The Brachionus plicatilis complex represents the most studied group of rotifers, although the systematics of the species complex has not been completely clarified. Many studies have been conducted trying to explore the diversity within the complex, leading to the recognition of three major morphotypes: large (L), small-medium (SM), and small (SS). Currently six species have been described and classified under these types and another nine taxa have been identified but not formally described. Within the L group, three species have been officially described [B. plicatilis s.s. (L1), B. manjavacas (L2), and B. asplanchnoidis (L3)], while a formal description of L4, unofficially known as B. ‘Nevada’, is still lacking. In the present study, a new species, Brachionus paranguensissp. nov., is formally described and presented as a representative of the L4 clade. The species has been named after a high altitude saline crater lake from Central Mexico, where the specimens were collected. An integrated approach using DNA taxonomy through COI and ITS1 markers, morphology, and ecology was used to confirm the identity of the new species.
In this work we present the results of a study conducted on the benthic macroinvertebrate community of a Southern Spain seasonal stream over a year. We constructed the food web focusing on the benthic fauna and we studied the ecology and dynamics of the community in terms of trophic resources. The benthic trophic web was composed by 35 families; these were not all present at the same time, but were incorporating and disappearing throughout the study period. Connectance between trophospecies varied from 0.24 to 0.59. The functional feeding group (FFG) composition of the community turned out to be fairly constant with time with a predominance of scrapers and collector-gatherers. Furthermore, data obtained from the Bray-Curtis measure and the niche overlap study, evidence the stability of the stream from a trophic point of view. Rather widespread is omnivory that plays an important role in the survival of some families. We compared the results of the trophic web study with those of other temporary streams of the same region of Southern Spain.
Here, we analyse the annual dynamics in the diversity and the food web structure of the macroinvertebrate community in a Mediterranean permanent stream. Then, we also tested the validity of different proposed predictive models in their ability to fit our results. We calculated the Shannon-Wiener diversity index, the evenness, several food web properties and the proportion of functional feeding groups throughout the year. Our results showed a great variability of the studied parameters with time, mainly in terms of trophic relationships among macroinvertebrates. Diversity did not fluctuate substantially, but functional feeding groups did. In the same manner, complexity of the food web also varied substantially along the year. Comparisons with the considered models showed that, overall, none of the models predicted accurately the observed values. Nevertheless, within them, at least some estimated relatively realistic values, mainly when considering data monthly. From a functional point of view, collector-gatherers were the most abundant group throughout the sampling period except in autumn, when scrapers were also proportionally important. Predators were present during the entire period but with a low abundance. Thus, this study underlines the importance of considering not only static, but also dynamic data when studying food webs.
The European spruce bark beetle Ips typographus (L.) is a pest causing severe damage to Norway spruce-dominated forests in Europe. Microorganisms play an essential role in the species life history, including nutrition, fitness as well as in overcoming host defenses. Here, we performed high-throughput 16S rRNA metabarcoding of I. typographus across different populations in Europe. We investigated four postglacial refugial areas in Europe and focused specifically on a current bark beetle hot spot in the Dolomites where we compared populations with different epidemiological phases (outbreaking vs. non-outbreaking) and across different seasons (pre-overwintering vs. overwintering). Our results show that the bacterial community structure varied among populations from the refugial areas and geographic regions within the Dolomites. We found a significant difference in the bacterial community between pre-overwintering and overwintering individuals, highlighting a potential role of the microbiome in I. typographus overwintering but we did not find differences between epidemic and endemic populations. The genera Erwinia and Pseudoxanthomonas - previously reported for their role in nutrition and protection from conifer defense compounds - were present in every individual across all populations, suggesting that these taxa form the bacterial core community of I. typographus. Furthermore, several additional bacterial taxa occurred in all populations, but with variable frequencies within and between individuals. This study highlights a complex interaction of various bacterial taxa across different regions and ecological phases of I. typographus populations and provides new insights into the role of microorganisms in the biology of this important pest species.
In this paper we present the results of a study of different populations of the genus Tyrrhenoleuctra, which includes morphologically cryptic species, in the Iberian Peninsula. A total of six populations were analysed from a molecular point of view and a behavioural study was conducted on three of them. Two phylogenetic trees, maximum likelihood (ML) and neighbour joining (NJ), were constructed using both new COI sequences and COI sequences already available in GenBank. Furthermore, intra- and interspecific p-distances were calculated within and between sequences of the different populations. As regards behavioural analyses, the male call of individuals from three of the studied populations was recorded, analysed and described. Both phylogenetic approaches used, ML and NJ, were congruent in discriminating five well-defined clusters, representing the four known Iberian Tyrrhenoleuctra species and a previously unknown taxon. The sequences from the six studied populations produced in this study fell within two clades: T. lusohispanica (four populations) and the new taxon (two populations). These results were supported also by the behavioral study, in which the drumming calls of individuals belonging to the two clades differed in some important parameters such as the number of sequences, intersequence interval and interbeat interval. The obtained results expand the previously known distribution of T. lusohispanica and show the existence of a new species (Tyrrhenoleuctra hynesi sp. n.) within this genus from a more restricted area, that will be described in this paper.
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