scholarly journals Speciation in Heliconius Butterflies: Minimal Contact Followed by Millions of Generations of Hybridisation

2015 ◽  
Author(s):  
Simon Henry Martin ◽  
Anders Eriksson ◽  
Krzysztof M. Kozak ◽  
Andrea Manica ◽  
Chris D. Jiggins
Keyword(s):  
Gene Flow ◽  
Hybrid Sterility ◽  
Theoretical Work ◽  
Genomic Changes ◽  
The Face ◽  
Genomic Studies ◽  
Minimal Contact ◽  
Female Hybrid ◽  
Approximate Bayesian ◽  
Over Time

Documenting the full extent of gene flow during speciation poses a challenge, as species ranges change over time and current rates of hybridisation might not reflect historical trends. Theoretical work has emphasized the potential for speciation in the face of ongoing hybridisation, and the genetic mechanisms that might facilitate this process. However, elucidating how the rate of gene flow between species may have changed over time has proved difficult. Here we use Approximate Bayesian Computation (ABC) to fit a model of speciation between the Neotropical butterflies Heliconius melpomene and Heliconius cydno. These species are ecologically divergent, rarely hybridize and display female hybrid sterility. Nevertheless, previous genomic studies suggests pervasive gene flow between them, extending deep into their past, and potentially throughout the speciation process. By modelling the rates of gene flow during early and later stages of speciation, we find that these species have been hybridising for hundreds of thousands of years, but have not done so continuously since their initial divergence. Instead, it appears that gene flow was rare or absent for as long as a million years in the early stages of speciation. Therefore, by dissecting the timing of gene flow between these species, we are able to reject a scenario of purely sympatric speciation in the face of continuous gene flow. We suggest that the period of minimal contact early in speciation may have allowed for the accumulation of genomic changes that later enabled these species to remain distinct despite a dramatic increase in the rate of hybridisation.

scholarly journals Pervasive genetic associations between traits causing reproductive isolation in Heliconius butterflies

2010 ◽  
Vol 278 (1705) ◽  
pp. 511-518 ◽  
Author(s):  
Richard M. Merrill ◽  
Bas Van Schooten ◽  
Janet A. Scott ◽  
Chris D. Jiggins
Keyword(s):  
Gene Flow ◽  
Reproductive Isolation ◽  
Hybrid Sterility ◽  
Mate Recognition ◽  
Colour Pattern ◽  
Genetic Associations ◽  
Male Preference ◽  
Heliconius Melpomene ◽  
The Face ◽  
Heliconius Cydno

Ecological speciation proceeds through the accumulation of divergent traits that contribute to reproductive isolation, but in the face of gene flow traits that characterize incipient species may become disassociated through recombination. Heliconius butterflies are well known for bright mimetic warning patterns that are also used in mate recognition and cause both pre- and post-mating isolation between divergent taxa. Sympatric sister taxa representing the final stages of speciation, such as Heliconius cydno and Heliconius melpomene , also differ in ecology and hybrid fertility. We examine mate preference and sterility among offspring of crosses between these species and demonstrate the clustering of Mendelian colour pattern loci and behavioural loci that contribute to reproductive isolation. In particular, male preference for red patterns is associated with the locus responsible for the red forewing band. Two further colour pattern loci are associated, respectively, with female mating outcome and hybrid sterility. This genetic architecture in which ‘speciation genes’ are clustered in the genome can facilitate two controversial models of speciation, namely divergence in the face of gene flow and hybrid speciation.

Regret in the Face of Bereavement: Adaptation to Loss Over Time

2009 ◽  
Author(s):  
Nicky Newton ◽  
Cynthia Torges ◽  
Abigail Stewart ◽  
Susan Nolen-Hoeksema
Keyword(s):  
The Face ◽  
Over Time

Conventions and temporal differences in painted faces: A study of posture and color distribution

2020 ◽  
Vol 2020 (11) ◽  
pp. 267-1-267-8
Author(s):  
Mitchell J.P. van Zuijlen ◽  
Sylvia C. Pont ◽  
Maarten W.A. Wijntjes
Keyword(s):  
Scientific Community ◽  
Human Face ◽  
Art Galleries ◽  
Art Collections ◽  
Color Distribution ◽  
Scientific Domain ◽  
The Face ◽  
And Gender ◽  
Changes Over Time ◽  
Over Time

The human face is a popular motif in art and depictions of faces can be found throughout history in nearly every culture. Artists have mastered the depiction of faces after employing careful experimentation using the relatively limited means of paints and oils. Many of the results of these experimentations are now available to the scientific domain due to the digitization of large art collections. In this paper we study the depiction of the face throughout history. We used an automated facial detection network to detect a set of 11,659 faces in 15,534 predominately western artworks, from 6 international, digitized art galleries. We analyzed the pose and color of these faces and related those to changes over time and gender differences. We find a number of previously known conventions, such as the convention of depicting the left cheek for females and vice versa for males, as well as unknown conventions, such as the convention of females to be depicted looking slightly down. Our set of faces will be released to the scientific community for further study.

The New Economic Populism and the Future of Inequality in the United States

2017 ◽  
Author(s):  
William W. Franko ◽  
Christopher Witko
Keyword(s):  
United States ◽  
Federal Government ◽  
Labor Unions ◽  
Republican Party ◽  
The United States ◽  
The Public ◽  
Empirical Results ◽  
Income Disparities ◽  
The Face ◽  
Over Time

The authors conclude the book by recapping their arguments and empirical results, and discussing the possibilities for the “new economic populism” to promote egalitarian economic outcomes in the face of continuing gridlock and the dominance of Washington, DC’s policymaking institutions by business and the wealthy, and a conservative Republican Party. Many states are actually addressing inequality now, and these policies are working. Admittedly, many states also continue to embrace the policies that have contributed to growing inequality, such as tax cuts for the wealthy or attempting to weaken labor unions. But as the public grows more concerned about inequality, the authors argue, policies that help to address these income disparities will become more popular, and policies that exacerbate inequality will become less so. Over time, if history is a guide, more egalitarian policies will spread across the states, and ultimately to the federal government.

Witches and Succubi: Male Sexual Fantasies

2017 ◽  
Author(s):  
Serinity Young
Keyword(s):  
Sexual Intercourse ◽  
Sexual Fantasies ◽  
Medieval Church ◽  
The Face ◽  
Ancient Times ◽  
The Dead ◽  
Over Time ◽  
The Demonic

Witches, women believed to have supernatural powers, have been with us since ancient times. Often they were beautiful, highly sexual women whom men bedded at their own risk. They had magical powers (including that of flight), communed with the dead, and did not conform to patriarchal ideas of womanhood. Their sexuality led them to be classified as succubi, or female spirits who visited men at night and had sexual intercourse with them while they slept. In medieval Christian Europe, witches were refigured as ugly over time, and they became the face of evil. They were believed to fly to their unholy Sabbaths, where they participated in orgies with Satan and sacrificed babies. In truth, most people who were accused of being witches were women caught up in the changing mores and beliefs of the medieval Church, which began to view women as more susceptible to the demonic than men, a Church that needed evidence of their unholy activities, even if extracted by torture.

Money and Flows of Coinage in the Red Sea Trade

2017 ◽  
Author(s):  
Dario Nappo
Keyword(s):  
Red Sea ◽  
Precious Metal ◽  
Metal Content ◽  
Silver Content ◽  
Second Century ◽  
Roman Coins ◽  
Precious Metal Content ◽  
The Face ◽  
Over Time

This chapter considers the financial scale of Indo-Roman trade via the Red Sea, comparing the large sums mentioned by Pliny with the evidence of customs dues, ostraca from the Red Sea port of Berenike, and hoards of Roman coins found in India. Analysis of the finds of Roman coins in India by value rather than number over time suggests that, contrary to prevailing opinion, there was not a major diminution in the value of the trade after the reign of Tiberius. Although there was apparently some decline in the Flavian period, the face value of coin finds recovers in the second century until the reign of Antoninus Pius. Coins for export to India were specially selected for their higher precious metal content, and older issues with a higher silver content continued to be exported to India long after they had largely ceased to circulate within the Roman Mediterranean.

The silence of the ellipses: Why history can’t be about telling our children lies

2021 ◽  
Vol 102 (5) ◽  
pp. 8-11
Author(s):  
Sam Wineburg
Keyword(s):  
History Textbooks ◽  
Historical Study ◽  
The Face ◽  
The Many ◽  
Over Time ◽  
Boston Massacre

History textbooks are less likely to be complete renderings of the truth than a series of stories textbook authors (and the many stakeholders who influence them) consider beneficial. Sam Wineburg describes how the process of writing history textbooks often leads to sanitized and inaccurate versions of history. As an example, he describes how the story of Crispus Attucks and the Boston massacre has evolved over time. The goal of historical study, he explains, is not to cultivate love or hate of the country. Rather, it should provide us with the courage needed to look ourselves unflinching in the face, so that we may understand who we were and who we might aspire to become.

Shallow genetic divergence and distinct phenotypic differences between two Andean hummingbirds: Speciation with gene flow?

The Auk ◽  
2019 ◽  
Vol 136 (4) ◽  
Author(s):  
Catalina Palacios ◽  
Silvana García-R ◽  
Juan Luis Parra ◽  
Andrés M Cuervo ◽  
F Gary Stiles ◽  
...  
Keyword(s):  
Gene Flow ◽  
Genetic Differentiation ◽  
Incomplete Lineage Sorting ◽  
Lineage Sorting ◽  
Phenotypic Differences ◽  
Adaptive Mechanisms ◽  
The Face ◽  
Gloger’S Rule ◽  
Divergence With Gene Flow ◽  
Neutral Markers

Abstract Ecological speciation can proceed despite genetic interchange when selection counteracts the homogenizing effects of migration. We tested predictions of this divergence-with-gene-flow model in Coeligena helianthea and C. bonapartei, 2 parapatric Andean hummingbirds with marked plumage divergence. We sequenced putatively neutral markers (mitochondrial DNA [mtDNA] and nuclear ultraconserved elements [UCEs]) to examine genetic structure and gene flow, and a candidate gene (MC1R) to assess its role underlying divergence in coloration. We also tested the prediction of Gloger’s rule that darker forms occur in more humid environments, and examined morphological variation to assess adaptive mechanisms potentially promoting divergence. Genetic differentiation between species was low in both ND2 and UCEs. Coalescent estimates of migration were consistent with divergence with gene flow, but we cannot reject incomplete lineage sorting reflecting recent speciation as an explanation for patterns of genetic variation. MC1R variation was unrelated to phenotypic differences. Species did not differ in macroclimatic niches but were distinct in morphology. Although we reject adaptation to variation in macroclimatic conditions as a cause of divergence, speciation may have occurred in the face of gene flow driven by other ecological pressures or by sexual selection. Marked phenotypic divergence with no neutral genetic differentiation is remarkable for Neotropical birds, and makes C. helianthea and C. bonapartei an appropriate system in which to search for the genetic basis of species differences employing genomics.

scholarly journals Integrating knowledge in the face of epistemic uncertainty: Dialogically drawing distinctions

2018 ◽  
Vol 49 (5) ◽  
pp. 595-612 ◽  
Author(s):  
Jeanne Mengis ◽  
Davide Nicolini ◽  
Jacky Swan
Keyword(s):  
Knowledge Integration ◽  
Interdisciplinary Collaboration ◽  
Epistemic Uncertainty ◽  
Ethnographic Study ◽  
Homogeneous Process ◽  
The Face ◽  
Over Time

In this article, we contribute to a processual understanding of knowledge integration in interdisciplinary collaboration by foregrounding the role of dialogue in dealing with epistemic uncertainty. Drawing on an ethnographic study of collaboration among scientists involved in developing a highly novel bioreactor, we suggest that knowledge integration is not a homogeneous process but requires switching between different knowledge integration practices over time. This is particularly notable in the case of ‘epistemic breakdowns’ – deeply unsettling events where hitherto-held understandings of the nature of problems appear unworkable. In such cases, it is not sufficient to deal solely with coordination issues; collaborators need to find ways to address generative knowledge integration processes and to venture, collectively, into the unknown. We demonstrate how this generative quest of knowledge integration is achieved through a dialogical process of drawing and testing new distinctions that allows actors to gradually handle the epistemic uncertainty they face.

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