20th International Congress of Arachnology

DENVER MUSEUM OF NATURE & SCIENCE

REPORTS

No. 3, July 2, 2016

families have colonized the Hawaiian Islands, several of

these groups have diversified rapidly into large radia-

tions with diverse ecologies compared to their mainland

counterparts. The first study examined the early diversifi-

cation of Hawaiian representatives of the genus

Ariamnes

(Theridiidae), a lineage with approximately 20 described

species endemic to the islands. We investigated the popu-

lation dynamics of spider populations on the islands of

Hawaii, Molokai, and Maui in order to gain insight into

how colonization and admixture play roles in population

differentiation. We use several novel tools previously not

used on populations and species with short divergence

times. The second study makes use of whole-genome

sequencing and low-coverage methods to investigate the

basis of repeated ecomorph evolution in the adaptive

radiation of Hawaiian

Tetragnatha

(Tetragnathiidae).

Here, we present whole genome assemblies comparing the

use of different sequencing techniques. Future work will

sequence additional genomes in order to answer ques-

tions regarding the adaptive evolution of the spiders and

their general genomic architecture.

Keywords: genomics, adaptive radiation

Oral presentation

Multiple colonizations, parallel evolu-

tion and adaptive radiation of linyphiid

spiders in the Juan Fernández archipelago

Miquel A. Arnedo

, Gustavo Hormiga

Department of Evolutionary Biology, Ecology and

Environmental Sciences and Biodiversity Research

Institute (IRBio), Universitat de Barcelona, Avinguda

Diagonal 643, 08071 Barcelona, Catalonia, Spain;

Department of Biological Sciences, The George Wash-

ington University, Washington, D.C. 20052, USA

marnedo@ub.edu

We report on the colonization and diversification of

linyphiid spiders in the oceanic archipelago of Juan

Fernández. This subtropical volcanic archipelago is

located in the southeastern Pacific, about 667 km west

of continental Chile and comprises three islands ranging

from 2.2 to 50 sq. km in size and from six to one million

years in age. About fifty spider species occur naturally

in these islands, most of them are insular endemisms

and about half of them are linyphiids. Linyphiidae have

independently colonized Juan Fernández multiple times

and include no less than 14 species of the Neotropical

genus

Laminacauda

and two of

Neomaso

, all of them

are single island endemics. In addition, there are three

linyphiid genera endemic to this archipelago. To date,

little if any data on the distribution and natural history

of native linyphiids was available. We have recently

conducted new collections on the archipelago that have

revealed that while the continental species of

Lamina-

cauda

and

Neomaso

are rather uniform both in somatic

morphology and in the foraging webs (small sheet

webs on the ground), some endemics exhibit morpho-

logical features and life history traits that are very rare

or unknown in any other linyphiids, including gigantism,

massive chelicerae or elongated legs. Some species may

have even abandoned web-building. Moreover, some of

these rare phenotypic traits seem to have evolved multiple

times independently within the Juan Fernández islands.

The taxonomic revision of museum collections and the

newly collected specimens have allowed us to discover new

species, complete descriptions and uncover new synony-

mies. A multi-locus genetic analysis of the endemic species

confirms the multiple colorizations, even within the same

genus, and the morphology based species boundaries, and

further reveals that the

Laminacauda

species from Rob-

inson Crusoe underwent rapid local diversification.

Keywords: adaptive radiation, ecological shift, biogeog-

raphy, phylogeny, systematics, speciation

Poster presentation

Diversity patterns of spider communi-

ties in white oak forests of the Spanish

National Parks

Miquel A. Arnedo

, Marc Domènech-Andreu

, Luis Carlos

Crespo

, Pedro Cardoso

, Jordi Moya-Laraño

, Carles Ribera

Department of Evolutionary Biology, Ecology and

Environmental Sciences and Biodiversity Research

institute (IRBio), Universitat de Barcelona, Av.

Diagonal 643 - 08028, Barcelona, Catalonia, Spain;

Finnish Museum of Natural History, University

International Congress of Arachnology