Report 2 Description and Assignment

Report 2 Description and Assignment - Sta 6166, Fall 2005...

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Sta 6166, Fall 2005 Report #2: The Effect Of Sampling Effort On Data Collected To Study Biodiversity Of Obligate Cave Invertebrates In Slovenia Due: November 1 at the start of class Usual constraint : 2-3 people may work on the report together. If there are more than 2, please indicate how each person contributed to the analyses and report writing. Background A cave biologist is studying hotspots, regions of high biodiversity, in Europe and the US. He and his colleagues have been focusing on species richness of subterranean terrestrial invertebrates in caves in the Alps in Europe. The data had been collected by collating historical records, records maintained by caving organizations (e.g. the “Society of Slovenian Spelunkers”), and records provided by researchers actively working in the area. When their paper on hotspot biodiversity was submitted for publication, one of the criticisms was that the data were based on different sampling efforts and hence were difficult to interpret. The comment “based on different sampling efforts” refers to the fact that this was a retrospective study and so the amount of effort to obtain a measure of species richness differed among the caves in the region. Some caves had been known and hence studied for a much longer time period, some were known to yield many new species and hence visited more often, some were difficult to reach, or there are other reasons that would cause differential sampling effort. This would imply that the data have measurement error that is not the same everywhere and so introduces bias. As a response, the biologist decided to do a small study to compare the change in our knowledge of species richness over time as a way of capturing the effect of sampling effort on his conclusions. He started by organizing the data in various ways. First, he summarized the data for individual caves into hexagonal regions overlaid over three geographic areas of Slovenia (figure 1 shows the hexagonal cover for the Dinaric region.). Second, he determined the number of species known in each hexagon as of 1940, 1970 and 2000 (JMP file: “Slovenia sampling effort
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Report 2 Description and Assignment - Sta 6166, Fall 2005...

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