DOCSLIB.ORG

The Evolutionary History of Drosophila Thorax Length

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
The Evolutionary History of Drosophila Thorax Length Heredity 68 (1992) 557-563 Received 31 July 1991 Genetical Society of Great Britain The evolutionary history of Drosophila buzzatii. XXIV. Second chromosome inversions have differentaverage effects on thorax length ESTEBAN HASSON, JUAN J. FANARA, CONSTANTINA RODRIGUEZ, JUAN C. VILARDI*, OSVALDO A. REIG & ANTONIO FONTDEVI LA t GIBE Departamento de Ciencias BiolOgicas, Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires, Ciudad Universitaria Pab. II, 1428 Buenos Aires, Argentina, *Laboratorio de Genética, Departamento de Ciencias B/old gicas, Facultad Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, 1428 Buenos Aires, Argentina and tDepartmento de Genética y Microbiologia, Un/versidad AutOnoma de Barcelona, 08193 Bellaterra (Barcelona), Spain Wedemonstrate a genetic correlation between rearrangements of the second chromosome of D. buzzatii and thorax length, as a measure of body size. The results indicate that 2j and 2jz3 arrange- ments are correlated with large size, whereas 2st arrangement is correlated with small size. Some inversions (2st and 2jz3) show dominant effects and others (2j/f3) exhibit overdominance. These results show that at least 25 per cent of body size variation may be accounted for by the studied karyotypes. The possible integration of the genotypic, phenotypic and fitness levels, and also the possible implications to life-history evolution theories, are discussed. These results suggest that, under moderate to high heritability values, some kinds of chromosomal endocyclic and/or balancing selection may be valuable mechanisms for maintenance of body size variation. Keywords: bodysize, chromosomal inversions,Drosophila buzzatii, fitness, selection, life-history traits.. ness-related morphometric character that is easy to Introduction observe and measure. Body size is one such trait. Although the adaptive basis of chromosomal poly- Several studies have shown that thorax length, as a morphisms in Drosophila is universally accepted, the measure of body size is correlated with adult fitness selective forces involved are only inferred from components, e.g. fecundity (Robertson 1957a, b), indirect evidence from natural and experimental mating success (Butlin eta!., 1982; Taylor eta!., 1987; populations (Sperlich & Pfriem, 1986). Direct Partridge et aL, 1987; Santos et a!., 1988; Taylor & demonstrations of the selective significance of these Kekié, 1988), and longevity (Partridge eta!., 1987). inversion polymorphisms in nature are practically non- Nonetheless, the existence of a relationship between existent (Endler, 1986). In recent years, however, it has the phenotype and the chromosomal rearrangements is been possible to show that selection acts directly on rather controversial. Lande (1979) and John (1983) these polymorphisms through several fitness com- claim that chromosomal repatternings have no effect ponents in natural populations (Anderson et a!., 1979; on the morphological exophenotype. However, a posi- Ruiz eta!., 1986; Salceda & Anderson, 1988; Ruiz & tive relationship has been postulated in some insect Santos, 1989; Santos eta!., 1989; Hasson eta!., 1991). species, although a significant correlation has only been Bearing in mind that selection acts primarily at the demonstrated in a few cases (White & Andrew, 1960; phenotypic level and only secondarily at the genotypic White et a!., 1963; Butlin et aL, 1982; Colombo, one, population biologists have been searching for a fit- 1989). As regards species of Drosophi!a, a relationship between body size and chromosome polymorphism Correspondence: A. Fontdevila, Department of Ecology and Evo- lutionary Biology, University of California, Irvine, California was also reported for the D. subobscura A chromo- 92717, U.S.A. some (Krimbas, 1967) and for the D. pseudoobscura 557 558 E. HASSON ETAL. third chromosome (Thomson, 1971). Additional evi- 2st, respectively. The karyotypes of each collected dence pointing to the effect of chromosomal variation female and her mate were identified by analysing the on morphological characters comes from the corre- polytene chromosomes of 11 progeny larvae. In a few lated response of chromosomal frequencies to pheno- cases both parents were homozygous for the 2j typic artificial selection in D. subobscura (Prevosti, arrangement and these isofemale lines were selected as 1960; Prevosti 1967) and D. pseudoobscura (Druger, homokaryotypes. However, most of the lines were 1962). segregating and the homokaryotypic lines had to be Data on the genetic basis of body size in natural obtained by progeny selection of full sib crosses. This populations is of high relevance to the understanding progeny testing was determined with an accuracy of the evolutionary consequences of natural pheno- higher than 95 per cent by the cytological analysis of 13 typic selection. In D. buzzatii, Santos et al., (1988) and progeny larvae (Barbadilla & Naveira, 1988). The lines Ruiz & Santos (1989) have found that body size is did not attain fixation simultaneously and some lines positively correlated with mating success in a Spanish were kept by mass culturing until all the homokaryo- natural population. These studies have also shown that typic lines were obtained. The maximum number of different karyotypes differ in their mean value for generations before fixation was five. thorax length (Ruiz & Santos, 1989). In this paper we The experimental homokaryotypic stocks were present data showing that non-inbred flies with founded with eggs collected in optimal conditions from different second chromosome karyotypes extracted egg-laying cages, similar to those described by Ruiz et from an Argentinian natural population differ signi- a!. (1986). For each homokaryotypic stock, a total of ficantly in their thorax lengths and we give some infor- 150 mature (4—5 day-old) virgin males and 150 mature mation on the genetic determination of the chromo- virgin females of the same homokaryotypic lines were somal polymorphism on body size. introduced into one of these cages. Each homokaryo- typic line contributed with equal numbers of flies to this founding population. A large sample of collected Materialsand methods eggs was seeded in a culture and this stock was main- tained by mass culturing during four generations The species Drosophila buzzatli before the experiment was initiated. D. buzzatiiis a cactophilic species of the repleta group (mullen complex) that breeds mainly in the rotting cla- Derivationand analysis of different karyotypes dodes of cacti belonging to several Opuntia species. It Atotal of nine (Table 1) homo- and heterogametic probably originated in Argentina (Fontdevila, 1981; crosses were conducted by introducing 100 mature Fontdevila et al., 1982) and has successfully colonized (4—5 day-old) virgin males and 100 mature females of the Mediterranean region (Fontdevila et a!., 1981; the homokaryotypic stocks to egg collecting chambers. Fontdevila, 1981; 1989) and Australia (Barker, 1982) Reciprocal heterogametic crosses were performed in following its natural host plants. Chromosomally, this order to test possible maternal effects. species is highly polymorphic mainly for its second Eggs were allowed to hatch and first instar larvae chromosome (Ruiz eta!., 1985), and fitness differences were seeded in culture vials at optimal density, i.e. 40 have been demonstrated among these arrangements larvae in 6 ml of culture medium, as determined by (Ruiz eta!., 1986; Hasson eta!., 1991). Fanara (1988). Eight to ten replicates were run simul- taneously for each cross. Cultures were maintained at 25°C under continuous light until all adult flies Derivationof homokaryotypic stocks emerged. A random sample of each progeny was Weanalysed flies derived from a collection performed measured 24 h after individual emergences. Thorax in May 1987 at Arroyo Escobar, a locality situated 30 length was measured to the nearest 0.02 5 mm with a km north-west of Buenos Aires city (for a description binocular microscope fitted with an ocular micrometer. of the population, see Fontdevila eta!., 1982). Previous The measure was taken from the anterior margin of the studies showed that this population is polymorphic for thorax to the posterior tip of the scutellum, as laterally four arrangements in the second chromosome (st, j,jz3 viewed. All measurements were done by one of us and jq7) and two in the fourth (Stands) (Fontdevila et (JJF). a!., 1982). A modified formula of David's killed yeast culture Three homokaryotypic stocks involving 17, 14 and medium (David, 1962) was employed. Polytene chro- 4 independently derived chromosomes were obtained mosome slides were obtained following the technique for the second chromosome arrangements: 2j, 2jz3 and described by Fontdevila eta!. (1981). CHROMOSOMAL INVERSION EFFECTS ON DROSOPHILA SIZE 559 Table 1 Mean thorax length and the corresponding Statistical analysis standard error for the different second chromosome karyotypes of D. buzzatii. Sample sizes are indicated in ANOVAwith sex and karyotype as fixed factors and replicates as a random factor nested in karyotypes was parenthesis employed for the analysis of data. The mixed model Number ofMale thorax Female thorax employed can be expressed as: Karyotypes (*) replicateslength (mm) length (mm) X,Jk/=+ af+/3J+FkO)+(a/3)+(aF)k+ EkI st/st 10 1.0273±0.03041.1288±0.0277 (116) (119) whereX,Jklisthe individual value; 1u is the overall mean; j/j 10 1.0396 0.02871.1303 0.0280 a1 is the sex effect, fixed; j3. is the karyotypic effect, (135) (131) 10
Load more

Recommended publications
  • The Genetics of Drosophila Subobscura Populations
    Heredity (1980), 45 (3) 335-350 0018-067X/80/0216 0335 $02.00 1980. The Genetical Society of Great Britain THEGENETICS OF DROSOPHILA SUBOBSCURA POPULATIONS XV.EFFECTIVE SIZE OF A NATURAL POPULATION ESTIMATED BY THREE INDEPENDENT METHODS MICHAEL BEGON*, COSTAS B. KRIMBASt, and MICHAEL LOUKASt * Department of Zoology, University of Liverpool, Liverpool L69 3BX, U.K; t Department of Genetics, Agricultural College of Athens, Votanikos, Athens, Greece Received27.ii.80 SUMMARY An estimate is presented of the effective size of a natural, Greek population of Drosophila subobscura, based on data on lethal allelism. It is compared with further estimates for the same population obtained from newly-reported data by the "temporal" and the "ecological" methods. The lethal allelism and ecological estimates both suggest that the population is extremely large and effectively infinite. The conclusions from the temporal method conform to this, with the exception of data from two loci: Est-5 and Aph. Directional selection at these loci is therefore suggested. Each method is described and explained, and their validity discussed. The results are compared with the few previous estimates of effective population size. 1. INTRODUCTION POPULATION genetics theories, in general, deal with "ideal" populations, which are closed, of constant size, have discrete generations, random mating (including seif-fertilisation at random), and a random distribution of family sizes. Effective population number, Ne—a concept developed by Wright (1931, 1938)—relates theory to practice, and, essentially, is the size of the ideal population with which an actual population can be equated genetically. Thus Wright (1969) described the estimation of Ne as ".
    [Show full text]
  • Cytogenetic Mapping of Enzyme Loci on Chromosomes J and U of Drosophila Subobscura
    Copyright 0 1984 by the Genetics Society of America CYTOGENETIC MAPPING OF ENZYME LOCI ON CHROMOSOMES J AND U OF DROSOPHILA SUBOBSCURA W. PINSKER AND D. SPERLICH Lehrstuhl fur Populationsgenetik, Institut fur Biologie 11, Universitat Tubingen, Auf der Morgenstelle 28, 0-7400Tubingen, Federal Republic of Germany Manuscript received April 24, 1984 Revised copy accepted July 20, 1984 ABSTRACT Enzyme loci located on chromosome J and U were mapped cytologically by means of a Y translocation technique. A linkage map of the two chromosomes was established in a parallel experiment and the recombination frequency in different regions of the chromosomes determined. A comparison of the cyto- genetic localization of the enzyme genes in D. subobscura and D. melanogaster indicates that many paracentric inversions must have taken place in the course of divergent evolution. However, no displacements of genes from one element to another due to pericentric inversions, reciprocal translocations or transpos- ing elements can be observed. In spite of the large number of structural rear- rangements that have occurred in the phylogeny of the genus Drosophila, gross similarities of banding pattern in homologous regions of the chromosomes of the two species become apparent. ITH the introduction of gel electrophoresis, enzyme loci have become W very important marker genes for population genetic studies. Allozyme variation has proved especially useful for the estimation of the amount of genetic variation and for the calculation of genetic relationship between pop- ulations, species and other taxa. In addition, a number of studies have been devoted to the search for nonrandom associations between alleles of different loci or linkage disequilibrium, maintained by selective forces favoring certain allele associations by epistatic interaction.
    [Show full text]
  • Rapid Evolution of Wing Size Clines in Drosophila Subobscura
    Genetica 112–113: 273–286, 2001. 273 © 2001 Kluwer Academic Publishers. Printed in the Netherlands. Rapid evolution of wing size clines in Drosophila subobscura George W. Gilchrist1, Raymond B. Huey2 &Llu´ıs Serra3 1Department of Biology Box 5805, Clarkson University, Potsdam, NY 13699-5805, USA (Phone: 315-268- 2359; E-mail: [email protected]); 2Department of Zoology Box 351800, University of Washington, Seattle, WA 98195-1800, USA; 3Departamento de Gen`etica, Universidat de Barcelona, 08071 Barcelona, Spain Key words: clines, Drosophila subobscura, evolutionary rates, species introductions, wing size Abstract Parallel latitudinal clines across species and continents provide dramatic evidence of the efficacy of natural selec- tion, however little is known about the dynamics involved in cline formation. For example, several drosophilids and other ectotherms increase in body and wing size at higher latitudes. Here we compare evolution in an ancestral European and a recently introduced (North America) cline in wing size and shape in Drosophila subobscura.We show that clinal variation in wing size, spanning more than 15 degrees of latitude, has evolved in less than two decades. In females from Europe and North America, the clines are statistically indistinguishable however the cline for North American males is significantly shallower than that for European males. We document that while overall patterns of wing size are similar on two continents, the European cline is obtained largely through changing the proximal portion of the wing, whereas the North American cline is largely in the distal portion. We use data from sites collected in 1986/1988 (Pegueroles et al. 1995) and our 1997 collections to compare synchronic (divergence between contemporary populations that share a common ancestor) and allochronic (changes over time within a population) estimates of the rates of evolution.
    [Show full text]
  • Drosophila Subobscura Short Sperm Have No Biochemical Incompatibilities with Fertilization Maria Enrica Pasini*
    The Open Entomology Journal, 2010, 4, 25-29 25 Open Access Drosophila subobscura Short Sperm have no Biochemical Incompatibilities with Fertilization Maria Enrica Pasini* Università degli Studi di Milano, Dipartimento di Scienze Biomolecolari e Biotecnologie, Via Celoria, 26-20133 Milano, Italy Abstract: Drosophila obscura group species produce two distinct sizes of nucleated sperm that differ only in head and tail lenghts. Between both sperm there is no differences in location of the acrosome and flagellum during spermiogenesis where each sperm type develops in its own bundle. Fertile sperm accumulate in the seminal vesicles. Fertilization is ex- clusively monospermic and in a previous study we suggested that both types of sperm are fertilization-competent on the basis of similar DNA content and storage in females also if morph variations are consistent with a fertilization-related se- lection for optimal sperm size. This assumption is in agreement with previous studies that demonstrated that only long sperm fertilize eggs. In this study fertilization of Drosophila subobscura is examined using anti-sperm surface -N- acetylhexosaminidases and -L-fucosidase antibodies. Beta hexosaminidases are intrinsic proteins of the sperm plasma membrane in spermomomorphic species of the melanogaster group closely related to Drosophila melanogaster. These enzymes had been previously identified as putative receptors for glycoconjugates of the egg surface, structurally and func- tionally conserved. Here their localization has been investigated in Drosophila subobscura. Consistent with our previ- ous study, short and long sperm are functionally equivalent. More data are needed to clarify the consequences and adapta- tive significance of morph variations. Keywords: Drosophila, reproduction, sperm dimorphism, gametes.
    [Show full text]
  • Amyrel, a Paralogous Gene of the Amylase Gene Family in Drosophila Melanogaster and the Sophophora Subgenus
    Proc. Natl. Acad. Sci. USA Vol. 95, pp. 6848–6853, June 1998 Evolution Amyrel, a paralogous gene of the amylase gene family in Drosophila melanogaster and the Sophophora subgenus JEAN-LUC DA LAGE*, EMMANUELLE RENARD,FRE´DE´RIQUE CHARTOIS,FRANC¸OISE LEMEUNIER, AND MARIE-LOUISE CARIOU Populations, Ge´ne´tiqueet Evolution, Centre National de la Recherche Scientifique, 91198 Gif sur Yvette cedex, France Communicated by Wyatt W. Anderson, University of Georgia, Athens, GA, March 26, 1998 (received for review January 16, 1997) ABSTRACT We describe a gene from Drosophila melano- Focusing on amylase evolution in Drosophilids, we observed gaster related to the alpha-amylase gene Amy. This gene, which that some species harbored two types of genes: those with an exists as a single copy, was named Amyrel. It is strikingly intron at position 177, which is supposed to be ancestral (14), and divergent from Amy because the amino acid divergence is 40%. those without an intron at this position. This was the case in The coding sequence is interrupted by a short intron at Drosophila takahashii, Drosophila lucipennis, and in the Drosoph- position 655, which is unusual in amylase genes. Amyrel has ila obscura group. Phylogenetic trees clearly showed that “intron- also been cloned in Drosophila ananassae, Drosophila pseudoob- less” genes of these species were excluded from the Amy tree but scura, and Drosophila subobscura and is likely to be present remained clustered together, suggesting that they were paralogs throughout the Sophophora subgenus, but, to our knowledge, (14). Given the tree topology, we suspected that such a divergent it has not been detected outside.
    [Show full text]
  • Variation in Egg Size and Number in Drosophila Subobscura
    W&M ScholarWorks Dissertations, Theses, and Masters Projects Theses, Dissertations, & Master Projects 2006 Variation in Egg Size and Number in Drosophila subobscura Minyoung Janet Yi College of William & Mary - Arts & Sciences Follow this and additional works at: https://scholarworks.wm.edu/etd Part of the Entomology Commons Recommended Citation Yi, Minyoung Janet, "Variation in Egg Size and Number in Drosophila subobscura" (2006). Dissertations, Theses, and Masters Projects. Paper 1539626847. https://dx.doi.org/doi:10.21220/s2-fee0-t039 This Thesis is brought to you for free and open access by the Theses, Dissertations, & Master Projects at W&M ScholarWorks. It has been accepted for inclusion in Dissertations, Theses, and Masters Projects by an authorized administrator of W&M ScholarWorks. For more information, please contact [email protected]. VARIATION IN EGG SIZE AND NUMBER IN DROSOPHILA SUBOBSCURA Maternal and paternal effects revealed through intrapopulation and interpopulation crosses A Thesis Presented to The Faculty of the Department of Biology The College of William and Mary in Virginia In Partial Fulfillment Of the Requirements for the Degree of Master of Science by Minyoung Janet Yi 2006 APPROVAL SHEET This thesis is submitted in partial fulfillment of the requirements for the degree of Master of Science Minyoung Janet Yi Approved by the Committee, June 2006 George Wf Gilchrist, Chair j£ L Martha A. Case, Professor John P. Swaddle, Professor My parents who imbued in me an appreciation for learning. Materi Ecclesiae who taught me all the things worth knowing. Mariae semper virgini who points me closer to the Truth every day. TABLE OF CONTENTS Page Acknowledgments vi List of Tables vii List of Figures viii Abstract ix Chapter I.
    [Show full text]
  • Kosuda, K. Viability of Drosophila Melanogaster Female Flies Carrying
    Dros. Inf. Serv. 96 (2013) Research Notes 75 106; Moore, P.J., and A.J. Moore 2001, Proc. Natl. Acad. Sci. USA 98: 9171-9176; Pavkovic, L.S., and V. Kekic 2009, Russian Journal of Genetics 45(7): 875-877; Pavkovic, L.S., and V. Kekic 2013, Eur. J. Entomol. 110(1): 31-37; Ravi Ram, K., and S.R. Ramesh 2001, Biochem. Genet. 39: Nos. 314; Rezaei, A., 2012, Egypt. Acad. J. Biol. Sci. 5(1): 81-87; Roopashree, S., K. Raviram, and S.R. Ramesh 2001, Dros. Inf. Serv. 84: 93-95; Serradilla, J.M., and F.J. Ayala 1983, Proc. Nat. Acad. Sci. USA 80: 2022-2025; Shivanna, N., and S.R. Ramesh 1995, Ind. J. Exp. Biol. 33: 668; Shivanna, N., G.S. Siddalingamurthy, and S.R. Ramesh 1996, Genome 39: 105; Singh, S.R., and B.N. Singh 2000, Zool. Sci. 17: 389; Singh, S.R., and B.N. Singh 2004, Current Science 86: 465; Watanabe, T.K., and Seido Ohnishi 1975, Genetics 80: 807-819; YiShi, Li, 2008, Characterization of Drosophila Longevity and Fecundity Regulating. University of Southern California Los Angeles, California 2008: 1-150. Influence of extremely low frequency magnetic field (50 Hz, 0.5 mT) exposure on fitness components of Drosophila subobscura. Dimitrijević, D.1, M. Andjelković2,3,4, and T. Savić2. 1Vinča Institute of Nuclear Sciences, University of Belgrade, Serbia; 2Institute for Biological Research “Siniša Stanković”, University of Belgrade, Serbia; 3Faculty of Biology, University of Belgrade, Serbia; 4Serbian Academy of Sciences and Arts, Serbia; *Corresponding author: [email protected]; [email protected] Summary In addition to naturally occurring radiation, magnetic fields which are introduced by a man with the advanced development of industry and technology present an additional factor in environment that could have a significant influence on living systems.
    [Show full text]
  • Drosophila Information Service
    Drosophila Information Service Number 103 December 2020 Prepared at the Department of Biology University of Oklahoma Norman, OK 73019 U.S.A. ii Dros. Inf. Serv. 103 (2020) Preface Drosophila Information Service (often called “DIS” by those in the field) was first printed in March, 1934. For those first issues, material contributed by Drosophila workers was arranged by C.B. Bridges and M. Demerec. As noted in its preface, which is reprinted in Dros. Inf. Serv. 75 (1994), Drosophila Information Service was undertaken because, “An appreciable share of credit for the fine accomplishments in Drosophila genetics is due to the broadmindedness of the original Drosophila workers who established the policy of a free exchange of material and information among all actively interested in Drosophila research. This policy has proved to be a great stimulus for the use of Drosophila material in genetic research and is directly responsible for many important contributions.” Since that first issue, DIS has continued to promote open communication. The production of this volume of DIS could not have been completed without the generous efforts of many people. Except for the special issues that contained mutant and stock information now provided in detail by FlyBase and similar material in the annual volumes, all issues are now freely-accessible from our web site: www.ou.edu/journals/dis. For early issues that only exist as aging typed or mimeographed copies, some notes and announcements have not yet been fully brought on line, but key information in those issues is available from FlyBase. We intend to fill in those gaps for historical purposes in the future.
    [Show full text]
  • The Origin of Chromosomal Inversions As a Source of Segmental
    www.nature.com/scientificreports OPEN The origin of chromosomal inversions as a source of segmental duplications in the Sophophora Received: 07 June 2016 Accepted: 05 July 2016 subgenus of Drosophila Published: 29 July 2016 Eva Puerma, Dorcas J. Orengo & Montserrat Aguadé Chromosomal inversions can contribute to the adaptation of organisms to their environment by capturing particular advantageous allelic combinations of a set of genes included in the inverted fragment and also by advantageous functional changes due to the inversion process itself that might affect not only the expression of flanking genes but also their dose and structure. Of the two mechanisms originating inversions —ectopic recombination, and staggered double-strand breaks and subsequent repair— only the latter confers the inversion the potential to have dosage effects and/or to generate advantageous chimeric genes. In Drosophila subobscura, there is ample evidence for the adaptive character of its chromosomal polymorphism, with an important contribution of some warm- climate arrangements such as E1+2+9+12. Here, we have characterized the breakpoints of inversion E12 and established that it originated through the staggered-break mechanism like four of the five inversions of D. subobscura previously studied. This mechanism that also predominates in the D. melanogaster lineage might be prevalent in the Sophophora subgenus and contribute to the adaptive character of the polymorphic and fixed inversions of its species. Finally, we have shown that the D. subobscura inversion breakpoint regions have generally been disrupted by additional structural changes occurred at different time scales. Structural variation ranging from chromosomal inversions to chromosome fusions does not only lead to genome reorganization through time but it can also contribute to the adaptation of organisms to their environment.
    [Show full text]
  • Drosophila Subobscura
    Journal of Thermal Biology 25 (2000) 267±272 www.elsevier.com/locate/jtherbio Size and seasonal temperature in free-ranging Drosophila subobscura J.S. Kari, Raymond B. Huey* Department of Zoology, Box 351800, University of Washington, Seattle, WA 98105-1800, USA Received 14 July 1999; accepted 3 August 1999 Abstract Body size of diverse ectotherms is inversely related to developmental temperature in the laboratory. We monitored seasonal variation in wing length of two populations (Oregon, Washington) of D. subobscura, which was introduced in the Paci®c Northwest in the late 1970s. Wing length varied seasonally and was shortest in summer. In Washington, however, wing length was longest in spring, not winter. Wing length was inversely and curvilinearly related to mean ambient temperature, as in a few previous studies of drosophilids. Mid-winter D. subobscura might not be the largest either because extremely low temperatures depress size or because ¯ies collected in winter were in fact born the previous autumn, when developmental temperatures were more moderate. 7 2000 Elsevier Science Ltd. All rights reserved. Keywords: Drosophila subobscura; Drosophila melanogaster; Drosophila simulans; Temperature; Body size; Reaction norm 1. Introduction universality of the inverse relationship for size versus temperature has recently attracted considerable atten- Reaction norms (Schmalhausen, 1949) that map tion (e.g. Atkinson, 1994, 1996; Berrigan and Charnov, adult body size on developmental temperatures are 1994; Partridge and French, 1996; van der Have and remarkably consistent in shape for diverse ectotherms: de Jong, 1996), and both adaptive and non-adaptive speci®cally, adult body size of laboratory reared indi- explanations of the pattern have been proposed viduals is almost always inversely related to develop- (reviewed in Atkinson and Sibly, 1997).
    [Show full text]
  • Mating Activity of Homo- and Heterokaryotypes in Drosophila Pavanii
    MATING ACTIVITY OF HOMO- AND HETEROKARYOTYPES IN DROSOPHILA PAVANII DANK0 BRNCIC AND SUS1 KOREF-SANTIBANEZ University of Chile, Santiago2 Received October 9. 1963 ANY species of Drosophila exhibit chromosomal polymorphism due to in- versions of chromosome sections. Species differ in the number, location, size, and frequency of the inversions. The differences can sometimes be correlated with the distribution, abundance, and other ecological characteristics of the popu- lations, as well as with the physiological properties of the carriers of the inversions (review in DOBZHANSKY1951; DA CUNHA1960; SPIES 1962). Two kinds of polymorphic species may be distinguished: (1) Species or populations in which the polymorphism is “flexible”, i.e., the frequencies of the arrangements are modified by environmental changes, both in nature and under laboratory con- ditions. Some populations of D.pseudoobscura and D.persimilis (DOBZHANSKY 1956), D. robusta (CARSON1958), D. subobscura (SPERLICH1961) and D. flauopilosa (BRNCIC1962) belong to this group. (2) Species or populations with more rigid polymorphisms, in which there is no good evidence for geographical, seasonal, or altitudinal fluctuations of the frequency of polymorphic inversions. Rigid polymorphisms seem to be present in some populations of D. robusta (CARSON1958), D.subobscura ( KUNZE-MUHL,MULLER and SPERLICH1958), D.willistoni ( DOBZHANSKY1962) and D.pauani ( BRNCIC1957). Within a single Mendelian population, flexible and rigid polymorphism may both be present, but for different chromosomal arrangements ( DOBZHANSKY1962). The reasons why a chromosomal polymorphism in Drosophila may be more rigid or more flexible are not well known; this may depend on the selective values of the homozygotes (homokaryotypes) and heterozygotes (heterokaryotypes) within each population. A selection which would favor homo- or heterokaryotypes according to the environment, will give a flexible polymorphism.
    [Show full text]
  • Multiple Matings, Effective Population Size And
    Heredity (1980), 45(2), 281-292 0018-067X/80/02170281$02.00 1980. The Genetical Society of Great Britain MULTIPLEMATINGS, EFFECTIVE POPULATION SIZE AND SEXUAL SELECTION IN DROSOPHILA MELANOGASTER C. PETIT, P. BOURGERON and H. MERCOT Laboratoire de Génétique des Populations de l'Université Paris 7, Tour 42, 2 place Jussieu. 75005 Paris, France (*) Received27.ii.80 SUMMARY The distribution of sexually efficient males has been analysed in two populations made up of 5 times more females than males. When observation stops as soon as the number of inseminated females equals the number of males, 25 per cent of males in both strains had not mated, 50 per cent of the matings were performed by 50 per cent of the males who mated only once and the other 50 per cent of matings were performed by 25 per cent of the males who mated 2 or 3 times. Productivity of the successive matings falls drastically after the third mating. The relative role of sexual selection and multiple matings as components of fitness are discussed, as well as their implications for the effective population size. 1. INTRODUCTION THE fact that males can mate with more than one female forms one of the bases for sexual selection, especially because females generally accept a limited number of mates. Manning (1962) reported that Drosophila melanogaster females will not mate in less than 2-day intervals, a time varying according to the strain and the species. Wheeler (1947) described the insemination reaction that prevents the female from mating immediately in many Drosophila species. Differences between male and female behaviour and the resulting sex-ratio bias are especially clear in some species of birds or mammals which need parental care, namely, sage grouse (Wiley, 1973, 1974), elephant seals (Le Boeuf, 1976; Cox and Le Boeuf, 1977) and baboons (de Vore, 1965).
    [Show full text]