Evolution of single characters in the Jurassic ammonite Kosmoceras

The classic biometrical study of phyletic evolution in Kosmoceras (Brinkmann 1929) is evaluated using unpublished raw data provided by Professor Brinkmann. Most morphological characters show statistically significant changes over time yet it is difficult to provide an unequivocal biological interpretation for these changes. In a few cases, runs tests indicate that evolution was nonrandom in the sense that fewer reversals in the direction of evolution occurred than would be predicted from a null hypothesis based on a random walk. These cases suggest persistence of natural selection regimes for fairly long periods of time. In other cases, and with other kinds of testing, the random walk model cannot be rejected although failure to reject the hypothesis does not justify its acceptance! Thus, the contribution of random factors (either genetic drift or selection in a randomly changing environment) cannot be assessed with confidence. It is problematical also whether the Kosmoceras series represent significant evolution by phyletic gradualism or just the natural temporal variation that characterizes stasis (sensu Eldredge and Gould 1972).

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Applications of Supercomputers in Population Genetics

Advances in Systems Analysis, Software Engineering, and High Performance Computing - Research and Applications in Global Supercomputing ◽

10.4018/978-1-4666-7461-5.ch007 ◽

2015 ◽

pp. 176-200

Author(s):

Gerard G. Dumancas

Keyword(s):

Population Genetics ◽

Natural Selection ◽

Genetic Drift ◽

Critical Role ◽

Allele Frequency Distribution ◽

Modern Approach ◽

Mathematical Discipline ◽

Modern Evolutionary Synthesis ◽

Changes Over Time ◽

Over Time

Population genetics is the study of the frequency and interaction of alleles and genes in population and how this allele frequency distribution changes over time as a result of evolutionary processes such as natural selection, genetic drift, and mutation. This field has become essential in the foundation of modern evolutionary synthesis. Traditionally regarded as a highly mathematical discipline, its modern approach comprises more than the theoretical, lab, and fieldwork. Supercomputers play a critical role in the success of this field and are discussed in this chapter.

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Applications of Supercomputers in Population Genetics

Biotechnology ◽

10.4018/978-1-5225-8903-7.ch028 ◽

2019 ◽

pp. 693-719

Author(s):

Gerard G. Dumancas

Keyword(s):

Population Genetics ◽

Natural Selection ◽

Genetic Drift ◽

Critical Role ◽

Allele Frequency Distribution ◽

Modern Approach ◽

Mathematical Discipline ◽

Modern Evolutionary Synthesis ◽

Changes Over Time ◽

Over Time

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Cultural evolution

Routledge Encyclopedia of Philosophy ◽

10.4324/9780415249126-q128-1 ◽

2018 ◽

Author(s):

Matteo Mameli ◽

Kim Sterelny

Keyword(s):

Natural Selection ◽

Social Learning ◽

Cultural Change ◽

Biological Evolution ◽

Phenotypic Traits ◽

Or Groups ◽

Cumulative Change ◽

Cultural Traits ◽

Changes Over Time ◽

Over Time

Cultural traits are those phenotypic traits whose development depends on social learning. These include practices, skills, beliefs, desires, values, and artefacts. The distribution of cultural traits in the human species changes over time. But this is not enough to show that culture evolves. That depends on the mechanisms of change. In the cultural realm, one can often observe something similar to biology’s ‘descent with modification’: cultural traits are sometimes modified, their modifications are sometimes retained and passed on to others through social learning, until new modifications are added. In this way, new modifications are piled on top of old modifications, generating cumulative change. But, again, this is not enough to show that culture evolves. For culture to evolve, cumulative change must be the result of hidden-hand mechanisms similar to those that explain cumulative biological change. If cumulative cultural change cannot be explained in these terms, the analogy between cultural change and biological evolution is unhelpful. The best-known biological mechanism is natural selection. There are reasons to think that cultural change is at least sometimes due to natural-selection-like mechanisms. The adaptive fit often found between cultural traits and the environment in many cases has been built gradually and in a way that involves natural selection operating at the cultural level. The parallel with morphological adaptation is compelling. No complete and universally accepted account of natural-selection-like processes operating at the cultural level exists at this stage. But at least three kinds of processes seem possible: - A natural-selection-like process can be generated by culturally heritable differences in fitness between individuals. - A natural-selection-like process can be generated by culturally heritable differences in fitness between groups. - A natural-selection-like process can operate at the level of cultural variants themselves, independently of the effects that cultural variants have on the fitness of individuals or groups. The theory of memes (initially presented by Dawkins and then developed by Dennett) is one possible account of how (iii) might work; but other accounts exist too.

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The pattern of evolution in Pleistocene human brain size

Paleobiology ◽

10.1017/s0094837300018054 ◽

2003 ◽

Vol 29 (2) ◽

pp. 186-196 ◽

Cited By ~ 24

Author(s):

Sang-Hee Lee ◽

Milford H. Wolpoff

Keyword(s):

Human Brain ◽

Null Hypothesis ◽

Brain Size ◽

New Method ◽

Cranial Capacity ◽

Size Change ◽

Time Period ◽

Single Process ◽

Changes Over Time ◽

Over Time

With a sample of 94 Pleistocene cranial capacities between the time period of 1.8 Ma and 50 Ka now known, we consider the evolution of cranial capacity in Homo, with the null hypothesis that the changes over time are a result of one process. We employ a new method that uses a resampling approach to address the limitations imposed on the methods of previous studies. To test the null hypothesis, we examine the distribution of changes in adjacent temporal samples and ask whether there are differences between earlier and later samples. Our analyses do not reject the hypothesis of a single process of brain size change, but they are incompatible with an interpretation of punctuated equilibrium during this period. The results of this paper are difficult to reconcile with the case for cladogenesis in the Homo lineage during the Pleistocene.

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Frequencies of mitochondrial DNA haplotypes in laboratory cage populations of the mosquito, Aedes albopictus.

Genetics ◽

10.1093/genetics/132.1.205 ◽

1992 ◽

Vol 132 (1) ◽

pp. 205-209 ◽

Cited By ~ 2

Author(s):

S Kambhampati ◽

K S Rai ◽

D M Verleye

Keyword(s):

Mitochondrial Dna ◽

Statistical Analysis ◽

Aedes Albopictus ◽

Genetic Drift ◽

Random Genetic Drift ◽

Haplotype Frequencies ◽

F2 Generation ◽

Changes Over Time ◽

Over Time ◽

F1 Generation

Abstract A laboratory cage experiment was undertaken to study changes over time in the frequencies of two mitochondrial DNA (mtDNA) haplotypes in the mosquito, Aedes albopictus, under two conditions: bidirectionally compatible matings and unidirectionally incompatible matings. Frequencies were monitored for 10 generations in three replicate cages for each of the two conditions above. In cages with bidirectionally compatible strains, changes in haplotype frequencies were nondirectional and neither haplotype increased in frequency. Statistical analysis of relative proportions of the two haplotypes in each generation indicated that the magnitude of the observed fluctuations could be expected under an assumption of random genetic drift alone. In cages with unidirectionally incompatible matings, mtDNA of females that lay inviable eggs upon mating with males of another strain, decreased significantly in the F1 generation and was completely replaced in the F2 generation.

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Is phonological consonant epenthesis possible? A series of artificial grammar learning experiments

Phonology ◽

10.1017/s0952675718000234 ◽

2018 ◽

Vol 35 (4) ◽

pp. 649-688

Author(s):

Rebecca L. Morley

Keyword(s):

Individual Variation ◽

Null Hypothesis ◽

Formal Theory ◽

Artificial Grammar Learning ◽

Artificial Grammar ◽

Linguistic Data ◽

Grammar Learning ◽

Gradual Accumulation ◽

Changes Over Time ◽

Over Time

Consonant epenthesis is typically assumed to be part of the basic repertoire of phonological grammars. This implies that there exists some set of linguistic data for which epenthesis is the best analysis. However, a series of artificial grammar learning experiments found no evidence that learners ever selected an epenthesis analysis. Instead, phonetic and morphological biases were revealed, along with individual variation in how learners generalised and regularised their input. These results, in combination with previous work, suggest that synchronic consonant epenthesis may only emerge very rarely, as a result of a gradual accumulation of changes over time. It is argued that stored stem–allomorph pairs should be adopted as the null hypothesis in cases of potential epenthesis, and that a universal criterion is needed for rejecting this hypothesis. Such a criterion requires a formal theory of exceptions, a necessity for falsifiability in phonological theory.

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Testing Natural Selection vs. Genetic Drift in Phenotypic Evolution Using Quantitative Trait Locus Data

Genetics ◽

10.1093/genetics/149.4.2099 ◽

1998 ◽

Vol 149 (4) ◽

pp. 2099-2104 ◽

Cited By ~ 15

Author(s):

H Allen Orr

Keyword(s):

Quantitative Trait Locus ◽

Natural Selection ◽

Genetic Drift ◽

Quantitative Trait ◽

Null Hypothesis ◽

Sign Test ◽

Phenotypic Evolution ◽

Phenotypic Difference ◽

Quantitative Trait Locus Data ◽

Trait Locus

Abstract Evolutionary biologists have long sought a way to determine whether a phenotypic difference between two taxa was caused by natural selection or random genetic drift. Here I argue that data from quantitative trait locus (QTL) analyses can be used to test the null hypothesis of neutral phenotypic evolution. I propose a sign test that compares the observed number of plus and minus alleles in the “high line” with that expected under neutrality, conditioning on the known phenotypic difference between the taxa. Rejection of the null hypothesis implies a role for directional natural selection. This test is applicable to any character in any organism in which QTL analysis can be performed.

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Demography and Evolution in an Immigrant Ethnic Community: Hungarian Settlement, Louisiana, USA

Journal of Biosocial Science ◽

10.1017/s0021932000014516 ◽

1983 ◽

Vol 15 (2) ◽

pp. 223-236 ◽

Cited By ~ 1

Author(s):

Tibor Koertvelyessy

Keyword(s):

Gene Flow ◽

Natural Selection ◽

Genetic Drift ◽

Demographic Characteristics ◽

Ethnic Population ◽

Marriage Patterns ◽

Evolutionary Forces ◽

Evolutionary Force ◽

Demographic Processes ◽

Over Time

SummaryThis paper describes the fertility, mortality, and marriage patterns of the Hungarian Settlement, Louisiana, USA, immigrant ethnic population and relates these demographic processes to the evolutionary forces of natural selection, genetic drift, and gene flow. The results indicate that the maximum opportunity for natural selection decreased over time, and natural selection could have operated in the case of this population at only a very moderate level. The demographic characteristics of this population suggest that genetic drift may be important as an agent of microdifferentiation. Gene flow, however, appears to be the most important evolutionary force in this population. The process, based on the increasing incorporation of non-Hungarians into the gene pool, is causing the breakdown of this ethnic/genetic isolate.

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Comparison of two devices for measuring exercise transcutaneous oxygen pressures in patients with claudication

VASA ◽

10.1024/0301-1526/a000454 ◽

2015 ◽

Vol 44 (5) ◽

pp. 355-362 ◽

Cited By ~ 8

Author(s):

Marie Urban ◽

Alban Fouasson-Chailloux ◽

Isabelle Signolet ◽

Christophe Colas Ribas ◽

Mathieu Feuilloy ◽

...

Keyword(s):

Oxygen Pressure ◽

Optical Sensors ◽

Chemical Sensors ◽

Transcutaneous Oxygen ◽

Starting Values ◽

Two Systems ◽

Transcutaneous Oxygen Pressure ◽

New Sensors ◽

Changes Over Time ◽

Over Time

Abstract. Summary: Background: We aimed at estimating the agreement between the Medicap® (photo-optical) and Radiometer® (electro-chemical) sensors during exercise transcutaneous oxygen pressure (tcpO2) tests. Our hypothesis was that although absolute starting values (tcpO2rest: mean over 2 minutes) might be different, tcpO2-changes over time and the minimal value of the decrease from rest of oxygen pressure (DROPmin) results at exercise shall be concordant between the two systems. Patients and methods: Forty seven patients with arterial claudication (65 + / - 7 years) performed a treadmill test with 5 probes each of the electro-chemical and photo-optical devices simultaneously, one of each system on the chest, on each buttock and on each calf. Results: Seventeen Medicap® probes disconnected during the tests. tcpO2rest and DROPmin values were higher with Medicap® than with Radiometer®, by 13.7 + / - 17.1 mm Hg and 3.4 + / - 11.7 mm Hg, respectively. Despite the differences in absolute starting values, changes over time were similar between the two systems. The concordance between the two systems was approximately 70 % for classification of test results from DROPmin. Conclusions: Photo-optical sensors are promising alternatives to electro-chemical sensors for exercise oximetry, provided that miniaturisation and weight reduction of the new sensors are possible.

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