88 
Psyche 
[March 
may not. (For more detailed discussion see Shear 1970; Kullman 
1972; Lubin 1974; Burgess 1978; Buskirk, in press). 
Hopefully, future research on this species and other group living 
spiders will shed more light on the evolution of sociality in an 
otherwise asocial group of animals. 
Summary 
Data on habitat preference and group size in Metepeira spinipes 
F. P.-Cambridge, a colonial orb weaving spider from Central Mex¬ 
ico, are presented. M. spinipes colonies are associated with micro¬ 
habitats of permanent structure, and occur most frequently in 
maguey plants (Agave sp.)- Colony size appears to be independent 
of microhabitat structure. Distribution of group size in two con¬ 
trasted habitats (Agaves and willows) showed a significant differ¬ 
ence from a zero-truncated Poisson distribution and a good fit to a 
zero-truncated Negative Binomial distribution, indicating a ten¬ 
dency to aggregate independently of habitat. Amount of individual 
space decreased with increased colony size, indicating a tolerance of 
conspecifics greater than expected if spiders merely attached indi¬ 
vidual webs together. The combination of solitary and colonial 
behaviors exhibited by this species suggests that it may represent an 
intermediate stage in the evolution of social behavior in orb¬ 
weaving spiders. Possible selective advantages to group-living in this 
’ species and the evolution of coloniality are discussed. 
Acknowledgements 
This research was supported in part by National Science Founda¬ 
tion grant BNS-75-09915-A03 to Dr. Peter Witt. Additional finan¬ 
cial assistance by Ms. Colette Croze is gratefully acknowledged. 
Thanks to Peter Witt and Thomas Kane for reviewing the manu¬ 
script. Special thanks to Joan Sattler, who typed the manuscript. 
References Cited 
Burgess, J. W. 
1976. Social spiders. Sci. Amer. 234: 100-106. 
1978. Social behavior in group-living spider species. Symp. Zool. Soc. Lond. 
42: 69-78. 
Burgess, J. W. & P. N. Witt. 
1976. Spider webs: design and engineering. Interdisc. Sci. Review. 1: 322-335. 
