Other

Burns (1988, 1993) found that geographic variation, exemplified by Red Fox Sparrow and Thick-billed Fox Sparrow, results from both different relative growth rates and relative timing of onset and offset of growth. Bill and tarsus length differ in relative growth rates, while wing and tail length differ in timing of onset of a similar growth rate (Burns 1988, 1993). Therefore, differences in adult morphology of different Fox Sparrow populations are reached via repatterning of developmental trajectories (Burns 1993).

Zink (1983) and (Burns and Zink 1990) assessed levels of temporal variation in morphology and allozymes. Across 50 yr for 7 populations, most morphological characters showed no significant differences; however, an average of 2.2 (7.1%) significant character differences was observed in these populations (Zink 1983). Multivariate analysis revealed these significant differences in only 2 of 7 sites. Burns and Zink (1990) found no temporal change in allozymic variation over 8–10 generations.