20th International Congress of Arachnology

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36 DENVER MUSEUM OF NATURE & SCIENCE REPORTS | No. 3, July 2, 2016
Cushing
patterns, and frequencies of sexual cannibalism. Both L.
mariana and L. argyra females can have mating plugs,
but in L. mariana they are composed by substances
transferred by both sexes, while in L. argyra they are pro-
duced only by females. Furthermore, in this last species
mating plugs function as mortal traps for males. In both
Leucauge female decision of plug production is linked to
male pre-copulatory and copulatory courtship. Both sexes
in L. argyra show unusual derived genital structures
that could have evolved under sexual selection. In this
presentation we will compare genital morphology and
sexual behavior in L. mariana and L. argyra, discussing
the differences under sexual selection hypotheses. We will
also expose recent studies on cryptic female choice in L.
mariana and suggest fertile areas for future research.
Keywords: sexual selection, cryptic female choice,
genital plugs, copulatory courtship
Student–Poster presentation
Substrate choice by burrowing males of
Allocosa brasiliensis (Araneae, Lycosidae)
*A. Albín1,2, M. Simó2, A. Aisenberg1
1Laboratorio de Etología, Ecología y Evolución, Insti-
tuto de Investigaciones Biológicas Clemente Estable,
Montevideo, Uruguay; 2Sección Entomología, Facultad
de Ciencias, Universidad de la República, Montevideo,
Uruguay
The burrowing spider A. brasiliensis inhabits beaches with
different granulometry in Uruguay, characteristics that
could affect burrow dimensions and excavation energy
costs. Males construct longer burrows than females, and
burrow length is under female selection. We analyzed
A. brasiliensis male digging preferences between coarse
or fine sand, and compared digging behaviors in the two
substrates. We collected A. brasiliensis males at a fine-
sand beach (San José de Carrasco, Canelones), and a
coarse-sand beach (Paso del Molino, Lavalleja). Spiders
were placed for 48 hours in glass terraria with fine-grain
sand in one half of the terrarium, and coarse sand in the
remaining half (n=30 males from each substrate). Males
preferred digging in coarse sand, independently of their
origin (fine sand males: 20 coarse sand versus 10 fine
sand, p=0.02; coarse sand males: 23 coarse sand versus
seven fine sand, p=0.001). Fine sand males that con-
structed in coarse sand showed longer burrow compared
with coarse grain males that preferred that substrate
(U=147.5, p=0.04). General digging patterns were similar,
but occurrences (mean±SD, fine sand: 25.70±26.30,
coarse sand: 50.70±39.09; U=21.5, p=0.03 and durations
of resting behavior (351.21±200.35 sec, coarse sand:
728.35±382.32 sec; U=21.0, p=0.03 were higher in coarse
sand. Digging in coarse sand would be faster and less ener-
getically demanding than in fine sand.
Keywords: granulometry, burrow, fine sand, coarse sand
Student - poster presentation
Inmunocompetence tests to determine
burrow-digging costs in Allocosa brasil-
iensis (Araneae, Lycosidae)
A. Albín1,2, M. Simó2, A. Aisenberg 1, L. Calbacho-Rosa3
1Laboratorio de Etología, Ecología y Evolución, Insti-
tuto de Investigaciones Biológicas Clemente Estable,
Montevideo, Uruguay; 2Sección Entomología, Facultad
de Ciencias, Universidad de la República, Montevideo,
Uruguay; 3 Laboratorio de Biología Reproductiva y
Evolución, Cátedra de Diversidad Animal I, Facultad
de Ciencias Exactas, Físicas y Naturales, Universidad
Nacional de Córdoba, CONICET, Argentina
Allocosa brasiliensis inhabits sandy coastal areas in
Argentina, Brazil and Uruguay. Males build burrows in
the sand, and females prefer to mate with those males
presenting longest burrows. In some species of spiders
there is a trade-off between characters, in the history of
life and immune functions. Our objective was to deter-
mine if male digging behavior affected immune response
in A. brasiliensis. We compared the immune response
of digging males vs. non-digging males (control), and
immune function was estimated through lytic activity
(LA). LA was expressed as changes in optical density (with
decreasing readings of optical density, higher LA). We did
not find significant differences in optical density between
the two groups, though results were close to significance