20th International Congress of Arachnology

124 / 232

123
DENVER MUSEUM OF NATURE & SCIENCE REPORTS | No. 3, July 2, 2016
Oral presentation
The evolution of genital complexity and
mating rates in size dimorphic spiders
Matjaž Kuntner1,2, Ren-Chung Cheng1, Simona Kralj-
Fišer1, Chen-Pan Liao3, Jutta M. Schneider 4, Mark A.
Elgar5
1Evolutionary Zoology Laboratory, Biological Institute
ZRC SAZU, Ljubljana, Slovenia; 2National Museum of
Natural History, Smithsonian Institution, Washington,
D.C., USA; 3Department of Life Science, Tunghai
University, Taichung, Taiwan; 4 Zoological Institute,
Biozentrum Grindel, University of Hamburg, Hamburg,
Germany; 5School of BioSciences, University of Melbourne,
Victoria 3010, Australia
Genital diversity may derive from a sexual conflict
over polyandry, where male genital features function
to manipulate female mating frequency against her
interest. Correlated genital evolution across animal
groups is consistent with this view, but linking genital
complexity with mating frequencies remains untested.
In extremely sexually size dimorphic spiders (Nephili-
dae) males mutilate genitals to form genital plugs, but
these plugs do not always prevent female polyandry.
We tested, using phylogenetic comparative methods,
whether male and female genital complexity coevolve,
and how they relate with the evolution of monogamy
and polygamy. We found a positive correlation between
male and female genital complexity, and the prevalence
of monogamy in species with complex male genitals,
suggesting that male genital complexity increases to
limit female mating rates. Perhaps complex genitals
are required to facilitate breakage in which the geni-
tals remain in the female. In turn, females may evolve
mechanisms to evade sexual monopolization by males,
including sexual cannibalism and genital simplifica-
tion. These data highlight the close evolutionary links
between post-mating sexual selection and sexual
conflict.
Keywords: sexual selection, sexual size dimorphism,
female gigantism, genital complexity, sexually antago-
nistic coevolution, Nephila
Oral presentation
Spider feet evolution: multiple acquisitions of
distal articulations in homologous location
Facundo M. Labarque1,2, Jonas O. Wolff 3,9, Alexander
Sanchez Ruiz1, Peter Michalik4, Charles E. Griswold2,5-7,
Martín J. Ramírez8
1Lab. Esp. Colecões Zoológicas, Instituto Butantan, Av.
Vital Brasil, 1500, 05503-900 São Paulo, SP Brazil; 2Cali-
fornia Academy of Sciences, 55 Music Concourse Drive,
San Francisco, CA 94118 USA; 3Functional Morphology
and Biomechanics, Zoological Institute, University of
Kiel, Kiel, Germany; 4Zoologisches Institut und Museum,
Ernst-Moritz-Arndt-Universität, Greifswald, Germany;
5Biology Department, San Francisco State University,
1600 Holloway Ave, San Francisco, CA 94132, USA; 6Envi-
ronmental Science, Policy and management, University
of California, 101 Sproul Hall, Berkeley, CA 94704, USA;
7Biology Department, The George Washington University,
2121 I St NW, Washington, DC 20052, USA; 8 Museo Argen-
tino de Ciencias Naturales “Bernardino Rivadavia”,
Consejo Nacional de Investigaciones Científicas y Técnicas
(CONICET), Av. Ángel Gallardo 470, C1405DJR, Buenos
Aires, Argentina; 9Department of Biological Sciences,
Macquarie University, Sydney, NSW 2109, Australia
Most of the interaction of spiders with the substrate where
they live occur just on the tips of their legs. Because of
that, the different lifestyles have a profound impact on
their feet anatomy. Web builders and vagrant spiders
with adhesive setae are just two exemplary lifestyles
where the functional anatomy is relatively well known
from a few exemplary species with mostly solid tarsi (i.e.,
without distal articulations), but there are many spiders
with apical divisions in the tarsus. Recently it has been
described eight exemplary configurations of feet from
diverse clades with various lifestyles and ethological
specializations, to illustrate the diversity of structures and
shapes that occur in spiders. Here we present new data on
the tarsal evolution of Caponiidae, cryptic vagrant spiders
that live in the lift litter, which presents a simple foot
configuration without suture but some genera may present
a distal articulation, an enormously pretarsus, cuticular
20th International Congress of Arachnology