20th International Congress of Arachnology

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86 DENVER MUSEUM OF NATURE & SCIENCE REPORTS | No. 3, July 2, 2016
Cushing
negatively related to distance run. We conclude that
the metabolic “machinery” is important for the overall
performance of males, independent of morphology, and
discuss these results in the context of body size evolu-
tion in highly dimorphic spider species.
Keywords: sexual selection, sexual size dimorphism,
performance traits
Oral presentation
The effect of elevation and time on moun-
tain spider diversity: a view of two aspects
in the Cederberg Mountains of South Africa
S.H. Foord1, A.S. Dippenaar-Schoeman2,3
1Department of Zoology, Chair in Biodiversity Value
and Change, University of Venda, Private Bag
X5050, Thohoyandou, 0950, South Africa; 2ARC-Plant
Protection Research Institute, Private Bag X134,
Queenswood, Pretoria, 0121, South Africa; 3Depart-
ment of Zoology and Entomology, University of
Pretoria, Pretoria, 0001, South Africa
Our aim was to test if long-term patterns in α and β
diversity along an elevational transect on two aspects
of a mountain are consistent through time using
spiders as model organisms, quantify the role of eleva-
tion, time (seasonal and inter-annual) in explaining
these patterns and partition the relative contribution
of nestedness, species turnover and species loss in
richness in explaining these diversity patterns. The
transect is across the Cederberg mountains in the Cape
Floristic Kingdom, South Africa and constitutes 17 sites
with an elevational range of 1900 m on two aspects
of the mountain (east and west) spider assemblages
were sampled biannually (wet and dry seasons) over
six years. Four replicates per site, each consisting of a
5 × 2 pitfall grid, were sampled for five days sessions.
GLMM α- and β diversity ( Jaccard dissimilarity β jac
and its partitioned components (βjtu and βjne)) was
used to model the effects of elevation and season on
these two indices respectively. Spider alpha diversity
had a hump-shaped pattern on the western aspect
and U-shaped on the eastern aspect. However, season
interacted with elevation to produce more complex pat-
terns during the dry season. There was no significant
nestedness. Replacement accounted for 60–70 % of beta
diversity between sites, and elevational distance decay
in beta diversity was the result of increased turnover
on the western aspect and increased species loss on the
eastern aspect. Standardized patterns suggest that there
are no effect of season on beta diversity except for a
decreased rate of distance decay during the dry season
on the western aspect. Large-scale predictors of spider
alpha diversity explained a small amount of variation
in spider diversity, pointing to the importance of local
and stochastic processes. Regional turnover of spider
diversity is mainly the result of niche processes, point-
ing to localized adaptation of taxa, this is supported by
the lack of nestedness in assemblages.
Keywords: α-diversity, Araneae, β-diversity, Cape Floris-
tic Region, epigeal, long-term
Student - oral presentation
Biodiversity survey of solifuge species
within Big Bend National Park, Texas
(Arachnida, Solifugae)
*David Footle
1200 Perry St., Denver, CO 80204
Solifuges (Arachnida, Solifugae) are a wide ranging arach-
nid found in xeric and arid areas across the globe. Despite
nearly 1,100 species of Solifugae having thus far been
described within the 12 recognized families, there exists a
lack of basic ecological and natural history data; in addition
to much left to be learned about behavior, as well morphol-
ogy and physiology. A wide ranged biodiversity survey of
solifuges within the protected area of Big Bend National
Park (BBNP), Texas was conducted over two field seasons.
The goal of the study was to collect initial biodiversity and
biogeographical data with which to build upon for solifuge
research within the full range of the Chihuahuan Desert eco-
system. Wet pitfall traps- filled with propylene glycol-based
anti-freeze were set up in arrays as the primary collection
method. Seventeen species were found from the two North
American families Eremobatidae and Ammotrechidae, with