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Minas Gerais;

3

California Academy of Sciences, 55 Music

Concourse Drive, San Francisco, CA, 94118, USA

ghfazevedo@gmail.com

Spiders 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.edu

Historical 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

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No. 3, July 2, 2016

Cushing