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Abstract
Latitudinal diversity gradients are among the most striking patterns in nature. Despite a large body of work investigating both geographic and environmental drivers, biogeographical provinces have not been included in statistical models of diversity patterns. Instead, spatial studies tend to focus on species-area and local-regional relationships. Here, we investigate correlates of a latitudinal diversity pattern in Australian coastal molluscs. We use an online database of greater than 300 000 specimens and quantify diversity using four methods to account for sampling variation. Additionally, we present a biogeographic scheme using factor analysis that allows for both gradients and sharp boundaries between clusters. The factors are defined on the basis of species composition and are independent of diversity. Regardless of the measure used, diversity is not directly explained by combinations of abiotic variables. Instead, transitions between regions better explain the observed patterns. Biogeographic gradients can in turn be explained by environmental variables, suggesting that environmental controls on diversity may be indirect. Faunas within provinces are homogeneous regardless of environmental variability. Thus, transitions between provinces explain most of the variation in diversity because small-scale factors are dampened. This explanation contrasts with the species-energy hypothesis. Future work should more carefully consider biogeographic gradients when investigating diversity patterns.
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Affiliation(s)
- Matthew R. Kerr
- Centre for Environment, Fisheries and Aquaculture Science, Lowestoft NR33 0HT, UK
| | - John Alroy
- Department of Biological Sciences, Macquarie University, Sydney 2109, Australia
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Pos E, Guevara Andino JE, Sabatier D, Molino JF, Pitman N, Mogollón H, Neill D, Cerón C, Rivas G, Di Fiore A, Thomas R, Tirado M, Young KR, Wang O, Sierra R, García-Villacorta R, Zagt R, Palacios W, Aulestia M, Ter Steege H. Are all species necessary to reveal ecologically important patterns? Ecol Evol 2014; 4:4626-36. [PMID: 25558357 PMCID: PMC4278815 DOI: 10.1002/ece3.1246] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2014] [Revised: 08/05/2014] [Accepted: 08/24/2014] [Indexed: 11/12/2022] Open
Abstract
While studying ecological patterns at large scales, ecologists are often unable to identify all collections, forcing them to either omit these unidentified records entirely, without knowing the effect of this, or pursue very costly and time-consuming efforts for identifying them. These “indets” may be of critical importance, but as yet, their impact on the reliability of ecological analyses is poorly known. We investigated the consequence of omitting the unidentified records and provide an explanation for the results. We used three large-scale independent datasets, (Guyana/ Suriname, French Guiana, Ecuador) each consisting of records having been identified to a valid species name (identified morpho-species – IMS) and a number of unidentified records (unidentified morpho-species – UMS). A subset was created for each dataset containing only the IMS, which was compared with the complete dataset containing all morpho-species (AMS: = IMS + UMS) for the following analyses: species diversity (Fisher's alpha), similarity of species composition, Mantel test and ordination (NMDS). In addition, we also simulated an even larger number of unidentified records for all three datasets and analyzed the agreement between similarities again with these simulated datasets. For all analyses, results were extremely similar when using the complete datasets or the truncated subsets. IMS predicted ≥91% of the variation in AMS in all tests/analyses. Even when simulating a larger fraction of UMS, IMS predicted the results for AMS rather well. Using only IMS also out-performed using higher taxon data (genus-level identification) for similarity analyses. Finding a high congruence for all analyses when using IMS rather than AMS suggests that patterns of similarity and composition are very robust. In other words, having a large number of unidentified species in a dataset may not affect our conclusions as much as is often thought.
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Affiliation(s)
- Edwin Pos
- Ecology and Biodiversity Group, Utrecht University Utrecht, the Netherlands ; Section Botany, Naturalis Biodiversity Center Leiden, the Netherlands
| | | | | | | | - Nigel Pitman
- The Field Museum 1400 S. Lake Shore Drive, Chicago, Illinois, 60605-2496 ; Center for Tropical Conservation, Nicholas School of the Environment, Duke University Durham, North Carolina, 27708
| | - Hugo Mogollón
- Endangered Species Coalition 8530 Geren Rd., Silver Spring, Maryland, 20901
| | | | - Carlos Cerón
- Universidad Central Herbario Alfredo Paredes, Escuela de Biología Herbario Alfredo Paredes Ap. Postal 17.01.2177, Quito, Ecuador
| | - Gonzalo Rivas
- Wildlife Ecology and Conservation & Quantitative Spatial Ecology, University of Florida 110 Newins-Ziegler Hall, PO Box 110430, Gainesville, Florida
| | - Anthony Di Fiore
- Department of Anthropology, University of Texas at Austin SAC 5.150, 2201 Speedway Stop C3200 Austin, Texas, 78712
| | - Raquel Thomas
- Iwokrama International Programme for Rainforest Conservation Georgetown, Guyana
| | - Milton Tirado
- GeoIS El Día 369 y El Telégrafo, 3° Piso, Quito, Ecuador
| | - Kenneth R Young
- Geography and the Environment, University of Texas Austin, Texas, 78712
| | - Ophelia Wang
- Northern Arizona University Flagstaff, Arizona, 86011
| | - Rodrigo Sierra
- GeoIS El Día 369 y El Telégrafo, 3° Piso, Quito, Ecuador
| | - Roosevelt García-Villacorta
- Institute of Molecular Plant Sciences, University of Edinburgh Mayfield Rd, Edinburgh, EH3 5LR, UK ; Royal Botanic Garden of Edinburgh 20a Inverleith Row, Edinburgh, EH3 5LR, UK
| | - Roderick Zagt
- Tropenbos International Lawickse Allee 11, PO Box 232, Wageningen, 6700 AE, the Netherlands
| | - Walter Palacios
- Universidad Técnica del Norte, Herbario Nacional del Euador Quito, Ecuador
| | - Milton Aulestia
- Herbario Nacional del Ecuador Casilla 17-21-1787, Avenida Río Coca E6-115, Quito, Ecuador
| | - Hans Ter Steege
- Ecology and Biodiversity Group, Utrecht University Utrecht, the Netherlands ; Section Botany, Naturalis Biodiversity Center Leiden, the Netherlands
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