Main Menu (Mobile)- Block

Main Menu - Block

custom | custom

Search Results

general_search_page-panel_pane_1 | views_panes

44 Janelia Publications

Showing 1-10 of 44 results
Your Criteria:
    05/03/20 | Co-evolving wing spots and mating displays are genetically separable traits in Drosophila.
    Massey JH, Rice GR, Firdaus A, Chen C, Yeh S, Stern DL, Wittkopp PJ
    Evolution. 2020 May 03:. doi: 10.1111/evo.13990

    The evolution of sexual traits often involves correlated changes in morphology and behavior. For example, in Drosophila, divergent mating displays are often accompanied by divergent pigment patterns. To better understand how such traits co-evolve, we investigated the genetic basis of correlated divergence in wing pigmentation and mating display between the sibling species Drosophila elegans and D. gunungcola. Drosophila elegans males have an area of black pigment on their wings known as a wing spot and appear to display this spot to females by extending their wings laterally during courtship. By contrast, D. gunungcola lost both of these traits. Using Multiplexed Shotgun Genotyping (MSG), we identified a ∼440 kb region on the X chromosome that behaves like a genetic switch controlling the presence or absence of male-specific wing spots. This region includes the candidate gene optomotor-blind (omb), which plays a critical role in patterning the Drosophila wing. The genetic basis of divergent wing display is more complex, with at least two loci on the X chromosome and two loci on autosomes contributing to its evolution. Introgressing the X-linked region affecting wing spot development from D. gunungcola into D. elegans reduced pigmentation in the wing spots but did not affect the wing display, indicating that these are genetically separable traits. Consistent with this observation, broader sampling of wild D. gunungcola populations confirmed the wing spot and wing display are evolving independently: some D. gunungcola males performed wing displays similar to D. elegans despite lacking wing spots. These data suggest that correlated selection pressures rather than physical linkage or pleiotropy are responsible for the coevolution of these morphological and behavioral traits. They also suggest that the change in morphology evolved prior to the change in behavior. This article is protected by copyright. All rights reserved.

    View Publication Page
    03/06/20 | A large genomic insertion containing a duplicated follistatin gene is linked to the pea aphid male wing dimorphism.
    Li B, Bickel RD, Parker BJ, Saleh Ziabari O, Liu F, Vellichirammal NN, Simon J, Stern DL, Brisson JA
    eLife. 2020 Mar 06;9:. doi: 10.7554/eLife.50608

    Wing dimorphisms have long served as models for examining the ecological and evolutionary tradeoffs associated with alternative phenotypes. Here, we investigated the genetic cause of the pea aphid () male wing dimorphism, wherein males exhibit one of two morphologies that differ in correlated traits that include the presence or absence of wings. We mapped this trait difference to a single genomic region and, using third generation, long-read sequencing, we identified a 120 kb insertion in the wingless allele. This insertion includes a duplicated gene, which is a strong candidate gene in the minimal mapped interval to cause the dimorphism. We found that both alleles were present prior to pea aphid biotype lineage diversification, we estimated that the insertion occurred millions of years ago, and we propose that both alleles have been maintained in the species, likely due to balancing selection.

    View Publication Page
    03/01/20 | Characterization of the Genetic Architecture Underlying Eye Size Variation Within Drosophila melanogaster and Drosophila simulans.
    Gaspar P, Arif S, Sumner-Rooney L, Kittelmann M, Bodey AJ, Stern DL, Nunes MD, McGregor AP
    Genes|Genomes|Genetics. 2020 Mar 01;10(3):1005-18. doi: 10.1534/g3.119.400877
    10/15/19 | The yellow gene influences Drosophila male mating success through sex comb melanization.
    Massey JH, Chung D, Siwanowicz I, Stern DL, Wittkopp PJ
    eLife. 2019 Oct 15;8:. doi: 10.7554/eLife.49388

    males perform a series of courtship behaviors that, when successful, result in copulation with a female. For over a century, mutations in the gene, named for its effects on pigmentation, have been known to reduce male mating success. Prior work has suggested that influences mating behavior through effects on wing extension, song, and/or courtship vigor. Here, we rule out these explanations, as well as effects on the nervous system more generally, and find instead that the effects of on male mating success are mediated by its effects on pigmentation of male-specific leg structures called sex combs. Loss of expression in these modified bristles reduces their melanization, which changes their structure and causes difficulty grasping females prior to copulation. These data illustrate why the mechanical properties of anatomy, not just neural circuitry, must be considered to fully understand the development and evolution of behavior.

    View Publication Page
    07/08/19 | Changes throughout a genetic network mask the contribution of Hox gene evolution.
    Liu Y, Ramos-Womack M, Han C, Reilly P, Brackett KL, Rogers W, Williams TM, Andolfatto P, Stern DL, Rebeiz M
    Current Biology. 2019 Jul 08;29(13):2157-66. doi: 10.1016/j.cub.2019.05.074

    Hox genes pattern the anterior-posterior axis of animals and are posited to drive animal body plan evolution, yet their precise role in evolution has been difficult to determine. Here, we identified evolutionary modifications in the Hox gene Abd-Bthat dramatically altered its expression along the body plan of Drosophila santomeaAbd-B is required for pigmentation in Drosophila yakuba, the sister species of D. santomea, and changes to Abd-B expression would be predicted to make large contributions to the loss of body pigmentation in D. santomea. However, manipulating Abd-B expression in current-day D. santomea does not affect pigmentation. We attribute this epistatic interaction to four other genes within the D. santomea pigmentation network, three of which have evolved expression patterns that do not respond to Abd-B. Our results demonstrate how body plans may evolve through small evolutionary steps distributed throughout Hox-regulated networks. Polygenicity and epistasis may hinder efforts to identify genes and mechanisms underlying macroevolutionary traits.

    View Publication Page
    05/28/19 | Evolution of Mechanisms that Control Mating in Drosophila Males.
    Ahmed OM, Avila-Herrera A, Tun KM, Serpa PH, Peng J, Parthasarathy S, Knapp J, Stern DL, Davis GW, Pollard KS, Shah NM
    Cell Reports. 2019 May 28;27(9):2527-2536.e4. doi: 10.1016/j.celrep.2019.04.104

    Genetically wired neural mechanisms inhibit mating between species because even naive animals rarely mate with other species. These mechanisms can evolve through changes in expression or function of key genes in sensory pathways or central circuits. Gr32a is a gustatory chemoreceptor that, in D. melanogaster, is essential to inhibit interspecies courtship and sense quinine. Similar to D. melanogaster, we find that D. simulans Gr32a is expressed in foreleg tarsi, sensorimotor appendages that inhibit interspecies courtship, and it is required to sense quinine. Nevertheless, Gr32a is not required to inhibit interspecies mating by D. simulans males. However, and similar to its function in D. melanogaster, Ppk25, a member of the Pickpocket family, promotes conspecific courtship in D. simulans. Together, we have identified distinct evolutionary mechanisms underlying chemosensory control of taste and courtship in closely related Drosophila species.

    View Publication Page
    05/01/19 | Pleiotropic effects of ebony and tan on pigmentation and cuticular hydrocarbon composition in Drosophila melanogaster.
    Massey JH, Akiyama N, Bien T, Dreisewerd K, Wittkopp PJ, Yew JY, Takahashi A
    Frontiers in Physiology. 05/2019;10:518. doi: 10.3389/fphys.2019.00518

    Pleiotropic genes are genes that affect more than one trait. For example, many genes required for pigmentation in the fruit fly also affect traits such as circadian rhythms, vision, and mating behavior. Here, we present evidence that two pigmentation genes, and , which encode enzymes catalyzing reciprocal reactions in the melanin biosynthesis pathway, also affect cuticular hydrocarbon (CHC) composition in females. More specifically, we report that loss-of-function mutants have a CHC profile that is biased toward long (>25C) chain CHCs, whereas loss-of-function mutants have a CHC profile that is biased toward short (<25C) chain CHCs. Moreover, pharmacological inhibition of dopamine synthesis, a key step in the melanin synthesis pathway, reversed the changes in CHC composition seen in mutants, making the CHC profiles similar to those seen in mutants. These observations suggest that genetic variation affecting and/or activity might cause correlated changes in pigmentation and CHC composition in natural populations. We tested this possibility using the Genetic Reference Panel (DGRP) and found that CHC composition covaried with pigmentation as well as levels of and expression in newly eclosed adults in a manner consistent with the and mutant phenotypes. These data suggest that the pleiotropic effects of and might contribute to covariation of pigmentation and CHC profiles in .

    View Publication Page
    03/08/19 | Neural evolution of context-dependent fly song.
    Ding Y, Lillvis JL, Cande J, Berman GJ, Arthur BJ, Long X, Xu M, Dickson BJ, Stern DL
    Current Biology : CB. 2019 Mar 08;29(7):1089-99. doi: 10.1016/j.cub.2019.02.019

    It is unclear where in the nervous system evolutionary changes tend to occur. To localize the source of neural evolution that has generated divergent behaviors, we developed a new approach to label and functionally manipulate homologous neurons across Drosophila species. We examined homologous descending neurons that drive courtship song in two species that sing divergent song types and localized relevant evolutionary changes in circuit function downstream of the intrinsic physiology of these descending neurons. This evolutionary change causes different species to produce divergent motor patterns in similar social contexts. Artificial stimulation of these descending neurons drives multiple song types, suggesting that multifunctional properties of song circuits may facilitate rapid evolution of song types.

    View Publication Page
    12/13/18 | Gene flow mediates the role of sex chromosome meiotic drive during complex speciation.
    Meiklejohn CD, Landeen EL, Gordon KE, Rzatkiewicz T, Kingan SB, Geneva AJ, Vedanayagam JP, Muirhead CA, Garrigan D, Stern DL, Presgraves DC
    eLife. 2018 Dec 13;7:. doi: 10.7554/eLife.35468

    During speciation, sex chromosomes often accumulate interspecific genetic incompatibilities faster than the rest of the genome. The drive theory posits that sex chromosomes are susceptible to recurrent bouts of meiotic drive and suppression, causing the evolutionary build-up of divergent cryptic sex-linked drive systems and, incidentally, genetic incompatibilities. To assess the role of drive during speciation, we combine high-resolution genetic mapping of X-linked hybrid male sterility with population genomics analyses of divergence and recent gene flow between the fruitfly species, and . Our findings reveal a high density of genetic incompatibilities and a corresponding dearth of gene flow on the X chromosome. Surprisingly, we find that a known drive element recently migrated between species and, rather than contributing to interspecific divergence, caused a strong reduction in local sequence divergence, undermining the evolution of hybrid sterility. Gene flow can therefore mediate the effects of selfish genetic elements during speciation.

    View Publication Page
    10/05/18 | Correlated evolution of two copulatory organs via a single cis-regulatory nucleotide change.
    Nagy O, Nuez I, Savisaar R, Peluffo AE, Yassin A, Lang M, Stern DL, Matute DR, David JR, Courtier-Orgogozo V
    Current Biology : CB. 2018 Oct 05;28(21):3450-7. doi: 10.1016/j.cub.2018.08.047

    Diverse traits often covary between species [1-3]. The possibility that a single mutation could contribute to the evolution of several characters between species [3] is rarely investigated as relatively few cases are dissected at the nucleotide level. Drosophila santomea has evolved additional sex comb sensory teeth on its legs and has lost two sensory bristles on its genitalia. We present evidence that a single nucleotide substitution in an enhancer of the scute gene contributes to both changes. The mutation alters a binding site for the Hox protein Abdominal-B in the developing genitalia, leading to bristle loss, and for another factor in the developing leg, leading to bristle gain. Our study suggests that morphological evolution between species can occur through a single nucleotide change affecting several sexually dimorphic traits. VIDEO ABSTRACT.

    View Publication Page