scholarly journals Approximating the coalescent under facultative sex

2019 ◽  
Author(s):  
Matthew Hartfield
Keyword(s):  
Population Size ◽  
Evolutionary History ◽  
Sampling Strategies ◽  
Effective Population ◽  
Sexual Species ◽  
History Of ◽  
Mitotic Gene Conversion ◽  
Evolutionary Consequences ◽  
Insight Into ◽  
Coalescent Time

AbstractGenome studies of facultative sexual species, which can either reproduce sexually or asexually, are providing insight into the evolutionary consequences of mixed reproductive modes. It is currently unclear to what extent the evolutionary history of facultative sexuals’ genomes can be approximated by the standard coalescent, and if a coalescent effective population size Ne exists. Here, I determine if and when these approximations can be made. When sex is frequent (occurring at a frequency much greater than 1/N per reproduction per generation, for N the actual population size), the underlying genealogy can be approximated by the standard coalescent, with a coalescent Ne ≈ N. When sex is very rare (at frequency much lower than 1/N), approximations for the pairwise coalescent time can be obtained, which is strongly influenced by the frequencies of sex and mitotic gene conversion, rather than N. However, these terms do not translate into a coalescent Ne. These results are used to discuss the best sampling strategies for investigating the evolutionary history of facultative sexual species.

scholarly journals Recombination Gives a New Insight in the Effective Population Size and the History of the Old World Human Populations

2011 ◽  
Vol 29 (1) ◽  
pp. 25-30 ◽  
Author(s):  
Marta Melé ◽  
Asif Javed ◽  
Marc Pybus ◽  
Pierre Zalloua ◽  
Marc Haber ◽  
...  
Keyword(s):  
Population Size ◽  
Effective Population Size ◽  
Human Populations ◽  
Effective Population ◽  
Old World ◽  
History Of

The amphibamiform Nanobamus macrorhinus from the early Permian of Texas

2019 ◽  
Vol 94 (2) ◽  
pp. 366-377 ◽  
Author(s):  
Bryan M. Gee ◽  
Robert R. Reisz
Keyword(s):  
Phylogenetic Analysis ◽  
Evolutionary History ◽  
Phylogenetic Position ◽  
Early Permian ◽  
Larval Form ◽  
Terrestrial Environments ◽  
History Of ◽  
Insight Into

AbstractNanobamus macrorhinus Schoch and Milner, 2014 is a small amphibamiform temnospondyl from the early Permian Arroyo Formation of Texas. It is most readily characterized by an elongate and partially subdivided naris. This condition is superficially reminiscent of that seen in the coeval trematopids, the group to which N. macrorhinus was originally referred to under an interpretation of the holotype as a larval form. This was discounted by later workers, but the amphibamiform affinities of the specimen were not formalized until recently. The specimen has never been described in the context of its amphibamiform affinities and remains poorly characterized, never having been sampled in a phylogenetic analysis. Here we present a complete, updated osteological description of N. macrorhinus, including an improved characterization of its unique mosaic of plesiomorphic and apomorphic features and clarification of the taxon's autapomorphies. Our analysis of the taxon's phylogenetic position within Amphibamiformes shows that N. macrorhinus was recovered as diverging after basal amphibamiforms, e.g., the micropholids, and before derived amphibamiforms, e.g., the amphibamids. This is supported by the unique mixture of retained plesiomorphies, e.g., nonforeshortened postparietals and an oval choana, and apomorphies, e.g., a narrow interorbital region and slender palatal rami of the pterygoid. These results reflect the complexity of terrestrial amphibamiform diversity and provide further insight into the evolutionary history of the lissamphibian stem in terrestrial environments.

scholarly journals Ancient origins and multiple appearances of carotenoid-pigmented feathers in birds

2014 ◽  
Vol 281 (1788) ◽  
pp. 20140806 ◽  
Author(s):  
Daniel B. Thomas ◽  
Kevin J. McGraw ◽  
Michael W. Butler ◽  
Matthew T. Carrano ◽  
Odile Madden ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
High Performance ◽  
Evolutionary History ◽  
Carotenoid Pigments ◽  
Biological Functions ◽  
The Family ◽  
Family Level ◽  
History Of ◽  
Living Species ◽  
Insight Into

The broad palette of feather colours displayed by birds serves diverse biological functions, including communication and camouflage. Fossil feathers provide evidence that some avian colours, like black and brown melanins, have existed for at least 160 million years (Myr), but no traces of bright carotenoid pigments in ancient feathers have been reported. Insight into the evolutionary history of plumage carotenoids may instead be gained from living species. We visually surveyed modern birds for carotenoid-consistent plumage colours (present in 2956 of 9993 species). We then used high-performance liquid chromatography and Raman spectroscopy to chemically assess the family-level distribution of plumage carotenoids, confirming their presence in 95 of 236 extant bird families (only 36 family-level occurrences had been confirmed previously). Using our data for all modern birds, we modelled the evolutionary history of carotenoid-consistent plumage colours on recent supertrees. Results support multiple independent origins of carotenoid plumage pigmentation in 13 orders, including six orders without previous reports of plumage carotenoids. Based on time calibrations from the supertree, the number of avian families displaying plumage carotenoids increased throughout the Cenozoic, and most plumage carotenoid originations occurred after the Miocene Epoch (23 Myr). The earliest origination of plumage carotenoids was reconstructed within Passeriformes, during the Palaeocene Epoch (66–56 Myr), and not at the base of crown-lineage birds.

WHEAT EVOLUTION

1995 ◽  
Vol 43 (2) ◽  
pp. 85-98 ◽  
Author(s):  
Adina Breiman ◽  
Dan Graur
Keyword(s):  
Phylogenetic Relationships ◽  
Evolutionary History ◽  
Wild Relatives ◽  
Wheat Species ◽  
Polyploid Species ◽  
Wheat Evolution ◽  
History Of ◽  
Nuclear Genomes ◽  
Evolutionary Consequences ◽  
Independent Evolutionary History

Many wild and cultivated wheat species are amphidiploid, i.e., they are polyploid species containing two or more distinct nuclear genomes, each with its own independent evolutionary history, but whose genetic behavior resembles that of diploids. Amphidiploidy has important evolutionary consequences in wheat. Since the beginning of this century different methods have been employed to identify the diploid donors of the coexisting genomes in the polyploids. To date, several of the genomic donors have been identified, and the search for the others has been narrowed down considerably. Molecular methodologies that are being increasingly used in studies aimed at reconstructing the evolutionary history of wheat species and their wild relatives have resolved many of the phylogenetic relationships among the various taxa.

scholarly journals In with the Old, in with the New: The Promiscuity of the Duplication Process Engenders Diverse Pathways for Novel Gene Creation

2012 ◽  
Vol 2012 ◽  
pp. 1-24 ◽  
Author(s):  
Vaishali Katju
Keyword(s):  
Gene Duplication ◽  
Population Size ◽  
Population Genetic ◽  
Effective Population ◽  
Evolutionary Potential ◽  
Dna And Rna ◽  
Duplication Events ◽  
History Of ◽  
Theoretical Population ◽  
Novel Exon

The gene duplication process has exhibited far greater promiscuity in the creation of paralogs with novel exon-intron structures than anticipated even by Ohno. In this paper I explore the history of the field, from the neo-Darwinian synthesis through Ohno’s formulation of the canonical model for the evolution of gene duplicates and culminating in the present genomic era. I delineate the major tenets of Ohno’s model and discuss its failure to encapsulate the full complexity of the duplication process as revealed in the era of genomics. I discuss the diverse classes of paralogs originating from both DNA- and RNA-mediated duplication events and their evolutionary potential for assuming radically altered functions, as well as the degree to which they can function unconstrained from the pressure of gene conversion. Lastly, I explore theoretical population-genetic considerations of how the effective population size (Ne) of a species may influence the probability of emergence of genes with radically altered functions.

scholarly journals Genome-specific histories of divergence and introgression between an allopolyploid unisexual salamander lineage and two sexual species

2018 ◽  
Author(s):  
Robert D. Denton ◽  
Ariadna E. Morales ◽  
H. Lisle Gibbs
Keyword(s):  
Genetic Variation ◽  
Evolutionary History ◽  
Parental Species ◽  
Extended Period ◽  
Reproductive Mode ◽  
Mapping Method ◽  
Genetic Introgression ◽  
Sexual Species ◽  
History Of ◽  
Genomic Material

AbstractQuantifying genetic introgression between sexual species and polyploid lineages traditionally thought to be asexual is an important step in understanding what factors drive the longevity of putatively asexual groups. However, the presence of multiple distinct subgenomes within a single lineage provides a significant logistical challenge to evaluating the origin of genetic variation in most polyploids. Here, we capitalize on three recent innovations—variation generated from ultraconserved elements (UCEs), bioinformatic techniques for assessing variation in polyploids, and model-based methods for evaluating historical gene flow—to measure the extent and tempo of introgression over the evolutionary history of an allopolyploid lineage of all-female salamanders and two ancestral sexual species. We first analyzed variation from more than a thousand UCEs using a reference mapping method developed for polyploids to infer subgenome specific patterns of variation in the all-female lineage. We then used PHRAPL to choose between sets of historical models that reflected different patterns of introgression and divergence between the genomes of the parental species and the same genomes found within the polyploids. Our analyses support a scenario in which the genomes sampled in unisexuals salamanders were present in the lineage ∼3.4 million years ago, followed by an extended period of divergence from their parental species. Recent secondary introgression has occurred at different times between each sexual species and their representative genomes within the unisexuals during the last 500,000 years. Sustained introgression of sexual genomes into the unisexual lineage has been the defining characteristic of their reproductive mode, but this study provides the first evidence that unisexual genomes have also undergone long periods of divergence without introgression. Unlike other unisexual, sperm-dependent taxa in which introgression is rare, the alternating periods of divergence and introgression between unisexual salamanders and their sexual relatives could reveal the scenarios in which the influx of novel genomic material is favored and potentially explain why these salamanders are among the oldest described unisexual animals.

scholarly journals An insight into the evolutionary history of Indonesian cattle assessed by whole genome data analysis

PLoS ONE ◽  
2020 ◽  
Vol 15 (11) ◽  
pp. e0241038
Author(s):  
Pita Sudrajad ◽  
Subiharta Subiharta ◽  
Yudi Adinata ◽  
Af’idatul Lathifah ◽  
Jun Heon Lee ◽  
...  
Keyword(s):  
Demographic History ◽  
Bos Indicus ◽  
Molecular Evidence ◽  
Effective Population ◽  
Genome Data ◽  
Bos Javanicus ◽  
History Of ◽  
Genome Data Analysis ◽  
Almost All ◽  
Insight Into

The domestication of Indonesian cattle was investigated through a study of their genetic diversity, up to the genome level. Little documentation exists regarding the history of domestication of Indonesian cattle and questions remain despite a growing body of molecular evidence. In this study, we genotyped seven Indonesian cattle breeds using an Illumina BovineSNP50 Bead Chip to provide insight into their domestication and demographic history in a worldwide population context. Our analyses indicated the presence of hybrid cattle, with Bos javanicus and Bos indicus ancestries being most prevalent, as well as purebred cattle. We revealed that all the breeds were interconnected through several migration events. However, their demographic status varied widely. Although almost all the Indonesian cattle had an effective population size higher than the minimum level required to ensure breed fitness, efforts are still needed to maintain their genetic variability and purity.

scholarly journals Diversity and Paleodemography of the Addax (Addax nasomaculatus), a Saharan Antelope on the Verge of Extinction

Genes ◽  
2021 ◽  
Vol 12 (8) ◽  
pp. 1236
Author(s):  
Elisabeth Hempel ◽  
Michael V. Westbury ◽  
José H. Grau ◽  
Alexandra Trinks ◽  
Johanna L. A. Paijmans ◽  
...  
Keyword(s):  
Population Size ◽  
Population History ◽  
Phylogeographic Structure ◽  
Recent Common Ancestor ◽  
Mitochondrial Genomes ◽  
Effective Population ◽  
Mammal Species ◽  
Human Disturbances ◽  
Most Recent Common Ancestor ◽  
History Of

Since the 19th century, the addax (Addax nasomaculatus) has lost approximately 99% of its former range. Along with its close relatives, the blue antelope (Hippotragus leucophaeus) and the scimitar-horned oryx (Oryx dammah), the addax may be the third large African mammal species to go extinct in the wild in recent times. Despite this, the evolutionary history of this critically endangered species remains virtually unknown. To gain insight into the population history of the addax, we used hybridization capture to generate ten complete mitochondrial genomes from historical samples and assembled a nuclear genome. We found that both mitochondrial and nuclear diversity are low compared to other African bovids. Analysis of mitochondrial genomes revealed a most recent common ancestor ~32 kya (95% CI 11–58 kya) and weak phylogeographic structure, indicating that the addax likely existed as a highly mobile, panmictic population across its Sahelo–Saharan range in the past. PSMC analysis revealed a continuous decline in effective population size since ~2 Ma, with short intermediate increases at ~500 and ~44 kya. Our results suggest that the addax went through a major bottleneck in the Late Pleistocene, remaining at low population size prior to the human disturbances of the last few centuries.

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