Appendix A. Sources of data and notes used in the compilation of Table 1.
HORIZONTAL TRANSECTS AND GRIDS
Willig and Lyons (1998)
Marsupial data from Fig. 2a; entire New World as domain. Bat data from Fig. 3a.
Lees et al. (1999)
Data for all Mycalesine spp. on a latitudinal gradient are from Fig. 6.; Fig. 7 for elevational gradient. 2-D data for all species are from Fig. 11. We assumed that the observed values at each latitude order in the same way as the predicted. In cases where symbols overlapped at a given latitude such that it was not possible to pair predicted and observed data, we omitted all observations from that latitude. This occurred at 4 of 47 latitudes.
Bokma et al. (2001)
Data from Fig. 3a.
Jetz and Rahbek (2001)
1-D latitude:Fig. 1a; 1-D longitude:Fig. 1B; 2-D latitude: Fig. 1E; 2-D longitude: Fig. 1F.
Koleff and Gaston (2001)
Predicted values are taken from results shown for Model E. Parrots: Fig. 1a; woodpeckers: Fig. 1B.
Diniz-Filho et al. (2002)
Original data not shown. Statistics reported on p. 50.
Ellison (2002)
Data from Fig. 4.
Hawkins and Diniz-Filho (2002)
The statistics are taken from Table 1.
Jetz and Rahbek (2002)
Table S1 reports that n = 1738 and t = 19.76 for the non-spatial model. From this, one can calculate that R2=0.1836 for a regression including MDE model predictions as the sole independent variable.
Laurie and Silander (2002)
Data from Fig. 6B.
Connolly et al. (2003)
Data from Figs. 2A, B,C, D.
McCain (2003)
Data from Fig. 3A.
Rangel and Diniz-Filho (2003)
Original data not shown. Statistics reported on p. 206.
Aliabadian et al. (2005)
Original data not shown. Statistics reported on p. 21
.
Arita et al. (2005)
Data from Figs. 4a and 5a, data type 2.
Bellwood et al. (2005)
Original data not reported.
Ferrer-Castan and Vetaas (2005)
Orginal not shown. Conclusion taken from the Abstract.
Hernández et al (2005)
Data from Fig. 2.
Mora and Robertson (2005)
Data from Fig. 1a.
Romdal et al. (2005)
Data from Fig. 1a, using randomized empirical ranges (-RER). Analysis of the data from Fig. 1B, in which richness and the MDE prediction are both adjusted for area shows: Expected R2 = 0.39, observed R2 = 0.47, observed B = 1.12, and the runs test has P < 10–4.
Smith et al. (2005)
Data from Fig. 3. The predicted richness was assumed to be the median between the limits of the confidence limits. We always used the more narrowly define potential geographical domain for the animals. Using the broader domain would yield substantially poorer fit.
Kerr et al. (2006)
The data are those that were used to construct Figs. 4a (latitudinal transects) and 5.
Moreno et al. (2006)
Data from Fig. 2.
Storch et al. (2006)
Appropriate data are reported in Fig. 2b; however, the points form a solid cloud that could not be digitized. The authors’ conclusions about the results are reported instead.
Rahbek et al. (2007)
Statistics and significance tests are reported in Table 1.
VERTICAL TRANSECTS
Rahbek (1997)
Original data are not shown. The relevant results are reported at the bottom of p. 885.
Fleishman et al. (1998)
Original data are not shown. The relevant results are reported on p. 2487.
Pineda and Caswell 1998
Data are not shown. The relevant results are reported in the Abstract.
Lees et al. (1999)
Data from Fig. 7.
Kessler (2001)
Results of statistical tests reported in Table 1.
Grytnes and Vetaas (2002)
Original data not given. Conclusions taken from Abstract.
Sanders (2002)
Data from Fig. 1.
Smith and Brown (2002)
Original data not shown. Conclusion taken from Abstract.
Grytnes (2003)
Data not shown. Conclusion taken from Abstract.
Bachman et al. (2005)
Richness data are from Fig. 4a. Area data are from Fig. 2. Figure 3 shows that richness in equal-area bands in New Guinea peaks in the sixth of 15 bands. However, since area per band decreases more or less exponentially with elevation, the sixth equal-area band is at low elevation. The total area of the island (based on Fig. 2) is about 905000 km2. Fifteen equal area bands would each contain 60333 m2. The sixth band would therefore have a cumulative area of 301666 km2 below it, and 362000 km2 at its top. This is less than the area of the lowest band in Fig. 2 : the 0–500 m band has an area of 595000 km2. The relationship between log elevation and log cumulative area is approximately linear from 0–3000 m. A regression yields log(cumulative area) = 5.1915 + 0.2175 log(elevation), n = 6, R2 = 0.996, P < 10–5. From this, one can calculate that the sixth equal-area band extends approximately from 21 m to 48 m of elevation.
McCain et al. (2004)
Data from Fig. 5a.
Carpenter (2005)
Original data not shown. Conclusion taken from the Abstract.
Herzog et al. (2005)
Data from Fig. 3c.
Krömer et al. (2005)
Predicted values not shown. Conclusion taken from the Abstract.
McCain (2005)
Meta-analysis; only the overall conclusions reported.
McClain and Etter (2005)
Data from Fig. 6, null model 5.
Mena and Vásquez-Dominguez (2005)
Original data not shown. Conclusion taken from Abstract.
Ooman and Shanker (2005)
Data from Fig. 3.
Alameida-Neto et al. (2006)
Data from Fig. 1d, the regional pattern.
Brehm et al. (2007)
Data from Fig. 3.
Cardelús et al. (2006)
Data from Fig. 6.
Cardelus et al. tested for the relationships between observed richness and both MDE-predicted richness and climatic variables. They did not, however, use any variable that accounts for a temperature × precipitation interaction (alternatives might include actual evapotranspiration or primary productivity). We repeated these analyses using the richness data from Cardelus et al. Figure 6 and the rainfall and temperature data in Cardelus et al. Table 1. We found that, in a multiple regression that includes rainfall and a temperature × rainfall interaction, both variables are significant, and together they explain more variance than the MDE prediction.
Model |
Model R2 |
|
MDE prediction |
0.014 |
0.81 |
Precip |
0.009 |
0.94 |
MDE |
0.25 |
0.97 |
In a model with both MDE and the climatic variables, the collinearity between climate and MDE is so strong that the marginal contribution of any of the three variables is nonsignificant. Sample sizes are too small (n = 6) to distinguish the effects of climate and MDE. Variance partitioning:
Note that the same gradient was sampled in the studies of Watkins et al. (2006) and Brehm et al. (2007). Their richness gradients are just as strongly collinear with environment as those of Cardelús et al..
Dunn et al. (2006)
Data from Fig. 1, top panels.
Fu et al. (2006)
Data from Figs. 2a and 2b.
Jankowski and Weyhenmeyer (2006)
Data from Fig. 3, panels I and II.
Kendall and Haedrick (2006)
Data from Figs. 1–5.
Kluge et al (2006)
Data from Fig. 2a.
McCain (2007)
Meta-analysis.
Watkins et al. (2006)
Data from Fig. 6. The data are the same as those reported in Cardelús et al. (2006). This study also cannot distinguish between the richness-climate and the richness-MDE relationships because of very strong collinearity and very weak statistical power.
Brehm et al. (2007)
Data from Fig. 3b. The samples are taken from the same transect as in the studies of Watkins et al. (2006) and Cardelús et al. (2006). Similar analyses lead to similar conclusions: MDE predictions and the climatic gradient are too strongly collinear to distinguish between the two hypothesized influences on richness.
Model
P
Model R2
MDE prediction
0.014
0.92
Precip
Temp
Precip × Temp0.01
0.04
0.020.99
MDE
Precip
Temp
Precip × Temp0.58
0.31
0.23
0.270.99
LITERATURE CITED
Aliabadian, M., C. S. Roselaar, V. Nijman, R. Sluys, and M. Vences 2005. Identifying contact zone hotspots of passerine birds in the Palaearctic region. Biology Letters 1:21–23.
Arita, H., P. Rodríguez, and E. Vásquez-Domínguez. 2005. Continental and regional ranges of North American mammals:Rappoport's rule in real and null worlds. Journal of Biogeography 32:961–971.
Bachman, S., W. J. Baker, Brummitt. N., J. Dransfield, and J. Moat. 2004. Elevational gradients, area and tropical island diversity:an example from the palms of New Guinea. Ecography 27:299–310.
Bellwood, D. R., T. P. Hughes, S. R. Connolly, and J. Tanner. 2005. Environmental and geometric constraints on Indo-Pacific coral reef biodiversity. Ecology Letters 8:643–651.
Bokma, F., J. Bokma, and M. Mönkkönen. 2001. Random processes and geographic species richness patterns:why so few species in the North? Ecography 24:43–49.
Brehm, G., R. K. Colwell, and J. Kluge. 2007. The role of environment and mid-domain effect on moth species richness along a tropical elevational gradient. Global Ecology and Biogeography 16:205–219.
Cardelús, C. E., R. W. Colwell, and J. E. Watkins 2006. Vascular epiphyte distribution patterns:explaining the mid-elevation peak in richness. Journal of Ecology 94:144–156.
Carpenter, C. 2005. The environmental control of plant species density on a Himalayan elevation gradient. Journal of Biogeography. 32:999–1018.
Connolly, S. R., D. R. Bellwood, and T. P. Hughes. 2003. Indo-Pacific biodiversity of coral reefs:deviations from a mid-domain model. Ecology 84:2178–2190.
Diniz-Filho, J. A. F., E. R. De Sant'Ana, M. C. De Souza, and T. F .L. V. B. Rangel. 2002. Null models and spatial patterns of species richness in South American birds of prey . Ecology Letters 5:47–55.
Dunn, R. R., R. K.Colwell, and C. Nilsson 2006. The river domain:why are there more species halfway up the river? Ecography 29:251–259.
Ellison, A. M. 2002. Macroecology of mangroves:large-scale patterns and processes in tropical coastal forests. Trees:Structure and Function 16:181–194.
Ferrer-Castán, D., and O. R. Vetaas. 2005. Pteridophyte richness, climate and topography in the Iberian Peninsula:comparing spatial and nonspatial models of richness patterns. Global Ecology and Biogeography 14:155–165.
Fleishman, E., G. T. Austin, and A. D. Weiss. 1998. An empirical test of Rapoport's rule:elevational gradients in montane butterfly communities. Ecology 79:2482–2493.
Fu, C., X. Hua, J. Li, Z. Chang, Z. Pu, and J. Chen. 2006. Elevational patterns of frog species richness and endemic richness in the Hengduan Mountains, China:geometric constraints, area, and climatic effects. Ecography 29:919–927.
Grytnes, J. A. 2003.Species-richness patterns of vascular plants along several altitudinal transects in Norway. Ecography 26:291–300.
Grytnes, J. A., and O. R. Vetaas. 2002. Species richness and altitude:A comparison between null models and interpolated plant species richness along the Himalayan altitudinal gradient, Nepal. American Naturalist 159:294–304.
Hawkins, B. A., and J. A. F. Diniz-Filho. 2002. The mid-domain effect cannot explain the diversity gradient of Nearctic birds. Global Ecology and Biogeography 11:419–426.
Hernández, C. E., R. A. Moreno, and N. Rozbaczylo. 2005. Biogeographical patterns and Rappoport's rule in southeastern Pacific benthic polychaetes of the Chilean coast. Ecography 28:363–373.
Herzog, S. K., M. Kessler, and K. Bach. 2005. The elevational gradient in Andean bird species richness at the local scale:a foothill peak and a high-elevation plateau. Ecography 28:209–222.
Jankowski, T. A., and G. Weyhenmeyer. 2006. The role of spatial scale and area in determining richness-altitude gradients in Swedish lake phytoplankton communities. Oikos 115:433–442.
Jetz, W., and C. Rahbek. 2001. Geometric constraints explain much of the species richness pattern in African birds. Proceedings of the National Academy of Science of the USA 98:5661–5666.
Jetz, W., and C. Rahbek. 2002. Geographic range size and determinants of avian species richness. Science 297:1548–1551.
Kendall, V. J., and R. L. Haedrich. 2006. Species richness in Atlantic deep-sea fishes assessed in terms of the mid-domain effect and Rapoport's rule. Deep-Sea Research I 53:506–515.
Kerr, J. T., M. Perring, and D. J. Currie. 2006. The missing Madagascan mid-domain effect. Ecology Letters 9:149–159.
Kessler, M. 2001. Patterns of diversity and range size of selected plant groups along an elevational transect in the Bolivean Andes. Biodiversity and Conservation 10:1897–1921.
Kluge, J., M. Kessler, and R. R. Dunn. 2006. What drives elevational patterns of diversity? A test of geometric constraints, climate and species pool effects for pteridophytes on an elevational gradient in Costa Rica. Global Ecology and Biogeography 15:358–371.
Koleff, P., and K. J. Gaston. 2001. Latitudinal gradients in diversity:real patterns and random models. Ecography 24:341–351.
Krömer, T. K. M., M. R. Gradstein, and A. Acebey. 2005. Diversity patterns of vascular epiphytes along an elevational gradient in the Andes. Journal of Biogeography 32:1799–1809.
Laurie, H., and J. A. J. Silander. 2002. Geometric constraints and spatial patterns of species richness:critique of range-based models. Diversity and Distributions 8:351–364.
Lees, D. C., C. Kremen, and L. Andriamampianina. 1999. A null model for species richness gradients:bounded range overlap of butterflies and other rainforest endemics in Madagascar. Biological Journal of the Linnean Society 67:529–584.
McCain, C. 2003. North American desert rodents:a test of the mid-domain effect in species richness. Journal of Mammology 84:967–980.
McCain, C. 2004. The mid-domain effect applied to elevational gradients:species richness of small mammals in Costa Rica. Journal of Biogeography 31:19–31.
McCain, C. M. 2005. Elevational gradients in diversity of small mammals. Ecology 86:366–372.
McCain, C. 2007. Could temperature and water availability drive elevational richness? A global case study for bats. Global Ecology and Biogeography 16:1–13.
McClain, C. R., and R. J. Etter. 2005. Mid-domain models as predictors of species diversity patterns:bathymetric diversity gradients in the deep sea. Oikos 109:555–566.
Mena, J. L., and E. Vázquez-Domínguez. 2005. Species trunover on elevational gradients in small rodents. Global Ecology and Biogeography 14:539–547.
Mora, C., and D. R. Robertson. 2005. Causes of latitudinal gradients in species richness:A test with fishes of the Tropical Eastern Pacific. Ecology 86:1771–1782.
Moreno, R. A., C. E. Hernandez, M. M. Rivadeneira, M. A. Vidal, and N. Rozbaczylo. 2006. Patterns of endemism in south-eastern Pacific benthic polychaetes of the Chilean coast. Journal of Biogeography 33:750–759.
Oommen, M. A., and K. Shanker. 2005. Elevational species richness patterns emerge from multiple local mechanisms in Himalayan woody plants. Ecology 86:3039–3047.
Pineda, J., and H. Caswell 1998. Bathymetric species-diversity patterns and boundary constrinats on vertical range distributions. Deep Sea Research II 45:83–101.
Rahbek, C. 1997. The relationship among area, elevation and regional species richness in Neotropical birds. American Naturalist 149:875–902.
Rahbek, C., N. Gotelli, R. Colwell, G. Entsminger, T. Rangel, and G. Graves. 2007. Predicting continental-scale patterns of bird species richness with spatially explicit models. Proceedings of the Royal Society B 274:165–174.
Rangel, T. F. L., and J. A. F. Diniz-Filho. 2003. Spatial patterns in species richness and the geometric constraint simulation model:a global analysis of mid-domain effect in Falconiformes. Acta OEcologica 24:203–207.
Romdal, T. S., R. K. Colwell, and C. Rahbek 2005. The infulence of band sum area, domain extent, and range sizes on the latitudinal mid-domain effect. Ecology 86:235–244.
Sanders, N. L. 2002. Elevational gradients in ants species richness:area, geometry and Rapoport's rule. Ecography 25:25–32.
Smith, K. F., and J. H. Brown. 2002. Patterns of diversity, depth range and body size among pelagic fished along a gradient of depth. Global Ecology and Biodiversity 11:313–322.
Smith S. A., P. R. Stephens, and J. J. Wiens. 2005. Replicate patterns of species richness, historical biogerography and phylogeny in holarctic treefrogs. Evolution 59:2433–2450.
Storch, D., R. G. Davies, S. Zajicek, C. D. L. Orme, V. Olson, G. H. Thomas, T.-S. Ding, P. C. Rasmussen, R. S. Ridgely, P. M. Bennett, T. M. Blackburn, I. P. F. Owens, and K. J. Gaston. 2006. Energy, range dynamics and global species richness patterns:reconciling mid-domain effects and environmental determinants of avian diversity. Ecology Letters 9:1308–1320.
Watkins, J. E. J., C. Cardelus, R. K. Colwell, and R. C. Moran. 2006. Species richness and distribution of ferns along an elevational gradient in Costa Rica. American Journal of Botany 93:73–83.
Willig, M. R., and S. K. Lyons. 1998. An analytical model of latitudinal gradients of species richness with an empirical test for marsupials and bats in the New World. Oikos 73:579–582.