Divergence and Reticulation among Montane Populations of a Jumping Spider (Habronattus pugillis Griswold)

Abstract.—Populations of the jumping spiderHabronattus pugillisGriswold isolated on nearby moun-tain ranges in southern Arizona are differentiated in many features of the males (color, shape, and orientation of setae on face; shape of carapace; markings of palpi and legs; motions during courtship behavior). These features are (mostly) consistent within a range and different between ranges. The concentration of differences in male courtship behavior and body parts exposed to the female during courtship and correlations between form and courtship behavior suggest sexual selection was in-volved in the differentiation. A phylogenetic analysis of the populations yields a tree that for the most part groups geographic neighbors, but the history of H. pugillis populations may not be adequately described by a tree. Geographic proximity of apparent convergences suggests that populations from at least some of the mountain ranges acquired characteristics through introgression. Lowering of the woodland habitat during the last glacial period probably brought some populations into contact, but it is not clear whether the interrange woodlands would have provided corridors for extensive mix-ing. [Differentiation; geographic variation; homoplasy; hybridization; phylogeny; Salticidae; sexual selection; speciation; spiders.] Phylogenetic diversications that occur rapidly and in small geographical areas may be particularly difcult to reconstruct. When phylogenetic branches are short (in time), not only might the novel charac-ters evolving be too few to mark them, but also ancestral polymorphisms are more likely to be retained through several speci-ation events and then to sort to monomor-phism variously in the descendants (Pamilo and Nei, 1988; Takahata, 1989). This sort-ing can generate character distributions that are discordant with one another and with the phylogenetic relationships of the specie