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MASS‐MORTALITY LAYERS OF FOSSIL STICKLEBACK FISH: CATASTROPHIC KILLS OF POLYMORPHIC SCHOOLS
Author(s) -
Bell Michael A.,
Wells Christina E.,
Marshall James A.
Publication year - 1989
Publication title -
evolution
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.84
H-Index - 199
eISSN - 1558-5646
pISSN - 0014-3820
DOI - 10.1111/j.1558-5646.1989.tb04256.x
Subject(s) - stickleback , biology , gasterosteus , oncorhynchus , population , zooplankton , fish <actinopterygii> , varve , ecology , zoology , fishery , paleontology , demography , sediment , sociology
Stickleback fish ( Gasterosteus doryssus ) from late middle‐Miocene lacustrine deposits of the Truckee Formation in west‐central Nevada are abundant and well preserved. They occasionally occur in unusually high densities on single annual laminations (varves) in “mass‐mortality layers.” We demonstrate that stickleback mass‐mortality layers consist of members of schools and may be used as population samples. Comparison of stickleback mass‐mortality samples to time‐averaged samples, which accumulated over hundreds or thousands of years in the same deposit, indicates that, for some purposes, the time‐averaged samples are acceptable surrogates for instantaneous population samples from the G. doryssus lineage. Mass‐mortality and time‐averaged samples are similar for variation of pelvic structure and dorsal‐spine number, but associations between states of different characters may be weaker in mass‐mortality samples than in time‐averaged samples. Thus, character variances in time‐averaged samples of G. doryssus are comparable to those of living populations, but character correlations are suspect. Character variances and correlations in time‐averaged fossil samples must be evaluated on a case‐by‐case basis and interpreted with caution.