Life History Variation in North American Freshwater Minnows: Effects of Latitude and Phylogeny

Abstract

tion in life history traits of 21 species of North American minnows with a wellresolved phylogeny. Only one life history trait was significantly correlated with latitude: species at higher latitudes had shorter spawning seasons than did species at lower latitudes. Two measures of body size showed evidence of a phylogenetic correlate. Total female body length at maturity and maximum total female body length were more similar for closely related species pairs than for distantly related species pairs. Moreover, total female body length at maturity was correlated with the position of each species in Mayden's cladogram of cyprinid fishes: species close to the root of the cladogram had relatively small body sizes compared with species that were more distant from the cladogram root. This pattern is reminiscent of Cope's Law of phyletic increase in body size within a lineage. Although phylogenetic correlates are most common at high taxonomic levels (the taxon-level effect of Pagel and Harvey), phylogeny was a significant predictor of body size in this closely related group of minnows. Both historical factors, such as phylogenetic relationships, and ecological factors, such as latitude, probably contribute to interspecific variation in life history traits of minnows.