20th International Congress of Arachnology

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DENVER MUSEUM OF NATURE & SCIENCE REPORTS | No. 3, July 2, 2016
or slow developmental pathways can be made. Our second
hypothesis proposed an early, while the third allowed for
later choice between the pathways. To test these hypoth-
eses, we used long term collection and weather data of
seven natural P. agrestis populations in Hungary between
1992 and 2000. Weather conditions indeed affect the
number of individuals in late summer, as the number of
adults in late summer (i.e., rapidly developing individuals)
was significantly higher in years of optimal early weather,
while the number of juveniles showed an opposing trend
to that. Interestingly though, the between-year variation in
late adult proportion did not correlate with early weather
conditions. However, the proportion of late summer adults
was higher in optimal late conditions. These results
indicate that early weather do have considerable effects
on developmental strategy, but at the same time, a later
choice between the different developmental pathways (as
proposed by our third hypothesis) might also contribute to
the overall occurrence of rapidly developing individuals.
Keywords: developmental plasticity, cohort splitting,
life history, unpredictable environment, agrobiont, wolf
spider
Oral presentation
The phylogeny of dionychan spiders: a com-
bined analysis of sequences and morphology
Martín J. Ramírez1, Charles Griswold2, Ward Wheeler3
1Division of Arachnology, Museo Argentino de Ciencias
Naturales - CONICET. Av. Angel Gallardo 470,
C1405DJR Buenos Aires, Argentina; 2Arachnology
(Emeritus), California Academy of Sciences, San Fran-
cisco, USA; 3 Division of Invertebrate Zoology, American
Museum of Natural History, New York, USA.
The Dionycha comprise a large clade of two-clawed
spiders and a tuft of tenent setae, including about 30%
of the known spider species. Since the loss of the inferior
claw and acquisition of adhesive setae is one of the most
plastic syndromes in spider evolution, the phylogeny
and precise demarcation of Dionycha are contentious. A
recent morphological phylogeny produced novel synapo-
morphies for large dionychan clades, and the molecular
data (target gene and transcriptomic, published and in
progress) are helping to define Dionycha and some of
their main lineages, and disentangle morphological
convergences. Both sources of data are illuminating and
largely congruent, but also have important differences,
due to different signal and unequal coverage. While
morphological analyses are more sensitive to convergence
syndromes, sequence data produce groupings without
morphological synapomorphies, thus with limited
prediction over the taxonomic diversity of spiders. By
combining both data sources we provide synapomorphies
for important dionychan clades, confirm the monophyly
and placement of many families (e.g., the placement of
crab spiders among lycosoids, the inclusion of viridasiids
in Dionycha), and propose new higher rank-clades.
Keywords: phylogenetics, systematics, higher rank-
clades, adhesive setae
Oral presentation
The visual ecology of anti-predator wing
displays: a case study with jumping spiders
Dinesh Rao1, Samuel Aguilar-Argüello2 , Ajay Narendra3,
Skye Long4, Elizabeth Jakob 4
1Inbioteca, Universidad Veracruzana, Av. Culturas
Veracruzanas No.101, Col. E. Zapata, CP 91090,
Xalapa, Veracruz, México; 2Inecol, A.C. Instituto de
Ecología, A.C, Apartado Postal 63, CP 91000, Xalapa,
Veracruz, México; 3Department of Biological Sciences,
Macquarie University, North Ryde, Sydney, NSW
2109, Australia; 4Psychology Department, University
of Massachusetts, Amherst, USA
Any species of tephritid flies (Diptera: Tephritidae) perform
a wing waving display (‘supination’) to deter attacks from
jumping spiders. This display, along with the dark bands
on the wings, has been thought to deter spiders through a
form of mimicry termed ‘predator mimicry’. In a series of
studies with jumping spiders and the Mexican fruit fly, we
explored this interaction from a visual ecology perspective.
Using a custom built eye-tracker that traces the movement
of the retina in the principal eyes, we played videos of dis-
playing flies and monitored the response. We describe the
20th International Congress of Arachnology