Abstract
Sampling at the species level; impact of spatial and temporal biases on diversity gradients
Abstracts with programs - Geological Society of America, Vol.32(7), p.131
Geological Society of America, 2000 annual meeting
2000
Abstract
While there is broad agreement that the overall pattern of Phanerozoic taxonomic diversity has not been compromised seriously by sample bias, the adequacy of the fossil record continues to be questioned at finer taxonomic, spatial and temporal scales. Here we evaluate the impact of variability in sampling intensity on estimates of species diversity patterns of Late Cambrian trilobite faunas of Laurentian North America. For each of nearly 2000 samples from the published literature, we compiled data on species occurrences (taxonomically standardized to eliminate synonyms), as well as geographic and stratigraphic location, and lithofacies type. Lithofacies information was used to assign each sample to one of six environmental groupings, arrayed along a gradient from nearshore to deep shelf. We estimated levels of alpha diversity in each environmental grouping from the number of species in field collections (rarefied to a standard sample size of 90 individuals). The resulting diversity gradient was used as a baseline for comparison with literature-based counts of species richness. Geographic and environmental distribution of samples displayed profound bias. Nearly half of the sample horizons are from two regions in the United States. Distribution among environmental groupings is equally uneven, with shallow subtidal carbonates accounting for about half of the collections. Despite the strong bias, raw counts of species from the literature correctly retrieved the shape of the gradient established from field collections, including low diversity in nearshore environments and peak diversity in shelf-margin carbonate buildups. The success of the literature-based method in the face of heavily biased sampling likely reflects the presence of finite species pools for each environment, so that a substantial increase in sampling effort does not significantly boost recovered diversity. The data indicate that uneven sampling may not prevent recovery of diversity gradients through literature-based compilations, even at the species level.
Details
- Title: Subtitle
- Sampling at the species level; impact of spatial and temporal biases on diversity gradients
- Creators
- Stephen R Westrop - University of OklahomaJonathan M Adrain - University of Iowa
- Resource Type
- Abstract
- Publication Details
- Abstracts with programs - Geological Society of America, Vol.32(7), p.131
- Conference
- Geological Society of America, 2000 annual meeting
- Publisher
- Geological Society of America (GSA)
- ISSN
- 0016-7592
- Alternative title
- Geological Society of America, 2000 annual meeting
- Language
- English
- Date published
- 2000
- Academic Unit
- Earth and Environmental Sciences
- Record Identifier
- 9984240898102771
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