The Evolution of Trait Disparity during the Radiation of the Plant Genus Macrocarpaea (Gentianaceae) in the Tropical Andes

The evolutionary processes responsible for the extraordinary diversity in the middle elevation montane forests of the Tropical Andes (MMF; 1000–3500 m) remain poorly understood. It is not clear whether adaptive divergence, niche conservatism or geographical processes were the main contributors to the radiation of the respective lineages occurring there. We investigated the evolutionary history of plant lineages in the MMF. We used the vascular plant genus Macrocarpaea (Gentianaceae) as a model, as it consists of 118 morphologically diverse species, a majority of which are endemic to the MMF. We used a time-calibrated molecular phylogeny and morphological and climatic data to compare a set of evolutionary scenarios of various levels of complexity in a phylogenetic comparative framework. In this paper, we show that the hypothesis of adaptive radiation for Macrocarpaea in the MMF is unlikely. The genus remained confined to the upper montane forests (UMF > 1800 m) during more than a half of its evolutionary history, possibly due to evolutionary constraints. Later, coinciding with the beginning of the Pleistocene (around 2.58 Ma), a phylogenetically derived (recently branching) clade, here referred to as the M. micrantha clade (25 species), successfully colonized and radiated in the lower montane forests (LMF < 1800 m). This colonization was accompanied by the evolution of a new leaf phenotype that is unique to the species of the M. micrantha clade that likely represents an adaptation to life in this new environment (adaptive zone). Therefore, our results suggest that niche conservatism and geographical processes have dominated most of the diversification history of Macrocarpaea, but that a rare adaptive divergence event allowed a transition into a new adaptive zone and enabled progressive radiation in this zone through geographical processes.

The preeminent role of directional selection in generating extreme morphological change in Glyptodonts (Cingulata; Xenarthra)

The prevalence of stasis on paleontological and comparative data has been classically taken as evidence of the strong role of stabilizing selection in shaping morphological evolution. When confronted against biologically informed predictions, empirical rates of evolution tend to fall below what is expected under genetic drift, suggesting that the signal for directional selection is erased at longer time scales. However, empirical tests of these claims are few and tend to focus on univariate traits, ignoring the potential roles of trait covariances in constraining evolution. Here we investigated the multivariate rates of morphological evolution in a fossil lineage that underwent extreme morphological modification, the glyptodonts. Contrary to what was expected, biologically informed models of evolution suggest a preeminent role of directional selection on the divergence of glyptodonts from living armadillos. Furthermore, the reconstruction of selection patterns shows that traits selected to generate a glytodont morphology are markedly different from those necessary to explain the extant armadillos' morphological diversity. Changes in both direction and magnitude of selection are probably tied to the invasion of a specialist-herbivore adaptive zone by glyptodonts. These results suggest that directional selection might have played a more important role in the evolution of extreme morphologies than previously imagined.

Reaction of micromycetes of leached chernozem on the application of different forms of nitrogen fertilizers

Application of nitrogen fertilizers did not significantly affect the number of micromycetes. The restructuring of the species structure of the mycobiome did not exceed the adaptive zone of “stress” – a change in the frequency of occurrence of typical species. Typical types of leached chernozem micromycetes include deuteromycetes of the genera Aspergillus, Penicillium, Trichoderma, Gliocladium, Humicola, Fusarium, zygomycetes (genus Rhizopus), ascomycetes (genera Thalaromyces, Chaetomium). On average, the density of dominant species of micromycetes increased by 20 %, which indicates the development of the “dominance concentration” of typical species and a decrease in the share of rare and random species of fungi in the mycocomplex. In the experiment variants, the density of Penicillium daleae, P. funiculosum, Fusarium solani, and Aspergillus ustus species increased compared to control. These types of micromycetes are toxigenic and synthesize broad-spectrum mycotoxins (fungicidal, antibiotic, and phytotoxic). As a result, the phytotoxic activity of the soil increased to 7 and 20 % (native soil) and to 19-34 % (initiated microbial community). More pronounced changes were observed in the variant with ammonium sulfate. Thus, nitrogen fertilizers at a dose of N90 cause a “stress” reaction of the mycobiome, an increase in the share of toxigenic species and phytotoxic activity of leached chernozem. With long-term systematic use of nitrogen fertilizers, even in medium doses, it is possible to reduce the potential fertility of chernozems.

Intra-species DNA exchange: Bacillus subtilis prefers sex with less related strains

B. subtilis is a soil dwelling bacterium with a diverse social life that includes quorum sensing-regulated interactions 1. These interactions result in bacterial equivalent of sex, and subsequently have a profound influence on bacterial evolution2. Sexual isolation in B. subtilis predicts for more frequent uptake of DNA isolated from closely related strains3–5, but DNA exchange between two interacting B. subtilis strains has never been addressed previously. Recently we discovered kin discrimination among highly related strains of B. subtilis, where less related strains showed antagonistic behaviour towards each other in the form of killing6. Here we show that antagonistic interactions between two less closely related B. subtilis strains result in increased recombination, which is in contrast to current dogma. We demonstrate that the induction of competence between non-kin strains is responsible for the observed elevated DNA uptake, which, through increased genetic variation, can increase the rate of adaptation as demonstrated here by the successful exploitation of a novel adaptive zone by a recombinant strain. Our results demonstrate an important evolutionary mechanism of ‘’promiscuous but safe sex’’: a type of bacterial cell-contact dependent DNA exchange that could promote diversification of conspecifics and exclude non-specific and potentially risky DNA of other species. Our findings could help understand the vast diversity of B. subtilis species at the genomic level despite existing mechanisms limiting less-related DNA integration during transformation. It is possible that this (or similar) mechanism could be accountable for the diversification of many other bacterial species capable of natural transformation.

ADAPTIVE ZONE, PETERSEN-TYPE COMMUNITIES, GEOGRAPHICAL RANGE AND ECOLOGICAL NICHE. REPORT 2. APPLIED VALUE OF A NEW CONCEPT ON THE EXAMPLE OF FAUNA OF THE FAR-EASTERN SEAS AND NORTH PACIFIC

The review started in 195 volume of «Izvestiya TINRO» is continued. The most important aspects of a new concept of adaptive zone are illustrated on cited data and results of trawl and plankton surveys collected by Pacific Fish. Res. Center (TINRO) in the FarEastern Seas and North Pacific for several decades. Practical benefits of this concept are shown and prospects of its further application are outlined, as managing of fishery and aquaculture and some issues of agriculture, forestry, hunting, natural nidality, fighting against alien species, weeds, pests and parasites, environmental protection and preservation, and artificial ecosystems creation.