Study system:
I
work with sponge-dwelling snapping shrimps of the genus Synalpheus. These tiny critters are an excellent
study system for this research. In some
species (e.g. Synalpheus regalis), individuals live in easily-collected
colonies of 300+ workers and a single reproductive queen inside tropical marine
sponges (4). Other species within
the genus exhibit an unusually wide range of social behavior, from solitary
lifestyles to large colonies with few reproductives (5). This range of behavior will allow comparison
of the genetic basis of behavior among closely related, behaviorally divergent
species. Because Synalpheus can be kept
in lab aquaria, I can conduct tightly controlled experiments on the
relationship between ecological parameters, gene expression, and social
behavior.
Methods:
I
will use next-generation RNA-seq techniques to assess
gene expression (6). The basic
idea behind gene expression techniques is to look at what genes are actually
activated in an individual at a given time or under a given condition. This set of expressed genes (called the transcriptome) is typically much smaller than the entire
set of an individual's genes (the genome), and, because it describes the genes
that are being used in the moment, is highly relevant to the question at hand.
By
using high-throughput quantitative sequencing techniques (e.g. Solexa and 454), I will
assemble complete transcriptomes for individuals from a variety of species
and behavioral roles. Comparison of
those profiles will identify genes which are consistently differentially
expressed in various groups. Further
research will seek to determine which genes lead to behavioral differences, as
well as the environmental conditions under which they are expressed.
I
intend to compare gene expression in Synalpheus in the following ways:
1: Among
reproductives and workers within colonies. What is the genetic basis of
social behavior in these species?
2:
Among workers and reproductives from multiple species of Synalpheus. Is
the genetic basis of sociality conserved among these species?
3: Under varying ecological conditions. How
do ecological factors and developmental plasticity affect behavior?
References
1: West-Eberhard, M.J.
(2003) Developmental Plasticity and Evolution. Oxford University Press, Oxford
2: Whitfield, C.W., Cziko,
A. & Robinson, G.E. (2003) Gene expression profiles in the brain predict
behavior in individual honey bees. Science, 302, 296-299.
3: Wang, J., Ross, K.G. & Keller, L. (2008)
Genome-Wide Expression Patterns and the Genetic Architecture of a Fundamental
Social Trait. PLoS Genetics, 4.
4: Duffy, J.E. (1996) Eusociality
in a coral-reef shrimp. Nature, 381, 512-514.
5: Duffy, J.E. (2003) The ecology and evolution of
eusociality in sponge-dwelling shrimp. Genes,
behavior, and evolution in Social Insects.Higashi,
S.), University of Hokkaido Press, Sapporo, Japan, Sapporo, Japan.
6: Wilhelm, B.T. & Landry, J.R. (2009) RNA-Seq-quantitative measurement of expression through
massively parallel RNA-sequencing. Methods, 48, 249-257.