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498 result(s) for "Reynolds, Graham"
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Hurricane effects on Neotropical lizards span geographic and phylogenetic scales
Extreme climate events such as droughts, cold snaps, and hurricanes can be powerful agents of natural selection, producing acute selective pressures very different from the everyday pressures acting on organisms. However, it remains unknown whether these infrequent but severe disruptions are quickly erased by quotidian selective forces, or whether they have the potential to durably shape biodiversity patterns across regions and clades. Here, we show that hurricanes have enduring evolutionary impacts on the morphology of anoles, a diverse Neotropical lizard clade. We first demonstrate a transgenerational effect of extreme selection on toepad area for two populations struck by hurricanes in 2017. Given this short-term effect of hurricanes, we then asked whether populations and species that more frequently experienced hurricanes have larger toepads. Using 70 y of historical hurricane data, we demonstrate that, indeed, toepad area positively correlates with hurricane activity for both 12 island populations of Anolis sagrei and 188 Anolis species throughout the Neotropics. Extreme climate events are intensifying due to climate change and may represent overlooked drivers of biogeographic and large-scale biodiversity patterns.
A NEW BAYESIAN METHOD FOR FITTING EVOLUTIONARY MODELS TO COMPARATIVE DATA WITH INTRASPECIFIC VARIATION
Phylogenetic comparative methods thatincorporate intraspecific variability are relatively new and, so far, not especially widely used in empirical studies. In the present short article we will describe a new Bayesian method for fitting evolutionary models to comparative data that incorporates intraspecific variability. This method differs from an existing likelihood-based approach in that it requires no a priori inference about species means and variances; rather it takes phenotypic values from individuals and a phylogenetic tree as input, and then samples species means and variances, along with the parameters of the evolutionary model, from their joint posterior probability distribution. One of the most novel and intriguing attributes of this approach is that jointly sampling the species means with the evolutionary model parameters means that the model and tree can influence our estimates of species mean trait values, not just the reverse. In the present implementation, we first apply this method to the most widely used evolutionary model for continuously valued phenotypic trait data (Brownian motion). However, the general approach has broad applicability, which we illustrate by also fitting the λ model, another simple model for quantitative trait evolution on a phylogeny. We test our approach via simulation and by analyzing two empirical datasets obtained from the literature. Finally, we have implemented the methods described herein in a new function for the R statistical computing environment, and this function will be distributed as part of the 'phytools' R library.
ASSORTATIVE MATING IN POISON-DART FROGS BASED ON AN ECOLOGICALLY IMPORTANT TRAIT
The origin of new species can be influenced by both deterministic and stochastic factors. Mate choice and natural selection may be important deterministic causes of speciation (as opposed to the essentially stochastic factors of geographic isolation and genetic drift). Theoretical models predict that speciation is more likely when mate choice depends on an ecologically important trait that is subject to divergent natural selection, although many authors have considered such mating/ecology pleiotropy, or “magic-traits” to be unlikely. However, phenotypic signals are important in both mate choice and ecological processes such as avoiding predation. In chemically defended species, it may be that the phenotypic characteristics influencing mate choice are the same signals being used to transmit a warning to potential predators, although few studies have demonstrated this in wild populations. We tested for assortative mating between two color morphs of the Strawberry Poison-Dart Frog, Dendrobates pumilio, a group with striking geographic variation in aposematic color patterns. We found that females significantly prefer individuals of their own morph under two different light treatments, indicating strong assortative mating based on multiple coloration cues that are also important ecological signals. This study provides a rare example of one phenotypic trait affecting both ecological viability and nonrandom mating, indicating that mating/ecology pleiotropy is plausible in wild populations, particularly for organisms that are aposematically colored and visually orienting.
Antibiotic Prophylaxis and Recurrent Urinary Tract Infection in Children
This study from four Australian centers examined whether low-dose, continuous oral antibiotic therapy would prevent urinary tract infection in children (under the age of 18 years) who had already had one or more microbiologically proven urinary tract infections. Long-term, low-dose trimethoprim–sulfamethoxazole was associated with a modest decrease in the number of urinary tract infections in predisposed children. Long-term, low-dose trimethoprim–sulfamethoxazole was associated with a modest decrease in the number of urinary tract infections in predisposed children. Urinary tract infection is a very common illness in children, affecting 2% of boys and 8% of girls by the age of 7 years. 1 Urinary tract infection is associated with long-term morbidity, with renal damage reported in about 5% of affected children. 2 The observation that urinary tract infection and vesicoureteral reflux are associated with renal damage 3 – 5 led to the standard clinical practice of assessment with voiding cystourethrography for the presence of vesicoureteral reflux in children who had had urinary tract infection 6 , 7 and the administration of daily low-dose antibiotics for many years 8 to prevent further urinary tract infections and . . .
Canadian copyright protections for neurodata: ethical and legal implications
Abstract This essay examines how Canadian copyright law treats neurodata generated for neuroprediction and further probes if copyright or similar protections would offer mechanisms to safeguard individuals who produce those data. Using a hypothetical fact pattern, we apply the conditions for subsistence of copyright to neurodata created by a research participant and processed by a researcher. The results of the analysis indicate that both parties can credibly argue that copyright subsists in the neurodata, although such an outcome is neither established nor guaranteed under current law. We then explore the policy significance of this legal analysis from a neuroethics perspective. Drawing together literatures on data justice, political economy, and neurotechnology governance, we argue that when people produce neurodata, legal systems should appropriately honor their contributions. This could be accomplished through protections of the integrity of neurodata from harmful misuse, akin to what moral rightsholders can accomplish under Canadian moral rights doctrine. We further highlight the need to protect individual autonomy over brain data, whether via copyright or another mechanism. We conclude that the Canadian approach to copyright law and moral rights offers a model for policy and governance as neurodata find their way into legally and socially consequential technologies.
A revision of the Anolis carolinensis subgroup supports three species in Cuba, including a new cryptic species (Squamata: Anolidae)
Abstract Cuba is the only landmass with more than one species in the Anolis carolinensis subgroup. We test the hypothesis that three rather than two distinct species occur on Cuba, based on substantial prior evidence of paraphyly. To test this hypothesis, we collected phenotypic data from all described species in the subgroup, including eastern and west-central Cuban populations of A. porcatus , and assessed phenotypic diagnosability using uni- and multivariate analyses. We also examined geographic isolation using all available occurrence records for Cuban lineages. Additionally, we conducted ecological niche modeling and niche overlap analyses, considering only Cuban lineages, to test for ecological differentiation. Finally, we reconstructed phylogenetic trees, incorporating all species from the subgroup for the first time. Our results support the recognition of three species in Cuba: A. allisoni and eastern and west-central A. porcatus as two distinct cryptic species, showing minimal phenotypic differentiation but clear geographic isolation, distinct ecological niches, and deep genetic divergence. We restrict the name A. porcatus to west-central Cuba, with Havana as the type locality, and formally describe the eastern Cuban populations as Anolis torresfundorai sp. nov. , designating Baracoa, Guantánamo, as the type locality.
Archipelagic genetics in a widespread Caribbean anole
Aim: We examine the influence of fluctuating sea levels in a land-bridge archipelago on the apportioning of intraspecific genetic diversity and divergence in the wide-spread Puerto Rican crested anole (Anolis cristatellus). We compare three alternative scenarios for genetic diversification in an archipelagic species that contrast the relative influences of periodic isolation versus island connectedness driven by fluctuating sea levels. Our approach combines information from geography and population genetics to assess the influence of island size, island isolation, island historical geography, and population genetic processes such as drift on the contemporary distribution of genetic variation within and among islands. Location: The Puerto Rico Bank in the Caribbean focusing primarily on the Spanish, British and U.S. Virgin Islands. Methods: We used nuclear and mitochondrial DNA sequences and microsatellite genotypes sampled from A. cristatellus populations to investigate: (1) the broad-scale pattern of phylogeographical divergence across Puerto Rico Bank islands and (2) diversification within the Virgin Islands archipelago. For the first component, we used sequence data to reconstruct the relationships among 542 samples from across the species range. For the second component, we examined the relative influences of island size, isolation, and population genetic processes on the distribution of genetic diversity across the Virgin Islands. Results: In the Virgin Islands, A. cristatellus is represented by a monophyletic clade except on the island of Vieques, where two divergent clades coexist. We found evidence for non-equilibrium dynamics in the Virgin Islands, suggesting spatial population expansion during intraglacial periods of low sea level. Main conclusions: We found limited evidence that periods of island isolation affected patterns of genetic diversity and differentiation. Instead, we found that the patterns of genetic diversity and divergence in A. cristatellus in the Virgin Islands archipelago are likely shaped by long-term persistence in the region and periods of population spatial expansion.
Chromosome-scale genome assembly of the brown anole (Anolis sagrei), an emerging model species
Rapid technological improvements are democratizing access to high quality, chromosome-scale genome assemblies. No longer the domain of only the most highly studied model organisms, now non-traditional and emerging model species can be genome-enabled using a combination of sequencing technologies and assembly software. Consequently, old ideas built on sparse sampling across the tree of life have recently been amended in the face of genomic data drawn from a growing number of high-quality reference genomes. Arguably the most valuable are those long-studied species for which much is already known about their biology; what many term emerging model species. Here, we report a highly complete chromosome-scale genome assembly for the brown anole, Anolis sagrei – a lizard species widely studied across a variety of disciplines and for which a high-quality reference genome was long overdue. This assembly exceeds the vast majority of existing reptile and snake genomes in contiguity (N50 = 253.6 Mb) and annotation completeness. Through the analysis of this genome and population resequence data, we examine the history of repetitive element accumulation, identify the X chromosome, and propose a hypothesis for the evolutionary history of fusions between autosomes and the X that led to the sex chromosomes of A. sagrei . A highly-complete chromosome-scale genome assembly of the brown anole, Anolis sagrei , provides insight into the evolution of sex chromosomes and is a crucial resource for this model lizard species.
Mitochondrial genome of the critically Endangered silver boa (Chilabothrus argentum; Squamata: Boidae)
We present the complete mitochondrial genome of Chilabothrus argentum, which is 17,345 bp in length, has 22 transfer ribonucleic acids (tRNAs), 2 ribosomal subunits (rRNAs), 13 protein-coding genes, an origin of the light-strand replication (O L ), and two control regions (CR1, CR2). A maximum likelihood phylogenetic estimate using nine other snake mitochondrial genomes yields agreement with previous investigations into the evolutionary relationships of snakes.
Tests of two methods for identifying founder effects in metapopulations reveal substantial type II error
Genetic analysis has been promoted as a way to reconstruct recent historical dynamics (“historical demography”) by screening for signatures of events, such as bottlenecks, that disrupt equilibrium patterns of variation. Such analyses might also identify “metapopulation” processes like extinction and recolonization or source-sink dynamics, but this potential remains largely unrealized. Here we use simulations to test the ability of two currently used strategies to distinguish between a set of interconnected subpopulations (demes) that have undergone bottlenecks or extinction and recolonization events (metapopulation dynamics) from a set of static demes. The first strategy, decomposed pairwise regression, provides a holistic test for heterogeneity among demes in their patterns of isolation-by-distance. This method suffered from a type II error rate of 59–100 %, depending on parameter conditions. The second strategy tests for deviations from mutation-drift equilibrium on a deme-by-deme basis to identify sites likely to have experienced recent bottlenecks or founder effects. Although bottleneck tests have good statistical power for single populations with recent population declines, their validity in structured populations has been called into question, and they have not been tested in a metapopulation context with immigration (or colonization) and population recovery. Our simulations of hypothetical metapopulations show that population recovery can rapidly eliminate the statistical signature of a bottleneck, and that moderate levels of gene flow can generate a false signal of recent population growth for demes in equilibrium. Although we did not cover all possible metapopulation scenarios, the performance of the tests was disappointing. Our results indicate that these methods might often fail to identify population bottlenecks and founder effects if population recovery and/or gene flow are influential demographic features of the study system.