Abstracts (first author)
The role of transient versus balanced color polymorphism In adaptive radiation: spiders in the Hawaiian Islands
Color variation, when genetically determined, provides a visual tool for examining selection. Moreover, variation is a key to rapid adaptive response, which in turn forms the basis for adaptive radiation. Our work focuses on different genera of spiders in the Hawaiian Islands, in particular: (1) Long jawed spiders in the genus Tetragnatha (Tetragnathidae) that are characterized by exuberant adaptive radiation. This genus has colonized the islands an estimated 5mya and shows evolutionary progression from older to younger islands. One lineage, the “spiny leg clade”, is represented throughout the archipelago by four distinct color ecomorphs and molecular phylogenetic analyses indicate that each ecomorph has evolved repeatedly. However, species on the older islands (Kauai and Oahu) show a developmental switch between two ecomorphs – Green and Maroon. More derived species on the younger islands exhibit a single ecomorph, Green or Maroon, at all life stages, though species formation is associated with multiple shifts between ecomorphs. We are currently using a genomic approach to understand how the color-switching characteristic of species on the older islands has translated into diversification of species representing different ecomorphs on the younger islands. This system contrasts with (2) the exuberantly patterned Hawaiian Happy Face spider, Theridion grallator, a single species which displays a visible and balanced genetic color polymorphism. The happy face spider retains variability between individuals within a population (as compared to within individuals or between species in Tetragnatha). Moreover, while the frequency of color morphs is similar in different populations of happy face spiders, the mode of inheritance of the color polymorphism has changed between islands in the Hawaiian chain. Together, these studies provide insights into how, and under what circumstances, variability can translate into diversity.