20th International Congress of Arachnology

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72 DENVER MUSEUM OF NATURE & SCIENCE REPORTS | No. 3, July 2, 2016
Cushing
T. waikamoi, is widespread across East Maui, while the
other species (juxtaposed with T. waikamoi) are localized
and more closely related to populations on other volcanoes.
Regardless the phylogenetic proximity there is no evidence
of hybridization between these species. This result adds a
new layer of complexity to recent allopatric speciation
events in the context of an adaptive radiation.
Keywords: Tetragnatha, ecomorph, exon capture,
phylogeography, speciation
Student - oral presentation
Broad species comparative meta-analysis
of key amino acid densities and silk struc-
tural properties
*Hamish Craig1, Dakota Piorkowski2, Michael Kasumovic1,
Sean Blamires1, Shinichi Nakagawa1
1School of BEES The University of New South Wales UNSW
Sydney, NSW 2052 Australia; 2No. 181, Section 3, Taic-
hung Port Road, Taichung City 40704, Taiwan, R.O.C.
The presence and density of key amino acids (Alanine,
Glycine, Glutamine, Serine, and Proline) is posited to
provide spider silk with its distinctive properties of both
strength and extensibility. Various hypotheses exist to
explain the role of each amino acid in forming the dis-
tinctive properties and to outline a working molecular
model of spider silk. Despite all these studies, we still
have a poor understanding of how the different amino
acids interact to provide different silk properties across
different species. The main objective of this study was to
determine the relative importance of amino acid compo-
sition and spinning processes in determining spider silk
properties. We performed a meta-analysis comparing the
amino acid composition, modulus, extensibility, strength
and overall toughness of silk of 77 spider species (phy-
logenetically controlled) from 64 papers sampled from
1,680 publications. I will focus on discussing the relative
importance of the various major amino acids on the
material properties of spider silk and discuss the role of
spinning processes in the final properties of the silk.
Keywords: silk, amino acid, mechanical properties,
meta-analysis
Oral presentation
Extreme striking in Selenops (Araneae:
Selenopidae)
Sarah Crews
California Academy of Sciences, Dept. of Entomology, 55
Music Concourse Drive, San Francisco, CA, 94118, USA
Many predators attack prey by ambushing, the success of
which largely depends on high speed. However, given the
tradeoff between speed and maneuverability, ambush strikes
are typically constrained within a specific angular range
and thus not adapted for attacking prey from an unlimited
range of direction. This research shows that flattie spiders
(Selenopidae) are capable of performing rapid strike
maneuvers to capture prey approaching from an uncon-
strained range of direction, exhibiting one of the greatest
rotational movements in animals. Additionally, radially
aligned, long laterigrade legs act as a modularized system
covering a wide range of direction, and each leg can readily
drive the striking movement towards the prey. In particular,
legs function as planar manipulators to direct the rapid
turn-and-reach body motion. Using a generalized mechani-
cal model, how controlled manipulation of long segmented
legs enables rapid, efficient generation of body translation
and rotation is revealed. Thus, leg manipulability can
enhance maneuverability in multi-legged locomotion.
Keywords: biomechanics, flatties, locomotion, ambush
predation
Student - oral presentation
Phylogenetic analysis of Stygnopsidae
(Opiliones), based on three molecular
markers and morphology
*Jesús Alberto Cruz-López1,2, Oscar Francke Ballvé2
1Posgrado en Ciencias Biológicas, Universidad
Nacional Autónoma de México, Av. Universidad
3000, C.P. 04510, Coyoacán, Mexico City, Mexico;
2Colección Nacional de Arácnidos, Departamento de
Zoología, Instituto de Biología, Universidad Nacional
Autónoma de México. Mexico City, Mexico.