PhD Arthur Decae 2010 - Ghent Ecology - Universiteit Gent

Motivation for this thesis
This thesis is written as an effort to contribute basic knowledge to the study of Arachnology,
hoping this will help future research in a branch of biology that I regard as a potentially rich
source of important scientific insight. All papers in this thesis contain original information on
Mediterranean mygalomorph spiders provided in order to facilitate and stimulate more
detailed future research and understanding of these fascinating, yet little known, animals.
Aim
The central goal of this thesis is to gain insight in the historical build-up of regional
mygalomorph diversity in the expectation that this will aid a more general understanding of
growing faunal complexity as it has occurred on earth.
Personal Note
When in 1983 I took my exams for a Master Degree in Biology at the University of
Groningen one of the members in the jury asked me if I did not think that my studies had been
too narrowly focused at just one animal group. I had worked on subjects in taxonomy,
biogeography, ecology, ethology and comparative morphology of sensory organs all in one
genus of mygalomorph spiders; the genus Cyrtocarenum Ausserer 1871. To my relief, and
before I could answer, another member on the committee countered that there would have
been no critical questions on this point if the one animal group had been fruit flies
(Drosophila melanogaster), rats (Rattus norvegicus) or zebra fish (Brachydanio rerio). The
point of course is that fruit flies, rats, zebra fish and a hand full of other animals are widely
considered ideal model organisms for a range of interests in zoological research and that it
remains to be seen if we could learn anything important from mygalomorph spiders. In fact, I
believe we can learn something new and important from indiscriminately which animal we
choose to study, but that the study of mygalomorph spiders offers more.
The study of spiders in general offers more than the study of other animal groups because
spiders are unique in producing a wide range of intricate and seemingly intelligent and/or
geometric constructions made of a combination of material found in nature and self produced
excretions: such as saliva and silk. These constructions, nests, webs, drag lines, cocoons,
trapdoors, wrappings, ties and a number of other functional devices, may be seen as material
expressions of complex behavior that no other animal, save the human species, leaves
behind 1 . To produce their complex constructs spiders of course possess a range of
morphological, physiological and neurological qualities not found in any other animal group
and it is only because spiders are not of any obvious economical or medical interest that
araneology (the study of spiders) is a relatively remote branch of the biological sciences 2 .
This is to be regretted, because spiders not only possess all these unique qualities of direct
biological interest, they also preserve, within their diversity, the reflection of an evolutionary
history that dates back to the beginning of terrestrial animal life (Decae 1984). Although the
fossil record of spiders is relatively poor, spiders do not fossilize easily (Selden & Penney
2010), much of the history of spiders can be read from extant species. Apparently spiders
have been a marked biological success throughout evolutionary time, surviving in great
1 Beavers, birds, termites, bees and other animals produce amazing constructions in size and
complexity, but rarely as versatile, intricate, geometrical and multifunctional as spiders and
humans do (see e.g. Von Frisch 1974, Hansell 2007).
2 Although properties of spider silk and venom in particular might offer prospects of medical,
agricultural and other applications (e.g. Bailey & Chada 1968, Sterling et. al 1992, Patrick &
Canard 1997, Novak 2001, Scheller et. al. 2001, Escoubas & Rash 2004) it seems to be very
difficult to economically exploit spider products.