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Poster Full Abstracts - Evolution and Quantitative Genetics
Poster board number is above title. The first author is the presenter
261
Riyue Bao. Dept Biological Sci, Wayne State Univ, Detroit, MI.
Gene duplication is an important source of evolutionary innovation. To explore the genetic basis of macroevolutionary differences between major insect
orders, we performed a genome-wide study of lineage-specific gene duplications in
Drosophila melanogaster
(fruit fly),
Anopheles gambiae
(mosquito),
Tribolium castaneum
(red flour beetle), and
Apis mellifera
(honey bee). In 5547 gene families conserved across these species, we discovered 467 families
with lineage-specific duplications in
Drosophila
compared to only 168 in
Anopheles
, 218 in
Tribolium
, and 120 in
Apis
. Based on sister-paralog synonymous
substitution divergencies, most of the
Drosophila
-specific duplications are old, dating back to the early diversification of the higher Diptera. This inference
is corroborated by the results of ortholog searches in the genome of the Hessian fly
Mayetiola destructor
. Gene ontology analysis reveals that energy
metabolism-related genes are significantly enriched in the
Drosophila
-specific duplications. We conclude that the early evolution of the higher Diptera was
exceptionally impacted by gene duplication. One of the consequences was an expansion of the energy metabolism related transcriptome. The correlated
emergence of exceptionally fast and hence energy expensive flight capacities in the higher Diptera is highly suggestive of a causal link.
482B
Premature Stop Codon Mutations and Evolution in the Drosophila pseudoobscura Complex.
Kenneth B Hoehn, Mohamed AF Noor. Biology Dept,
Duke University, Durham, NC.
A number of recent studies have shown that loss of function mutations caused by premature stop codons (PSCs) can have a significant impact on adaptive
evolution to new environments. Despite this, most PSC studies have been limited to specific genes within a specific species pair, and little is known about
the adaptive effects of premature stop codon mutations across the full genomes of multiple species. This represents a large gap in our understanding of
adaptive evolution, and investigating levels of polymorphism within species as well as differences between closely related species for PSCs can give us
insights into the evolutionary forces acting upon them. Because of the recently available genome sequences, the fruit fly Drosophila pseudoobscura
represents a promising system for investigating these effects. This project has two distinct phases. First, custom Perl scripts were written to detect premature
stop codons mutations in 11 D. pseudoobscura, 3 D. persimilis, and 3 D. miranda full genome sequences. Once found, genes of interest were selected on the
basis of a) known orthologs in D. melanogaster used to predict gene function which may have been lost, b) how early in the coding sequence the PSC occurs,
and c) whether or not the mutation was identified in multiple genome sequences. Expression was then confirmed by reverse-transcriptase PCR in the
published genome strain and at least one PSC strain. In total, our initial computational approach found 2114 unconfirmed PSC's affecting 748 genes. Of
these, 299 PSC's affecting 130 genes passed initial filtering based on presence of orthologs and severity of truncation. Specific results are discussed in the
context of the likely evolutionary forces acting on these genomes.
483C
Birth, death, and replacement of importins in Drosophila.
Emily Hsieh
1,2
, Nitin Phadnis
2
, Harmit Malik
2
. 1) University of Washington, Seattle, WA; 2)
Fred Hutchinson Cancer Research Center, Seattle,WA.
The nuclear transport pathway performs the fundamental function of moving cargo between the cytoplasm and nucleus in eukaryotes. Nuclear transport is
an essential function and is carried out through a highly conserved mechanism across all eukaryotes. Yet, in
Drosophila
, several components of the nuclear
transport apparatus evolve rapidly under positive selection. Genetic conflict with selfish elements has been suggested as a possible cause for this pattern of
rapid evolution. Here, we present a comprehensive phylogenomic analysis of importin gene evolution in
Drosophila
. Importins are adapter molecules that
directly mediate the transport of cargo into the nucleus. Our analysis reveals a recurrent gain and loss pattern of the copies of importins in
Drosophila
across
independent lineages. Interestingly, we discovered that almost all new copies of importins have acquired a testes-specific pattern expression since their birth
through gene duplication. This pattern of repeated gains of testes-specific copies of importins and signatures of episodic lineage-specific positive selection
suggests a function in suppressing segregation distortion in the male germline. Segregation distorters such as
SD
in
Drosophila melanogaster
act by
impairing nuclear transport in the testes. We are currently performing functional tests of the hypothesis that an increased dosage of these non-canonical
importins in the testes may serve a role in suppressing segregation distortion in males through restoring nuclear transport during spermatogenesis.
484A
A second generation assembly of the
Drosophila simulans
genome and its implications for genome evolution studies.
Tina Hu
1
, Michael Eisen
2
, Kevin
Thornton
3
, Peter Andolfatto
1
. 1) Department of Ecology and Evolutionary Biology and the Lewis-Sigler Institute for Integrative Genomics, Princeton
University, Princeton, NJ; 2) Howard Hughes Medical Institute and the Lawrence Berkeley Laboratory, University of California Berkeley, Berkeley, CA; 3)
Department of Ecology and Evolutionary Biology, University of California Irvine, Irvine, CA.
The amount of divergence between species is a function of mutation rate and the direction and intensity of natural selection. Previous analyses surveying
rates of sequence divergence between
Drosophila melanogaster
and its sister species
D. simulans
have suggested that rates of divergence for
nonsynonymous and synonymous sites are somewhat accelerated along the
D. melanogaster
lineage relative to
D. simulans
(Begun et al, 2007). This trend
has been interpreted as resulting from a relaxation of selection associated with a reduced effective population size in
D. melanogaster
. Most noncoding DNA
in Drosophila has also been shown to be subject to weak purifying selection. However, unlike coding regions, Begun et al. paradoxically document
accelerated evolution of noncoding DNA along the
D. simulans
lineage. We revisit these observations by combining Illumina short read with available
Sanger data for
D. simulans
strain
wt501
. Using this improved
D. simulans
reference, we revisit levels of divergence along the
D. melanogaster
and
D.
simulans
lineages.
485B
Genomic satellite DNA repeats and small RNAs: An evolutionary analysis of the
Responder
satellite in the
Drosophila melanogaster
genome.
Amanda M. Larracuente, Daven C. Presgraves. Biology Department, University of Rochester, Rochester, NY.
Responder
(
Rsp
) is a satellite DNA repeat found in the pericentric heterochromatin of chromosome
2
in
Drosophila melanogaster
.
Rsp
is well-known for
being the target of
Segregation Distorter
(
SD
)— a meiotic drive system found on chromosome
2
of
D. melanogaster
.
SD/SD
+
heterozygous males transmit
the
SD
chromosome to >95% of their progeny when the
SD
+
chromosome bears a sensitive
Rsp
allele.
Rsp
copy number in the pericentric heterochromatin of
chromosome
2
is positively correlated with the sensitivity to segregation distortion, although
Rsp
repeats have been found outside of the 2nd chromosome