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
Do silk properties evolve during adaptive
radiations of Hawaiian spiders?
*Angela M. Alicea-Serrano1, Dharamdeep Jain2 , Ali
Dhinojwala2, Todd A. Blackledge1
1Department of Biology, University of Akron, Ohio,
USA; 2Department of Polymer Science, University of
Akron, Ohio, USA
Web architecture evolved rapidly during adaptive radia-
tion of Hawaiian Tetragnatha, with a divergence of web
forms in the same island but repeated convergence of web
forms on different islands. But, whether silk properties
also evolve during adaptive radiations remains a mystery.
In this study we tested for diversification in silk properties.
We predicted a relationship between silk properties and the
performance of webs, where differences in web architecture
selects for changes in silk tensile strength, extensibility
and toughness, and glue adhesive forces. As silk density
decrease in the webs of some species, we expected that
toughness for major ampullate and capture spiral silk will
increase as compensation. Adhesion forces on the other
hand is expected to increase with web size since bigger
spiders produce bigger glue droplets. Orb webs from three
species were collected at two sites in the archipelago. Tet-
ragnatha hawaiensis was found in Upper Waiakea Forest
Reserve, Hawai’i and T. stelarobusta, T. trituberculata
and T. hawaiensis were found at Waikamoi Nature Conser-
vancy Preserve, Maui. Major ampullate and capture spiral
silk were obtained directly from orb webs and tensile and
adhesion tests were performed using a Nano Bionix test
system. Since salts present in the glue determine in part
adhesion forces, solution state NMR was done and salt
composition of glues was assessed. Preliminary results
showed higher adhesion forces of glue and higher tough-
ness for T. trituberculata, the species with the lowest
amount of capture spiral silk in its web. However further
analysis is still needed to draw conclusions from this data.
Results of this study will help us see if spider silk material
properties are coupled to its architectures, which is impor-
tant for understanding spider diversification, and may aid
in the development of new “green” biomaterials.
Keywords: spider silk, silk properties, biomechanics,
adhesion, adaptive radiation
Oral presentation
Cyberdiversity of Araneomorphae in Mexico
Fernando Alvarez-Padilla
Universidad Nacional Autonoma de Mexico, Facultad de
Ciencias, Biologia Comparada, Lab. Aracnologia. 3000
Av. Universidad, Ciudad Universitaria, Mexico CP 04510
The Order Araneae has approximately 46,000 described
species, most of them included in Araneomorphae, and
this number is estimated to represent between one-half to
one-fifth of the total. The spider fauna of tropical and sub-
tropical regions has been poorly studied and is expected
to contain most of the new species. In Mexico about 2,500
species have been recorded in various catalogs, but this
represents only a fraction of the total. Three ideas are
discussed to expedite the documentation of Mexican spider
diversity: the use of collecting protocols that allow some
type of analysis, making the morphological and genomic
information of these morphospecies easily accessible to
the spider community and lending the specimens to spe-
cialist for formal species description. The theoretical bases
for these ideas come from The New Taxonomy book and
the Cyberdiversity initiatives with spiders and ants.
Keywords: faunistics, New Taxonomy, diversity
Oral presentation
Population structure of Plesiophrictus
nilagiriensis (Araneae, Mygalomorphae,
Theraphosidae) in the Western Ghats of India
Sudhikumar Ambalaparambil
Department of Zoology, Centre for Animal Taxonomy
and Ecology, Christ College, Irinjalakuda, Kerala, India
This study is an attempt to characterize the population
structure of an endemic burrowing spider Plesiophrictus
nilagiriensis (Araneae, Mygalomorphae, Theraphosidae)
distributed along the Western Ghats, one of the biodiver-
sity hotspots of the world, based on mitochondrial DNA