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Poster Full Abstracts - Evolution and Quantitative Genetics
Poster board number is above title. The first author is the presenter
272
compensate for the lack of protein in restricted diets by increasing food intake, and may store this excess energy as fat, often leading to obesity. Ongoing
experiments in our lab investigate the dietary restriction response of life span and fecundity in Drosophila melanogaster using two different diets: one high in
protein content (20% yeast) and one restricted in protein content (5% yeast). In order to substantiate if the observed dietary restriction response from those
studies is influenced by differences in feeding behavior or if it is a result of the dietary treatment itself, we measured the feeding rates of several Drosophila
genotypes on each dietary treatment. The flies were allowed to feed on radioactively labeled media for 24 hours and the total volume of food ingested by
each individual was quantified by measuring isotope levels in a scintillation counter. We also measured the thorax length of each fly as an indication of body
size, which was used as a covariate in our statistical analyses. This work provides evidence that the dietary restriction response of life span and fecundity
observed in previous studies is largely an effect of the dietary treatment rather than changes in feeding rates of individuals. Flies reared on a high protein diet
tend to eat more food than those reared on a restricted diet, so those reared on a restricted diet are clearly not compensating for the decrease in nutrients by
eating a greater volume of food. Furthermore, since the genotypes we used in this study are part of a genome reference panel used for genome wide
association, we can extend this study to gain a better understanding of how specific genes function and interact to regulate feeding rates and physiological
responses to dietary restriction in Drosophila and many other organisms.
526A
Genome-wide association analysis of natural variation in tergite melanization in
Drosophila melanogaster
.
Lauren Dembeck
1,2
, Michael Magwire
1,2
,
Faye Lawrence
1
, Richard Lyman
1
, Trudy Mackay
1,2
. 1) Department of Genetics, North Carolina State University, Raleigh, NC; 2) W.M. Keck Center for
Behavioral Biology, North Carolina State University, Raleigh, NC.
Pigmentation varies within and between species and is often an adaptive trait crucial for fitness.
D. melanogaster
females generally have light to medium
stripes of melanization on the posterior end of each tergite. We measured natural variation in female abdominal pigmentation in 158 sequenced inbred lines
of the
Drosophila
Genetic Reference Panel, derived from the Raleigh, NC population. We visually scored females for the proportion of melanization on
tergites 4-6 on a scale from 0 (no melanization) to 5 (total melanization). We found significant genetic variation in melanization for each tergite, with broad
sense heritabilities ranging from 0.239 - 0.876. We performed genome-wide association analyses for each tergite using 2.5 million single nucleotide
polymorphisms (SNPs). We identified 30 SNPs associated with the proportion of melanization on tergite 6, the most significant of which was in
bric-a-brac
1
, a gene known to affect the proportion of melanization in female
D. melanogaster
. We also identified a SNP in the
cis
-regulatory element of
tan
, which
was previously shown to affect interspecific differences in pigmentation. After accounting for linkage disequilibrium and imputing missing genotypes, we
conducted a forward regression to estimate the fraction of variance explained. Five SNPs constituting 22 haplotypes account for 52% of the variance among
the lines. We are currently conducting studies to further confirm the effects of these SNPs. This study will provide insight into the genetic architecture of
melanization and also shed light on the question of whether genes causing variation within a species are the same as those involved in trait divergence
between species. L.M.D. is supported by NIH Training Grant # GM045146.
527B
High levels of sex-specific additive genetic variation has strong implications for the heritability of lifespan in
Drosophila melanogaster
.
Urban
Friberg
1
, Anne Lehtovaara
2
, Holger Schielzeth
3
, Ilona Flis
4
. 1) Ageing Research Group, Evolutionary Biology, Uppsala university, Uppsala, Sweden; 2)
Anne.Lehtovaara@gmail.com; 3) Evolutionary Biology, Uppsala university, Uppsala, Sweden; 4) anolis.silf@gmail.com.
Understanding the genetic architecture of lifespan and rate of ageing is important both from the perspectives of evolutionary biology and medicine, as they
both are central life history traits and sum over the expression of all genetic variants that contribute to mortal disease. In virtually all taxa, including humans,
lifespan and rate of ageing are sexually dimorphic. Sexual dimorphism results from genes that are differentially expression in males and females. As a result
the genetic architecture of a sexually dimorphic trait can be very different in the two sexes. Here we investigate the additive genetic architecture (AGA) of
lifespan and rate of aging in males and females of
Drosophila melanogaster
. We show that the sexes have distinct AGAs for these traits and that these differ
substantially across social environments. About half of the additive genetic variation was sex-specific. The high proportion of sex-specific additive genetic
variation had a profound impact on the heritability of lifespan, which became highly dependent on the sex of the parent and the offspring considered. While
father-to-son and mother-to-daughter heritabilities were moderate (ranging from 0.25 to 0.40), father-to-daughter and mother-to-son heritabilities were
significantly and substantially lower (ranging from 0.10 to 0.12). In sum our results show that the AGA for lifespan and rate of ageing is very complex and
depends critically on sex and social environment.
528C
Correlated changes in body melanization and mating success in
Drosophila melanogaster
.
Babita Kajla, Ravi Parkash, Vineeta Sharma, Jyoti Chahal,
Chanderkala Lambhod. Lab no. 19, Department of Genetics, M. D.UNIVERSITY, ROHTAK, Haryana, India.
Mating speed and copulation duration respond rapidly to laboratory selection in
Drosophila melanogaster
Meigen (Diptera: Drosophilidae), but there is a
lack of data on the evolutionary response to natural selection in the wild. Further, it is not clear whether body melanization and mating behavior are
correlated traits. Accordingly, we tested whether variation in body color impacts on mating latency, copulation duration, and fecundity in latitudinal
populations of
D. melanogaster
. We observed geographical variation (cline) for mating propensity, i.e., mating speed as well as copulation duration
increased along latitude. Phenotypic plastic responses for body melanization at 17 and 25 ° C also showed significant correlations with mating latency and
copulation duration. Within population analysis based on assorted dark and light flies of five geographical populations showed significant positive
correlations of copulation duration and fecundity with body melanization. To assess the role of males and/ or females on mating speed and copulation
duration, we used atypical body color strains (i.e., dark and light males of
D. melanogaster
) for no-choice mating tests. Our data showed major influence of
males for copulation duration and of females for mating speed. Furthermore, a difference in impact of body melanization on mating speed and copulation
duration was demonstrated between species, i.e., low melanization in
Drosophila ananassae
Doleschall is correlated with lower mating speed and shorter
copulation duration than in
D. melanogaster
. Geographical changes in mating propensity were significantly correlated with body melanization at three
levels, i.e., within and between populations and between species. Thus, we have shown that a relationship exists between body melanization and mating
success. Further, we found seasonal changes in temperature and humidity to confer selection pressures on mating-related traits.