Interspecific-Competition Strongly Constrains Species-Richness and Species-Abundance Evenness in a Tropical Marine Molluscan Community Inhabiting Caulerpa Beds, as Compared to Coral-Reefs

Increasing species-richness at the local scale (within species communities) is accommodated, first, by the diversification of the niches respectively associated to species. Yet, in case of excessive supply in colonizing species issued from the regional pool, the corresponding increase in the number of solicited niches may lead to some “niche-overcrowding” resulting in significant niche-overlaps. Then, second, strong interspecific competition for shared resource can arise, triggered by the density in individuals among those species co-occurring at niche-overlaps. Accordingly, the accommodation of species-richness within a local community involves a balance between (i) the positive contribution of improved niche-diversification and (ii) the negative consequence of induced interspecific-competition at increasing niche-overlaps once the number of colonizing species becomes too large. This balance can strongly differ according to the local ecological conditions, since the latter are expected to strongly influence the range of “overcrowding-free” diversification of niches. So that, concretely, each community requires a specific analysis, in order to disentangle and quantify the respective contributions of the niche-diversification and the intensity of interspecific-competition to this balance. And, in particular, their respective roles upon both the species-richness and the degree of unevenness of species abundance within community. Beyond its speculative interest, this deeper understanding of the process involved in the hierarchic-like organization of species within community also answers more practical concerns, in particular the stability of species-richness, partly dependent on the intensity of interspecific-competition. In this perspective, we quantify and compare how species-richness accommodation proceeds in two major taxonomic groups, Bivalves and Gastropods respectively, both belonging to a same molluscan community inhabiting Caulerpa beds, in the intertidal-zone of Siquijor Island (Philippines). Then, after having compared these two different taxonomic groups, the influence of environmental conditions on species-richness accommodation is addressed, showing that “Caulerpa-beds” habitat features far-less rewarding to Gastropods communities than can be the classical “coral-reef” habitat.

Synopsis of Euphorbia section Anisophyllum (Euphorbiaceae) in Italy, with an insight on variation of distribution over time in Tuscany

We present an updated taxonomic study of Euphorbia sect. Anisophyllum (Euphorbiaceae) for Italy. A comprehensive body of knowledge has been developed thanks to the examination of about 1,250 herbarium specimens from 13 Italian herbaria, field surveys, and an extensive literature analysis. As a result, our revision included 10 species considered as currently occurring in Italy, of which 2 native (Euphorbia chamaesyce and E. peplis) and 8 alien (E. glyptosperma, E. humifusa, E. hypericifolia, E. maculata, E. nutans, E. ophthalmica, E. prostrata, and E. serpens). The revision included also additional 5 species previously erroneously recorded in Italy (E. berteroana, E. engelmannii, E. hyssopifolia, E. indica, and E. thymifolia) and other two species (E. hirta and E. humistrata) not occurring in Italy but closely related to recorded species and already established and considered as alien species in other countries. Current distribution and status at the regional level is updated for 7 species (E. berteroana, E. engelmannii, E. humifusa, E. hypericifolia, E. indica, E. nutans, and E. prostrata) and typification of 18 names (Chamaesyce glomerifera, E. boliviana, E. bracteolaris, E. brasiliensis, E. chamaesyce var. maculata, E. engelmannii, E. humifusa, E. hypericifolia var. communis, E. indica, E. klotzschiana, E. nutans, E. peplis, E. perforata, E. pinnulosa, E. preslii, E. procumbens, E. reichenbachiana, and E. trichogona) is also provided. For all taxa we report information about nomenclature, morphology, ecology, chorology, distribution, taxonomy, as well as an identification key for species identification and original photos. In addition, we provided a detailed statement of species of the section for Tuscany and we performed an analysis of distribution variation of different species over time in this region. Our results evaluate the current state of E. sect. Anisophyllum in Italy and highlight the presence of fluxes in densities of different species populations. In particular, a reduction of native and formerly colonizing species and an increase of more recently colonizing species is recorded.

Hermaphroditism and Gonochorism

This chapter compares two sexual systems: hermaphroditism (each individual can produce gametes of either sex) and gonochorism (each individual produces gametes of only one of the two distinct sexes) in crustaceans. These two main sexual systems contain a variety of alternative modes of reproduction, which are of great interest from applied and theoretical perspectives. The chapter focuses on the description, prevalence, analysis, and interpretation of these sexual systems, centering on their evolutionary transitions. The ecological correlates of each reproductive system are also explored. In particular, the prevalence of “unusual” (non-gonochoristic) reproductive strategies has been identified under low population densities and in unpredictable/unstable environments, often linked to specific habitats or lifestyles (such as parasitism) and in colonizing species. Finally, population-level consequences of some sexual systems are considered, especially in terms of sex ratios. The chapter aims to provide a broad and extensive overview of the evolution, adaptation, ecological constraints, and implications of the various reproductive modes in this extraordinarily successful group of organisms.

Red Grouper (Epinephelus morio) Shape Faunal Communities via Multiple Ecological Pathways

Organisms that modify the availability of abiotic resources for other species can alter the structure and function of ecological communities through multiple pathways. In Florida Bay, red grouper (Epinephelus morio) engineer habitats by excavating sediment and detritus from karst solution holes and are also predators that consume a variety of benthic crustaceans and fish, some of which colonize engineered habitats. The effect of red grouper on these communities is complex as colonizing species interact with red grouper in different ways, including both direct (e.g., predator–prey) and indirect interactions. Here, I present the results of an experiment designed to test the direct effects of red grouper on faunal communities associated with Florida Bay solution holes by excluding red grouper from solution holes for four weeks. Red grouper presence generally had positive effects on the abundance, richness, and diversity of faunal communities associated with engineered habitats. Few strong interactions were observed between red grouper and colonizing species, mainly juvenile coral reef fishes. These results suggest that by acting as both a predator and habitat engineer, red grouper shape unique communities, distinct from those of surrounding areas, and influence the composition of communities associated with manipulated habitats.

Insects of forensic importance associated to cadaveric decomposition in a rural area of the Andean Amazon, Caquetá, Colombia

ABSTRACT Forensic entomology is a frequently used tool to estimate the time interval between death and the discovery of the corpse. Succession of arthropods associated with cadaveric decomposition was monitored in a rural area of the Municipality of Florencia, Department of Caquetá, Colombia. Three pigs (Sus scrofa) were used as study models. Insect sampling, and monitoring of carcasses and environmental conditions were carried out every five hours. The total time from death to skeletonization was of 545 hours (22.7 days). A total of 30833 insect individuals were collected. Specimens were distributed in nine orders, 46 families, 95 genera and 106 species. Diptera was the most abundant, with 23215 individuals (75.3%), followed by Coleoptera, with 3711 individuals (12%), and Hymenoptera, with 3154 individuals (10.2%). Immature stages of Cochliomyia macellaria, Chrysomya albiceps, Hemilucilia semidiaphana and Ophyra aenescens were the main species involved in tissue consumption and acceleration of the decomposition process. Due to the presence of ants Cheliomyrmex sp., Camponotus sp. and Dinoponera sp., and coleopterans Hister sp., Acylophorus sp. and Philonthus spp., it was not possible to obtain sufficient Diptera egg masses for rearing the colonizing species. These results can be used as a standard to determine the postmortem interval in criminal investigations in the rural area of the Andean Amazon, Caquetá, Colombia.