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Evidencias de Altas Tasas de Extinción y Amenaza en Taxones Pobremente Estudiados
Author(s) -
McKinney Michael L.
Publication year - 1999
Publication title -
conservation biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.2
H-Index - 222
eISSN - 1523-1739
pISSN - 0888-8892
DOI - 10.1046/j.1523-1739.1999.97393.x
Subject(s) - extinction (optical mineralogy) , taxon , extinction event , ecology , biology , threatened species , invertebrate , habitat , demography , population , biological dispersal , paleontology , sociology
Mass extinctions in the past have been characterized by abnormally high species extinction rates within almost all taxa. Attempts to estimate relative rates of extinction and threat among modern taxa, such as insects, plants, and vertebrates, are impeded by differences in the quality of information about each group. Insects and marine groups, for example, have much smaller percentages of known threatened species but also have many more undescribed species than do plants or vertebrates. I tested the possibility that all major groups have equally high rates of extinction and threat. The first test was a model assuming that differences in apparent global extinction and threat rate are caused by two sampling biases that produce artificially low rates in understudied taxa: (1) a common‐species bias in which taxonomists tend to record common (more extinction‐resistant) species first and (2) evaluative neglect, which is a tendency to spend relatively less effort evaluating the extinction and threat status of recorded species in understudied taxa. Global extinction and threat data from a number of groups generally follow the pattern predicted by this model. The second test shows that in direct measurements of extinction and threat between taxa in well‐studied regions, such as the United States and United Kingdom, the apparent global disparity among taxa is greatly reduced. Indeed, many globally understudied taxa, such as insects and other invertebrates, have higher rates of threat than many other taxa, including mammals, in these well‐studied areas. These two tests provide quantitative support for previous suggestions that the wide disparity in rates of species extinction and threat among groups represents an artifactual distortion of the actual rates. Specific suggestions for improved estimates of actual threat include (in order of increasing accuracy): use of well‐studied proxy taxa such as mammals; comparison of threat data among taxa only in well‐studied regions; and, especially important, increased efforts to evaluate the threat status of recorded species of understudied taxa.