Phase Of Diversification Research Articles

Benthic pterobranchs from the Cambrian (Drumian) Marjum Konservat‐Lagerstätte of Utah

AbstractPterobranchs are rare in Cambrian strata of North America despite discoveries of more than 30 exceptionally preserved fossil biotas. Miaolingian pterobranchs from this continent typically form low‐diversity and low‐abundance assemblages. Here we describe an abundant pterobranch material from the Drumian Marjum Formation recently collected at the Gray Marjum Quarry in the House Range of Utah, USA. The faunule is composed of two new species: Sphenoecium marjumensis, an encrusting representative forming compact bushy colonies of more than 80 tubes with poorly developed rhizomes, and Tarnagraptus cupidus, an erect growing taxon characterized by intertwining stems and a monopodial colonial growth. Known in extant rhabdopleurids, this mode of colonial growth had hitherto never been observed in fossil pterobranchs. Its documentation in a c. 500‐myr‐old taxon attests to its deep origin in the evolutionary history of the group. Although the new species almost exclusively occur in the Marjum strata, this pterobranch faunule is broadly similar to those recovered from other Miaolingian Burgess Shale‐type deposits of North America in terms of genus‐level composition, species richness, and ecological structure. This may indicate that pterobranchs were poorly diverse components of animal communities at that time, or that they mostly thrived in more proximal shelf environments where conditions conducive to their preservation rarely developed. The common co‐occurrence of taxa with fundamentally different ecomorphotypes in the Miaolingian Series of North America strongly suggests an earlier phase of morphological diversification of benthic pterobranchs during the early Cambrian, which remains insufficiently documented by fossils.

Developmental biology of Spiralicellula and the Ediacaran origin of crown metazoans.

The early Ediacaran Weng'an biota (Doushantuo Formation, South China) provides a rare window onto the period of Earth history in which molecular timescales have inferred the initial phase of crown-metazoan diversification. Interpretation of the embryo-like fossils that dominate the biota remains contentious because they are morphologically simple and so difficult to constrain phylogenetically. Spiralicellula from the Weng'an biota is distinguished by spiral internal bodies, allied through development to Megasphaera or Helicoforamina and interpreted variously as metazoan embryos, encysting protists, or chlorophycean green algae. Here we show, using X-ray microtomography, that Spiralicellula has a single-layered outer envelope and no more than 32 internal cells, often preserving a nucleus and yolk granules. There is no correlation between the extent of spiral development and the number of component cells; rather, the spiral developed with each palintomic stage, associated with cell disaggregation and reorientation. Evidence for envelope thinning and cell loss was observed in all developmental stages, reflecting non-deterministic shedding of gametes or amoebae. The developmental biology of Spiralicellula is similar to Megasphaera and Helicoforamina, which otherwise exhibit more rounds of palintomy. We reject a crown-metazoan affinity for Spiralicellula and all other components of the Weng'an biota, diminishing the probability of crown-metazoan diversification before the early Ediacaran.

Multiple and diversified transposon lineages contribute to early and recent bivalve genome evolution

BackgroundTransposable elements (TEs) can represent one of the major sources of genomic variation across eukaryotes, providing novel raw materials for species diversification and innovation. While considerable effort has been made to study their evolutionary dynamics across multiple animal clades, molluscs represent a substantially understudied phylum. Here, we take advantage of the recent increase in mollusc genomic resources and adopt an automated TE annotation pipeline combined with a phylogenetic tree-based classification, as well as extensive manual curation efforts, to characterize TE repertories across 27 bivalve genomes with a particular emphasis on DDE/D class II elements, long interspersed nuclear elements (LINEs), and their evolutionary dynamics.ResultsWe found class I elements as highly dominant in bivalve genomes, with LINE elements, despite less represented in terms of copy number per genome, being the most common retroposon group covering up to 10% of their genome. We mined 86,488 reverse transcriptases (RVT) containing LINE coming from 12 clades distributed across all known superfamilies and 14,275 class II DDE/D-containing transposons coming from 16 distinct superfamilies. We uncovered a previously underestimated rich and diverse bivalve ancestral transposon complement that could be traced back to their most recent common ancestor that lived ~ 500 Mya. Moreover, we identified multiple instances of lineage-specific emergence and loss of different LINEs and DDE/D lineages with the interesting cases of CR1- Zenon, Proto2, RTE-X, and Academ elements that underwent a bivalve-specific amplification likely associated with their diversification. Finally, we found that this LINE diversity is maintained in extant species by an equally diverse set of long-living and potentially active elements, as suggested by their evolutionary history and transcription profiles in both male and female gonads.ConclusionsWe found that bivalves host an exceptional diversity of transposons compared to other molluscs. Their LINE complement could mainly follow a “stealth drivers” model of evolution where multiple and diversified families are able to survive and co-exist for a long period of time in the host genome, potentially shaping both recent and early phases of bivalve genome evolution and diversification. Overall, we provide not only the first comparative study of TE evolutionary dynamics in a large but understudied phylum such as Mollusca, but also a reference library for ORF-containing class II DDE/D and LINE elements, which represents an important genomic resource for their identification and characterization in novel genomes.

Evolution of family Arecaceae on the Indian Plate modulated by the Early Palaeogene climate and tectonics

Arecaceae (palms) is a pantropical plant family with an ancient origin. It shows distinct spatial patterns of species richness in tropical regions having greatest diversity within the Neotropical regions and Southeast Asia. The wider palaeobiogeographic records of palms in relation to current distribution requires a re–examination of their palaeobiogeographic history. The present study reports eleven fossil pollen form–species from the early Palaeogene of India, enhancing our understanding of the evolution of four palm subfamilies: Arecoideae, Calamoideae, Coryphoideae and Nypoideae, on the Indian Plate prior to the India–Asia collision. We suggest the dispersal of diverse palms from Africa to India via the Kohistan– Ladakh Island Arc during Maastrichtian–Palaeocene as part of the Africa–India Floristic Interchange. Subsequently, with wet and humid climates across much of the Indian Plate during the Palaeocene–early Eocene, they underwent a phase of diversification and adaptation leading to habitat expansion. Thus, Indian Plate served as an evolutionary hotspot for the diversification of palms during the early Palaeogene. An in–depth investigation of Palaeogene palm fossils revealed that many palms, currently endemic to Southeast Asia, initially evolved and diversified on the Indian Plate and later dispersed to Southeast Asia following India–Asia collision. The present study thus favours the “Out–of–India” dispersal hypothesis for the Asian palms. The expansion of seasonal climates, and aridification during Neogene and Quaternary led extinction in numerous palm lineages on the Indian subcontinent. This study proposes that deep time climate change and plate tectonism have highly influenced the heterogeneity in spatial and temporal distribution of Asian palms.

Paleogene Ficus leaves from India and their implications for fig evolution and diversification.

Ficus is a scientifically and economically important genus with abundant fossil records from the Paleocene to Pleistocene, but with an intriguing early evolutionary history that remains unresolved. Here, the foliage of three well-preserved figs is described from the early Paleogene succession of the Gurha mine, Rajasthan, India. These fossils provide new morphological data that strengthens our understanding of the past occurrences of Ficus and, alongside all validly published records of fossil figs, helps to trace the evolutionary history of figs. Fossils were identified and described by comparison with their closest modern analogs using the Nearest Living Relative (NLR) technique. Validated fig records are listed and categorized into six geological time frames. Modern precipitation data for the current distributions of NLRs were downloaded from the Climatic Research Unit Timeseries. Fossil leaves assigned to three new species Ficus paleodicranostyla, F. paleovariegata, and F. paleoauriculata closely resemble their modern analogs based on leaf morphology. Reliable fossil records were used to hypothesize historical fig distributions and paleodispersal pathways. Precipitation data suggest higher precipitations at the fossil locality during the early Paleogene than at present. The fossils described herein supplement fig fossil records known from other regions indicating that figs were widely diverse across low latitudes by the early Paleogene. These data support a Eurasian origin for figs, highlight a pivotal role for the Indian subcontinent during the early phase of fig diversification, and depict a perhumid-to-humid climate with high rainfall concordant with paleoclimate evidence from the Gurha mine.

Quantitative Insights into the Contribution of Nematocysts to the Adaptive Success of Cnidarians Based on Proteomic Analysis

Simple SummaryCnidarians (such as corals, anemones, jellyfish) are ancient and successful animals. Previous studies have offered a variety of explanations for the adaptive success of certain cnidarian taxa. However, common strategies for the long-term persistence of cnidarians have not been identified. One factor that may contribute to their evolutionary success of the lineage is the nematocyst, a sting organelle able to deliver venom into prey or enemies. Using bioinformatics analyses, we aimed to quantitatively investigate the role of nematocysts in cnidarian adaptation. We identified the extensive species-specific adaptation in nematocyst proteins (NEMs) and demonstrate that both a unique evolutionary pattern of NEMs and the long evolutionary lag between nematocysts and cnidarians support their key adaptive role. Further, we find NEMs experience approximately 50% more adaptive changes on average compared to non-NEMs, and positively selected cnidarian-conserved proteins are enriched in NEMs. These results support a key role of nematocysts in successful cnidarian adaptation and provide a general quantitative framework for assessing the role of a phenotypic novelty in adaptation. Moreover, the findings will be critical for reassessing the evolutionary history of many established models, enhancing our understanding of both the mechanisms and evolutionary preference of adaptive evolution.Nematocysts are secretory organelles in cnidarians that play important roles in predation, defense, locomotion, and host invasion. However, the extent to which nematocysts contribute to adaptation and the mechanisms underlying nematocyst evolution are unclear. Here, we investigated the role of the nematocyst in cnidarian evolution based on eight nematocyst proteomes and 110 cnidarian transcriptomes/genomes. We detected extensive species-specific adaptive mutations in nematocyst proteins (NEMs) and evidence for decentralized evolution, in which most evolutionary events involved non-core NEMs, reflecting the rapid diversification of NEMs in cnidarians. Moreover, there was a 33–55 million year macroevolutionary lag between nematocyst evolution and the main phases of cnidarian diversification, suggesting that the nematocyst can act as a driving force in evolution. Quantitative analysis revealed an excess of adaptive changes in NEMs and enrichment for positively selected conserved NEMs. Together, these findings suggest that nematocysts may be key to the adaptive success of cnidarians and provide a reference for quantitative analyses of the roles of phenotypic novelties in adaptation.

Nitrogen isotope evidence for stratified ocean redox structure during late Ediacaran to Cambrian Age 3 in the Yangtze Block of South China

The Ediacaran–Cambrian (E–C) transition witnessed profound biological and oceanic changes, among which the appearance of explosive radiation of skeletonized animals is considered as the most remarkable one. Although the prominent rise of oxygen concentration in atmosphere and ocean is considered to be the major trigger of the “Cambrian Explosion”, the links between the oxygenated process of deep ocean and the diversification of Cambrian metazoans are still under debate. In this study, δ15N and δ13Corg values, TOC and TN contents, as well as trace elements concentrations of fresh shale core samples were analyzed to explore the redox condition and nitrogen cycle of deep oceans and their relationships with biological evolution. The Mo concentrations, Mo–U covariations and Th/U ratios of our samples indicate suboxic/anoxic waters in the mid-depth ocean during the late Ediacaran to Cambrian Fortunian age, widespread anoxic/euxinic waters with temporary sulfidic waters during Cambrian Age 2 to early Age 3, and suboxic waters again during the middle to late Age 3. The positive δ15N values from late Ediacaran to Cambrian Age 2 indicate a large NO3− reservoir with a deep chemocline. In contrast, the low δ15N values (<0‰) in the deepwater slope regions suggest a dominant biological N2-fixation, and/or partial NH4+-assimilation in the photic zone during Cambrian Age 3. Integrated δ15N values of this study and early publications suggest a continuous redox stratified paleo-ocean with anoxic/suboxic deep waters from late Ediacaran to Cambrian Age 3. It is also worthy to note that although the deep ocean may not experience substantial oxygenation during the main phase of Cambrian diversification, the expanding oxic surface waters and supply of bioavailable fixed nitrogen may satisfy complex high O2-demanding animals, and thus at least have promoted the Cambrian biodiversity in shallow waters.

Mercury anomalies across the Ediacaran–Cambrian boundary: Evidence for a causal link between continental erosion and biological evolution

Significant perturbations in ocean redox states have been thought to be one of the major causes for the biological evolution from the Ediacara biota to the Cambrian fauna. However, the driving force of these changes in the ecosystem across the Ediacaran–Cambrian (E–C) boundary is still a matter of debate. In this study, we reported stratigraphic variations of Hg content and Hg isotopes in E–C sediments from the Mussoorie section, Lesser Himalaya, India. Dolomites from the late Ediacaran Krol D and E members have increasing Hg/Al ratios and decreasing Δ199Hg values from the base upwards, which were most likely originated from a prolonged and enormous terrestrial-Hg input into the E–C ocean. The overlying cherty phosphorites in the lowest Tal Group are highly rich in Re relative to Mo, indicative of a suboxic-anoxic depositional environment on the earliest Cambrian shelf that was coincident with the disappearance of the Ediacara biota. Such an O2-deficient condition was possibly led by a consumption of atmospheric O2 during the oxidative weathering of sedimentary organic matter and shallow-water eutrophication, with evidence from the coupled δ202Hg and δ13C values in late-Ediacaran dolomites and high Cd/TOC and Zn/TOC ratios in early Cambrian phosphorites. The overlying black shales have decreasing contents of Hg and micronutrients (Cd and Zn) and increasing values of Δ199Hg, representing notable declines of terrestrial flux and seawater nutrient at the Cambrian Stage 2 before the major phase of Cambrian diversification. Therefore, we conclude that enhanced continental erosion and pervasive upwelling had led to major changes in redox state and nutrient content in shallow seawaters on shelves, which in turn had promoted the biological evolution across the E–C boundary.

Evolution, inactivation and loss of short wavelength-sensitive opsin genes during the diversification of Neotropical cichlids.

Natural variation in the number, expression and function of sensory genes in an organism's genome is often tightly linked to different ecological and evolutionary forces. Opsin genes, which code for the first step in visual transduction, are ideal models for testing how ecological factors such as light environment may influence visual system adaptation. Neotropical cichlid fishes are a highly ecologically diverse group that evolved in a variety of aquatic habitats, including black (stained), white (opaque) and clear waters. We used cross-species exon capture to sequence Neotropical cichlid short wavelength-sensitive (SWS) opsins, which mediate ultraviolet (UV) to blue visual sensitivity. Neotropical cichlid SWS1 opsin (UV-sensitive) underwent a relaxation of selective constraint during the early phases of cichlid diversification in South America, leading to pseudogenization and loss. Conversely, SWS2a (blue-sensitive) experienced a burst of episodic positive selection at the base of the South American cichlid radiation. This burst coincides with SWS1 relaxation and loss, and is consistent with findings in ecomorphological studies characterizing a period of extensive ecological divergence in Neotropical cichlids. We use ancestral sequence reconstruction and protein modelling to investigate mutations along this ancestral branch that probably modified SWS2a function. Together, our results suggest that variable light environments played a prominent early role in shaping SWS opsin diversity during the Neotropical cichlid radiation. Our results also illustrate that long-term evolution under light-limited conditions in South America may have reduced visual system plasticity; specifically, early losses of UV sensitivity may have constrained the evolutionary trajectory of Neotropical cichlid vision.

Remarkable multicuspid teeth in a new elusive skate (Chondrichthyes, Rajiformes) from the Mediterranean Pliocene

Here we report on four highly peculiar skate teeth from Arcille and Certaldo, two Pliocene localities of Tuscany (central Italy). While being attributable to Rajiformes and somewhat reminiscent of Dipturus and Rostroraja, these specimens display an unusual multicuspid tooth design that does not match any extinct or extant skate taxon known to date. The studied teeth are thus referred to a new genus and species of Rajiformes, Nebriimimus wardi gen. et sp. nov., which is here tentatively assigned to the family Rajidae. Based on pronounced morphological similarities between the rather large-sized teeth of the latter and those of extant nurse sharks, we hypothesise that N. wardi might have been capable of actively foraging upon relatively large food items compared to other rays. This extinct skate species was likely not a common component of the Pliocene Tuscan marine vertebrate assemblages. The palaeoenvironmental scenarios that N. wardi inhabited were marginal-marine and open shelf settings characterised by tropical climate conditions. As N. wardi is currently known only from lower to mid-Pliocene deposits of the Mediterranean Basin, it is tempting to speculate that its speciation dates back to an earliest Pliocene phase of diversification that also contributed to the emergence of the Mediterranean endemic stock of extant skate species.

Phylogenomics and the Genetic Architecture of the Placental Mammal Radiation.

The genomes of placental mammals are being sequenced at an unprecedented rate. Alignments of hundreds, and one day thousands, of genomes spanning the rich living and extinct diversity of species offer unparalleled power to resolve phylogenetic controversies, identify genomic innovations of adaptation, and dissect the genetic architecture of reproductive isolation. We highlight outstanding questions about the earliest phases of placental mammal diversification and the promise of newer methods, as well as remaining challenges, toward using whole genome data to resolve placental mammal phylogeny. The next phase of mammalian comparative genomics will see the completion and application of finished-quality, gapless genome assemblies from many ordinal lineages and closely related species. Interspecific comparisons between the most hypervariable genomic loci will likely reveal large, but heretofore mostly underappreciated, effects on population divergence, morphological innovation, and the origin of new species.

Основные приоритеты диверсификации российской химической промышленности

There foreign economic activities of domestic chemical industry are considering in the article. There the prerequisites of the industry diversification are revealed, the enhancement priorities of the industry structure are marked. The authors outline main phases of the chemistry diversification in Russian present-day conditions.

Rapid macrobenthic diversification and stabilization after the end-Cretaceous mass extinction event

Abstract Previous ichnological analysis at the Chicxulub impact crater, Yucatán Peninsula, México (International Ocean Discovery Program [IODP]/International Continental Scientific Drilling Program [ICDP] Site M0077), showed a surprisingly rapid initial tracemaker community recovery after the end-Cretaceous (Cretaceous-Paleogene [K-Pg]) mass extinction event. Here, we found that full recovery was also rapid, with the establishment of a well-developed tiered community within ∼700 k.y. Several stages of recovery were observed, with distinct phases of stabilization and diversification, ending in the development of a trace fossil assemblage mainly consisting of abundant Zoophycos, Chondrites, and Planolites, assigned to the Zoophycos ichnofacies. The increase in diversity is associated with higher abundance, larger forms, and a deeper and more complex tiering structure. Such rapid recovery suggests that favorable paleoenvironmental conditions were quickly reestablished within the impact basin, enabling colonization of the substrate. Comparison with the end-Permian extinction reveals similarities during recovery, yet postextinction recovery was significantly faster after the K-Pg event. The rapid recovery has significant implications for the evolution of macrobenthic biota after the K-Pg event. Our results have relevance in understanding how communities recovered after the K-Pg impact and how this event differed from other mass extinction events.

Impact of petroleum and non-petroleum indices on financial development in Oman

This study analyzes the impact of petroleum and non-petroleum indices on the financial development of the Sultanate of Oman from 1978 to 2017. To this end, it uses the petroleum proxy of oil rents (% of gross domestic product, GDP) and the non-petroleum proxy of industry (including construction) value added (% of GDP); agriculture, forestry, and fishing value added (% of GDP); and services value added (% of GDP) to determine the effect on financial development, measured by the amount of domestic credit extended to the private sector by banks (% of GDP). It applies an autoregressive distributed lag (ARDL) model. The long-term equation illustrates that the agriculture and industry GDPs have a negative and significant relationship with domestic credit in Oman. However, the oil and service sector GDPs promote financial development. The short-term equation illustrates that the oil, agricultural, and service sectors have positive and significant effects on domestic credit. The conclusion is that the economy of Oman is still in the first phase of economic diversification. Accordingly, the government should use oil revenues to develop various non-oil industrial sectors. This would enhance the country’s competitiveness in the global economy and positively contribute to improving the liquidity of the banking sector for stimulating credit at the macroeconomic level.

L’Église, la femme et l’affect : récits sur la désirabilité du modèle laïc au Québec ou comment fabriquer un projet politique en contexte séculier?

This article is based on life stories collected between 2014 and 2018 among a population of baby boomers of French Canadian descent, whose personal path echoes the social and political history of the province. Following their socialization in a Catholic context, this generation has known a rapid phase of secularization, modernization and diversification that, since the end of the 1960s, have impacted the local social and political landscape of the province. The entanglement between individual and collective experiences shapes a particular rhetoric on the « laïc » (secularist) project in Quebec that hinges on memories of Catholicism, concern for gender equity and pluralist ethics. Drawing on Maclure and Taylor’s model of open and closed secularism, the author discuss the means and ends of the moral principles underlying baby boomers’ narratives.

LumReader: Designing your luminescence experiment with R

During the last decades, luminescence dating has entered a phase of diversification. This evolution is strongly linked to a series of technical advances, including but not limited to the improvement of EMCCD cameras and the use of violet and yellow LEDs. New measurement techniques have been developed, such as post infra-red infra-red stimulated luminescence (postIR-IRSL) measurement protocols and thermally-transferred OSL (TT-OSL), and the luminescence properties of new materials, such as gypsum and apatite, have been reinvestigated.The appropriate configuration of detection equipment is key to the design of new experimental investigations. The R-package LumReader has been designed to simulate both the detection properties of luminescence readers and the emission properties of materials. It allows optimisation of the experimental detection window for a given filter and detector (PMT or EMCCD camera) combination through comparison of the detection window, the stimulation signal and the luminescence emission of the studied material. With the development of a reference database and its flexibility for accommodating user defined functions, this package will allow the spectral information of any luminescence experiment to be simulated, also facilitating experimental design.

Shift in limiting nutrients in the late Ediacaran–early Cambrian marine systems of South China

The Ediacaran to Cambrian periods are characterized by the diversification and extinction of metazoans, carbon-cycle perturbation, and ocean oxygenation. Ocean nutrient cycles play a major role in the primary production and productivity-driven shallow water anoxia that was responsible for mass extinction in some Phanerozoic intervals. However, the relationships between these cycles and primary production and biological events during the Ediacaran to Cambrian periods have not previously been well-explored. This study presents stratigraphic profiles of nitrogen and organic carbon isotopes for sections belonging to the shelf and deep basin regions of the Yangtze Platform, South China. The nitrogen isotope profiles for these two regions share a similar trend, showing 1) relatively stable δ15N values of 5–6‰ in the early–middle Ediacaran (635 Ma–ca. 560 Ma) and 2) a shift towards lower δ15N values (3–4‰) since the Shuram δ13Ccarb Excursion. The δ15N values in the shelf section experienced a two-stage decrease from the late Ediacaran to Cambrian Stage 2 of the Terreneuvian series (down to −1‰) and then an increase from −1‰ to +4‰ across the Cambrian Stage 2/3 boundary (i.e., the Terreneuvian/Cambrian Series 2 boundary at 521 Ma). These data, in combination with previously reported nutrient profiles (δ15N, P, and Mo), allow the following new conclusions to be drawn. 1) The early–middle Ediacaran ocean was characterized by NMo colimitation of primary production on a geological timescale that is different from the P limitation on long-term primary production in the modern ocean. 2) A shift in the ultimate limiting nutrient from N and Mo to P likely occurred in late Ediacaran–early Cambrian marine systems. This shift may have been a prerequisite for the extinction of small shelly fossils in response to the development of photic zone anoxia for several million years in Cambrian Stage 2, which was followed by the third and most prominent phase of metazoan diversification.

The Rise of Apomixis in Natural Plant Populations.

Apomixis, the asexual reproduction via seed, has many potential applications for plant breeding by maintaining desirable genotypes over generations. Since most major crops do not express natural apomixis, it is useful to understand the origin and maintenance of apomixis in natural plant systems. Here, we review the state of knowledge on origin, establishment and maintenance of natural apomixis. Many studies suggest that hybridization, either on diploid or polyploid cytotypes, is a major trigger for the formation of unreduced female gametophytes, which represents the first step toward apomixis, and must be combined to parthenogenesis, the development of an unfertilized egg cell. Nevertheless, fertilization of endosperm is still needed for most apomictic plants. Coupling of these three steps appears to be a major constraint for shifts to natural apomixis. Adventitious embryony is another developmental pathway toward apomixis. Establishment of a newly arisen apomictic lineage is often fostered by side-effects of polyploidy. Polyploidy creates an immediate reproductive barrier against the diploid parental and progenitor populations; it can cause a breakdown of genetic self-incompatibility (SI) systems which is needed to establish self-fertility of pseudogamous apomictic lineages; and finally, polyploidy could indirectly help to establish an apomictic cytotype in a novel ecological niche by increasing adaptive potentials of the plants. This step may be followed by a phase of diversification and range expansion, mostly described as geographical parthenogenesis. The utilization of apomixis in crops must consider the potential risks of pollen transfer and introgression into sexual crop fields, which might be overcome by using pollen-sterile or cleistogamous variants. Another risk is the escape into natural vegetation and potential invasiveness of apomictic plants which needs careful management and consideration of ecological conditions.

Understanding local adaptation in a freshwater salmonid fish: evolution of a research programme

AbstractLinking ecology and evolution can be challenging, particularly as these fields evolve rapidly tracking technological and theoretical developments. Thus, it is important for practitioners of different biological disciplines to understand new opportunities and challenges. Since theory and methods evolve, so will research programmes—often tracking opportunity. Here, we describe a research programme where we have investigated the population biology of grayling Thymallus thymallus in a Norwegian alpine landscape over three decades. Starting with classical ecological studies, we identified a set of populations that had evolved population-specific phenotypic traits over a relatively short time span (10–30 generations). These observations led us into evolutionary studies at various levels of biological organization, using population and quantitative genetic, transcriptomic and proteomic approaches. Overall, the results show that the populations exhibit evolutionary responses to local-scale differences in environment (mainly water temperature during early development). Further, plastic responses are important in the early phase of population diversification. Population genomic studies are now becoming possible following the completion of an annotated genome. This will help us and others in addressing questions about the genetic architecture of traits important for local adaptation, thus emphasizing that combining ecological and evolutionary approaches is more important and interesting than ever.

Palynological analysis of a Lower Cretaceous subsurface succession from the south flank of the Golfo San Jorge Basin, Argentina

Abundant and well-preserved palynological assemblages recovered from the Las Heras Group and Pozo D-129 Formation in the YPF.SC.PL x-2 (Puesto Ludden) are analyzed. This well includes the most complete Lower Cretaceous succession along the south flank of the Golfo San Gorge Basin. The palynofloras comprise fifty spore species, twenty-eight pollen taxa (including two angiosperm pollen taxa) and four algae. A late Valanginian–Hauterivian age is suggested for the Las Heras Group based mainly on the presence of Cyclusphaera psilata, Foraminisporis variornatus and Celyphus rallus and the absence of angiosperm pollen. These assemblages can be correlated with the Interulobites-Foraminisporis Zone (upper Valanginian–Hauterivian) of the Austral Basin. On the other hand, a Barremian-early Aptian age for the palynofloras from the Pozo D-129 Formation is suggested based on the sparse angiosperm pollen grains identified (Clavatipollenites sp. and Afropollis sp.) and it is correlated with the Antulsporites-Clavatipollenites Zone (Aptian) of the Austral Basin. These palynofloras from the Pozo D-129 Formation are representative of the initial late Barremian-Aptian phase of the early angiosperm diversification in central and southern Argentinean basins.