Highly divergent karyotypes and barcoding of the East African genus Gonatoxia Karsch (Orthoptera: Phaneropterinae)

East Africa is a hotspot of biodiversity of many orthopteran taxa, including bushcrickets. Gonatoxia Karsch, 1889 species are fully alate Phaneropterinae, which are perfectly adapted to the foliage of forests. We examined five species using combined cytogenetic and molecular data to determine the inter- and intraspecific genetic diversity. The variation in the diploid number of chromosomes in males ranged from 2n = 28 + X0 and 26 + X0 to 2n = 6 + X0. Fluorescence in situ hybridization showed from one to many 18S rDNA loci as well as interstitial sequences, especially in G. helleri. 18S rDNA loci coincided with active NOR and C-banding patterns. The isolation of populations of the species explains differences in the number of chromosomes (G. maculata), chromosomal polymorphism and chromosomal heterozygosity (G. helleri). Our molecular phylogeny based on the COI locus supported the monophyly of the genus Gonatoxia and separateness of the five examined species in accordance with their morphological features and chromosome numbers as well as the species’ distribution.

Intraspecific Genetic Diversity of Cistus creticus L. and Evolutionary Relationships to Cistus albidus L. (Cistaceae): Meeting of the Generations?

Cistus (Cistaceae) comprises a number of white- and purple-flowering shrub species widely distributed in the Mediterranean basin. Within genus Cistus, many taxa are subject to various taxonomic uncertainties. Cistus creticus, a prominent member of the purple-flowered clade, is a prime case of the current taxonomic troubles. Floras and databases approve different species names and utilise different or additional/fewer synonyms. Various intraspecific classification systems based on subspecies or varieties are in use. The inconsistent determination of plant material makes it difficult to compare literature regarding the phytochemical diversity and biological activities of plant material and impedes a systematic utilization of the manifold medicinal properties of C. creticus. In the present investigation, we used DNA sequence data from one nuclear region (ITS) and two chloroplast regions (trnL-trnF, rpl32-trnL) to test the intraspecific genetic diversity of C. creticus and its evolutionary relationships to the closely related C. albidus. The combined DNA data confirmed C. creticus as a rather heterogeneous species that integrates two major evolutionary lineages with clearly different genetic characteristics. The ‘Eastern Mediterranean clade’ seems to represent old and ancestral characteristics. This lineage exhibits a close relationship to the geographically distant C. albidus, expressed by very closely related ribotypes and an interspecifically shared chlorotype. The ‘Western Mediterranean clade’ is characterized by a distinctive ITS polymorphism (co-occurring paralogous ribotypes) and more distantly related chlorotypes. The formation of the genetically complex ‘Western Mediterranean clade’ seems to have involved hybridization and recurrent formation or migration movements.

DNA barcoding-based assessment of the invasive and native non-crustose Codium species in the central Cantabrian Sea, southern Bay of Biscay

In this work, we identified non-crustose invasive (Codium fragile subsp. fragile) and native Codium spp. (Codium tomentosum and Codium vermilara) in the central Cantabrian Sea using DNA barcoding (tufA and rbcL genes). We designed a new FCOtufA genetic marker for identifying Codium spp. in fresh and herbarium material. The tufA and rbcL sequences revealed three different single haplotypes for each of the species and a lack of intraspecific genetic diversity. The FCOtufA genetic marker revealed one new haplotype of C. fragile within the native region (South Korea), suggesting the possibility of higher genetic diversity in the donor region of this invasive species.

Can metabarcoding resolve intraspecific genetic diversity changes to environmental stressors? A test case using river macrozoobenthos

Genetic diversity is the most basal level of biodiversity and determines the evolutionary capacity of species to adapt to changing environments, yet it is typically neglected in routine biomonitoring and stressor impact assessment. For a comprehensive analysis of stressor impacts on genetic diversity, it is necessary to assess genetic variants simultaneously in many individuals and species. Such an assessment is not as straightforward and usually limited to one or few focal species. However, nowadays species diversity can be assessed by analysing thousands of individuals of a community simultaneously with DNA metabarcoding. Recent bioinformatic advances also allow for the extraction of exact sequence variants (ESVs or haplotypes) in addition to Operational Taxonomic Units (OTUs). By using this new capability, we here evaluated if the analysis of intraspecific mitochondrial diversity in addition to species diversity can provide insights into responses of stream macrozoobenthic communities to environmental stressors. For this purpose, we analysed macroinvertebrate bulk samples of three German river systems with different stressor levels using DNA metabarcoding. While OTU and haplotype number were negatively correlated with stressor impact, this association was not as clear when studying haplotype diversity across all taxa. However, stressor responses were found for sensitive EPT (Ephemeroptera, Plecoptera, Trichoptera) taxa and those exceedingly resistant to organic stress. An increase in haplotype number per OTU and haplotype diversity of sensitive taxa was observed with an increase in ecosystem quality and stability, while the opposite pattern was detected for pollution resistant taxa. However, this pattern was less prominent than expected based on the strong differences in stressor intensity between sites. To compare genetic diversity among communities in river systems, we focussed on OTUs, which were present in all systems. As OTU composition differed strongly between rivers, this led to the exclusion of a high number of OTUs, especially in diverse river systems of good quality, which potentially diminished the increase in intraspecific diversity. To better understand responses of intraspecific genetic diversity to environmental stressors, for example in river ecosystems, it would be important to increase OTU overlap between compared sites, e.g. by sampling a narrower stressor gradient, and to perform calibrated studies controlling for the number of individuals and their haplotypes. However, this pioneer study shows that the extraction of haplotypes from DNA metabarcoding datasets is a promising source of information to simultaneously assess intraspecific diversity changes in response to environmental impacts for a metacommunity.