DOCSLIB.ORG

Speciation Through Evolution of Sex-Linked Genes

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Speciation Through Evolution of Sex-Linked Genes Heredity (2009) 102, 4–15 & 2009 Macmillan Publishers Limited All rights reserved 0018-067X/09 $32.00 www.nature.com/hdy SHORT REVIEW Speciation through evolution of sex-linked genes A Qvarnstro¨m and RI Bailey Department of Ecology and Evolution, Evolutionary Biology Centre, Uppsala University, Norbyva¨gen, Uppsala, Sweden Identification of genes involved in reproductive isolation expectation but mainly in female-heterogametic taxa. By opens novel ways to investigate links between stages of the contrast, there is clear evidence for both strong X- and speciation process. Are the genes coding for ecological Z-linkage of hybrid sterility and inviability at later stages of adaptations and sexual isolation the same that eventually speciation. Hence genes coding for sexual isolation traits are lead to hybrid sterility and inviability? We review the role of more likely to eventually cause hybrid sterility when they are sex-linked genes at different stages of speciation based on sex-linked. We conclude that the link between sexual four main differences between sex chromosomes and isolation and evolution of hybrid sterility is more intuitive in autosomes; (1) relative speed of evolution, (2) non-random male-heterogametic taxa because recessive sexually antag- accumulation of genes, (3) exposure of incompatible onistic genes are expected to quickly accumulate on the recessive genes in hybrids and (4) recombination rate. At X-chromosome. However, the broader range of sexual traits early stages of population divergence ecological differences that are expected to accumulate on the Z-chromosome may appear mainly determined by autosomal genes, but fast- facilitate adaptive speciation in female-heterogametic spe- evolving sex-linked genes are likely to play an important role cies by allowing male signals and female preferences to for the evolution of sexual isolation by coding for traits with remain in linkage disequilibrium despite periods of gene flow. sex-specific fitness effects (for example, primary and Heredity (2009) 102, 4–15; doi:10.1038/hdy.2008.93; secondary sexual traits). Empirical evidence supports this published online 10 September 2008 Keywords: speciation; sex-linkage; sexual selection; adaptation; genetic incompatibility; genetic mapping Introduction preferences or sperm-egg incompatibilities). Postzygotic isolation can be caused by extrinsic factors such as Understanding the speciation process remains a chal- inferior niche adaptation or reduced attractiveness of lenge in evolutionary biology (Coyne and Orr, 2004; hybrids or by intrinsic incompatibilities leading to Dieckmann et al., 2004; Price, 2007) but in recent decades reduced fertility or viability of hybrids. In general, much progress has been made regarding our knowledge closely related species are reproductively isolated be- of how reproductive isolation evolves. This focus on the cause of many different characteristics that have evolved evolution of reproductive isolation probably has its basis at different stages of their divergence. The build-up of in the biological species concept, which defines species as different forms of isolation often follow a temporal groups of organisms that are reproductively isolated pattern in which ecological differentiation and sexual from other such groups (Mayr, 1995). A species is then a isolation evolve rapidly and may often precede any form group of organisms that share the same gene pool. The of intrinsic genetic incompatibilities. Reduced fertility of rapid development of molecular tools has only recently hybrids then invariably precedes the rise of reduced made it possible to dive into those gene pools and viability. approach the process of speciation at the level of genes. Why do ecological and behavioural isolation tend to Studies identifying genes underlying reproductive isola- evolve quicker than intrinsic incompatibilities? Are the tion are starting to accumulate, opening up new genes coding for traits underlying ecological adaptations possibilities to answer central theoretical questions on and sexual isolation the same genes that eventually speciation. At the same time, this development causes become differentiated enough to cause hybrid sterility novel questions to arise. and inviability? Genomic studies have a clear role to play Reproductive isolation in sexually reproducing organ- in answering such central questions and also in revealing isms is caused by one or a combination of prezygotic and the underlying mechanisms behind general patterns of postzygotic isolation. Prezygotic isolation can be caused evolution of genetic incompatibilities such as Haldane’s by reduced probability of meeting (spatial or temporal rule. The nature of the genes underlying each form of isolation), mating (sexual isolation) or successful isolation may be intrinsically linked to their genomic fertilization (for example due to homogametic sperm distribution, and both are likely to affect the magnitude and chronology of their role in the speciation process. Correspondence: Associate Professor A Qvarnstro¨m, Department of Just as forms of isolation follow a temporal pattern, the Ecology and Evolution, Evolutionary Biology Centre, Uppsala University, genetics of reproductive isolation may change through Norbyva¨gen 18D, SE-752 36 Uppsala, Sweden. time such that genes and genomic regions causing E-mail: [email protected] Received 8 February 2008; revised 16 July 2008; accepted 26 July isolation early in the speciation process may differ from 2008; published online 10 September 2008 those involved later on. Speciation and sex-linked genes A Qvarnstro¨m and RI Bailey 5 In this review we will ask whether genes causing mammals are unusual because all birds are female- reproductive isolation are often likely to be disproportio- heterogametic and all mammals male-heterogametic nately sex chromosome-linked and we will survey (Bull, 1983). This scattered taxonomic distribution and empirical studies to examine the level of support for the repeated evolution of sex chromosome systems (for the hypotheses of the association between sex linkage example, Charlesworth, 2002; Mank et al., 2006a) and of and speciation. The term ‘sex-linkage’ typically refers to male and female heterogamety should provide sufficient loci present on the sex chromosomes, which are defined statistical power for comparative analyses to examine as the chromosome pair that carries the constitutive their roles in speciation (for example, Mank et al., 2006b). genes controlling whether an individual develops into a male or a female (Box 1). Hence only organisms with separate sexes, as defined by the relative size of their Sex chromosomes and speciation gametes, have sex chromosomes. However, there are alternative mechanisms such as environmental sex Why expect sex-linked genes to have a disproportionately determination (for example, Sarre et al., 2004) or large influence on reproductive isolation? haplodiploidy, in which one sex is haploid and the other In the absence of differences in relevant features between diploid (for example, Hedrick and Parker, 1997). There sex chromosomes and autosomes, their influence on are also many species with genetic sex determination but speciation would be expected to be proportional to their with unidentified sex chromosomes (Ezaz et al., 2006; contribution to the genome in terms of size or the Mank et al., 2006a). The most widely known sex number of genes they carry (Ritchie and Phillips, 1998). chromosome systems are the XX/XY (females are However, there are at least four main factors that may homogametic and have two copies of the X chromosome lead to differences between sex chromosomes and whereas males are heterogametic and have one X and autosomes in their relationship with speciation, all of one Y) and ZZ/ZW (males have two Z chromosomes and which are linked to hemizygosity (Figure 1): (1) relative females have one Z and one W) systems. In general, the Y speed of evolution, (2) non-random accumulation of or W is smaller (Bull, 1983) and recombination between genes, (3) exposure of incompatible recessive genes in X/Z and Y/W chromosomes is often restricted to small hybrids and (4) recombination rate. Below we will regions. The fact that the X or Z is hemizygous in the discuss, in the light of different mechanisms of specia- heterogametic sex causes population genetic differences tion, whether components of reproductive isolation are between sex chromosomes and autosomes, and non- expected to be determined by sex-linked genes to a larger random accumulation of particular classes of genes on extent than is expected by chance. Our main aim is to sex chromosomes. These differences and their link to pinpoint how the four outlined differences between sex speciation will be discussed in this article. chromosomes and autosomes may influence the relative Chromosomal sex determination appears to have role of sex-linked genes at different stages of the evolved many times independently in both plants and speciation process. We focus on sex determination animals, with male heterogamety being more common. systems with stable heteromorphic sex chromosomes Insects, fishes, amphibians and reptiles contain a mix of and most of the following discussion will be of the X/Z male and female-heterogametic taxa, but birds and chromosome because it often contains more genes than Box 1 Sex chromosomes and sex determination The evolution of identifiable heteromorphic sex chromosomes is initiated by the spread of a sex-determining gene (SDG). This occurs when a new mutation
Load more

Recommended publications
  • Biology and Thermal Requirements of Utetheisa Ornatrix (L.) (Lepidoptera: Arctiidae) Reared on Artificial Diet
    647 Vol. 51, n. 4 : pp.647-653, July-Aug 2008 BRAZILIAN ARCHIVES OF ISSN 1516-8913 Printed in Brazil BIOLOGY AND TECHNOLOGY AN INTERNATIONAL JOURNAL Biology and Thermal Requirements of Utetheisa ornatrix (L.) (Lepidoptera: Arctiidae) Reared on Artificial Diet André Gustavo Corrêa Signoretti 1, Dori Edson Nava 2*, José Maurício Simões Bento 1 and José Roberto Postali Parra 1 1Departamento de Entomologia, Fitopatologia e Zoologia Agrícola; Escola Superior de Agricultura "Luiz de Queiroz"; Universidade de São Paulo; 13418-310; Piracicaba - SP - Brasil. 2Embrapa Clima Temperado; [email protected]; 96001-970; Pelotas - RS - Brasil ABSTRACT A study on the biology of Utetheisa ornatrix reared on the artificial diet, was conducted to determine the thermal requirements in each development stage. The aim was to find out the thermal regions in the São Paulo state where the pest could develop on Crotalaria spp. The insects were reared on an artificial diet based on the white beans and yeast. U. ornatrix thermal requirements were tested at 18, 20, 22, 25, 28, 30, and 32ºC 70±20% RH, and 14-h photophase. Lower threshold temperatures (TT) and thermal constants (K) for the egg, larval and pupal stages were 12.7ºC and 51.2 GDD, 13.5ºC and 290.9 GDD, 13.8ºC and 108.4 GDD, respectively; TT and K values for the biological cycle were 13.8ºC and 436.3 GDD. Key words: Crotalaria , Rattlebox moth, rearing technique INTRODUCTION In the past few years, the area planted to the crotalaria has increased significantly, reaching The Rattlebox moth, Utetheisa ornatrix (L., 1758) about 3,000 ha in Brazil (José Aparecido Donizete (Lepidoptera: Arctiidae), is considered to be the Cardoso, personal comunication).
    [Show full text]
  • Utetheisa Ornatrix)
    Female choice increases offspring fitness in an arctiid moth (Utetheisa ornatrix) Vikram K. Iyengar and Thomas Eisner* Department of Neurobiology and Behavior, W347 Mudd Hall, Cornell University, Ithaca, NY 14853 Contributed by Thomas Eisner, November 5, 1999 In Utetheisa ornatrix (Lepidoptera, Arctiidae), the female mates direct phenotypic benefits (from the nuptial gifts) and indirect preferentially with larger males. Having a larger father results in genetic benefits (from the expression of largeness in sons and the eggs being more richly endowed with defensive pyrrolizidine daughters). We postulated that these benefits should be mea- alkaloid (which the female receives from the male with the sperm surable and found that the offspring of preferred males do package, in quantity proportional to the male’s body mass, and indeed fare better than the offspring of nonpreferred males. passes on to the eggs); having a larger father also results in the Specifically, we showed that (i) eggs sired by preferred males are sons and daughters themselves being larger (body mass is herita- less vulnerable to predation; (ii) sons of preferred males are ble in Utetheisa). We provide evidence herein that these conse- more successful in courtship; and (iii) daughters of preferred quences enhance the fitness of the offspring. Eggs sired by larger males are more fecund. males are less vulnerable to predation (presumably because of Our basic protocol was as follows: (i) we confined a female their higher alkaloid content), whereas sons and daughters, by with two males (one large, one small) until she chose to mate virtue of being larger, are, respectively, more successful in court- with one of them (preferred male, primary mating); (ii)we ship and more fecund.
    [Show full text]
  • Paternal Inheritance of a Female Moth's Mating Preference
    letters to nature 11. Reznick, D. N., Shaw, F. H., Rodd, F. H. & Shaw, R. G. Evaluation of the rate of evolution in natural birds promote the evolution of exaggerated male traits through populations of guppies (Poecilia reticulata). Science 275, 1934–1936 (1997). 12. Majerus, M. E. N. Melanism: Evolution in Action (Oxford Univ. Press, Oxford, 1998). sexual selection. Specifically, the theory predicts that, because 13. Hendry, A. P.Adaptive divergence and the evolution of reproductive isolation in the wild: an empirical female preference alleles arising on the Z chromosome are demonstration using introduced sockeye salmon. Genetica 112, 515–534 (2001). transmitted to all sons that have the father’s attractive trait rather 14. Grant, P.R. & Grant, B. R. Unpredictable evolution in a 30-year study of Darwin’s finches. Science 296, than to only a fraction of the sons, such alleles will experience 707–711 (2002). 15. Baker, A. J. Genetic and morphometric divergence in ancestral European and descendent New Zeland stronger positive selection and be less vulnerable to chance loss populations of chaffinches (Fringilla coelebs). Evolution 46, 1784–1800 (1992). than would autosomal alleles. 16. Merila¨, J. & Crnokrak, P. Comparison of genetic differentiation at marker loci and quantitative traits. The benefits accrued by female Utetheisa as a result of mating J. Evol. Biol. 14, 892–903 (2001). 17. Wright, S. The genetical structure of populations. Ann. Eugen. 15, 323–354 (1951). preferentially with larger males have been characterized. The pheno- 18. Haugen, T. O. & Vøllestad, L. A. A century of life-history evolution in grayling. Genetica 112, 475–491 typic benefits take the form of nutrient and pyrrolizidine alkaloid (2001).
    [Show full text]
  • Chemical Defence of the Warningly Coloured Caterpillars of Methona Themisto (Lepidoptera: Nymphalidae: Ithomiinae)
    Eur. J. Entomol. 106: 253–259, 2009 http://www.eje.cz/scripts/viewabstract.php?abstract=1449 ISSN 1210-5759 (print), 1802-8829 (online) Chemical defence of the warningly coloured caterpillars of Methona themisto (Lepidoptera: Nymphalidae: Ithomiinae) KAMILA F. MASSUDA and JOSÉ R. TRIGO* Laboratório de Ecologia Química, Departamento de Zoologia, Instituto de Biologia, Universidade Estadual de Campinas, CP 6109, 13083-970 Campinas, SP, Brazil Key words. Aposematism, Brunfelsia uniflora, Camponotus crassus, Gallus gallus domesticus, learning, Lycosa erythrognatha, predation, Solanaceae, unpalatability Abstract. The caterpillars of the butterfly Methona themisto (Nymphalidae: Ithomiinae) are conspicuously coloured and feed exclu- sively on Brunfelsia uniflora (Solanaceae), a plant that is rich in secondary plant substances, which suggests the caterpillars are chemically protected against predators. Results of experiments indicate that predators determine the survival of Methona themisto caterpillars in the field and laboratory bioassays that this organism is eaten by ants and spiders but not chicks. Both the conspicuous orange and black striped colouration and chemical compounds of Methona themisto caterpillars seem to be related to protection against predation by visually hunting predators. Chicks ate proportionally more of the cryptically coloured 1st instar caterpillars than of the conspicuously coloured later instar caterpillars. That Methona themisto caterpillars are chemically defended is supported by the activity of the dichloromethanic extract of 5th instars in preventing predation by chicks. Caterpillars of Methona themisto are apo- sematic as they are both (1) unpalatable, and (2) their warning signal is easily recognized by potential predators. Chicks learned to avoid the aposematic 3rd or 5th instar caterpillars after one encounter. Mealworms painted to look like caterpillars were also rejected by chicks that had previously encountered Methona caterpillars.
    [Show full text]
  • Reproductive Mode and Speciation: the Viviparity-Driven Conflict Liypothesis David W
    Hypothesis Reproductive mode and speciation: the viviparity-driven conflict liypothesis David W. Zeh* and Jeanne A. Zeh Summary in the speciation process.*^"®' With patterns in nature (see In birds and frogs, species pairs retain the capacity to below) exhibiting profound between-lineage differences in produce viable hybrids for tens of millions of years, an order of magnitude longer than mammals. What the relative rates at which pre- and postzygotic isolation accounts for these differences in relative rates of pre- evolve,*^~^°' a unifying theory of speciation has remained and postzygotic isolation? We propose that reproduc- elusive. Here, we present a new hypothesis to account for the tive mode is a critically important but previously over- extreme disparity that exists between lineages in patterns of looked factor in the speciation process. Viviparity speciation. This viviparity-driven conflict hypothesis proposes creates a post-fertilization arena for genomic conflicts absent in egg-laying species. With viviparity, conflict that the reproductive stage at which divergence occurs most can arise between: mothers and embryos; sibling rapidly between populations is strongly influenced by the embryos in the womb, and maternal and paternal degree to which embryonic development involves physiolo- genomes within individual embryos. Such intra- and gical interactions between mother and embryo. After briefly intergenomic conflicts result in perpetual antagonistic reviewing between-lineage differences in patterns of specia- coevolution, thereby accelerating interpopulation post- zygotic isolation. In addition, by generating intrapopula- tion, we develop the hypothesis that postzygotic isolation tion genetic incompatibility, viviparity-driven conflict should evolve more rapidly in viviparous animals than in favors polyandry and limits the potential for precopula- oviparous species, because development of the embryo tory divergence.
    [Show full text]
  • Rad21l1 Cohesin Subunit Is Dispensable for Spermatogenesis but Not
    bioRxiv preprint doi: https://doi.org/10.1101/2020.09.23.309591; this version posted September 23, 2020. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY 4.0 International license. 1 Rad21l1 cohesin subunit is dispensable for spermatogenesis but not 2 oogenesis in zebrafish 3 4 Yana P. Blokhina1,2,¶, Michelle Frees1,¶, An Nguyen1,¶, Masuda Sharifi1,3, Daniel B. 5 Chu1,2, Bruce W. Draper1, Sean M. Burgess1* 6 7 8 1 Department of Molecular and Cellular Biology, University of California, Davis, 9 California, United States of America 10 11 2 Integrative Genetics and Genomics Graduate Group, University of California, Davis, 12 United States of America 13 14 3 Biochemistry, Molecular, Cellular, and Developmental Biology Graduate Group, 15 University of California, Davis, United States of America 16 17 18 * Corresponding author 19 Email: [email protected] 20 21 22 ¶ These authors contributed equally to this work. 23 1 bioRxiv preprint doi: https://doi.org/10.1101/2020.09.23.309591; this version posted September 23, 2020. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY 4.0 International license. 24 Abstract 25 Meiosis produces haploid gametes that will give rise to the next diploid 26 generation. Chromosome segregation errors occurring at one or both meiotic divisions 27 result in aneuploidy, which can lead to miscarriages or birth defects in humans.
    [Show full text]
  • The Plan for This Week: Today: Sex Chromosomes: Dosage
    Professor Abby Dernburg 470 Stanley Hall [email protected] Office hours: Tuesdays 1-2, Thursdays 11-12 (except this week, Thursday only 11-1) The Plan for this week: Today: Sex chromosomes: dosage compensation, meiosis, and aneuploidy Wednesday/Friday: Dissecting gene function through mutation (Chapter 7) Professor Amacher already assigned the following reading and problems related to today’s lecture: Reading: Ch 4, p 85-88; Ch 6, p 195, 200; Ch 11, p 415; Ch. 18, skim p 669-677, Ch 13, 481-482 Problems: Ch 4, #23, 25; Ch 13, #24, 27 - 31 Let’s talk about sex... chromosomes We’ve learned that sex-linked traits show distinctive inheritance patterns The concept of “royal blood” led to frequent consanguineous marriages among the ruling houses of Europe. Examples of well known human sex-linked traits Hemophilia A (Factor VIII deficiency) Red/Green color blindness Duchenne Muscular Dystrophy (DMD) Male-pattern baldness* *Note: male-pattern baldness is both sex-linked and sex-restricted - i.e., even a homozygous female doesn’t usually display the phenotype, since it depends on sex-specific hormonal cues. Sex determination occurs by a variety of different mechanisms Mating-type loci (in fungi) that “switch” their information Environmental cues (crocodiles, some turtles, sea snails) “Haplodiploid” mechanisms (bees, wasps, ants) males are haploid, females are diploid Sex chromosomes We know the most about these mechanisms because a) it’s what we do, and b) it’s also what fruit flies and worms do. Plants, like animals, have both chromosomal and non-chromosomal mechanisms of sex determination. The mechanism of sex determination is rapidly-evolving! Even chromosome-based sex determination is incredibly variable Mammals (both placental and marsupial), fruit flies, many other insects: XX ♀/ XY ♂ Many invertebrates: XX ♀or ⚥ / XO ♂ (“O” means “nothing”) Birds, some fish: ZW ♀ / ZZ ♂(to differentiate it from the X and Y system) Duckbilled platypus (monotreme, or egg-laying mammal): X1X1 X2X2 X3X3 X4X4 X5X5 ♀ / X1Y1 X2Y2 X3 Y 3 X4X4 X5Y5 ♂ (!!?) Note: these are given as examples.
    [Show full text]
  • Plant-Derived Pyrrolizidine Alkaloid Protects Eggs of a Moth (Utetheisa Ornatrix) Against a Parasitoid Wasp (Trichogramma Ostriniae)
    Plant-derived pyrrolizidine alkaloid protects eggs of a moth (Utetheisa ornatrix) against a parasitoid wasp (Trichogramma ostriniae) Alexander Bezzerides*, Tze-Hei Yong†, Julie Bezzerides*, Jad Husseini*, Joshua Ladau*, Maria Eisner*, and Thomas Eisner*‡ Departments of *Neurobiology and Behavior and †Entomology, Cornell University, Ithaca, NY 14853 Contributed by Thomas Eisner, April 13, 2004 Pyrrolizidine alkaloid (PA), sequestered by the moth Utetheisa ornatrix from its larval food plant, is transmitted by both males and females to the eggs. Males confer PA on the female by seminal infusion, and females pass this gift, together with PA that they themselves procured as larvae, to the eggs. Here we show that PA protects the eggs against parasitization by the chalcidoid wasp, Trichogramma ostriniae. Eggs laid subsequent to a first mating of an Utetheisa female receive most of their PA from the female. The amount they receive from the male is insufficient to provide for full protection. However, female Utetheisa are promiscuous and there- fore likely to receive PA on a cumulative basis from their male partners. chemical defense ͉ parasitism ͉ Arctiidae ͉ Trichogrammatidae he moth Utetheisa ornatrix (henceforth called Utetheisa), a Tmember of the tiger moth family (Arctiidae), is distasteful at all stages of development. As a larva, it feeds on plants of the genus Crotalaria (Fabaceae), from which it sequesters toxic, intensely bitter, pyrrolizidine alkaloids (PAs). The compounds are retained systemically through metamorphosis by both sexes and eventually are allocated in part to the eggs. Both sexes Fig. 1. Trichogramma on an egg of Utetheisa. The specimen was abruptly contribute to the egg endowment.
    [Show full text]
  • Pyrrolizidine Alkaloids: Biosynthesis, Biological Activities and Occurrence in Crop Plants
    molecules Review Pyrrolizidine Alkaloids: Biosynthesis, Biological Activities and Occurrence in Crop Plants Sebastian Schramm, Nikolai Köhler and Wilfried Rozhon * Biotechnology of Horticultural Crops, TUM School of Life Sciences Weihenstephan, Technical University of Munich, Liesel-Beckmann-Straße 1, 85354 Freising, Germany; [email protected] (S.S.); [email protected] (N.K.) * Correspondence: [email protected]; Tel.: +49-8161-71-2023 Academic Editor: John C. D’Auria Received: 20 December 2018; Accepted: 29 January 2019; Published: 30 January 2019 Abstract: Pyrrolizidine alkaloids (PAs) are heterocyclic secondary metabolites with a typical pyrrolizidine motif predominantly produced by plants as defense chemicals against herbivores. They display a wide structural diversity and occur in a vast number of species with novel structures and occurrences continuously being discovered. These alkaloids exhibit strong hepatotoxic, genotoxic, cytotoxic, tumorigenic, and neurotoxic activities, and thereby pose a serious threat to the health of humans since they are known contaminants of foods including grain, milk, honey, and eggs, as well as plant derived pharmaceuticals and food supplements. Livestock and fodder can be affected due to PA-containing plants on pastures and fields. Despite their importance as toxic contaminants of agricultural products, there is limited knowledge about their biosynthesis. While the intermediates were well defined by feeding experiments, only one enzyme involved in PA biosynthesis has been characterized so far, the homospermidine synthase catalyzing the first committed step in PA biosynthesis. This review gives an overview about structural diversity of PAs, biosynthetic pathways of necine base, and necic acid formation and how PA accumulation is regulated. Furthermore, we discuss their role in plant ecology and their modes of toxicity towards humans and animals.
    [Show full text]
  • Coupling, Reinforcement, and Speciation Roger Butlin, Carole Smadja
    Coupling, Reinforcement, and Speciation Roger Butlin, Carole Smadja To cite this version: Roger Butlin, Carole Smadja. Coupling, Reinforcement, and Speciation. American Naturalist, Uni- versity of Chicago Press, 2018, 191 (2), pp.155-172. 10.1086/695136. hal-01945350 HAL Id: hal-01945350 https://hal.archives-ouvertes.fr/hal-01945350 Submitted on 5 Dec 2018 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Distributed under a Creative Commons Attribution| 4.0 International License vol. 191, no. 2 the american naturalist february 2018 Synthesis Coupling, Reinforcement, and Speciation Roger K. Butlin1,2,* and Carole M. Smadja1,3 1. Stellenbosch Institute for Advanced Study, Wallenberg Research Centre at Stellenbosch University, Stellenbosch 7600, South Africa; 2. Department of Animal and Plant Sciences, The University of Sheffield, Sheffield S10 2TN, United Kingdom; and Department of Marine Sciences, University of Gothenburg, Tjärnö SE-45296 Strömstad, Sweden; 3. Institut des Sciences de l’Evolution, Unité Mixte de Recherche 5554 (Centre National de la Recherche Scientifique–Institut de Recherche pour le Développement–École pratique des hautes études), Université de Montpellier, 34095 Montpellier, France Submitted March 15, 2017; Accepted August 28, 2017; Electronically published December 15, 2017 abstract: During the process of speciation, populations may di- Introduction verge for traits and at their underlying loci that contribute barriers Understanding how reproductive isolation evolves is key fl to gene ow.
    [Show full text]
  • Sex Determination and Sex-Linked Characteristics
    Sex Determination and Sex- Linked Characteristics Chapter 4 Lecture Outline • Mechanisms of Sex Determination – Chromosomal – Genetic – Environmental • Sex-linked Characteristics Sex Determination • Sexual reproduction is the results of meiosis and fertilization • Sexual phenotypes (the sexes) – male and female – Differ in gamete size • Sex determination – mechanism by which sex is established • Monoecious – organisms with both male and female reproductive structures (hermphroditism) • Dioecious – organism has male or female reproductive structures – Chromosomal, genetic or environmental sex determination • In many organisms, sex is determined by a pair of chromosomes – sex chromosomes – Non-sex chromosomes = Autosomes • Heterogametic sex – gametes differ with respect to sex chromosomes • Homogametic sex – gametes are the same with respect to sex chromosomes Concept Check 1 How does the heterogametic sex differ from the homogametic sex? a. The heterogametic sex is male; the homogametic sex is female. b. Gametes of the heterogametic sex have different sex chromosomes; gametes of homogametic sex have the same sex chromosome. c. Gametes of the heterogametic sex all contain a Y chromosome. d. Gametes of the homogametic sex all contain an X chromosome. Concept Check 1 How does the heterogametic sex differ from the homogametic sex? a. The heterogametic sex is male; the homogametic sex is female. b. Gametes of the heterogametic sex have different sex chromosomes; gametes of homogametic sex have the same sex chromosome. c. Gametes of the heterogametic sex all contain a Y chromosome. d. Gametes of the homogametic sex all contain an X chromosome. Chromosomal Sex-Determination • XX-XO sex determination – grasshoppers – XX – female; homogametic – XO male; heterogametic • (O = absence of chromosome) • XX-XY sex determination – many species incl.
    [Show full text]
  • The Genetic Basis of Reproductive Isolation: Insights from Drosophila
    Colloquium The genetic basis of reproductive isolation: Insights from Drosophila H. Allen Orr* Department of Biology, University of Rochester, Rochester, NY 14627 Recent studies of the genetics of speciation in Drosophila have number of new and careful studies of the biogeography, ecology, focused on two problems: (i) identifying and characterizing the and genetics of speciation, and we now understand a good deal genes that cause reproductive isolation, and (ii) determining the about the evolution of reproductive isolation (3). We can, for evolutionary forces that drove the divergence of these ‘‘speciation instance, describe the rate at which this reproductive isolation genes.’’ Here, I review this work. I conclude that speciation genes evolves (Fig. 1), and the ecological factors that drive speciation, correspond to ordinary loci having normal functions within species. at least in some cases (6). We can also point to plausible examples These genes fall into several functional classes, although a role in in which the process of reinforcement may have completed transcriptional regulation could prove particularly common. More speciation (3, 7, 8). Finally, we know a fair amount about the important, speciation genes are typically very rapidly evolving, and number and location of the genes that cause reproductive this divergence is often driven by positive Darwinian selection. isolation (at least in its postzygotic form), and the causes of Finally, I review recent work in Drosophila pseudoobscura on the patterns like Haldane’s rule (3, 9, 10). possible role of meiotic drive in the evolution of the genes that Given this progress, it is natural to ask: What now are the cause postzygotic isolation.
    [Show full text]