Understanding why species richness peaks along the Andes is a fundamental question in the study of Neotropical biodiversity. Several biogeographic and diversification scenarios have been proposed in the literature, but there is confusion about the processes underlying each scenario, and assessing their relative contribution is not straightforward. Here, we propose to refine these scenarios into a framework which evaluates four evolutionary mechanisms: higher speciation rate in the Andes, lower extinction rates in the Andes, older colonization times and higher colonization rates of the Andes from adjacent areas. We apply this framework to a species-rich subtribe of Neotropical butterflies whose diversity peaks in the Andes, the Godyridina (Nymphalidae: Ithomiini). We generated a time-calibrated phylogeny of the Godyridina and fitted time-dependent diversification models. Using trait-dependent diversification models and ancestral state reconstruction methods we then compared different biogeographic scenarios. We found strong evidence that the rates of colonization into the Andes were higher than the other way round. Those colonizations and the subsequent local diversification at equal rates in the Andes and in non-Andean regions mechanically increased the species richness of Andean regions compared to that of non-Andean regions ('species-attractor' hypothesis). We also found support for increasing speciation rates associated with Andean lineages. Our work highlights the importance of the Andean slopes in repeatedly attracting non-Andean lineages, most likely as a result of the diversity of habitats and/or host plants. Applying this analytical framework to other clades will bring important insights into the evolutionary mechanisms underlying the most species-rich biodiversity hotspot on the planet.
AimDespite the greatest butterfly diversity on Earth occurring in the Neotropical Andes and Amazonia, there is still keen debate about the origins of this exceptional biota. A densely sampled calibrated phylogeny for a widespread butterfly subtribe, Oleriina (Nymphalidae: Ithomiini) was used to estimate the origin, colonization history and diversification of this species‐rich group.LocationNeotropics.MethodsAncestral elevation and biogeographical ranges were reconstructed using data generated from detailed range maps and applying the dispersal‐extinction‐cladogenesis model using stratified palaeogeographical time slice matrices. The pattern of diversification through time was examined by comparing constant and variable rate models. We also tested the hypothesis that a change in elevation is associated with speciation.ResultsThe Oleriina likely originated in the Andes in the Early to Middle Miocene and rapidly diversified to include four genera all of which also originated in the Andes. These clades, together with four species groups, experienced varying spatial and temporal patterns of diversification. An overall early burst and decreasing diversification rate is identified, and this pattern is reflected for most subclades.Main conclusionsChanges in the palaeogeological landscape, particularly the prolonged uplift of the Andes, had a profound impact on the diversification of the subtribe. The Oleriina mostly remained within the Andes and vicariant speciation resulted in some instances. Dynamic dispersal occurred with the disappearance of geological barriers such as the Acre System and the subtribe exploited newly available habitats. Our results confirm the role of the Andean uplift in the evolution of Neotropical biodiversity.
Aim The landscape of the Neotropical region has undergone dynamic evolution throughout the Miocene, with the extensive Pebas wetland occupying western Amazonia between 23 and c. 10 Ma and the continuous uplift of the Andes mountains. The complex interaction between the Andes and Amazonia probably influenced the trajectory of Neotropical biodiversity, but evidence from time‐calibrated phylogenies of groups that diversified during this period is lacking. We investigate the role of these landscape transformations in the dynamics of diversification in the Neotropical region using a 26‐Myr‐old endemic butterfly radiation. Location Neotropics. Time period Oligocene to present. Major taxa studied Ithomiini butterflies. Methods We generated one of the most comprehensive time‐calibrated molecular phylogenies of a large clade of Neotropical insects, the butterfly tribe Ithomiini, comprising 340 species (87% of extant species) and spanning 26 Myr of diversification. We applied a large array of birth–death models and historical biogeography estimations to assess the dynamics of diversification and biotic interchanges, especially at the Amazonia–Andes interface. Results Our results suggest that the Amazonian Pebas wetland system played a major role in the timing and geography of diversification of Ithomiini, by constraining dispersal and diversification in the Amazon basin until c. 10 Ma. During the Pebas wetland period, Ithomiini diversification mostly took place in the Andes, where terrestrial habitats were not affected. An explosion of interchanges with Amazonia and with the Northern Andes accompanied the demise of the Pebas system (11–8 Ma) and was followed by local diversification in those areas, which led to a substantial renewal of diversification. Main conclusions Many studies on Neotropical diversity have focused only on the Andes, whereas we show that it is the waxing and waning of the Pebas mega‐wetland, interacting with Andean uplift, that determined the timing and patterns of regional interchanges and diversification in Ithomiini.
The Neotropics harbour the most diverse flora and fauna on Earth. The Andes are a major centre of diversification and source of diversity for adjacent areas in plants and vertebrates, but studies on insects remain scarce, even though they constitute the largest fraction of terrestrial biodiversity. Here, we combine molecular and morphological characters to generate a dated phylogeny of the butterfly genus Pteronymia (Nymphalidae: Danainae), which we use to infer spatial, elevational and temporal diversification patterns. We first propose six taxonomic changes that raise the generic species total to 53, making Pteronymia the most diverse genus of the tribe Ithomiini. Our biogeographic reconstruction shows that Pteronymia originated in the Northern Andes, where it diversified extensively. Some lineages colonized lowlands and adjacent montane areas, but diversification here remained scarce. The recent colonization of lowland areas was reflected by an increase in the rate of evolution of species elevational ranges towards present. By contrast, speciation rate decelerated with time, with no extinction. The geological history of the Andes and adjacent regions have likely contributed to Pteronymia diversification by providing compartmentalized habitats and an array of biotic and abiotic conditions, and by limiting dispersal between some areas while promoting interchange across others.
In this retrospective multicentre study, we investigated the outcomes of elderly primary central nervous system lymphoma (PCNSL) patients (⩾65 years) who underwent high-dose chemotherapy followed by autologous stem cell transplantation (HDT-ASCT) at 11 centres between 2003 and 2016. End points included remission, progression-free survival (PFS), overall survival (OS) and treatment-related mortality. We identified 52 patients (median age 68.5 years, median Karnofsky Performance Status before HDT-ASCT 80%) who all underwent thiotepa-based HDT-ASCT. Fifteen patients (28.8%) received HDT-ASCT as first-line treatment and 37 (71.2%) received it as second or subsequent line. Remission status before HDT-ASCT was: CR 34.6%, PR 51.9%, stable disease 3.8% and progressive disease 9.6%. Following completion of HDT-ASCT, 36 patients (69.2%) achieved CR (21.2% first-line setting and 48.1% second or subsequent line setting) and 9 (17.3%) PR (5.8% first-line setting and 11.5% second or subsequent line setting). With a median follow-up of 22 months after HDT-ASCT, median PFS and OS were reached after 51.1 and 122.3 months, respectively. The 2-year PFS and OS rates were 62.0% and 70.8%, respectively. We observed two HDT-ASCT-associated deaths (3.8%). In selected elderly PCNSL patients, HDT-ASCT, using thiotepa-based conditioning regimes, is feasible and effective. Further prospective and comparative studies are warranted to further evaluate the role of HDT-ASCT in elderly PCNSL patients.
Background Exercise may improve fatigue in multiple myeloma survivors, but trial evidence is limited, and exercise may be perceived as risky in this older patient group with osteolytic bone destruction. Methods In this Phase 2 Zelen trial, multiple myeloma survivors who had completed treatment at least 6 weeks ago, or were on maintenance only, were enrolled in a cohort study and randomly assigned to usual care or a 6-month exercise programme of tailored aerobic and resistance training. Outcome assessors and usual care participants were masked. The primary outcome was the FACIT-F fatigue score with higher scores denoting less fatigue. Results During 2014–2016, 131 participants were randomised 3:1 to intervention ( n = 89) or usual care ( n = 42) to allow for patients declining allocation to the exercise arm. There was no difference between groups in fatigue at 3 months (between-group mean difference: 1.6 [95% CI: −1.1–4.3]) or 6 months (0.3 [95% CI: −2.6–3.1]). Muscle strength improved at 3 months (8.4 kg [95% CI: 0.5–16.3]) and 6 months (10.8 kg [95% CI: 1.2–20.5]). Using per-protocol analysis, cardiovascular fitness improved at 3 months (+1.2 ml/kg/min [95% CI: 0.3–3.7]). In participants with clinical fatigue ( n = 17), there was a trend towards less fatigue with exercise over 6 months (6.3 [95% CI: −0.6–13.3]). There were no serious adverse events. Conclusions Exercise appeared safe and improved muscle strength and cardiovascular fitness, but benefits in fatigue appeared limited to participants with clinical fatigue at baseline. Future studies should focus on patients with clinical fatigue. Clinical trial registration The study was registered with ISRCTN (38480455) and is completed.
BackgroundAposematic species advertise their unpalatability using warning signals such as striking coloration. Given that predators need to sample aposematic prey to learn that they are unprofitable, prey with similar warning signals share the cost of predator learning. This reduction in predation risk drives evolutionary convergence of warning signals among chemically defended prey (Müllerian mimicry). Whether such warning signal convergence is associated to similar defence levels among co-mimics is still an open question that has rarely been tested in wild populations. We quantified variation in cyanide-based (CN) chemical protection in wild caught individuals of eight aposematic Heliconius butterfly species belonging to four sympatric mimicry rings. We then tested for correlations between chemical protection and ecological species-specific traits.ResultsWe report significant differences in CN concentrations both within and between sympatric species, even when accounting for the phylogeny, and within and between mimicry rings, even after considering inter-specific variation. We found significant correlations between CN concentration and both hostplant specialization and gregarious behaviour in adults and larvae. However, differences in CN concentrations were not significantly linked to mimicry ring abundance, although the two most toxic species did belong to the rarest mimicry ring.ConclusionsOur results suggest that mimicry can explain the variation in the levels of chemical defence to a certain extent, although other ecological factors are also relevant to the evolution of such variability.Electronic supplementary materialThe online version of this article (doi:10.1186/s12862-016-0843-5) contains supplementary material, which is available to authorized users.
Multiple myeloma(MM) is the second commonest haematological malignancy and remains incurable. Beyond tumour biology and genomic features driving disease resistance, host factors including impaired immunity and frailty also contribute to poor outcomes. Despite reports of immune dysfunction in this cancer, clear evidence for the contribution to clinical outcomes remains lacking.We show, for the first time, that high abundance of Treg and PD-1+CD4 effector cells in bone marrow of newly diagnosed patients are independent predictors of early relapse. This work supports growing literature on the importance of CD4 effector cells in MM, and confirms a role for the PD-1/PD-L1 axis to MM pathobiology.Our work identifies Tregs and PD-1+CD4 effectors as potential therapeutic targets, and opens up avenues for further mechanistic studies into early relapse. Pending confirmation in future patient cohorts, such immune parameters may refine existing risk models, facilitating patient stratification for therapeutic strategies targeting key CD4 populations.Research.
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