It is a term coined by Stephen Jay Gould and Niles Eldredge to contrast with their model of punctuated equilibrium , which is gradualist itself , but argues that most evolution is marked by long periods of evolutionary stability ( called stasis ) , which is punctuated by rare instances of branching evolution .
`` Phyletic gradualism '' is a term coined by Stephen Jay Gould and Niles Eldredge to contrast with their model of punctuated equilibrium .