DOCSLIB.ORG

Life History Tradeoffs and the Evolutionary Biology of Aging

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Life History Tradeoffs and the Evolutionary Biology of Aging OUP CORRECTED PROOF – FINAL, 04/27/2013, SPi 5 Life history tradeoffs and the evolutionary biology of aging 5.1 Introduction We commonly talk about our lives in terms of the life course or life cycle. Although each of us goes through a life cycle only once, there is a continuity of life cycles from generation to generation. Some biologists view life cycles as the fundamental units of biological organiza- tion and think about evolution as the evolution of life cycles ( Bonner 1993 ; Sterelny and Griffi ths 1999 ). Evolutionary life history theory provides a framework for understanding how natural selection has shaped life cycles in ways that optimize reproductive fi tness ( Charnov 1993 ; Stearns 1992 ). Life history theory provides a coherent view of the entire human life cycle and is especially important for medicine because it underlies the evolutionary theory of aging. Organisms require nutrients and other resources—oxygen, water, heat, shelter, other organisms, etc.—to survive and reproduce. Th ey can acquire these resources directly from their environments or indirectly from others, most often their parents, and they have to allo- cate these resources, as well as their time, among a handful of tasks, including growth and development, reproduction, prevention and repair of bodily damage, external work, and stor- age. Prevention of bodily damage includes responding to and countering threats and stresses. And reproduction does not simply mean the energetic cost of having babies. It refers to all of the costs of producing and maintaining secondary sexual characteristics and fi nding mating partners, as well as bearing, raising, and providing resources for their off spring. In demo- graphic terms, organisms use resources to increase survival and to increase fertility. Life his- tory theory is a theory of the ways in which natural selection has shaped the physiological and behavioral mechanisms that regulate the acquisition and allocation of these resources over the life cycle. Th e human life cycle can be divided into several more or less distinct stages—prenatal, infant (nursing), post-weaning dependent child, puberty and adolescence, sexual and repro- ductive maturity, and post-reproductive life. Th ese stages are distinguished by diff erences in the ways we acquire and use nutrients and other resources. Natural selection has adjusted the timing of these stages as well as our activities in them. It has modulated the duration of gestation and of nursing, our overall growth rates and the growth of individual organs during childhood, the timing of puberty and the age at which we reach reproductive maturity, how Evolution and Medicine. First Edition. Robert L. Perlman © Robert L. Perlman 2013. Published 2013 by Oxford University Press. OUP CORRECTED PROOF – FINAL, 04/27/2013, SPi 52 Evolution and Medicine frequently we reproduce and how many children we have each time we do so, the age at which we cease reproduction, and the length of our post-reproductive lives ( Stearns et al. 2008 ). Hormones mediate many of these life history “decisions” and so they play a central role in life history theory. Each of these life history decisions involves tradeoff s or compromises. With respect to the duration of gestation, for example, there are advantages for fetuses to remain in utero, since the uterus provides a protected environment in which they can grow and develop. As fetuses grow larger, however, they become a bigger nutritional burden on the mother and suff er an increased risk of complications during labor and delivery. Th e timing of labor and delivery is apparently the optimal compromise between these two competing demands ( Ellison 2001 ). Th e age at which we reach puberty and sexual maturity also involves trade- off s. We need time to develop physically, psychologically, and socially to the point that we can bear and care for children. On the other hand, we need to become sexually mature and have the opportunity to reproduce when we are still young enough that we can have and raise our children before we’re likely to die. Yet again, there is a tradeoff between fertility and the survival of off spring that we discussed in Chapter 2, because the more children we have, the fewer resources we can allocate to each and the greater is their risk of dying before they reach reproductive maturity. Presumably because they are regulated by pleiotropic genes, many life history traits are correlated among primate or mammalian species. For example, the duration of childhood or juvenility among primates is correlated with their life expectancy ( Leigh 2001 ). Th ere may be tradeoff s among suites of traits that evolve together. Moreover, as we shall discuss later, our life history strategies are not fi xed but can change in response to environmental signals we receive during development. Th e range of life histories or other phenotypes that can be pro- duced by organisms of a single genotype developing in a range of environments is known as their norm of reaction ( Gilbert 2001 ). Natural selection does not act simply to optimize fi tness in one specifi c environment. It modulates the norm of reaction to optimize fi tness across the diversity of environments that a species has encountered during its evolutionary history. Our developmental fl exibility and our ability to survive and reproduce in diff erent environments may limit our adaptation to any one specifi c environment. Th e human life cycle resembles the life cycles of other great apes, especially chimpanzees, but has a number of special features that presumably arose during the past 6 million years or so, since the time the hominin (human) lineage diverged from the lineage leading to chim- panzees ( Robson et al. 2006 ). We have a slightly longer gestation period (9 vs 8 months) and lower rates of twinning than do chimpanzees. Women in many traditional societies nurse their babies for 2½–3 years, whereas chimpanzee mothers nurse for 4–5 years. Juvenile chim- panzees are able to acquire much of their own food by the time they are weaned and typically leave their mothers 2–3 years after weaning. We have a much longer period of childhood or juvenility, when children are no longer nursing but are still dependent on parents or others for food and survival. Because of this long period of childhood dependence, women typically have to care for several dependent children at the same time. Women have their fi rst babies at a considerably older age than do chimpanzee females (19–20 vs 13–14 years). Because of OUP CORRECTED PROOF – FINAL, 04/27/2013, SPi Life history tradeoffs and the evolutionary biology of aging 53 earlier weaning, women in natural fertility societies, i.e. in the absence of contraceptives or family planning, then have babies at shorter intervals than do chimpanzees (3–4 vs 5–6 years). Finally, although both women and chimpanzee mothers can have off spring until their early forties, we have much longer post-reproductive lives: chimpanzee females have life spans of 50–55 years while women have life spans of 80 or longer. Th e special features of the human life cycle must have been shaped by the environments in which ancestral humans evolved, including among other factors the composition of ances- tral human diets ( Kaplan et al. 2003 ). Chimpanzee diets are rich in foods such as fruits and piths (the soft, fl eshy material in the stems and branches of plants), which are relatively easy to obtain. Although we also eat fruits, they are a smaller component of our diets. We have evolved to eat a variety of energy-rich but diffi cult to acquire foods, such as nuts, seeds, roots, and meat. It takes a long time for children to acquire the skills needed to collect enough of these foods to be nutritionally self-suffi cient. After they acquire these skills, however, adults can gather or hunt much more than they themselves need. Our long period of childhood dependence is made possible by the contributions of adults to the nutritional, educational, and social support of children. Th ere are controversies over how long it takes children to acquire the skills they need to become self-suffi cient and over the relative roles of fathers, grandmothers, and other adults in helping to provision dependent children ( Hawkes 2004 ). Th ese aspects of child develop- ment and childcare may well diff er in diff erent societies. Despite these unresolved questions, this ecological perspective provides a plausible and attractive way of understanding the evo- lution of the human life cycle. Evolution of a prolonged childhood, which would have given children the opportunity to gain the knowledge and skills they needed to become self- suffi cient, would have been accompanied by evolution of a longer life span, which gave adults more time to provision their dependent children. Long before the recent advances in medi- cine and public health that have extended our life expectancy, many of our ancestors who survived infancy and childhood went on to have long lives. Even in a population with a life expectancy of only 20 years, about a quarter of the population lives until age 50 ( Coale 1974 ). 5 . 2 Th e causes of death change through the life cycle Diff erent stages of the life cycle are characterized by diff erent patterns of disease and death. Recall that the major causes of death in infancy and childhood include congenital malforma- tions and chromosomal abnormalities, genetic diseases, developmental defects, infectious diseases, and nutritional defi ciencies. Th e high mortality of adolescent and young sexually mature men is due in large part to accidents, violence, and suicide. Deaths due to cardiovas- cular diseases and most cancers increase from about age ten onward but these diseases don’t become the leading causes of death until around age 40, near the end of our period of repro- ductive maturity.
Load more

Recommended publications
  • History and Philosophy of Systematic Biology
    History and Philosophy of Systematic Biology Bock, W. J. (1973) Philosophical foundations of classical evolutionary classification Systematic Zoology 22: 375-392 Part of a general symposium on "Contemporary Systematic Philosophies," there are some other interesting papers here. Brower, A. V. Z. (2000) Evolution Is Not a Necessary Assumption of Cladistics Cladistics 16: 143- 154 Dayrat, Benoit (2005) Ancestor-descendant relationships and the reconstruction of the Tree of Lif Paleobiology 31: 347-353 Donoghue, M.J. and J.W. Kadereit (1992) Walter Zimmermann and the growth of phylogenetic theory Systematic Biology 41: 74-84 Faith, D. P. and J. W. H. Trueman (2001) Towards an inclusive philosophy for phylogenetic inference Systematic Biology 50: 331-350 Gaffney, E. S. (1979) An introduction to the logic of phylogeny reconstruction, pp. 79-111 in Cracraft, J. and N. Eldredge (eds.) Phylogenetic Analysis and Paleontology Columbia University Press, New York. Gilmour, J. S. L. (1940) Taxonomy and philosophy, pp. 461-474 in J. Huxley (ed.) The New Systematics Oxford Hull, D. L. (1978) A matter of individuality Phil. of Science 45: 335-360 Hull, D. L. (1978) The principles of biological classification: the use and abuse of philosophy Hull, D. L. (1984) Cladistic theory: hypotheses that blur and grow, pp. 5-23 in T. Duncan and T. F. Stuessy (eds.) Cladistics: Perspectives on the Reconstruction of Evolutionary History Columbia University Press, New York * Hull, D. L. (1988) Science as a process: an evolutionary account of the social and conceptual development of science University of Chicago Press. An already classic work on the recent, violent history of systematics; used as data for Hull's general theories about scientific change.
    [Show full text]
  • 1. Adaptation and the Evolution of Physiological Characters
    Bennett, A. F. 1997. Adaptation and the evolution of physiological characters, pp. 3-16. In: Handbook of Physiology, Sect. 13: Comparative Physiology. W. H. Dantzler, ed. Oxford Univ. Press, New York. 1. Adaptation and the evolution of physiological characters Department of Ecology and Evolutionary Biology, University of California, ALBERT F. BENNETT 1 Irvine, California among the biological sciences (for example, behavioral CHAPTER CONTENTS science [I241). The Many meanings of "Adaptationn In general, comparative physiologists have been Criticisms of Adaptive Interpretations much more successful in, and have devoted much more Alternatives to Adaptive Explanations energy to, pursuing the former rather than the latter Historical inheritance goal (37). Most of this Handbook is devoted to an Developmentai pattern and constraint Physical and biomechanical correlation examination of mechanism-how various physiologi- Phenotypic size correlation cal systems function in various animals. Such compara- Genetic correlations tive studies are usually interpreted within a specific Chance fixation evolutionary context, that of adaptation. That is, or- Studying the Evolution of Physiological Characters ganisms are asserted to be designed in the ways they Macroevolutionary studies Microevolutionary studies are and to function in the ways they do because of Incorporating an Evolutionary Perspective into Physiological Studies natural selection which results in evolutionary change. The principal textbooks in the field (for example, refs. 33, 52, 102, 115) make explicit reference in their titles to the importance of adaptation to comparative COMPARATIVE PHYSIOLOGISTS HAVE TWO GOALS. The physiology, as did the last comparative section of this first is to explain mechanism, the study of how organ- Handbook (32). Adaptive evolutionary explanations isms are built functionally, "how animals work" (113).
    [Show full text]
  • Auditory Experience Controls the Maturation of Song Discrimination and Sexual Response in Drosophila Xiaodong Li, Hiroshi Ishimoto, Azusa Kamikouchi*
    RESEARCH ARTICLE Auditory experience controls the maturation of song discrimination and sexual response in Drosophila Xiaodong Li, Hiroshi Ishimoto, Azusa Kamikouchi* Graduate School of Science, Nagoya University, Nagoya, Japan Abstract In birds and higher mammals, auditory experience during development is critical to discriminate sound patterns in adulthood. However, the neural and molecular nature of this acquired ability remains elusive. In fruit flies, acoustic perception has been thought to be innate. Here we report, surprisingly, that auditory experience of a species-specific courtship song in developing Drosophila shapes adult song perception and resultant sexual behavior. Preferences in the song-response behaviors of both males and females were tuned by social acoustic exposure during development. We examined the molecular and cellular determinants of this social acoustic learning and found that GABA signaling acting on the GABAA receptor Rdl in the pC1 neurons, the integration node for courtship stimuli, regulated auditory tuning and sexual behavior. These findings demonstrate that maturation of auditory perception in flies is unexpectedly plastic and is acquired socially, providing a model to investigate how song learning regulates mating preference in insects. DOI: https://doi.org/10.7554/eLife.34348.001 Introduction Vocal learning in infants or juvenile birds relies heavily on the early experience of the adult conspe- cific sounds. In humans, early language input is necessary to form the ability of phonetic distinction *For correspondence: and pattern detection in the phase of auditory learning (Doupe and Kuhl, 1999; Kuhl, 2004). [email protected] Because of the strong parallels between speech acquisition of humans and song learning of song- Competing interests: The birds, and the difficulties to investigate the neural mechanisms of human early auditory memory at authors declare that no cellular resolution, songbirds have been used as a predominant model in studying memory formation competing interests exist.
    [Show full text]
  • The Evolution of Bird Song: Male and Female Response to Song Innovation in Swamp Sparrows
    ANIMAL BEHAVIOUR, 2001, 62, 1189–1195 doi:10.1006/anbe.2001.1854, available online at http://www.idealibrary.com on The evolution of bird song: male and female response to song innovation in swamp sparrows STEPHEN NOWICKI*, WILLIAM A. SEARCY†, MELISSA HUGHES‡ & JEFFREY PODOS§ *Evolution, Ecology & Organismal Biology Group, Department of Biology, Duke University †Department of Biology, University of Miami ‡Department of Ecology and Evolutionary Biology, Princeton University §Department of Biology, University of Massachusetts at Amherst (Received 27 April 2000; initial acceptance 24 July 2000; final acceptance 19 April 2001; MS. number: A8776) Closely related species of songbirds often show large differences in song syntax, suggesting that major innovations in syntax must sometimes arise and spread. Here we examine the response of male and female swamp sparrows, Melospiza georgiana, to an innovation in song syntax produced by males of this species. Young male swamp sparrows that have been exposed to tutor songs with experimentally increased trill rates reproduce these songs with periodic silent gaps (Podos 1996, Animal Behaviour, 51, 1061–1070). This novel temporal pattern, termed ‘broken syntax’, has been demonstrated to transmit across generations (Podos et al. 1999, Animal Behaviour, 58, 93–103). We show here that adult male swamp sparrows respond more strongly in territorial playback tests to songs with broken syntax than to heterospecific songs, and equally strongly to conspecific songs with normal and broken syntax. In tests using the solicitation display assay, adult female swamp sparrows respond more to broken syntax than to heterospecific songs, although they respond significantly less to conspecific songs with broken syntax than to those with normal syntax.
    [Show full text]
  • The Unique Skeleton of Siliceous Sponges (Porifera; Hexactinellida and Demospongiae) That Evolved first from the Urmetazoa During the Proterozoic: a Review
    Biogeosciences, 4, 219–232, 2007 www.biogeosciences.net/4/219/2007/ Biogeosciences © Author(s) 2007. This work is licensed under a Creative Commons License. The unique skeleton of siliceous sponges (Porifera; Hexactinellida and Demospongiae) that evolved first from the Urmetazoa during the Proterozoic: a review W. E. G. Muller¨ 1, Jinhe Li2, H. C. Schroder¨ 1, Li Qiao3, and Xiaohong Wang4 1Institut fur¨ Physiologische Chemie, Abteilung Angewandte Molekularbiologie, Duesbergweg 6, 55099 Mainz, Germany 2Institute of Oceanology, Chinese Academy of Sciences, 7 Nanhai Road, 266071 Qingdao, P. R. China 3Department of Materials Science and Technology, Tsinghua University, 100084 Beijing, P. R. China 4National Research Center for Geoanalysis, 26 Baiwanzhuang Dajie, 100037 Beijing, P. R. China Received: 8 January 2007 – Published in Biogeosciences Discuss.: 6 February 2007 Revised: 10 April 2007 – Accepted: 20 April 2007 – Published: 3 May 2007 Abstract. Sponges (phylum Porifera) had been considered an axial filament which harbors the silicatein. After intracel- as an enigmatic phylum, prior to the analysis of their genetic lular formation of the first lamella around the channel and repertoire/tool kit. Already with the isolation of the first ad- the subsequent extracellular apposition of further lamellae hesion molecule, galectin, it became clear that the sequences the spicules are completed in a net formed of collagen fibers. of sponge cell surface receptors and of molecules forming the The data summarized here substantiate that with the find- intracellular signal transduction pathways triggered by them, ing of silicatein a new aera in the field of bio/inorganic chem- share high similarity with those identified in other metazoan istry started.
    [Show full text]
  • Basal Metazoans - Dirk Erpenbeck, Simion Paul, Michael Manuel, Paulyn Cartwright, Oliver Voigt and Gert Worheide
    EVOLUTION OF PHYLOGENETIC TREE OF LIFE - Basal Metazoans - Dirk Erpenbeck, Simion Paul, Michael Manuel, Paulyn Cartwright, Oliver Voigt and Gert Worheide BASAL METAZOANS Dirk Erpenbeck Ludwig-Maximilians Universität München, Germany Simion Paul and Michaël Manuel Université Pierre et Marie Curie in Paris, France. Paulyn Cartwright University of Kansas USA. Oliver Voigt and Gert Wörheide Ludwig-Maximilians Universität München, Germany Keywords: Metazoa, Porifera, sponges, Placozoa, Cnidaria, anthozoans, jellyfishes, Ctenophora, comb jellies Contents 1. Introduction on ―Basal Metazoans‖ 2. Phylogenetic relationships among non-bilaterian Metazoa 3. Porifera (Sponges) 4. Placozoa 5. Ctenophora (Comb-jellies) 6. Cnidaria 7. Cultural impact and relevance to human welfare Glossary Bibliography Biographical Sketch Summary Basal metazoans comprise the four non-bilaterian animal phyla Porifera (sponges), Cnidaria (anthozoans and jellyfishes), Placozoa (Trichoplax) and Ctenophora (comb jellies). The phylogenetic position of these taxa in the animal tree is pivotal for our understanding of the last common metazoan ancestor and the character evolution all Metazoa,UNESCO-EOLSS but is much debated. Morphological, evolutionary, internal and external phylogenetic aspects of the four phyla are highlighted and discussed. SAMPLE CHAPTERS 1. Introduction on “Basal Metazoans” In many textbooks the term ―lower metazoans‖ still refers to an undefined assemblage of invertebrate phyla, whose phylogenetic relationships were rather undefined. This assemblage may contain both bilaterian and non-bilaterian taxa. Currently, ―Basal Metazoa‖ refers to non-bilaterian animals only, four phyla that lack obvious bilateral symmetry, Porifera, Placozoa, Cnidaria and Ctenophora. ©Encyclopedia of Life Support Systems (EOLSS) EVOLUTION OF PHYLOGENETIC TREE OF LIFE - Basal Metazoans - Dirk Erpenbeck, Simion Paul, Michael Manuel, Paulyn Cartwright, Oliver Voigt and Gert Worheide These four phyla have classically been known as ―diploblastic‖ Metazoa.
    [Show full text]
  • EMPHASIS in EVOLUTION and SYSTEMATICS Emphasis Adviser: Dr
    CHECK LIST FOR THE B.S. DEGREE IN BIOLOGY EMPHASIS IN EVOLUTION AND SYSTEMATICS Emphasis Adviser: Dr. Tod Reeder (LS-264), 2008-09 Catalog (Use this as a worksheet. Refer to your catalog for official requirements.) Systematicists and evolutionary biologists study patterns of evolutionary relationships among species and evolutionary processes underlying these patterns. Systematics involves detailed study of a group of organisms to determine its evolutionary relationships (phylogeny), clarify its classification, and assess trends in ecology, biogeography, and evolutionary processes. Evolutionary biology explores mechanisms of evolutionary change, including studies of natural selection, migration, mating systems, and genetic drift. Specific studies in systematics or evolutionary biology may encompass anatomy, behavior, biogeography, development, ecology, genetics, and molecular biology of both living and fossil organisms. Graduates can work in universities, museums, botanical gardens, and zoos or with federal, state, and private agencies. Positions may include basic or applied research, such as assessment of biodiversity or environmental quality. Acquisition of laboratory skills, such as electron microscopy or nucleotide sequencing, are required for careers in evolutionary biology. Students should make a particular effort to gain research experience through Undergraduate Research or Special Studies. PREPARATION FOR THE MAJOR (39 units of lower division courses) Biol 201A Principles of Cell & Molecular Biol. 4 ____ Math 121 Calculus for the Life Sciences I 3 ____ Biol 201B Principles of Organismal Biology 4 ____ Math 122 Calculus for the Life Sciences II 3 ____ Biol 215 Biostatistics 3 ____ Phys 180A Fundamentals of Physics 3 ____ Chem 200 General Chemistry 5 ____ Phys 182A Physical Measurements 1 ____ Chem 201 General Chemistry 5 ____ Phys 180B Fundamentals of Physics 3 ____ Chem 231 Organic Chemistry (or 232 and 232L) 4 ____ Phys 182B Physical Measurements 1 ____ The Biology and Microbiology majors are designated as impacted majors.
    [Show full text]
  • Evolutionary History of Life
    Evolutionary history of life The evolutionary history of life on Earth traces the processes by which living and fossil organisms evolved, from the earliest emergence of life to the present. Earth formed about 4.5 billion years (Ga) ago and evidence suggests life emerged prior to 3.7 Ga.[1][2][3] (Although there is some evidence of life as early as 4.1 to 4.28 Ga, it remains controversial due to the possible non- biological formation of the purported fossils.[1][4][5][6][7]) The similarities among all known present-day species indicate that they have diverged through the process of evolution from a common ancestor.[8] Approximately 1 trillion species currently live on Earth[9] of which only 1.75–1.8 million have been named[10][11] and 1.6 million documented in a central database.[12] These currently living species represent less than one percent of all species that have ever lived on earth.[13][14] The earliest evidence of life comes from biogenic carbon signatures[2][3] and stromatolite fossils[15] discovered in 3.7 billion- Life timeline Ice Ages year-old metasedimentary rocks from western Greenland. In 2015, 0 — Primates Quater nary Flowers ←Earliest apes possible "remains of biotic life" were found in 4.1 billion-year-old P Birds h Mammals [16][17] – Plants Dinosaurs rocks in Western Australia. In March 2017, putative evidence of Karo o a n ← Andean Tetrapoda possibly the oldest forms of life on Earth was reported in the form of -50 0 — e Arthropods Molluscs r ←Cambrian explosion fossilized microorganisms discovered in hydrothermal
    [Show full text]
  • Evolutionary Biology
    EVOLUTIONARY BIOLOGY SUBDISCIPLINES OF EVOLUTIONARY BIOLOGY Behavioral Evolution • Evolution of mating systems, courtship behavior, foraging behavior, predator escape mechanisms, and cooperation. Evolutionary Developmental Biology (Evo-Devo) • Evolutionary change in the processes that translate genetic information (genotype) into its behavioral, anatomical, physiological, and biochemical characteristics (phenotype). Evolutionary Ecology • How the life histories, diets, and other ecological features of species evolve, and how these processes affect the composition and properties of communities and ecosystems, also, how species evolve in response to one another (e.g. evolution of predator-prey relationships). Evolutionary Genetics • The origin of variation; the patterns of variation within populations and species, along with the causes and consequences of these variations. Paleobiology • Large-scale evolutionary patterns in the fossil record. Examines origins and fates of lineages, major groups, and anatomical and behavioral novelties, evolutionary trends, and changes throughout geographic areas and geologic time. Evolutionary Physiology/Morphology • How physiological, biochemical, and anatomical features of an organism provide adaptation to its environment and lifeways. Also examines the history of these adaptations. Human Evolution • Many evolutionary biologists use conceptual issues of the subdisciplines to study a particular group of organisms. Of these groups, one draws special attention—the human lineage. Molecular Evolution • Investigates the history and causes of evolutionary changes in nucleotide sequences, the structure and number of genes, their physical arrangement on chromosomes, and other molecular phenomena, including the evolution of genomes. Systematics • Distinguishes and names species, infers phylogenetic relationships among species and classifies species based on their evolutionary relationships. CASE WESTERN RESERVE UNIVERSITY.
    [Show full text]
  • The Landekirkpatrick Mechanism Is
    PERSPECTIVE doi:10.1111/j.1558-5646.2010.01054.x THE LANDE–KIRKPATRICK MECHANISM IS THE NULL MODEL OF EVOLUTION BY INTERSEXUAL SELECTION: IMPLICATIONS FOR MEANING, HONESTY, AND DESIGN IN INTERSEXUAL SIGNALS Richard O. Prum1,2 1Department of Ecology and Evolutionary Biology, and Peabody Natural History Museum, Yale University, New Haven, Connecticut 06520-8150 2E-mail: [email protected] Received December 31, 2009 Accepted May 26, 2010 The Fisher-inspired, arbitrary intersexual selection models of Lande (1981) and Kirkpatrick (1982), including both stable and unstable equilibrium conditions, provide the appropriate null model for the evolution of traits and preferences by intersexual selection. Like the Hardy–Weinberg equilibrium, the Lande–Kirkpatrick (LK) mechanism arises as an intrinsic consequence of genetic variation in trait and preference in the absence of other evolutionary forces. The LK mechanism is equivalent to other intersexual selection mechanisms in the absence of additional selection on preference and with additional trait-viability and preference-viability correlations equal to zero. The LK null model predicts the evolution of arbitrary display traits that are neither honest nor dishonest, indicate nothing other than mating availability, and lack any meaning or design other than their potential to correspond to mating preferences. The current standard for demonstrating an arbitrary trait is impossible to meet because it requires proof of the null hypothesis. The LK null model makes distinct predictions about the evolvability of traits and preferences. Examples of recent intersexual selection research document the confirmationist pitfalls of lacking a null model. Incorporation of the LK null into intersexual selection will contribute to serious examination of the extent to which natural selection on preferences shapes signals.
    [Show full text]
  • Phylogenetics Laboratory: Reconstructing Evolutionary History
    Phylogenetics Laboratory: Reconstructing Evolutionary History Kefyn M. Catley Laura R. Novick Western Carolina University Vanderbilt University © June, 2016 Acknowledgments The development of this laboratory was supported by the Institute of Education Sciences, U.S. Department of Education, through Grant R305A080621 to Vanderbilt University (L. R. Novick, Principal Investigator; K. M. Catley, Co-Investigator). The opinions expressed are those of the authors and do not represent views of the Institute or the U.S. Department of Education. This laboratory was designed for use in an introductory biology class for science majors. It can be completed during the standard 3-hour laboratory section with students working in small groups. The laboratory materials include a student laboratory manual (appended here), an instructors’ guide with answer key (appended here), and various specimens. These are the typical specimens found in a general undergraduate biology laboratory and include preserved wet specimens, dried material, and cased skeletons of the nine taxa used in the lab (Annelida, Arthropoda, Chordata, Cnidaria, Echinodermata, Mollusca, Nematoda, Platyhelminthes, and Porifera). One or more undergraduate biology textbooks with which students are familiar should be made available. Students may also be encouraged to search the internet for information concerning the characters. Alternatively (or in addition), instructors may choose to provide pictures of some of the characters from such sources. The specimens, organismal chapters of the textbooks, and internet sources are resources students may use to complete the character matrix in Part I of the lab. 1 Phylogenetics Laboratory: Reconstructing Evolutionary History Kefyn M. Catley Laura R. Novick Western Carolina University Vanderbilt University Version 1 © February, 2010 Version 2 © August, 2010 Version 3.1 © June, 2011 Version 3.2 © August, 2012 Version 3.3 © June, 2016 Introduction Phylogenetics is the study of the history of life as reflected in the evolutionary relationships among taxa.
    [Show full text]
  • Understanding Evolutionary Trees
    Evo Edu Outreach (2008) 1:121–137 DOI 10.1007/s12052-008-0035-x ORIGINAL SCIENCE/EVOLUTION REVIEW Understanding Evolutionary Trees T. Ryan Gregory Published online: 12 February 2008 # Springer Science + Business Media, LLC 2008 Abstract Charles Darwin sketched his first evolutionary with the great Tree of Life, which fills with its dead tree in 1837, and trees have remained a central metaphor in and broken branches the crust of the earth, and covers evolutionary biology up to the present. Today, phyloge- the surface with its ever-branching and beautiful netics—the science of constructing and evaluating hypoth- ramifications. eses about historical patterns of descent in the form of evolutionary trees—has become pervasive within and Darwin clearly considered this Tree of Life as an increasingly outside evolutionary biology. Fostering skills important organizing principle in understanding the concept in “tree thinking” is therefore a critical component of of “descent with modification” (what we now call evolu- biological education. Conversely, misconceptions about tion), having used a branching diagram of relatedness early evolutionary trees can be very detrimental to one’s in his exploration of the question (Fig. 1) and including a understanding of the patterns and processes that have tree-like diagram as the only illustration in On the Origin of occurred in the history of life. This paper provides a basic Species (Darwin 1859). Indeed, the depiction of historical introduction to evolutionary trees, including some guide- relationships among living groups as a pattern of branching lines for how and how not to read them. Ten of the most predates Darwin; Lamarck (1809), for example, used a common misconceptions about evolutionary trees and their similar type of illustration (see Gould 1999).
    [Show full text]