Feeding ecology of Eigenmannia desantanai (Gymnotiformes: Sternopygidae) in southern Pantanal, Brazil

Aim This study investigated changes in the dietary composition and trophic niche breadth of Eigenmannia desantanai in the context of hydrological periods, rivers, and ontogeny. Methods Collections were performed monthly on the Paraguay and Amonguijá Rivers between February 2009 and January 2011. Results A total of 338 specimens of E. desantanai were collected, 224 of which came from the Amonguijá River and 114 from the Paraguay River. In all, 21 food items were identified. Fully remains of digested animals (RDA), Chironomidae, Cladocera, and Ostracoda showed greater importance in the diet of E. desantanai. Dietary composition was influenced by hydrological periods, followed by differences between sampled rivers, and ontogeny. In contrast, only hydrological periods explained variation in the E. desantanai trophic niche breadth. Conclusions The diet of E. desantanai is mainly composed of Chironomidae, Cladocera, and Ostracoda; however, individuals consumed other food items owing to changes in hydrological periods, followed by characteristics of the Amonguijá and Paraguay Rivers and ontogenetic variation. In this respect, the results of this study are germane to the food ecology of E. desantanai, providing guidelines for the management and conservation of the species.

Large Individual-Level Variability in Diel Activity and Depth Use for the Common Lionfish (Pterois miles)

The common lionfish, Pterois miles, a notoriously invasive species known for its harmful effect on native fish communities in the Atlantic Ocean, has recently begun spreading across the Mediterranean Sea. The wide niche breadth of the lionfish has been hypothesized to facilitate its invasion success. However, it is unclear to what extent this wide niche-breadth is associated with individual-level variation and repeatable behavior over time. Large individual-level behavioral variations may allow individuals to adapt quickly to local conditions, increasing the species’ chance of invasion success and complicating mitigation efforts. In this study, we used an acoustic telemetry system in P. miles’ native Red Sea environment to explore individual-level variation in depth preference and diel activity. A wide depth range may indicate an ability to tolerate a variety of biotic and abiotic conditions, and variability in diel activity may indicate an ability to exploit multiple diet sources. We found large individual-level variability in P. miles’ activity hours; although all tracked fish were active during both sunrise and sunset, certain individuals had prolonged activity hours to variable extents. Moreover, individuals often change their patterns over time, showing low repeatability. We also found that individuals had different depth preferences and commuted between shallow and deep waters over short periods of time. This study is one of the first to explore diel activity as an individual-level trait in wild fish. The variability found in depth and diel activity is likely one of the reasons P. miles has been so successful in invading the Mediterranean Sea. In addition, this variability may impact mitigation efforts within the Mediterranean Sea as nocturnal individuals from deeper waters might replenish diurnally culled shallow-water populations.

Parasitic infection patterns in Coleodactylus meridionalis (Squamata: Sphaerodactylidae) from Atlantic Forest fragments, northeast of the Neotropical Region

Summary Studies that seek to understand which factors influence the patterns of infection in the lizard Coleodactylus meridionalis are non-existent. In this way, we recorded the infection rates for these lizards from three different sized fragments of the Atlantic rainforest and investigated if there is influence of the size, mass and sex of the host regarding the endoparasite abundance. In addition, we investigated if there were possible associations between the host’s diet and parasitism, by calculating the diet niche breadth (based on the prey number of pooled stomachs) for each host population and comparing the diet between fragments and sexes (from the three sampled fragments). We collected 38 lizards across the three sampled forest fragments. We only found parasites in the lizards sampled from the smallest of the three forest fragments which included: Physaloptera lutzi, Haplometroides odhneri and Oligacanthorhynchus sp. For this population, lizards with greater length and body mass have a greater endoparasite abundance. In addition, based on the results obtained in our study, the diet of the lizards varies in food composition between sampled populations. Finally, knowing that among the infected lizards there is no sexual dimorphism in relation to size and body mass and that the stomach sampling for this population is insufficient to calculate the indexes related to the food niche; we used the number of prey lizards from all populations, thus we were able to associate the fact that female lizards have a greater endoparasite abundance due to variations in food composition between sexes.

Mono-specific algal diets shape microbial networking in the gut of the sea urchin Tripneustes gratilla elatensis

Background Algivorous sea urchins can obtain energy from a diet of a single algal species, which may result in consequent changes in their gut microbe assemblies and association networks. Methods To ascertain whether such changes are led by specific microbes or limited to a specific region in the gut, we compared the microbial assembly in the three major gut regions of the sea urchin Tripneustes gratilla elatensis when fed a mono-specific algal diet of either Ulva fasciata or Gracilaria conferta, or an algal-free diet. DNA extracts from 5 to 7 individuals from each diet treatment were used for Illumina MiSeq based 16S rRNA gene sequencing (V3–V4 region). Niche breadth of each microbe in the assembly was calculated for identification of core, generalist, specialist, or unique microbes. Network analyzers were used to measure the connectivity of the entire assembly and of each of the microbes within it and whether it altered with a given diet or gut region. Lastly, the predicted metabolic functions of key microbes in the gut were analyzed to evaluate their potential contribution to decomposition of dietary algal polysaccharides. Results Sea urchins fed with U. fasciata grew faster and their gut microbiome network was rich in bacterial associations (edges) and networking clusters. Bacteroidetes was the keystone microbe phylum in the gut, with core, generalist, and specialist representatives. A few microbes of this phylum were central hub nodes that maintained community connectivity, while others were driver microbes that led the rewiring of the assembly network based on diet type through changes in their associations and centrality. Niche breadth agreed with microbes' richness in genes for carbohydrate active enzymes and correlated Bacteroidetes specialists to decomposition of specific polysaccharides in the algal diets. Conclusions The dense and well-connected microbial network in the gut of Ulva-fed sea urchins, together with animal's rapid growth, may suggest that this alga was most nutritious among the experimental diets. Our findings expand the knowledge on the gut microbial assembly in T. gratilla elatensis and strengthen the correlation between microbes’ generalism or specialism in terms of occurrence in different niches and their metabolic arsenal which may aid host nutrition.

Macroevolutionary pattern of Saussurea (Asteraceae) provides insights into the drivers of radiating diversification

Evolutionary radiations have intrigued biologists for more than a century, yet our understanding of the drivers of radiating diversification is still limited. We investigate the roles of environmental and species-intrinsic factors in driving the rapid radiation of Saussurea (Asteraceae) by deploying a number of palaeoenvironment-, diversity- and trait-dependent models, as well as ecological distribution data. We show that three main clades of Saussurea began to diversify in the Miocene almost simultaneously, with increasing diversification rates (DRs) negatively dependent on palaeotemperature but not dependent on species diversity. Our trait-dependent models detect some adaptive morphological innovations associated with DR shifts, while indicating additional unobserved traits are also likely driving diversification. Accounting for ecological niche data, we further reveal that accelerations in DRs are correlated with niche breadth and the size of species' range. Our results point out a macroevolutionary scenario where both adaptive morphological evolution and ecological opportunities provided by palaeoenvironmental fluctuations triggered an exceptionally radiating diversification. Our study highlights the importance of integrating phylogenomic, morphological, ecological and model-based approaches to illustrate evolutionary dynamics of lineages in biodiversity hotspots.

Dietary niche breadth of endemic and introduced anurans (Amphibia: Anura) in Lombok, Lesser Sunda Islands– Indonesia

Anurans are important organisms as components of faunal community structure in ecosystems because of their roles as secondary and tertiary consumers in food webs. Anurans are opportunistic organisms that will consume any resources in their habitat. In this study, we dissected thirty-nine specimens of anurans from Museum Universitas Mataram (MUM) reference collection, it consists by three endemic (Ingerophrynus biporcatus, Limnonectes dammarmani and L. kadarsani) and one introduced species (Duttaphrynus melanostictus) of anurans. These reference collections were collected by authors during herpetofauna survey at Pusuk Forest, western Lombok in 2018. Based on stomach content analysis, both endemic and introduced anurans are generalist arthropod predators where hymenoptera, coleoptera, orthoptera and chilopoda are the most important food. In this study, we found positive correlations between body size and dietary niche breadth in which each anuran species has a high overlap of dietary niches. Anurans with large body size have a variety of prey than the small one.

Media Ecology: The Competition of Local Private Television on Seizing Audiences for Broadcasting Sustainability in South Kalimantan, Indonesia

Media ecology examined the interrelationships between the media and their supporting environment. This research article aimed to determine the category of life-support sources (niche breadth) and to measure the level of competition (niche overlap) of local private television in South Kalimantan in seizing for viewers. This research used a quantitative approach. Target audience data, as the main data, was obtained by data collection techniques in the form of a log book survey results or management estimates from each television. The collected data was processed using the niche breadth formula to determine the category of each television media, and the niche overlap formula to determine the level of television competition in seizing for its viewers. The findings showed that Duta TV was in the generalist category and Prima TV was in the specialist category. The niche overlap scores differed between a number of target audience types, where the level of competition in seizing for viewers between the two televisions was quite high in the gender category compared to the other four types of target audiences, namely age group, socioeconomic status, recent education, and occupation.