
doi: 10.2307/4135538 , 10.2307/3647340
As a beginning, I offer a quotation from MacLeod(2002): “ The fundamental observation of biology is mor-phology. Morphological data form the basis of virtuallyall systematic descriptions” . That this is so is reinforcedby the fact that the vast majority of systematic studiesbegin by grouping organisms on the basis of morpholog-ical similarity. Once they are so grouped, we begin tostudy relationships among the groups, often by carefulexamination of variation in morphological features, butincreasingly more often by using these morphologically-defined groups as the basis for conducting studies ofmolecular variation.To celebrate the 50th anniversary of
| selected citations These citations are derived from selected sources. This is an alternative to the "Influence" indicator, which also reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically). | 53 | |
| popularity This indicator reflects the "current" impact/attention (the "hype") of an article in the research community at large, based on the underlying citation network. | Top 10% | |
| influence This indicator reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically). | Top 10% | |
| impulse This indicator reflects the initial momentum of an article directly after its publication, based on the underlying citation network. | Top 10% |
