Evolutionary Demography

2021 ◽  
pp. 273-284
Author(s):  
Shripad Tuljapurkar ◽  
Wenyun Zuo
Keyword(s):  
Nonlinear Models ◽  
Large Body ◽  
Life History Evolution ◽  
General Concept ◽  
Life Cycles ◽  
Theoretical Methods ◽  
Evolutionary Demography ◽  
Variable Environments ◽  
Reproductive Life ◽  
Main Ideas

Evolutionary demography has grown rapidly in recent years, as the biological topics of life history evolution and evolution in population with complex life cycles have benefitted from and contributed to a broader focus on evolutionary biodemography. This chapter provides a critical summary of the central ideas and methods. The authors emphasise theoretical methods, starting with the main ideas that have attracted attention in the field, the assumptions behind these, and efforts to relax those assumptions, and provide a short account of some new directions. The chapter begins with the classic work of Peter Medawar and William Hamilton and discusses the connections, applications, assumptions, and limitations related to their ideas and results, e.g. sensitivity and corresponding elasticity of growth rate on fertility and survival. It highlights extensions to variable environments and the large body of theory around that topic. Next the chapter discusses how these theoretical methods are related to analyses and theories of post-reproductive life, via the general concept of ‘borrowing fitness’. Finally, the chapter discusses nonlinear models of mutation and selection and density-dependent models.

Life-history and the evolution of ontogeny in the ostracode genus Cyprideis

Paleobiology ◽  
1990 ◽  
Vol 16 (2) ◽  
pp. 107-125 ◽  
Author(s):  
Peter N. Schweitzer ◽  
G. P. Lohmann
Keyword(s):  
Life History ◽  
Fossil Record ◽  
Large Body ◽  
Life History Evolution ◽  
Age At Maturity ◽  
Geological Time ◽  
Large Size ◽  
Fourth Species ◽  
History Evolution ◽  
Duration Of Development

A large body of paleontological literature concerns the importance of ontogeny as a source of morphological variation for evolution; morphologies that appear during one stage of an organism's development are made available for use in another simply by modifying the developmental program. Paleontologists need to know why this occurs, so they can study the process of evolution in extinct animals and so they can discuss the fossil record in terms that are applicable to modern forms. If most cases of heterochrony can be attributed to life-history evolution then the fossil record provides evidence of the nature of selection (in particular the age-specific mortality) that extinct animals experienced. The hypothesis of interest here is that species in which maturity is accelerated will also show generalized morphology and small size, while those with delayed maturity will have more specialized morphology and large size.Four species of the ostracode genus Cyprideis were studied to determine whether differences in age at maturity are correlated with heterochrony in the expected manner. For each species the changes in size and shape through geological time were evaluated in the statistical context of modern geographic and seasonal variation. Living populations were sampled regularly to detect differences in seasonality and to estimate the duration of development.Evolution of ontogeny is apparent at the level of species in this group, but it is not simply related to differences in life-history. In comparisons among species, we find evidence of heterochrony where there is no difference in the age at maturity, and a difference in age at maturity where there is no heterochrony. Similarly, three of the four species show the expected positive correlation between size and age at maturity, yet the fourth species is relatively large and matures rapidly. Cyprideis does not support the generalization that life-history evolution causes heterochrony, and casts doubt on the inference of life-history evolution from heterochrony where the data are drawn exclusively from extinct forms.

Co-Delivery Nanosystems for Cancer Treatment: A Review

2019 ◽  
Vol 7 (2) ◽  
pp. 90-112 ◽  
Author(s):  
Reza Baradaran Eftekhari ◽  
Niloufar Maghsoudnia ◽  
Shabnam Samimi ◽  
Ali Zamzami ◽  
Farid Abedin Dorkoosh
Keyword(s):  
Drug Delivery Systems ◽  
Therapeutic Agents ◽  
General Concept ◽  
Delivery Systems ◽  
Cancer Growth ◽  
Massive Data ◽  
Biological Complexity ◽  
Single Drug ◽  
Or Gene ◽  
Main Ideas

Massive data available on cancer therapy more than ever lead our mind to the general concept that there is no perfect treatment for cancer. Indeed, the biological complexity of this disease is too excessive to be treated by a single therapeutic approach. Current delivery systems containing a specific drug or gene have their particular opportunities and restrictions. It is worth noting that a considerable number of studies suggest that single- drug delivery systems result in insufficient suppression of cancer growth. Therefore, one of the main ideas of co-delivery system designing is to enhance the intended response or to achieve the synergistic/combined effect compared to the single drug strategy. This review focuses on various strategies for co-delivery of therapeutic agents in the treatment of cancer. The primary approaches within the script are categorized into co-delivery of conventional chemotherapeutics, gene-based molecules, and plant-derived materials. Each one is explained in examples with the recent researches. In the end, a brief summary is provided to conclude the gist of the review.

scholarly journals Genome-Wide Analyses of Individual Strongyloides stercoralis (Nematoda: Rhabditoidea) Provide Insights into Population Structure and Reproductive Life Cycles

2016 ◽  
Vol 10 (12) ◽  
pp. e0005253 ◽  
Author(s):  
Taisei Kikuchi ◽  
Akina Hino ◽  
Teruhisa Tanaka ◽  
Myo Pa Pa Thet Hnin Htwe Aung ◽  
Tanzila Afrin ◽  
...  
Keyword(s):  
Population Structure ◽  
Strongyloides Stercoralis ◽  
Life Cycles ◽  
Genome Wide ◽  
Reproductive Life

scholarly journals Cyclical environments drive variation in life history strategies: a general theory of cyclical phenology

2018 ◽  
Author(s):  
John S. Park
Keyword(s):  
Life History ◽  
Life History Theory ◽  
Natural Populations ◽  
Life History Evolution ◽  
Life Cycles ◽  
Life History Strategies ◽  
Life History Variation ◽  
Trade Offs ◽  
Overwhelming Evidence ◽  
Phenological Shifts

ABSTRACTCycles, such as seasons or tides, characterize many systems in nature. Overwhelming evidence shows that climate change-driven alterations to environmental cycles—such as longer seasons— are associated with phenological shifts around the world, suggesting a deep link between environmental cycles and life cycles. However, general mechanisms of life history evolution in cyclical environments are still not well understood. Here I build a demographic framework and ask how life history strategies optimize fitness when the environment perturbs a structured population cyclically, and how strategies should change as cyclicality changes. I show that cycle periodicity alters optimality predictions of classic life history theory because repeated cycles have rippling selective consequences over time and generations. Notably, fitness landscapes that relate environmental cyclicality and life history optimality vary dramatically depending on which trade-offs govern a given species. The model tuned with known life history trade-offs in a marine intertidal copepod T. californicus successfully predicted the shape of life history variation across natural populations spanning a gradient of tidal periodicities. This framework shows how environmental cycles can drive life history variation—without complex assumptions of individual responses to cues such as temperature—thus expanding the range of life history diversity explained by theory and providing a basis for adaptive phenology.

scholarly journals A key role for UV sex chromosomes in the regulation of parthenogenesis in the brown algaEctocarpus

2018 ◽  
Author(s):  
Laure Mignerot ◽  
Komlan Avia ◽  
Remy Luthringer ◽  
Agnieszka P. Lipinska ◽  
Akira F. Peters ◽  
...  
Keyword(s):  
Life Cycle ◽  
Asexual Reproduction ◽  
Sex Chromosome ◽  
Natural Populations ◽  
Life History Evolution ◽  
Life Cycles ◽  
Negative Effects ◽  
Evolutionary Transitions ◽  
Trade Offs ◽  
Sexual And Asexual Reproduction

AbstractAlthough evolutionary transitions from sexual to asexual reproduction are frequent in eukaryotes, the genetic bases of these shifts remain largely elusive. Here, we used classic quantitative trait analysis, combined with genomic and transcriptomic information to dissect the genetic basis of asexual, parthenogenetic reproduction in the brown algaEctocarpus. We found that parthenogenesis is controlled by the sex locus, together with two additional autosomal loci, highlight the key role of the sex chromosome as a major regulator of asexual reproduction. Importantly, we identify several negative effects of parthenogenesis on male fitness, but also different fitness effects between parthenogenesis and life cycle generations, supporting the idea that parthenogenesis may be under both sexual selection and generation/ploidally-antagonistic selection. Overall, our data provide the first empirical illustration, to our knowledge, of a trade-off between the haploid and diploid stages of the life cycle, where distinct parthenogenesis alleles have opposing effects on sexual and asexual reproduction and may contribute to the maintenance of genetic variation. These types of fitness trade-offs have profound evolutionary implications in natural populations and may structure life history evolution in organisms with haploid-diploid life cycles.

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