scholarly journals Natural selection and neutral evolutionary processes contribute to genetic divergence in leaf traits across a precipitation gradient in the tropical oakQuercus oleoides

2018 ◽  
Vol 27 (9) ◽  
pp. 2176-2192 ◽  
Author(s):  
José A. Ramírez-Valiente ◽  
Nicholas J. Deacon ◽  
Julie Etterson ◽  
Alyson Center ◽  
Jed P. Sparks ◽  
...  
Keyword(s):  
Natural Selection ◽  
Genetic Divergence ◽  
Leaf Traits ◽  
Precipitation Gradient ◽  
Evolutionary Processes

Getting Beyond the Apemen

2021 ◽  
pp. 1-18
Author(s):  
Lesley Newson ◽  
Peter J. Richerson
Keyword(s):  
At Risk ◽  
Natural Selection ◽  
Human Evolution ◽  
Evolutionary Process ◽  
Adult Males ◽  
Evolutionary Processes ◽  
Complex Information ◽  
History Of ◽  
Evolution By Natural Selection

This introductory chapter explains why a new story of human evolution is needed, and also lays the foundations of the story told in this book. One of the reasons we need a new story is that previous stories have concentrated on what our male ancestors were doing. Since survival is most at risk in the first years of life, it makes much more sense to concentrate on children and their mothers than on adult males. A brief account of the history of ideas in evolution by natural selection and human evolution provides readers with a background in evolutionary processes. Humans are a product of evolution, but we are not like other animals, because we are connected and readily share complex information. We are unique and our evolution was the result of a unique evolutionary process. To understand ourselves in evolutionary terms, it’s necessary to consider two intertwined evolutionary processes—genes and culture.

scholarly journals Population genomics in two cave-obligate invertebrates confirms extremely limited dispersal between caves

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Andras Balogh ◽  
Lam Ngo ◽  
Kirk S. Zigler ◽  
Groves Dixon
Keyword(s):  
Genetic Divergence ◽  
Population Genomics ◽  
Sample Sizes ◽  
Dense Region ◽  
Evolutionary Processes ◽  
Cumberland Plateau ◽  
Selective Pressures ◽  
Genome Wide ◽  
Good Sample ◽  
Limited Dispersal

Abstract Caves offer selective pressures that are distinct from the surface. Organisms that have evolved to exist under these pressures typically exhibit a suite of convergent characteristics, including a loss or reduction of eyes and pigmentation. As a result, cave-obligate taxa, termed troglobionts, are no longer viable on the surface. This circumstance has led to an understanding of highly constrained dispersal capabilities, and the prediction that, in the absence of subterranean connections, extreme genetic divergence between cave populations. An effective test of this model would involve (1) common troglobionts from (2) nearby caves in a cave-dense region, (3) good sample sizes per cave, (4) multiple taxa, and (5) genome-wide characterization. With these criteria in mind, we used RAD-seq to genotype an average of ten individuals of the troglobiotic spider Nesticus barri and the troglobiotic beetle Ptomaphagus hatchi, each from four closely located caves (ranging from 3 to 13 km apart) in the cave-rich southern Cumberland Plateau of Tennessee, USA. Consistent with the hypothesis of highly restricted dispersal, we find that populations from separate caves are indeed highly genetically isolated. Our results support the idea of caves as natural laboratories for the study of parallel evolutionary processes.

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 Evolution of genetic variance during adaptive radiation

2017 ◽  
Author(s):  
Greg M. Walter ◽  
J. David Aguirre ◽  
Mark W. Blows ◽  
Daniel Ortiz-Barrientos
Keyword(s):  
Natural Selection ◽  
Adaptive Radiation ◽  
Genetic Variance ◽  
Allelic Variation ◽  
Genetic Correlations ◽  
Leaf Traits ◽  
Adaptive Divergence ◽  
Ecotypic Differentiation ◽  
Divergent Natural Selection ◽  
Rapid Divergence

AbstractGenetic correlations between traits can bias adaptation away from optimal phenotypes and constrain the rate of evolution. If genetic correlations between traits limit adaptation to contrasting environments, rapid adaptive divergence across a heterogeneous landscape may be difficult. However, if genetic variance can evolve and align with the direction of natural selection, then abundant allelic variation can promote rapid divergence during adaptive radiation. Here, we explored adaptive divergence among ecotypes of an Australian native wildflower by quantifying divergence in multivariate phenotypes of populations that occupy four contrasting environments. We investigated differences in multivariate genetic variance underlying morphological traits and examined the alignment between divergence in phenotype and divergence in genetic variance. We found that divergence in mean multivariate phenotype has occurred along two major axes represented by different combinations of plant architecture and leaf traits. Ecotypes also showed divergence in the level of genetic variance in individual traits, and the multivariate distribution of genetic variance among traits. Divergence in multivariate phenotypic mean aligned with divergence in genetic variance, with most of the divergence in phenotype among ecotypes associated with a change in trait combinations that had substantial levels of genetic variance in each ecotype. Overall, our results suggest that divergent natural selection acting on high levels of standing genetic variation might fuel ecotypic differentiation during the early stages of adaptive radiation.

Brain evolution by natural selection

2006 ◽  
Vol 29 (1) ◽  
pp. 23-24 ◽  
Author(s):  
Toru Shimizu
Keyword(s):  
Natural Selection ◽  
Brain Evolution ◽  
Evolutionary Processes ◽  
Evolution By Natural Selection

Principles of Brain Evolution (Striedter 2005) places little emphasis on natural selection. However, one cannot fully appreciate the diversity of brains across species, nor the evolutionary processes driving such diversity, without an understanding of the effects of natural selection. Had Striedter included more extensive discussions about natural selection, his text would have been more balanced and comprehensive.

scholarly journals A Test of Neutrality Based on Interlocus Associations

Genetics ◽  
1997 ◽  
Vol 146 (3) ◽  
pp. 1197-1206 ◽  
Author(s):  
John K Kelly
Keyword(s):  
Drosophila Melanogaster ◽  
Natural Selection ◽  
Neutral Theory ◽  
Upper Bounds ◽  
Statistical Properties ◽  
Neutral Model ◽  
Genetic Associations ◽  
Evolutionary Processes ◽  
Expected Values ◽  
Genomic Regions

The evolutionary processes governing variability within genomic regions of low recombination have been the focus of many studies. Here, I investigate the statistical properties of a measure of intrlocus genetic associations under the assumption that mutations are selectively neutral and sites are completely linked. This measure, denoted ZnS, is based on the squared correlation of allelic identity at pairs of polymorphic sites. Upper bounds for ZnS are determined by simulations. Various deviations from the neutral model, including several different forms of natural selection, will inflate the value of ZnS relative to its neutral theory expectations. Larger than expected values of ZnS are observed in genetic samples from the yellow-ac-scute and Adh regions of Drosophila melanogaster.

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