Basic HTML Version
Poster Full Abstracts - Evolution and Quantitative Genetics
Poster board number is above title. The first author is the presenter
276
541A
Screens to identify novel hybrid incompatibility genes in
D. melanogaster/D. simulans
interspecific hybrids.
Tawny Cuykendall, Daniel Barbash.
Molecular Biology & Genetics, Cornell University, Ithaca, NY.
Interspecific hybrids between
D. melanogaster
females and
D. simulans
males are characterized by F1 hybrid male lethality. Lethality is caused by an
epistatic interaction in the hybrid background between
D. melanogaster Hybrid male rescue (Hmr)
and
D. simulans Lethal hybrid rescue (Lhr)
. Both
Hmr
and
Lhr
were discovered in screens of natural populations for suppressors of lethality. There has been no systematic search for hybrid incompatibility (HI)
genes similar to
Hmr
and
Lhr
in either the
D. melanogaster
or the
D. simulans
genomes. Two lines of evidence suggest that additional factors contribute to
this lethal interaction: 1) expression of
D. simulans Lhr
in a
D. melanogaster
background is not lethal and 2) crosses between triploid
D. melanogaster
females and irradiated
D. simulans
males implicate the
D. melanogaster
X containing
Hmr
, the
D. simulans
2nd chromosome containing
Lhr
, and also the
D.
simulans
3rd chromosome in lethality. Our goal is to uncover novel HI genes hidden in the genomes of these two species.
We are using the Bloomington Deficiency kit to screen for hybrid male rescue to identify regions in
D. melanogaster
which contribute to lethality. To date
we have screened ~80% of the autosomal genome and found only one region that weakly suppresses lethality. This result suggests that there is not a large
number of major effect HI genes in the
D. melanogaster
genome. In order to identify HI genes in
D. simulans
, we are performing an EMS mutagenesis
screen. All live hybrid males are pre-screened for
Lhr
to verify rescue is due to a mutation in a novel HI gene. The males will then be subjected to whole
genome sequencing to identify the candidate rescuing mutation. The putative HI gene will be verified by exploiting the RNAi tools available in
D.
melanogaster
to specifically knock down the
D. simulans
ortholog in hybrids.
542B
Dissecting behavioral isolation in nature: Evolution of mate choice in the closely related species
Drosophila subquinaria
and
D. recens
.
Kelly A.
Dyer
1
, Erin Giglio
1
, Jacqueline Sztepanacz
2
, Brooke E White
1
, Emily R Peeden
1
, Howard D Rundle
2
. 1) Dept Genetics, Univ Georgia, Athens, GA; 2) Dept
Biology, Univ Ottawa, Ottawa, Canada.
The divergence among populations in male signal traits and female preferences may be an important source of behavioral isolation during the speciation
process. Here we investigate the traits involved during mate choice within, and behavioral isolation between, the closely related species
D. subquinaria
and
D. recens
. In sympatric populations,
D. subquinaria
females discriminate strongly against both
D. recens
males as well as allopatric conspecific
D.
subquinaria
males, consistent with a pattern of reinforcing selection to avoid mating with
D. recens
. Our long-term goal is to understand the mechanism(s)
by which the male signal traits and female preferences diverge in nature to cause these changes in mate discrimination and ultimately reproductive isolation.
To this end, we will present evidence that chemical forms of communication, namely male contact pheromones that consist of cuticular hydrocarbons
(CHCs), are an important form of communication in these species, and likely form the basis upon which females choose among conspecific mates and
discriminate against males of the opposite species.
543C
Testing the potential role of small RNAs in satellite DNA-based hybrid incompatibility between Drosophila melanogaster and D. simulans.
Karina E.
Gomez, Patrick M. Ferree. W.M. Keck Science Department, Claremont McKenna College, 925 N. Mills Ave, Claremont, CA 91711.
A central goal in speciation biology is identifying specific loci that cause post-zygotic reproductive isolation between species and understanding how these
loci operate at the cellular and molecular levels in hybrids. Previous work has demonstrated that a large block of D. melanogaster X-linked satellite DNA
kills hybrid female progeny produced from D. melanogaster fathers and D. simulans mothers. Unique to the D. melanogaster species, the 359-bp satellite
block exhibits stretching defects in female hybrids that lead to X chromosome bridges and early embryonic death. We have proposed that these defects are
due to mis-packaging of the 359-bp satellite DNA into heterochromatin by factors in the D. simulans maternal cytoplasm. Previous work in S. pombe and
other model organisms suggest that small RNAs complementary to repetitive sequences are involved in their heterochromatic packaging. Based on this idea,
359-bp DNA mis-packaging in hybrid female embryos may result from a lack of 359-bp-derived small RNAs in the D. simulans cytotype. In order to test
this specific model of hybrid incompatibility, we have made a set of transgenic Valium-22-derived constructs that can express small RNAs complementary
to the 359-bp satellite. Our long-term goal is to place these transgenes into D. simulans in order to determine if 359-bp small RNAs expressed through the
siRNA pathway can feed into the piRNA pathway and affect heterochromatin formation of the 359-bp satellite block in hybrids. As a step toward this goal,
we have introduced several of these constructs into the D. melanogaster pure species. We are currently testing if overexpression of these small RNAs affects
normal 359-bp packaging in D melanogaster.
544A
The effect of the X chromosome on regulation of gene expression in hybrids between
Drosophila yakuba
and
D. santomea
.
Ana Llopart, Evgeny Brud,
Emily Beck. Dept Biol, Univ Iowa, Iowa City, IA.
In interspecific crosses the
X
chromosome shows a disproportionately large effect on hybrid fitness, an effect known as ‘Coyne’s rule’. The faster-
X
hypothesis, proposed by Charlesworth and colleagues, posits that this large
X
-effect can be explained, at least partially, by
X
-linked genes showing a higher
fixation rate of recessive favorable mutations than autosomal genes because they are hemizygous in the heterogametic sex. To determine the effects of the
X
chromosome on transcriptional regulation in hybrids we studied whole-genome patterns of gene expression in
Drosophila yakuba
,
D. santomea
and their
hybrids using a combination of microarrays and mRNA-seq. We analyzed patterns of expression in female-, male- and nonsex-biased genes and took
advantage of attached-
X
stocks to uncover the effects of
X
-linked recessive mutations in hybrid females. Our results provide new insight into the molecular
basis of the Coyne’s rule applied to gene expression.
545B
Design and construction of a new Drosophila species, D.synthetica, by synthetic regulatory evolution.
Eduardo Moreno. Cell Biology, University of
Bern, Bern.
Synthetic biology is an area of biological research that combines science and engineering. Here, I merge the principles of synthetic biology and regulatory
evolution to create a new species with a minimal set of known elements. Using preexisting transgenes and recessive mutations of Drosophila melanogaster, a