Life Stage and Neighborhood-Dependent Survival of Longleaf Pine after Prescribed Fire

Determining mechanisms of plant establishment in ecological communities can be particularly difficult in disturbance-dominated ecosystems. Longleaf pine (Pinus palustris Mill.) and its associated plant community exemplify systems that evolved with disturbances, where frequent, widespread fires alter the population dynamics of longleaf pine within distinct life stages. We identified the primary biotic and environmental conditions that influence the survival of longleaf pine in this disturbance-dominated ecosystem. We combined data from recruitment surveys, tree censuses, dense lidar point clouds, and a forest-wide prescribed fire to examine the response of longleaf pine individuals to fire and biotic neighborhoods. We found that fire temperatures increased with increasing longleaf pine neighborhood basal area and decreased with higher oak densities. There was considerable variation in longleaf pine survival across life stages, with lowest survival probabilities occurring during the bolt stage and not in the earlier, more fire-resistant grass stage. Survival of grass-stage, bolt-stage, and sapling longleaf pines was negatively associated with basal area of neighboring longleaf pine and positively related to neighboring heterospecific tree density, primarily oaks (Quercus spp.). Our findings highlight the vulnerability of longleaf pine across life stages, which suggests optimal fire management strategies for controlling longleaf pine density, and—more broadly—emphasize the importance of fire in mediating species interactions.

Effects of intraspecific cooperative interactions in large ecosystems

We analyze the role of the Allee effect - a positive correlation between population density and mean individual fitness - for ecological communities formed by a large number of species. Our study is performed using the generalized Lotka-Volterra model with random interactions between species. We obtain the phase diagram and analyze the nature of the multiple equilibria phase. Remarkable differences emerge with respect to the logistic growth case, thus revealing the major role played by the functional response in determining aggregate behaviors of large ecosystems.

Increasing instability of a rocky intertidal meta-ecosystem

Climate change threatens to destabilize ecological communities, potentially moving them from persistently occupied “basins of attraction” to different states. Increasing variation in key ecological processes can signal impending state shifts in ecosystems. In a rocky intertidal meta-ecosystem consisting of three distinct regions spread across 260 km of the Oregon coast, we show that annually cleared sites are characterized by communities that exhibit signs of increasing destabilization (loss of resilience) over the past decade despite persistent community states. In all cases, recovery rates slowed and became more variable over time. The conditions underlying these shifts appear to be external to the system, with thermal disruptions (e.g., marine heat waves, El Niño–Southern Oscillation) and shifts in ocean currents (e.g., upwelling) being the likely proximate drivers. Although this iconic ecosystem has long appeared resistant to stress, the evidence suggests that subtle destabilization has occurred over at least the last decade.

What has become of our cenosis? For a renewed cenology

An opinion paper that tries to show that the concept of cenosis has been withheld over time, seeks to understand the reason why, and aims to rehabilitate it. Different definitions of biological and ecological communities types are then proposed. Finally, the paper presents some possible paths for a renewed science of cenosis (or cenology, or biocenotics).

First report of the Southern Gulf Coast Toad (Incilius valliceps Wiegmann), Common House Gecko (Hemidactylus frenatus Duméril and Bibron), Schmidt’s Black-Striped Snake (Coniophanes schmidti Bailey), and Cozumel Whiptail (Aspidoscelis cozumela Gadow), on Turneffe Atoll, Belize

Each year from 2012 to 2019, during a 12-day period in November or December, we photographed common herpetofauna on Calabash Caye, a small mangrove-dominated island on the eastern edge of Turneffe Atoll, Belize. Turneffe Atoll is home to the newest, largest, and most biodiverse marine protected area in Belize. Calabash Caye exemplifies the islands on Turneffe’s eastern edge whose elevated beach ridges enable the development of coastal strand plain and littoral forest habitats, which are among the most threatened habitats in the world. As no herpetofaunal survey has been published for Turneffe in over twenty years, and as the herpetofauna is a conspicuous indicator of the health of terrestrial ecological communities on islands, we leveraged our annual field excursions to Calabash Caye to compile a photographic record of the island’s reptiles and amphibians. In multiple years, we documented the presence of five lizards (Anolis sagrei mayensis, Aspidoscelis cozumela, Ctenosaura similis, Phyllodactylus tuberculosus, and the invasive species Hemidactylus frenatus), three snakes (Boa imperator, Leptophis mexicanus hoeversi, and Coniophanes schmidti), and one amphibian (Incilius valliceps). This represents the first report of A. cozumela, H. frenatus, C. schmidti, and I. valliceps on Calabash Caye or on any island in Turneffe Atoll; H. frenatus, C. schmidti, and I. valliceps have never been reported on any of the Belizean cayes. We did not observe four species that have previously been reported on Calabash Caye: Brown Basilisk (Basiliscus vittatus), Mesoamerican Cane Toad (Rhinella horribilis), Mayan Skink (Marisora lineola; formerly Mabuya unimarginata), or a blindsnake, provisionally identified as Indotyphlops braminus. We also include photos of Anolis allisoni, Ctenosaura similis, and Anolis sagrei mayensis obtained during four single-day excursions to Half Moon Caye on Lighthouse Atoll; this represents three of four species reported from that location during the 1990s.

Ecological constraints and trait conservatism drive functional and phylogenetic structure of amphibians larvae assemblages in the Atlantic Forest

Investigate how ecological and/or evolutionary factors could affect the structure of ecological communities is a central demand in ecology. In order to better understand that we assessed phylogenetic and functional structure of 33 tadpole communities in the Atlantic Forest coastal plains of Southeastern Brazil. We tested the assumption that phylogenetic conservatism drive tadpole traits. We identified 32 communities with positive values of phylogenetic structure, with 18 of those being significantly clustered. Twelve of 33 communities showed aggregated functional structure. Trait diversity was skewed towards the root, indicating phylogenetic trait conservatism and evolutionary factors as important drivers of tadpoles community structure. Six out of 11 environmental variables were selected in the best explanatory model of phylogenetic structure. Water conductivity, external and internal diversity of vegetation structure, canopy cover, and dissolved oxygen were negatively related with phylogenetic clustering, whereas presence of potential fish predators was positively related. Four of those environmental variables and area were also included in the best explanatory model of functional structure. All variables represent factors related to performance, survivorship, and distribution of anuran communities. From the 12 functionally structured communities, 10 were also phylogenetically structured. Thus, environmental factors may be acting as filters, interacting with phylogenetically conserved species traits, and driving linage occurrence in tadpole communities. Our study provides evidence that phylogenetic and functional structure in vertebrates are a result of interacting ecological and evolutionary agents, resulting in structured anuran assemblages.

Attracting pollinators vs escaping herbivores: eco-evolutionary dynamics of plants confronted with an ecological trade-off

A large number of plant traits are subject to an ecological trade-off between attracting pollinators and escaping herbivores. The interplay of both plant-animal interactions determines their evolution. Within a plant-pollinator-herbivore community in which interaction strengths depend on trait-matching, eco-evolutionary dynamics are studied using the framework of adaptive dynamics. We characterize the type of selection acting on the plant phenotype and the consequences for multispecies coexistence. We find that pollination favors stabilizing selection and coexistence. In contrast, herbivory fosters runaway selection, which threatens plant-animal coexistence. These contrasting dynamics highlight the key role of ecological trade-offs in structuring ecological communities. In particular, we show that disruptive selection is possible when such trade-offs are strong. While the interplay of pollination and herbivory is known to maintain plant polymorphism in several cases, our work suggests that it might also have fueled the diversification process itself.