

Minas Gerais;
3
California Academy of Sciences, 55 Music
Concourse Drive, San Francisco, CA, 94118, USA
ghfazevedo@gmail.comSpiders may be good models for studying genitalia
diversity and evolution given their peculiar copulatory
mechanism, with male external copulatory apparatus
located in palps. Gnaphosidae are remarkable in having
species with simple bipartite palps, with tripartite palps
and a few elements, and species with several structures
on tripartite palp. Some palpal homology studies suggest
intermediate palp complexity as ancestral condition for
the family from which both more complex and simpler
palp would have evolved, but with trend to sclerites fusion.
However, those hypotheses were never tested with phyloge-
netic background, since no Gnaphosidae phylogeny was
available until recently. Regarding female genitalia, both
the epigynum and vulva range from simple to complex,
but there is no information on its evolution. Thus, despite
the great diversity of Gnaphosidae, patterns of genital
evolution and mechanisms involved in copulatory organ
diversification in the family are barely known. The aim
of this study was to contribute to the understanding of
genital evolution through the exploration of macroevo-
lutionary patterns related to copulatory organ diversity in
Gnaphosidae. More specifically, the evolutionary trend in
complexity and predictions about genital evolution were
tested using phylogenetic comparative methods. A matrix
of 336 morphological characters scored for 99 taxa was
used to estimate the gnaphosid phylogeny. We sampled 35
female and 57 male characters to explore genital evolu-
tion, based on phylogenetic trees obtained. A bipartite
palp with intermediate complexity was found to be the
plesiomorphic condition, but there was no trend toward
simplification or increasing complexity. The same inter-
mediate complexity with no trend was found for females.
Additionally, we discovered that complexity of female
and male copulatory organs did not coevolve. Additional
information on copulatory behavior of gnaphosids might
contribute to the understanding of genital evolution.
Keywords: genital evolution, cryptic female choice,
genital morphology, complexity, sexual selection,
systematics
Student - oral presentation
Phylogenomics and historical biogeogra-
phy of the Gondwanan family Pettalidae
(Opiliones: Cyphophthalmi)
*Caitlin Baker
1
, Sarah Boyer
2
, Gonzalo Giribet
1
1
Museum of Comparative Zoology and Department
of Organismic and Evolutionary Biology, Harvard
University, 26 Oxford Street, Cambridge, MA 02138,
USA;
2
Biology Department, Macalester College, 1600
Grand Avenue, Saint Paul, MN 55105, USA
baker02@g.harvard.eduHistorical biogeographers have long looked for groups
of organisms that retain signals of Gondwanan vicari-
ance–that is, taxa with distributions across multiple
formerly contiguous southern hemisphere landmasses,
and that are old enough to predate the breakup of the
former supercontinent. One such group is the mite
harvestman family Pettalidae (Opiliones: Cyphoph-
thalmi), which has members in Chile, South Africa,
Madagascar, Sri Lanka, Western and Eastern Australia,
and New Zealand. While a four-locus phylogeny previ-
ously demonstrated the monophyly of the family and
each genus, relationships between the genera proved to
be recalcitrant. To address this, we sequenced densely
sampled transcriptomes of members of all genera for
which molecular grade samples were available (9 of 10
described genera) and performed phylogenomic analy-
ses on the mRNA dataset. We conducted maximum
likelihood and Bayesian inference on matrices of dif-
ferent gene occupancy (>95%, 159 orthologs; >75%,
1111 orthologs; >50%, 3196 orthologs) to account
for the effects of missing data. Finally, we dated the
tree using Paleozoic and Mesozoic Opiliones fossils as
calibration, as well as the Xiphosura-Arachnida split.
Our tree resolves key aspects of the pettalid phylogeny,
and we will discuss our findings regarding the timing
and order of cladogenetic events as they relate to the
breakup of Gondwana.
Keywords: phylogenomics, gondwana, biogeography,
Opiliones, systematics, vicariance
44
DENVER MUSEUM OF NATURE & SCIENCE
REPORTS
|
No. 3, July 2, 2016
Cushing