to 200% of the dispersion of daily rainfall crossed with 10% to 300% of the mean amounts of rainfall. The response of functional community structure to precipitation regimes differed across sites. These geographic differences were not consistent with the local adaptation hypothesis, as responses did not correlate with the current amplitude in precipitation. Geographic differences in community responses were consistent with the insurance hypothesis: sites with the lowest functional redundancy in their species pools had the strongest response to a gradient in hydrological variability induced by uneven precipitation. In such sites, an increase in the hydrologic variability induced a shift from communities with both pelagic and benthic traits using both green and brown energy channels to strictly benthic, brown energy communities. Our results predict uneven impacts of precipitation change on community structure and energy channels within communities across Neotropical regions. This geographic variation is due more to differences in the size and redundancy of species pools than to local adaptation. Strategies for climate change adaptation should thus seek to identify and preserve functionally unique species and their habitats. Read the free Plain Language Summary for this article on the Journal blog