scholarly journals The subjective nature of Linnaean categories and its impact in evolutionary biology and biodiversity studies

2010 ◽  
Vol 79 (4) ◽  
pp. 131-146 ◽  
Author(s):  
Michel Laurin
Keyword(s):  
Evolutionary Biology ◽  
Empirical Support ◽  
Evolutionary Models ◽  
Biodiversity Assessment ◽  
Review Of The Literature ◽  
Sampling Schemes ◽  
Higher Taxa ◽  
Evolutionary Studies ◽  
Continued Use ◽  
Phylogenetic Nomenclature

Absolute (Linnaean) ranks are essential to rank-based nomenclature (RN), which has been used by the vast majority of systematists for the last 150 years. They are widely recognized as being subjective among taxonomists, but not necessarily in other fields. For this reason, phylogenetic nomenclature (PN) and other alternative nomenclatural systems have been developed. However, reluctance to accept alternative nomenclatural systems and continued use of higher taxa of a given Linnaean category in comparative analyses presumably reflect a lack of appreciation of the deleterious effects of the subjective nature of Linnaean categories in other biological fields, such as conservation and evolutionary biology. To make that point clearer, evolutionary models under which such categories would be natural are presented and are shown to be highly unrealistic and to lack empirical support. Under all realistic evolutionary models, ranking of taxa into Linnaean categories is highly subjective. Solutions that could make taxonomic ranks objective are surveyed. A review of the literature illustrates two problems created by the use of Linnaean categories in comparative or evolutionary studies, namely suboptimal taxonomic sampling schemes in studies of character evolution, and unreliable biodiversity assessment drawn on the basis of counting higher taxa (taxon surrogacy).

scholarly journals The Remarkable Evolution of the Post-Agb Star FG SGE

1998 ◽  
Vol 11 (1) ◽  
pp. 363-363
Author(s):  
Johanna Jurcsik ◽  
Benjamin Montesinos
Keyword(s):  
Time Scales ◽  
Effective Temperature ◽  
Planetary Nebula ◽  
Planetary Nebulae ◽  
Central Star ◽  
Evolutionary Models ◽  
Single Star ◽  
Line Intensities ◽  
Evolutionary Changes ◽  
Evolutionary Studies

FG Sagittae is one of the most important key objects of post-AGB stellar evolutionary studies. As a consequence of a final helium shell flash, this unique variable has shown real evolutionary changes on human time scales during this century. The observational history was reviewed in comparison with predictions from evolutionary models. The central star of the old planetary nebula (Hel-5) evolved from left to right in the HR diagram, going in just hundred years from the hot region of exciting sources of planetary nebulae to the cool red supergiant domain just before our eyes becoming a newly-born post-AGB star. The effective temperature of the star was around 50,000 K at the beginning of this century, and the last estimates in the late 1980s give 5,000-6,500 K. Recent spectroscopic observations obtained by Ingemar Lundström show definite changes in the nebular line intensities. This fact undoubtedly rules out the possibility that, instead of FG Sge, a hidden hot object would be the true central star of the nebula. Consequently, the observed evolutionary changes are connected with the evolution of a single star.

scholarly journals Evolution in the cold

2000 ◽  
Vol 12 (3) ◽  
pp. 257-257 ◽  
Author(s):  
Andrew Clarke
Keyword(s):  
Evolutionary Biology ◽  
Antarctic Fish ◽  
The Arctic ◽  
Polar Regions ◽  
Evolutionary Studies ◽  
Adaptive Radiations ◽  
The Antarctic ◽  
The Impact ◽  
Insight Into

Theodosius Dobzhansky once remarked that nothing in biology makes sense other than in the light of evolution, thereby emphasising the central role of evolutionary studies in providing the theoretical context for all of biology. It is perhaps surprising then that evolutionary biology has played such a small role to date in Antarctic science. This is particularly so when it is recognised that the polar regions provide us with an unrivalled laboratory within which to undertake evolutionary studies. The Antarctic exhibits one of the classic examples of a resistance adaptation (antifreeze peptides and glycopeptides, first described from Antarctic fish), and provides textbook examples of adaptive radiations (for example amphipod crustaceans and notothenioid fish). The land is still largely in the grip of major glaciation, and the once rich terrestrial floras and faunas of Cenozoic Gondwana are now highly depauperate and confined to relatively small patches of habitat, often extremely isolated from other such patches. Unlike the Arctic, where organisms are returning to newly deglaciated land from refugia on the continental landmasses to the south, recolonization of Antarctica has had to take place by the dispersal of propagules over vast distances. Antarctica thus offers an insight into the evolutionary responses of terrestrial floras and faunas to extreme climatic change unrivalled in the world. The sea forms a strong contrast to the land in that here the impact of climate appears to have been less severe, at least in as much as few elements of the fauna show convincing signs of having been completely eradicated.

scholarly journals Switching attention from internal to external information processing: a review of the literature and empirical support of the resource sharing account

2019 ◽  
Author(s):  
Sam Verschooren ◽  
Sebastian Schindler ◽  
Rudi de Raedt ◽  
Gilles Pourtois
Keyword(s):  
Resource Sharing ◽  
Switch Cost ◽  
Control Mechanism ◽  
Empirical Support ◽  
Limited Resource ◽  
External Information ◽  
Second Phase ◽  
Review Of The Literature ◽  
Switch Costs ◽  
Domain Switch

Despite its everyday ubiquity, not much is currently known about cognitive processes involved in flexible shifts of attention between external and internal information. An important model in the task-switching literature, which can serve as a blueprint for attentional flexibility, states that switch costs correspond to the time needed for a serial control mechanism to reallocate a limited resource from the previous task context to the current one. To formulate predictions from this model when applied to a switch between perceptual attention (external component) and working memory (WM; internal component), we first need to determine whether a single, serial control mechanism is in place and, subsequently, whether a limited resource is shared between them. Following a review of the literature, we predicted that a between-domain switch cost should be observed, and its size should be either similar or reduced compared to the standard, within-domain, switch cost. These latter two predictions derive from a shared resource account between external and internal attention, or partial independence among them, respectively. In a second phase, we put to the test these opposing predictions in four successive behavioral experiments by means of a new paradigm suited to compare directly between- (internal to external) and within-domain (external to external) switch costs. Across them, we demonstrated the existence of a reliable between-domain switch cost whose magnitude was similar to the within-domain one, thereby lending support to the resource sharing account.

scholarly journals Evolution of correlated complexity in the radically different courtship signals of birds-of-paradise

2018 ◽  
Author(s):  
Russell A. Ligon ◽  
Christopher D. Diaz ◽  
Janelle L. Morano ◽  
Jolyon Troscianko ◽  
Martin Stevens ◽  
...  
Keyword(s):  
Sexual Selection ◽  
Natural Selection ◽  
Evolutionary Biology ◽  
Evolutionary Dynamics ◽  
Functional Integration ◽  
Empirical Support ◽  
Evolutionary Patterns ◽  
Evolutionary Innovation ◽  
Birds Of Paradise ◽  
Analytical Approaches

Ornaments used in courtship often vary wildly among species, reflecting the evolutionary interplay between mate preference functions and the constraints imposed by natural selection. Consequently, understanding the evolutionary dynamics responsible for ornament diversification has been a longstanding challenge in evolutionary biology. However, comparing radically different ornaments across species, as well as different classes of ornaments within species, is a profound challenge to understanding diversification of sexual signals. Using novel methods and a unique natural history dataset, we explore evolutionary patterns of ornament evolution in a group - the birds-of-paradise - exhibiting dramatic phenotypic diversification widely assumed to be driven by sexual selection. Rather than the tradeoff between ornament types originally envisioned by Darwin and Wallace, we found positive correlations among cross-modal (visual/acoustic) signals indicating functional integration of ornamental traits into a composite unit - the courtship phenotype. Furthermore, given the broad theoretical and empirical support for the idea that systemic robustness - functional overlap and interdependency - promotes evolutionary innovation, we posit that birds-of-paradise have radiated extensively through ornamental phenotype space as a consequence of the robustness in the courtship phenotype that we document at a phylogenetic scale. We suggest that the degree of robustness in courtship phenotypes among taxa can provide new insights into the relative influence of sexual and natural selection on phenotypic radiations.Author SummaryAnimals frequently vary widely in ornamentation, even among closely related species. Understanding the patterns that underlie this variation is a significant challenge, requiring comparisons among drastically different traits - like comparing apples to oranges. Here, we use novel analytical approaches to quantify variation in ornamental diversity and richness across the wildly divergent birds-of-paradise, a textbook example of how sexual selection can profoundly shape organismal phenotypes. We find that color and acoustic complexity, along with behavior and acoustic complexity, are positively correlated across evolutionary time-scales. Positive covariation among ornament classes suggests that selection is acting on correlated suites of traits - a composite courtship phenotype - and that this integration may be partially responsible for the extreme variation we see in birds-of-paradise.

Developmental biology and human evolution

2011 ◽  
Vol 1 (1) ◽  
pp. e2
Author(s):  
Jeffrey H. Schwartz
Keyword(s):  
Biological Sciences ◽  
Population Genetics ◽  
Evolutionary Biology ◽  
Molecular Change ◽  
Human Fossil ◽  
Evolutionary Studies ◽  
History Of ◽  
Modern Evolutionary Synthesis ◽  
Organismal Development ◽  
Taxic Diversity

The Evolutionary or Modern Evolutionary Synthesis (here identified as the Synthesis) has been portrayed as providing the foundation for uniting a supposed disarray of biological disciplines through the lens of Darwinism fused with population genetics. Rarely acknowledged is that the Synthesis’s success was also largely due to its architects’ effectiveness in submerging British and German attempts at a synthesis by uniting the biological sciences through shared evolutionary concerns. Dobzhansky and Mayr imposed their bias toward population genetics, population (as supposedly opposed to typological) thinking, and Morgan’s conception of specific genes for specific features (here abbreviated as genes for) on human evolutionary studies. Dobzhansky declared that culture buffered humans from the whims of selection. Mayr argued that as variable as humans are now, their extinct relatives were even more variable; thus the human fossil did not present taxic diversity and all known fossils could be assembled into a gradually changing lineage of time-successive species. When Washburn centralized these biases in the new physical anthropology the fate of paleoanthropology as a non-contributor to evolutionary theory was sealed. Molecular anthropology followed suit in embracing Zuckerkandl and Pauling’s assumption that molecular change was gradual and perhaps more importantly continual. Lost in translation was and still is an appreciation of organismal development. Here I will summarize the history of these ideas and their alternatives in order to demonstrate assumptions that still need to be addressed before human evolutionary studies can more fully participate in what is a paradigm shift-in-the-making in evolutionary biology.

Stereotypes, Bias, and Personnel Decisions: Strange and Stranger

2008 ◽  
Vol 1 (4) ◽  
pp. 379-392 ◽  
Author(s):  
Frank J. Landy
Keyword(s):  
Implicit Association Test ◽  
Research Study ◽  
Empirical Support ◽  
Implicit Associations ◽  
Implicit Association ◽  
Review Of The Literature ◽  
Demographic Groups ◽  
Work Settings ◽  
Personnel Decisions ◽  
Study Designs

Research on stereotyping as related to workplace evaluations and decisions has been going on for more than 30 years. Recently, implicit association theory has emerged as a less conscious manifestation of stereotyping mechanisms. In this article, I review the relevance of research on both stereotyping and one of the more popular tests of implicit associations, the Implicit Association Test (IAT). Claims have been made that both stereotyping research and, more recently, IAT research provide theoretical and empirical support for the argument that protected demographic groups (e.g., ethnic minorities, women) are the victims of biased personnel decisions and evaluations. My review of the literature suggests that both stereotyping and IAT research study designs are sufficiently far removed from real work settings as to render them largely useless for drawing inferences about most, but not all, forms of employment discrimination.

The H. A. Nicholson Collection of Paleozoic stenolaemate bryozoans: comparison of cladistic and phenetic classifications

1994 ◽  
Vol 68 (5) ◽  
pp. 978-994 ◽  
Author(s):  
Joseph F. Pachut ◽  
Robert L. Anstey ◽  
Alan S. Horowitz
Keyword(s):  
Cladistic Analysis ◽  
Higher Taxa ◽  
Evolutionary Studies ◽  
Family Level ◽  
Systematic Relationships ◽  
Taxonomic Assignments

Until the late 1960's, most of Nicholson's types of Paleozoic bryozoans were not available for study. We present a set of coded characters of many of Nicholson's types, which should assist in bringing his species into conformity with current taxonomic standards so that his species can be consistently recognized and used in biostratigraphic, paleobiogeographic, and evolutionary studies.Cladistic and phenetic analyses of these species permit comparisons between inferred phylogenies of Nicholson specimens, adaptive morphospace, and treatise-based systematic relationships. Specimen-based cladistic and phenetic analyses of Nicholson's species both produce clusters that are congruent with existing family-level taxonomic assignments of species in the collection. However, cladistic analysis more fully retrieves the pattern of branching, or degree of relatedness, among higher taxa. Phenetic clusters represent adaptive peaks in morphospace for these specimens, but higher level “phenons” are strongly affected by multiple evolution of the same character states.

scholarly journals What have humans done for evolutionary biology? Contributions from genes to populations

2017 ◽  
Vol 284 (1866) ◽  
pp. 20171164 ◽  
Author(s):  
Michael Briga ◽  
Robert M. Griffin ◽  
Vérane Berger ◽  
Jenni E. Pettay ◽  
Virpi Lummaa
Keyword(s):  
Natural Selection ◽  
Evolutionary Biology ◽  
Human Study ◽  
Human Studies ◽  
Human Populations ◽  
Evolutionary Processes ◽  
Biological Relevance ◽  
Evolutionary Studies ◽  
Almost All ◽  
Study Designs

Many fundamental concepts in evolutionary biology were discovered using non-human study systems. Humans are poorly suited to key study designs used to advance this field, and are subject to cultural, technological, and medical influences often considered to restrict the pertinence of human studies to other species and general contexts. Whether studies using current and recent human populations provide insights that have broader biological relevance in evolutionary biology is, therefore, frequently questioned. We first surveyed researchers in evolutionary biology and related fields on their opinions regarding whether studies on contemporary humans can advance evolutionary biology. Almost all 442 participants agreed that humans still evolve, but fewer agreed that this occurs through natural selection. Most agreed that human studies made valuable contributions to evolutionary biology, although those less exposed to human studies expressed more negative views. With a series of examples, we discuss strengths and limitations of evolutionary studies on contemporary humans. These show that human studies provide fundamental insights into evolutionary processes, improve understanding of the biology of many other species, and will make valuable contributions to evolutionary biology in the future.

scholarly journals Inferring restrictions in the temporal order of mutations during tumor progression: effects of passengers, evolutionary models, and sampling

2014 ◽  
Author(s):  
Ramon Diaz-Uriarte
Keyword(s):  
Tumor Progression ◽  
Cancer Progression ◽  
Performance Metrics ◽  
Simulated Data ◽  
Evolutionary Model ◽  
Data Sets ◽  
Evolutionary Models ◽  
Cross Sectional ◽  
Order Restrictions ◽  
Sampling Schemes

Cancer progression is caused by the sequential accumulation of mutations, but not all orders of accumulation of mutations are equally likely. When the fixation of some mutations depends on the presence of previous ones, identifying restrictions in the order of accumulation of mutations can lead to the discovery of therapeutic targets and diagnostic markers. Using simulated data sets, I conducted a comprehensive comparison of the performance of all available methods to identify these restrictions from cross-sectional data. In contrast to previous work, I embedded restrictions within evolutionary models of tumor progression that included passengers (mutations not responsible for the development of cancer, known to be very common). This allowed me to asses the effects of having to filter out passengers, of sampling schemes, and of deviations from order restrictions. Poor choices of method, filtering, and sampling lead to large errors in all performance metrics. Having to filter passengers lead to decreased performance, especially because true restrictions were missed. Overall, the best method for identifying order restrictions were Oncogenetic Trees, a fast and easy to use method that, although unable to recover dependencies of mutations on more than one mutation, showed good performance in most scenarios, superior to Conjunctive Bayesian Networks and Progression Networks. Single cell sampling provided no advantage, but sampling in the final stages of the disease vs.\ sampling at different stages had severe effects. Evolutionary model and deviations from order restrictions had major, and sometimes counterintuitive, interactions with other factors that affected performance. This paper provides practical recommendations for using these methods with experimental data. Moreover, it shows that it is both possible and necessary to embed assumptions about order restrictions and the nature of driver status within evolutionary models of cancer progression to evaluate the performance of inferential approaches.

scholarly journals Clergy Who Leave Congregational Ministry: A Review of the Literature

2021 ◽  
Author(s):  
Allison Hamm ◽  
David Eagle
Keyword(s):  
Common Factor ◽  
Empirical Support ◽  
Roman Catholic ◽  
Personal Goals ◽  
Review Of The Literature ◽  
System A ◽  
Large Numbers ◽  
The 1960S ◽  
Protestant Denominations ◽  
Congregational Ministry

Since its inception in the 1960s, research on premature (pre-retirement) clergy attrition from congregational ministry has focused on identifying the factors that precipitate and mitigate ministry exits, while the rates at which clergy leave the ministry have been inconsistently tracked. The literature on clergy attrition is peppered with claims of alarmingly high rates of departure, however, these studies lack strong empirical support. The evidence, while fragmentary, consistently shows that pastors do not leave congregational ministry in large numbers. Incidence of attrition of about 1–2 percent per year is typical across Protestant denominations and among Roman Catholic priests. In addition, contrary to popular conceptions, there is little evidence attrition is particularly high in the first 5 years of congregational ministry. In terms of the reasons for leaving, among Protestants, the most common factor named is conflict with the congregation or denominational system; a smaller number leave to pursue personal goals or to care for family. Among Catholics, loneliness and isolation, tied in major part to the celibacy requirement, are the most significant reasons cited for leaving. Finances or a loss of faith are rarely cited as reasons for leaving among either Catholics or Protestants.

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