The Irano-Turanian floristic region spans a topographically complex and climatically continental territory, which has served as a source of xerophytic taxa for neighboring regions and is represented ...by a high percent of endemics. Yet, a comprehensive picture of the abiotic and biotic factors that have driven diversification within this biota remains to be established due to the scarcity of phylogenetic studies.
is an important component of the subalpine steppe flora of the Irano-Turanian region, containing c. 200 cushion-forming sub-shrubby pungent-leaved species. Our recent molecular phylogenetic study has led to enlarging the circumscription of this genus to include eight mono- or oligospecific genera lacking the characteristic life-form and leaves. Using the same molecular phylogeny, here we investigate the tempo and mode of diversification as well as the biogeographic patterns in this genus, to test the hypothesis that a combination of key morphological innovations and abiotic factors is behind
high species diversity. Molecular dating analysis indicates that
s.l. started to diversify between the Late Miocene and the Pliocene and the biogeographic analysis points to an Eastern Iran-Afghanistan origin. Macroevolutionary models support the hypothesis that the high diversity of the genus is explained by accelerated diversification rates in two clades associated with the appearance of morphological key innovations such as a cushion life-form and pungent leaves; this would have favored the colonization of water-stressed, substrate-poor mountainous habitats along the newly uplifted IT mountains during the Mio-Pliocene. Given the apparent similarity of mountain habitats for most species of
, we hypothesize that its current high species diversity responds to a scenario of non-adaptive radiation fueled by allopatric speciation rather than evolutionary radiation driven by ecological opportunity. Similar scenarios might underlie the high diversity of other speciose genera in the topographically complex Irano-Turanian landscape, though this remains to be tested with fine-grained distribution and climatic data.
The 196 parties to the Convention on Biological Diversity (CBD) will soon agree to a post-2020 global framework for conserving the three elements of biodiversity (genetic, species, and ecosystem ...diversity) while ensuring sustainable development and benefit sharing. As the most significant global conservation policy mechanism, the new CBD framework has far-reaching consequences- it will guide conservation actions and reporting for each member country until 2050. In previous CBD strategies, as well as other major conservation policy mechanisms, targets and indicators for genetic diversity (variation at the DNA level within species, which facilitates species adaptation and ecosystem function) were undeveloped and focused on species of agricultural relevance. We assert that, to meet global conservation goals, genetic diversity within all species, not just domesticated species and their wild relatives, must be conserved and monitored using appropriate metrics. Building on suggestions in a recent Letter in Science (Laikre et al., 2020) we expand argumentation for three new, pragmatic genetic indicators and modifications to two current indicators for maintaining genetic diversity and adaptive capacity of all species, and provide guidance on their practical use. The indicators are: 1) the number of populations with effective population size above versus below 500, 2) the proportion of populations maintained within species, 3) the number of species and populations in which genetic diversity is monitored using DNA-based methods. We also present and discuss Goals and Action Targets for post-2020 biodiversity conservation which are connected to these indicators and underlying data. These pragmatic indicators and goals have utility beyond the CBD; they should benefit conservation and monitoring of genetic diversity via national and global policy for decades to come.
Cheilostomata is the most diverse and ecologically dominant order of bryozoans living today. We apply a Bayesian framework to estimate macroevolutionary rates of cheilostomes since the Late Jurassic ...across four datasets: (I) manually curated genus ranges; (II) published text‐mined genus ranges; (III) non‐revised Paleobiology Database (PBDB) records; (IV) revised and augmented PBDB records. All datasets revealed increased origination rates in the Albian, and a twin K–Pg and Danian extinction rate peak. High origination rates in the Late Selandian–Ypresian in Dataset I indicate the onset of an ascophoran‐grade radiation. Lineage‐through‐time plots confirm the macroevolutionary lag preceding the radiation of cheilostomes in the middle Cretaceous, and their renewed diversification in the late Paleocene and Eocene. A multivariate birth–death model indicates that origination rates are shaped by diversity‐dependent dynamics coupled with a positive correlation with sea surface temperature, while extinction rates negatively correlate with sea level. Text‐mined data provide broadly similar rate dynamics as manually curated data, although discrepancies could be attributed to the omission of key literature in Dataset II, and the inclusion of new published and unpublished data, and revised ranges in Dataset I. Revision and augmentation of PBDB occurrences were necessary to generate rate profiles akin to those of Datasets I and II and highlight the risks of using unedited occurrence data. Our results support the widely held assumption that diversification dynamics are controlled by both biotic and abiotic factors, and pave the way for integrating fossils with molecular phylogenies to study these processes in more detail.
Besides being one of the most popular ornamental bulbs in western horticulture, the Mediterranean genus Narcissus has been the subject of numerous studies focusing on a wide scope of topics, ...including cytogenetics, hybridization and the evolution of polymorphic sexual systems. Phylogenetic hypotheses based on chloroplast data have provided a backbone for the genus but a detailed phylogenetic framework is still lacking. To fill this gap, we present a phylogenetic study of the genus using five markers from three genomes: ndhF and matK (chloroplast DNA), cob and atpA (mitochondrial DNA), and ITS (nuclear ribosomal DNA). In addition, we use chromosome counts from 89 populations representing 69 taxa. All analyses confirm that Narcissus is monophyletic with two main lineages largely corresponding to subg. Hermione and subg. Narcissus, but with incongruences between organellar and nuclear ribosomal phylogenies. At the infrageneric levels, our phylogenetic results challenge well-established taxonomic groups, such as sect. Jonquillae, sect. Bulbocodii and sect. Pseudonarcissi, each of which contains at least two distinct lineages that do not constitute monophyletic groups, and highlight the influence of allopolyploid species in the monophyly of sections within subg. Hermione. The type of the genus and its section is also nested within sect. Pseudonarcissi supporting new nomenclatural changes. Our results also confirm the intersubgeneric hybrid nature of several hybrids including allopolyploids (e.g., N. dubius, N. tortifolius, N. miniatus). Morphological and cytogenetic evidence independently support the hypothesis that some of the incongruence can be attributed to hybridization, such as the splits of sect. Bulbocodii and sect. Pseudonarcissi or the disparate phylogenetic placements of sect. Aurelia and sect. Ganymedes. Together, this indicates a significant role for reticulate evolution in shaping the diversity of this genus. A Bayesian divergence time analysis suggests that the major diversification events took place during the Neogene and provides younger estimates for the main nodes than previous studies, which fit paleoclimatic and paleotectonic reconstructions of the western Mediterranean during this period.
The Irano-Turanian (IT) floristic region in Asia contains three biodiversity hotspots and has been a source of xerophytic taxa for neighboring regions. Despite its species richness and large ...territory, the evolutionary history and biogeography of this floristic region is poorly understood. Acanthophyllum, encompassing ca. 70 subshrubby mostly thorny-cushion species, is one of the important components of the steppe and mountain vegetation of this region. In this study, we investigate the tempo and mode of diversification as well as the biogeographic patterns of this genus. The ancestral area analysis suggests that Acanthophyllum originated east of the Zagros Mountains in the Miocene, from where it expanded westwards. A shift in the speciation rate in the late Pliocene (ca. 3.24 Ma) was detected, based on a nrDNA ITS tree, affecting the lineage of the largest section in the genus, Acanthophyllym sect. Oligosperma. Parallelisms with another IT species-rich genera in aspects such as largely coincident ranges and habitats, presence of a thorny-cushion life-form, similar areas reconstructed for their MRCA, and the inference of a shift in speciation in the region suggest common underlying abiotic and biotic factors or even drivers for diversification and speciation in the high elevation dry continental landscape of IT region.
Abstract
Acantholimon is an important component of the subalpine steppe flora in the Irano-Turanian region and the second largest genus of Plumbaginaceae with c. 200 cushion-forming subshrubby ...species. Because the genus has been poorly represented in previous phylogenetic studies, questions regarding its monophyly, phylogenetic relationships and infrageneric classification have not been addressed in a solid evolutionary framework. We used sequences from the nuclear ribosomal internal transcribed spacers and the plastid trnY
(GUA)–trnT
(GGU) intergenic spacer for 197 accessions of Acantholimon and nine putatively closely related Asian genera in Limonioideae. Contrary to previous results, Bayesian, maximum likelihood and maximum parsimony analyses show that Acantholimon is not monophyletic unless its limits are extended to include species currently placed in eight of these Asian genera. As circumscribed, the new Acantholimon s.l. is sister to Goniolimon and includes the following genera: Bamiania, Bukiniczia, Chaetolimon, Cephalorhizum, Dictyolimon, Gladiolimon, Popoviolimon and Vassilczenkoa. Our phylogenetic analyses also challenge the existing classification at the generic and infrageneric levels. A maximum likelihood reconstruction of ancestral states for morphological characters illustrates the possible scenarios by which the cushion architecture combined with linear acuminate leaves, also present in other steppic Irano-Turanian elements, were acquired in this group of Plumbaginaceae. Our study shows the importance of extensive taxon sampling for phylogenetic reconstruction of species-rich lineages.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
To perform a comparative epigenomic analysis of DNA methylation in spermatozoa from humans, mice, rats and mini-pigs.
Genome-wide DNA methylation analysis was used to compare the methylation profiles ...of orthologous CpG sites. Transcription profiles of early embryo development were analyzed to provide insight into the association between sperm methylation and gene expression programming.
We identified DNA methylation variation near genes related to the central nervous system and signal transduction. Gene expression dynamics at different time points of preimplantation stages were modestly associated with spermatozoal DNA methylation at the nearest promoters.
Conserved genomic regions subject to epigenetic variation across different species were associated with specific organ functions, suggesting their potential contribution to organ speciation and long-term adaptation to the environment.
PDF
