20th International Congress of Arachnology

DENVER MUSEUM OF NATURE & SCIENCE

REPORTS

No. 3, July 2, 2016

Cushing

story of spider silk, there are other silk proteins, and

they, too, are members of gene families. The evolution-

ary diversification of serial homologs, whether they are

morphological (silk glands, spigots, spinnerets, etc.) or

molecular (silk genes, iterated amino acid sequence

motifs), is a major theme in understanding spider silk

production.

PLENARY presentation–Thursday, July 7

Evolution of paternal care in harvestmen:

devoted fathers or selfish lovers?

Glauco Machado

Departamento de Ecologia, Universidade de São

Paulo, Brazil

glaucom@ib.usp.br

Exclusive paternal care is probably the rarest form

of post-zygotic parental investment in nature. This

behavior is known to have independently evolved

in 16 arthropod lineages, nine of them belong-

ing to the small order Opiliones, which comprises

nearly 6,500 species. Thus, harvestmen offer unique

opportunities to test hypotheses on the evolution of

exclusive paternal. In this talk, I will first review the

theoretical background on sex roles and parental care,

contrasting classical views with the most recent math-

ematical models. Then, I will present a series of studies

conducted by my research group using Neotropical har-

vestmen as study systems. Using both field observations

and experiments, we contrasted predictions from differ-

ent theoretical models and evaluated costs and benefits

of paternal care. Our findings indicate that paternal

care increases males’ attractiveness to females. More-

over, we show that paternal care confers high benefits

to the offspring when compared to relatively low costs

to the males in terms of decreasing survival and

foraging rates. To conclude, I will integrate the avail-

able information for harvestmen and other arthropod

species in order to derive general conclusions on the

evolution of paternal care.

Keywords: paternal care, sexual selection, costs and

benefits, Opiliones, sex roles.

PLENARY presentation–Friday, July 8

How the brown recluse got its bite: evolu-

tionary assembly of spider venoms

Greta Binford

Lewis & Clark College, Portland, Oregon, USA

binford@lclark.edu

Venoms are complex phenotypes with a large and diverse

set of interacting molecular components. Spider venoms

have particularly deep evolutionary histories, and are

strikingly complex. We have much to learn about the

structure of variability in venoms and factors that influ-

ence major evolutionary changes in venom function. I

will discuss ongoing work to understand how spiders in

the family Sicariidae, including the brown recluse, evolved

their unique venoms that have toxins that are insecticidal

and cause dermonecrosis in mammals (sphingomyelinase

D toxins in the SicTox gene family). In the context of

the biology and evolutionary history of these animals, I

will discuss our improving understanding of the timing

and circumstance of the evolutionary recruitment of the

SicTox lineage for insecticidal venom function. I will also

present comparative venomic data that integrates HiSeq

transcriptomes of venom glands, and Orbitrap proteomic

analyses that characterize gene families contributing to

venom protetomes. This will include comparative analyses

of evolutionary dynamics of these gene family lineages.

Our dataset includes sampling across representatives

of diverse sicariids with common ancestry spanning ~

10–100 million years, and a range of non-sicariid hap-

logyne spiders including three taxa in their sister lineage

(

Drymusa

Periogops

, and

Scytodes

) and other haplogy-

nes including pholcids and plectreurids.

Student - oral presentation

The mechanisms of chemical communica-

tion in

Tetragnatha

spiders

*Seira Ashley Adams

, Rosemary Gillespie

, Gabriele Uhl

Department of Environmental Science, Policy, and

Management University of California, Berkeley, 130

Mulford Hall #3114, Berkeley, CA 94720-3114, USA;

Department of General and Systematic Zoology,