20th International Congress of Arachnology

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DENVER MUSEUM OF NATURE & SCIENCE REPORTS | No. 3, July 2, 2016
20th International Congress of Arachnology
Student - oral presentation
Immune stress and sexual signal-
ing in the wolf spider ( Schizocosa
ocreata)
*Rachel Gilbert, George W. Uetz
University of Cincinnati, P.O. Box 210006, Cincin-
nati, OH 45221, USA
Having an effective immune system can be very costly, some-
times at the expense of other important life history traits,
including reproduction. This tradeoff can be exaggerated
in males of species that have costly sexual signaling, where
condition-dependent components of the signaling system
reflect the health status of the bearer. It is therefore vital for
a male to be able to adequately balance the costs of activat-
ing the immune system successfully while also expressing
high quality sexual signals. We examined whether static
condition-dependent components of sexual signaling in adult
males of the brush-legged wolf spider Schizocosa ocreata are
indicative of health status (immune stress response), and
whether female preference for these traits could be influenced
by male or female infection. After infecting adult males with
a bacterial pathogen, females were found to avoid chemical
cues from an infected male. However, the vibratory and visual
signaling modalities were not influenced by infection. As a
result, females did not discriminate against infected males in
a live mating context, and as a result, were infected through
the sexual transfer of the pathogen from males during copu-
lation. These results indicate that not all signaling modalities
in this multimodal sexual signaling system are honest indi-
cators of active infection, and while females appear to be able
to tell whether a male is infected based on chemical cues,
they do not always avoid mating with infected males.
Keywords: immune function, sexual selection, courtship,
Schizocosa ocreata
Student - Poster presentation
Gene expression analysis provides new
insights into the arachnid immune system
Rachel Gilbert, Emily Jennings, Joshua Benoit,
George W. Uetz
University of Cincinnati, P.O. Box 210006, Cincin-
nati, OH 45221, USA
Animals across a wide variety of species, including both
vertebrates and invertebrates, have evolved effective innate
immune systems to fight off parasites and pathogens.
While much is known about vertebrate and insect immune
systems, there is far less known about arachnids. Recent
genomic evidence has shown that arachnid immune
systems lack several integral components of insect immune
systems, which suggests that there may be some novel
mechanisms of innate immunity that can be learned
from a functional study of the genes involved in arachnid
immunity. We used the wolf spider Schizocosa ocreata to
examine the immune response at the transcriptomic level,
in order to evaluate changes in gene expression that occur
during infection at different developmental stages. Previous
studies in this species have shown that there is a measur-
able immune response after experimental infection with a
bacterial pathogen, and that the infection can be cleared
rapidly. After sequencing and assembling over 300 million
reads, we found 49,316 unique protein-coding contigs, with
over 1,000 genes being differentially expressed in infected
males compared to controls. As expected, many of these
genes are related to transcription, peptide synthesis, and
cellular adhesion and recognition. This study will provide
not only a reference transcriptome for this well-studied
species, but also the first functional evaluation of an arach-
nid immune system at the transcriptomic level.
Keywords: Transcriptomics, gene expression, immunity,
Schizocosa ocreata
Oral presentation
Diversity vs. disparity: contrasting
patterns of adaptive radiation among
Hawaiian spiders
Rosemary Gillespie
University of California, Berkeley, CA 94708, USA
Ecological and evolutionary processes interact syn-
ergistically to determine biodiversity patterns. The