20th International Congress of Arachnology

DENVER MUSEUM OF NATURE & SCIENCE

REPORTS

No. 3, July 2, 2016

International Congress of Arachnology

Oral presentation

The sampled Red List Index of spiders

Pedro Cardoso

1,2

, Sérgio Henriques

2,3

, Sini Seppälä

1,2

Michael L. Draney

2,4

, Alastair T. Gibbons

2,5

, Sarah Kariko

2,6

Jagoba Malumbres-Olarte

2,7

, Marc Milne

2,8

, Cor Vink

2,9

Paula Cushing

2,10

Finnish Museum of Natural History, University of

Helsinki, Finland; 2Spider & Scorpion Specialist Group,

Species Survival Commission, International Union

for the Conservation of Nature, Gland, Switzerland;

Institute of Zoology; University College London,

UK;

University of Wisconsin-Green Bay, Green Bay,

Wisconsin, USA;

School of Life Sciences, University of

Nottingham, Nottingham, United Kingdom;

Museum

of Comparative Zoology, Harvard University, Cam-

bridge, Massachusetts, USA;

Center for Macroecology,

Evolution and Climate, Natural History Museum

of Denmark, University of Copenhagen, Denmark;

University of Indianapolis, Indianapolis, USA;

Can-

terbury Museum, Christchurch, New Zealand;

Denver

Museum of Nature & Science, Denver, Colorado, USA

pedro.cardoso@helsinki.fi

The IUCN Spider & Scorpion Specialist Group (SSSG) pro-

motes the assessment of extinction risk of arachnid species

worldwide. All assessments follow the IUCN redlisting

criteria and guidelines by quantifying extent of occur-

rence (EOO), area of occupancy (AOO), habitat decline,

population trends, fragmentation, and extent of threats. By

randomly selecting a given number of species for assess-

ment, the Sampled Red List Index (SRLI) allows perceiving

general trends, threats and needed conservation actions for

entire groups from local to global scales without the need

to assess every single known species. One-hundred and fifty

species of spiders were selected from the global checklist

for a first attempt at the global SRLI. Prior to this congress,

a team of experts gathered and assessed many of these

species. Distribution maps were produced, and EOO, AOO

and threats quantified whenever information was available

and it is now possible to have a rough idea on the status

of the group as a whole. However, this is only a start and

new tools are planned to facilitate and promote the assess-

ment of many more species, including the release of an R

package for the semi-automated production of IUCN-com-

pliant results and a unique way of publishing peer-reviewed

assessments through the Biodiversity Data Journal.

Keywords: conservation assessment, endangered species,

extinction risk, IUCN, population trends, threats

Oral presentation

Morphological constraints on sprint

performance as drivers of anti-predator

behavior in scorpions

Brad Carlson

301 W Wabash Ave, Wabash College, Crawfordsville,

IN 47933, USA

carlsonb@wabash.edu

Optimal defensive strategies depend on the ability to

perform different anti-predator behaviors. Variation in such

performance may result from morphological differences,

such as between sexes (for which reproduction may select

for sexually dimorphic morphology) or among species (for

which morphology may evolve for species-specific activi-

ties). I explored this in scorpions by examining sex and

species differences in morphology, sprint performance (i.e.,

escape ability) and propensity to attack predators. First, in

Centruroides vittatus

scorpions, females were more likely

to sting and stung at faster rates, and were slower sprinters.

Female

C. vittatus

were relatively heavier than males, and

heavier bodies were correlated with reduced sprint speed

and increased stinging rates. This suggests that the heavier

bodies of females (due to reproduction) reduce sprinting

ability and that aggression towards predators is increased

to compensate. The longer legs of males further improved

sprinting performance. In a second study, I used modified

assays with six species of scorpions. There was significant

variation among species and sexes in size-adjusted mass

and leg length. Intriguingly, relatively heavier bodies were

associated with relatively longer legs, suggesting mor-

phological compensation for the costs of increased body

weight. Species and sexes also differed in relative sprint

speed, but overall size (rather than relative weight), leg

length, and gravidity were the only morphological drivers

of variation in sprinting performance. Species also varied

in aggression, but there was no evidence this was related to