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Poster Full Abstracts - Evolution and Quantitative Genetics
Poster board number is above title. The first author is the presenter
267
differing from yeast and mammals.
505A
Men are messy:
Wolbachia
stem cell niche tropism in
Drosophila
is evolutionary conserved only in females.
Michelle E. Toomey
1,2
, Eva Fast
1
, Horacio
M. Frydman
1,2
. 1) Dept. of Biology, Boston University, Boston, MA; 2) National Emerging Infectious Diseases Laboratory, Boston University, Boston, MA.
The intracellular bacteria Wolbachia infect up to 70% of all insect species. Even though Wolbachia infections are the largest pandemic on this planet, the
cellular and molecular mechanisms for bacterial spreading in nature are still unknown. Typically, Wolbachia are vertically transmitted through the female
germline. We have previously reported that Wolbachia target the somatic stem cell niche in the Drosophila melanogaster ovary, facilitating germline
infection and contributing to vertical transmission1. To assess if niche targeting is an evolutionarily conserved mechanism across the Drosophila genus, we
investigated niche targeting in ecologically diverse Wolbachia strain-Drosophila species pairs. Our data revealed different types of niche tropism among
naturally infected Drosophila species: 1) somatic stem cell niche tropism (Figure 1A); 2) germline stem cell niche tropism (Figure 1B); 3) hub tropism in the
testes (Figure 8). Each host-bacteria pair displays qualitative and quantitative differences in niche tropisms. Phylogenetic analyses suggest that the different
patterns of niche tropism are more closely related to the Wolbachia strain than the host species (Figure 2). Using hybrid introgression crosses and
transinfection experiments we confirm that bacterial factors play a major role in determining the characteristics of stem cell niche tropism in both the female
and male stem cell niches (Figures 3 and 7 respectively). This work highlights a widespread targeting of stem cell niches in the Drosophila genus,
contributing to Wolbachia transmission in nature.
506B
Recessive lethal accumulation increases chromosomal inversion polymorphisms in
Drosophila melanogaster
.
Shir-Fan Tung
1
, Takahiro Miyo
2
, Hsin-Yi
Chi
3
, Chau-Ti Ting
1,2,4,5
, Shu Fang
3
. 1) Institute of Ecology and Evolutionary Biology, National Taiwan University, Taiwan, ROC; 2) Department of Life
Science, National Taiwan University, Taiwan, ROC; 3) Biodiversity Research Center, Academia Sinica, Taiwan, ROC; 4) Institute of Zoology, National
Taiwan University, Taiwan, ROC; 5) Research Center for Developmental Biology and Regenerative Medicine, National Taiwan University, Taiwan, ROC.
Gene coadaptation has been proposed as the major mechanism to maintain chromosomal inversion polymorphisms in natural populations. Genetic load,
though less studied, is likely to be another as recessive deleterious mutations decrease the fitness of homozygotes, and in turn accumulate in the
recombination-suppression regions of inversion heterozygotes, leading to the increase of inversion heterozygosity. If the latter mechanism is acting in natural
populations, the recessive deleterious mutations would be expected to accumulate nearby the inversion breakpoints where recombination is greatly
suppressed in inversion heterozygotes. The Afrotropical population of
Drosophila melanogaster
with high chromosomal inversion heterozygosity and high
frequency of recessive lethals provides an ideal material to test this mechanism by examining whether recessive lethals located nearby the inversion
breakpoints. By using recombination and deficiency mappings, we identified 14 recessive lethal alleles from eight lethal-bearing third chromosomes. Of
which, 13 were mapped into the regions close to the breakpoints of inversions which were found to be polymorphic in the African population. This result
provides strong evidence that the accumulation of recessive deleterious mutations can contribute to the maintenance of high chromosomal inversion
polymorphisms.
507C
Evolution of the Hippo signaling pathway.
Stuart J. Newfeld
1
, Charlotte E. Konikoff
2
, Billie J. Swalla
2
. 1) Sch Life Sci, Arizona State Univ, Tempe, AZ;
2) Biology Dept, Univ Washington, Seattle, WA.
Initially discovered in flies less than 20 years ago the Hippo kinase pathway has emerged as an important modulator of cell proliferation and apoptosis
during development and as a regulator of homeostasis in adults. Here we report the first comprehensive phylogenetic analysis of the multigene families that
constitute this pathway. Our data revealed that Hippo is younger than the TGF-beta and Wnt pathways with its origin in the Bilaterian lineage after its
divergence from sponges and cnidarians. In vertebrate deuterostomes, well-known whole-genome duplications have expanded many pathway families while
relationships between family members generally follow the species tree - as seen in the TGF-beta pathway. Alternatively, in protostomes gene loss appears
to have occurred in several families - as seen in the Wnt pathway. In between these groups invertebrate deuterostome gene families show neither duplication
nor loss, yet individual trees for many families are inconsistent with their respective species tree. Overall, the data suggest that the Hippo pathway arose late
in animal evolution and likely played a role in the origin of the chordate bauplan.
508A
Genetic Population Structure of the Emergent Invasive Fruit Pest
Drosophila suzukii
.
Jeffrey Adrion, Nick Haddad, Hannah Burrack, Nadia Singh.
North Carolina State University, Raleigh, NC.
Biological invasions have been responsible for damaging modifications to ecosystem function in addition to diminishing native biodiversity.
Understanding the colonization history of invasive species is an integral aspect of developing effective pest management strategies. Native to Japan, the soft-
skinned fruit pest
Drosophila suzukii
has recently invaded the United States and Europe. The Eastern United States represents the most recent expansion of
their range, which presents an exciting opportunity to test alternative models of their colonization history. Here we investigate the genetic population
structure of an invasive fruit fly, with a focus on the eastern United States. We sequenced six 700 bp X-linked loci from 8-24 wild-caught males from each
of 15 populations. Eight of these populations are from the East Coast of the US, and the remaining 7 include populations from Japan, Spain, the West Coast
of the US and the Midwest US. We examine levels of nucleotide diversity in ancestral versus derived populations, and compare recently established
populations such as those on the East Coast with less recent invasions such as that found in Hawaii. We estimate the degree of genetic differentiation among
populations and explore alternative demographic models for the observed patterns of polymorphism. Moreover, we discuss implications for future range
expansion and pest management.
509B
Temporal and spatial dynamics of adaptive evolution in temperate Drosophila.
Alan O. Bergland
1
, Katherine O'Brien
2
, Emily Behrman
2
, Paul Schmidt
2
,
Dmitri Petrov
1
. 1) Dept. of Biology, Stanford University, Stanford, CA; 2) Dept. of Biology, University of Pennsylvania, Philadelphia, PA.