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Is Rarity Tied to Extinction During Background Intervals? A Case Study
Using Mollusk Species From the Mid-Atlantic Coastal Plain
Rowan Lockwood, Dept. of Geology, The College of William & Mary, P.O. Box 8795,
Williamsburg, VA 23187
Ecological studies suggest that rare taxa are more likely to go extinct than abundant ones, but the
relationship between rarity and extinction in the fossil record has received little attention.
 Are rare taxa more likely to go
extinct?
 Does the relationship between rarity
and extinction differ in mass versus
background extinctions?
 Does selectivity differ according to
metric of rarity?
Focusing on the record of Miocene and
Pliocene mollusks from the midAtlantic Coastal Plain
tapestry.usgs.gov
Mean
Variability
Occupancy
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Of the metrics assessed, geographic range yielded by far the
strongest correlation with survivorship, while habitat breadth
yielded the weakest. Species with large geographic ranges, high
abundance, low variability in abundance, and high occupancy tend
to have longer durations and are more likely to survive major
extinction events such as the end-Cretaceous extinction (above) .