( So ( , ( ( as ( ( a rule ) ( of thumb ) ) ) ( , ( macroevolution ( ( looks ( at ( ( ( changes ( above ( ( the level ) ( of species ) ) ) ) , ) ( such ( as ( ( ( ( the generation ) ( of ( ( ( new species ) and ) ( bigger groups ) ) ) ) , ) ( such ( as ( ( ( the mammals ) , ) ( while ( microevolution ( is ( about ( changes ( within species ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) . ) ) ) ) ) )
(ROOT (S (ADVP (RB So)) (, ,) (PP (IN as) (NP (NP (DT a) (NN rule)) (PP (IN of) (NP (NN thumb))))) (, ,) (NP (NN macroevolution)) (VP (VBZ looks) (PP (IN at) (NP (NP (NNS changes)) (PP (IN above) (NP (NP (DT the) (NN level)) (PP (IN of) (NP (NNS species))))) (, ,) (PP (JJ such) (IN as) (NP (NP (DT the) (NN generation)) (PP (IN of) (NP (NP (JJ new) (NNS species)) (CC and) (NP (JJR bigger) (NNS groups)))) (, ,) (PP (JJ such) (IN as) (NP (NP (DT the) (NNS mammals)) (, ,) (SBAR (IN while) (S (NP (NN microevolution)) (VP (VBZ is) (PP (IN about) (NP (NP (NNS changes)) (PP (IN within) (NP (NNS species))))))))))))))) (. .)))
So, as a rule of thumb, macroevolution looks at changes above the level of species, such as the generation of new species and bigger groups, such as the mammals, while microevolution is about changes within species.
(ROOT (S (NP (DT The) (NN term) (NN macroevolution)) (VP (VBZ refers) (PP (TO to) (NP (NP (JJR larger) (JJ evolutionary) (NNS changes)) (SBAR (WHNP (WDT that)) (S (VP (VBP result) (PP (IN in) (NP (JJ new) (NNS species))))))))) (. .)))