Dispersal or Drift? More to Plant Biodiversity Than Meets the Eye
PDF Abstract Reliable estimates on the ages of the major bee clades are needed to further understand the evolutionary history of bees and their close association with flowering plants. Divergence times have been estimated for a few groups of bees, but no study has yet provided estimates for all major bee lineages. To date the origin of bees and their major clades, we first perform a phylogenetic analysis of bees including representatives from every extant family, subfamily and almost all tribes, using sequence data from seven genes. We then use this phylogeny to place 14 time calibration points based on information from the fossil record for an uncorrelated relaxed clock divergence time analysis taking into account uncertainties in phylogenetic relationships and the fossil record. We explore the effect of placing a hard upper age bound near the root of the tree and the effect of different topologies on our divergence time estimates. We estimate that crown bees originated approximately Ma million years ago — Ma , concurrently with the origin or diversification of the eudicots, a group comprising 75 per cent of angiosperm species.
Dr Sven Buerki
It is an opportunity for us to reflect on the language and ideas that represented each year. So, take a stroll down memory lane to remember all of our past Word of the Year selections. Change It wasn’t trendy , funny, nor was it coined on Twitter , but we thought change told a real story about how our users defined
Ancient diversiﬁcation of Hyposmocoma moths in Hawaii William P. Haines1, 1University of Hawaii at Manoa, Department of Plant and Environmental Protection Sciences, Maile Way, Gilmore , Honolulu , Hawaii, The relaxed molecular clock analysis.
The cosmopolitan moss Bryum argenteum in Antarctica: Since the onset of glaciation following the Oligocene 30—28 Ma , the prevalence of increasingly Two hypotheses, postglacial recruitment from extra-regional locations and in situ persistence, have been proposed to explain the biogeography of the contemporary species-poor terrestrial Antarctic biota. Bryophytes, which form a major group of the Antarctic flora, exhibit a strong, inherent ability to survive cold conditions but also have high long-distance dispersal capacities, which are compatible with both hypotheses.
Here, we test these hypotheses by means of population genetic and phylogeographic analyses of the cosmopolitan moss Bryum argenteum. We find evidence for at least three independent colonisation events of the species in Antarctica. Ancestral area reconstruction coupled with molecular dating suggests colonisation times of the different Antarctic clades ranging from four million years for the oldest lineage to half a million years for the youngest lineage.
This suggests multiple colonisation events of Antarctica by this species during several glacial cycles within the Pleistocene, Pliocene and possibly late Miocene. This is the first study to demonstrate in situ persistence of bryophytes in Antarctica throughout previous glaciations.
A History: ’s Word of the Year
Licence This is an open access article distributed under the terms of the Creative Commons Attribution License , which permits unrestricted use, distribution, reproduction and adaptation in any medium and for any purpose provided that it is properly attributed. The reanalysis of biogeography of the Asian tree frog, Rhacophorus Anura: Abstract Rapid uplifts of the Tibetan Plateau and climate change in Asia are thought to have profoundly modulated the diversification of most of the species distributed throughout Asia.
The ranoid tree frog genus Rhacophorus, the largest genus in the Rhacophoridae, is widely distributed in Asia and especially speciose in the areas south and east of the Tibetan Plateau.
Main conclusionsMolecular dating and ancestral area reconstruction may be broadly consistent with the idea of a vicariant origin of the two major clades of Boraginales after the break-up of West Gondwana, followed by several independent trans-oceanic dispersal events into most areas of the world.
SHARE Although studying creativity is considered a legitimate scientific discipline nowadays, it is still a very young one. In the early s, a psychologist named J. Guilford was one of the first academic researchers who dared to conduct a study of creativity. He challenged research subjects to connect all nine dots using just four straight lines without lifting their pencils from the page. Today many people are familiar with this puzzle and its solution. In the s, however, very few were even aware of its existence, even though it had been around for almost a century.
Fungi and animals shared a common ancestor over a billion years ago. Since that time, animals evolved into herbivores and predators while fungi became specialized as decay agents and recyclers in the environment; as plant and animal pathogens; and as symbionts contributing as mycorrhizal partners to plant growth. Through a combination of field and laboratory work, students and postdoctoral researchers are finding and culturing fungi and fungus-like organisms, many of them new to science, and then applying microscopic and molecular phylogenetic techniques to place the origin and diversification of the fungi in a phylogenetic context.
Figure 2: Molecular dating analysis. The MCC chronogram of an Agaricomycetidae subset, with main focus on Boletales taxa, obtained from divergence time estimation using BEAST. The MCC chronogram of an Agaricomycetidae subset, with main focus on Boletales taxa, obtained from divergence time estimation using BEAST.
This is an open access article distributed under the Creative Commons Attribution License , which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Abstract Methods for estimating divergence times from molecular data have improved dramatically over the past decade, yet there are few studies examining alternative taxon sampling effects on node age estimates.
Here, I investigate the effect of undersampling species diversity on node ages of the South American lizard clade Liolaemini using several alternative subsampling strategies for both time calibrations and taxa numbers. Penalized likelihood PL and Bayesian molecular dating analyses were conducted on a densely sampled taxa mtDNA-based phylogenetic hypothesis of Iguanidae, including 92 Liolaemini species. Using all calibrations and penalized likelihood, clades with very low taxon sampling had node age estimates younger than clades with more complete taxon sampling.
The effect of Bayesian and PL methods differed when either one or two calibrations only were used with dense taxon sampling. Bayesian node ages were always older when fewer calibrations were used, whereas PL node ages were always younger. This work reinforces two important points: Introduction Alternative taxon sampling strategies are known to affect many facets of phylogenetic reconstruction [ 1 — 3 ].
Multiple global radiations in tadpole shrimps challenge the concept of ‘living fossils’
Accordingly, the evolution rate of Rice yellow mottle virus RYMV was calculated from sequences of the coat protein gene of isolates collected from rice over a year period in different parts of Africa. The evolution rate of RYMV was estimated by pairwise distance linear regression on five phylogeographically defined groups comprising a total of isolates. It was further assessed from isolates collected all over Africa by Bayesian coalescent methods under strict and relaxed molecular clock models and under constant size and skyline population genetic models.
to phylogeny-based island biogeography, with special reference to the Canary Islands divergence times using molecular clocks. Many plant and animal lineages, whose distributions were originally explained address other problems in historical biogeography, such as dispersal among areas in continental settings or reticulate area relationships.
In the early Jurassic circa. Indeed, the fact that the same animal and plant genera and sometimes same species is currently shared between many of these continents was taken as a line of evidence to support the now well established idea that these landmasses were once joined. When a plant genus is shared between geographical separate landmasses, the genus is said to have a disjunct distribution and the many instances of disjunctions of the Gondwanic flora has been and continue to evoke immense scientific interest and research.
Nothofagus glauca Ever since the early writings of the botanist J. Hooker , several explanations have been proposed to explain the patterns of disjunctions in the gondwanic flora: Southern migration might have occurred en route land bridges van Steenis, , long-distance dispersal events Darlington, ; Pole, , ; Hill, or rafting on drifting continents Brundin, Nothofagus Nothofagaceae are commonly known as southern beeches and consists of 36 species of evergreen or deciduous trees and shrubs which are in appearance somewhat reminiscent for oaks and beeches Fagus spp.
Nothofagus pumilio Three reasons for the significance of Nothofagus to biogeography: Investigations into Nothofagus have yielded many advances in the present understanding of the taxonomy, phylogeny and biogeography of the genus Hill,
Researchers Date the Origins of Photosynthesis to 1.25 Billion Years Ago
This study aimed to investigate the origin of Malesian Begonia, the directionality of dispersal events within the Malesian archipelago and the impact of ancient water gaps on colonization patterns, and to identify drivers of diversification. Location Asia, Southeast Asia, Malesia. Methods Plastid DNA sequence data of representatives of all families of the Cucurbitales and Fagales matK, rbcL, trnL intron, trnL—F spacer, aligned positions, 92 taxa and a sample of all major Asian Begonia sections ndhA intron, ndhF—rpl32 spacer, rpl32—trnL spacer, aligned positions, taxa were analysed under an uncorrelated-rates relaxed molecular clock model to estimate the age of the Begonia crown group divergence and divergence ages within Asian Begonia.
Ancestral areas were reconstructed using a likelihood approach implementing a dispersal—extinction—cladogenesis model, and with a Bayesian approach to dispersal—vicariance analysis. Results The results indicated an initial diversification of Asian Begonia in continental Asia in the Miocene, and subsequent colonization of Malesia by multiple lineages.
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The much-debated discrepancy between molecular and palaeontological estimates for the metazoan radiation has become a lot fuzzier lately. There has always been variation between molecular date estimates, but up until a few years ago most molecular dates were clearly Precambrian. Has the discrepancy between molecules and fossils dissolved? The history of molecular clock analyses is one of increasing statistical sophistication.
The earliest molecular clock studies of metazoan history assumed a strict clock a consistent rate of molecular evolution across all lineages , such as the pioneering studies of Runnegar and Wray et al. However, comparative studies of molecular evolution demonstrated that rates of change are not always uniform across lineages e.
To avoid this problem, many researchers relied upon clock tests such as the relative rates test to exclude rate-variable sequences and select apparently well-behaved, clock-like genes e.
Dating species divergences using rocks and clocks
International Association for Plant Taxonomy. The Journal’s web site is located at http: Abstract Generic delimitation of Cyathocalyx and Drepananthus has been controversial, with some authors recognizing them as distinct genera, and others recognizing a more broadly defined Cyathocalyx, inclusive of Drepananthus.
The results of historical biogeographic analysis using Fitch parsimony and Dispersal-Extinction-Cladogenesis methods, and molecular dating analysis using Bayesian relaxed-clock methods suggest that Elaeocarpus diverged from its sister – Aceratium – in the Eocene in Australia.
My research focuses on understanding how climate affects species diversification and species diversity patterns we observe today. Current Projects Extinction Risk in Plants National Geographic Society is currently funding my work on exploring extinction risk in plants. Range size is currently considered important in assessing the conservation status of species, but little is known about the link between extinction risk and ecological specialisation in plants.
Data from animal studies has shown that ecological specialisation, as measured by the diet or host plant specificity, correlates strongly with threat status. Read more about the project in Botanics Stories. Our aim is to build a composite distribution model for the seasonally dry tropical forest biome through modelling a larger set of individual species endemic to the biome.
We are also running similar analyses on the southern Brazilian high-elevation grasslands to model their distribution, and looking for funding to extend the work to test how biomes and their dominant plant species will respond to the predicted climate change scenarios. Solanaceae Molecular Systematics We have just finished our project on building a large, densely sampled molecular phylogeny for the whole of Solanaceae.
The phylogeny includes 1, of the total c. As part of the project, we did a complete review of the Solanaceae fossil record, and discovered 50 fossils previously assigned to the family. Some of these fossils show a set of unique characters that can be used to confidently place them in the family phylogeny, and we have used these fossils to time-calibrate the large phylogeny with Bayesian relaxed molecular clock models.
Publications from the project are currently in revision.
Bees diversified in the age of eudicots
There they evolved into their present-day forms: However, recent evidence indicates that this scenario is likely incorrect: The prevailing view has been that ratites are monophyletic, with the flighted tinamous as their sister group, suggesting a single loss of flight in the common ancestry of ratites. However, Harshman et al.
Phenomena that can mislead phylogenetic analyses e.
Thornhill, A, Popple, L, Carter, R et al , ‘Are pollen fossils useful for calibrating relaxed molecular clock dating of phylogenies? A comparative study using Myrtaceae’, Molecular Phylogenetics and Evolution, vol. 63, pp.
Highlight and copy the desired format. Emerging Infectious Diseases, 20 9 , Abstract Salmonella enterica serotype Enteritidis is one of the most commonly reported causes of human salmonellosis. Its low genetic diversity, measured by fingerprinting methods, has made subtyping a challenge. We used whole-genome sequencing to characterize S. Single-nucleotide polymorphisms were filtered to identify 4, reliable loci that distinguished all isolates from each other.
Our whole-genome single-nucleotide polymorphism typing approach was robust for S. Five major genetic lineages were recognized, which revealed possible patterns of geographic and epidemiologic distribution. Analyses on the population dynamics and evolutionary history estimated that major lineages emerged during the 17th—18th centuries and diversified during the s and s.
From the s through the mid s, the incidence of serotype Enteritidis infection increased dramatically; shelled eggs were a major vehicle for transmission. Despite a decrease in serotype Enteritidis infection since in the United States, outbreaks resulting from contaminated eggs continue to occur 3 , and Enteritidis remains among the most common serotypes isolated from humans worldwide 2.
Epidemiologic surveillance and outbreak investigation of microbial pathogens require subtyping that provides sufficient resolution to discriminate closely related isolates. Of the second-generation methods evaluated for S. Therefore, new methods are needed to better subtype and differentiate this serotype.