Is there an influence of historical events on contemporary fish species richn...

杨利霞

Is there an inflfluence of historical events on contemporary fifish species richness in rivers? Comparisons between WesternEurope and North America

. Freshwater fifish species richness on 132 West statistically signifificant, but add only a little to the variance
already explained by ecological factors. Our analyses further
European and North American rivers is analysed using
indicate that rivers (which flflow directly into the ocean)
eleven variables related to contemporary ecology (nine) and
support fewer species of fifish than do similarly sized
history (two). This is done in order to examine the relative
tributaries. The immigration-extinction hypothesis appears
and joint effffects of both historical and ongoing processes
to provide a plausible explanation for this observed pattern.
on the contemporary richness of these two regional fifish
The fact that in our fifinal model, a continental effffect is still
faunas. Relationships are quantifified by simple and stepwise
highly signifificant, leads us not to exclude the possibility of
multiple regression procedures. Species-area curves are
some other historical inflfluences in generating difffferent
presented for the fifish faunas within both continents. We
overall species richness levels on the two continents.
show that ecological factors statistically explain most of
the variation in freshwater fifish species richness for both
Key words. Community ecology, pisces, species-area
hypothesis, species-energy hypothesis, historical hypothesis.