TITLE:
Global environment- and space-richness ranking relationships: The effects of interaction and high-order terms of explanatory variables
AUTHORS:
Youhua Chen
KEYWORDS:
Global Species Distribution; Nonlinearity; Richness Ranking; Diversity Mapping; Environment Envelope
JOURNAL NAME:
Open Journal of Ecology,
Vol.3 No.6,
October
8,
2013
ABSTRACT:
In the present study,
the interplay and higher-order terms of environmental and spatial variables are
considered to evaluate the relations of environment and space-species richness
rankings at global scale. Three taxonomic groups composed of mammals, birds and
amphibians were analyzed for the study. Thek-means
clustering method was introduced for richness rankings detection and analysis
from published digital maps; and simple regression analysis and AIC criteria were
used for identifying mostimportant correlated explanatory variables.When comparing each
single variable, I found that latitude was the most important one influencing
global vertebrate richness rankings. When onlyconsidering environmental variables, I foundthat
precipitation was the only predictor of vertebrate richness rankings. However,
when the interaction and high-order terms of different independent variables
were considered, it was found that the interaction between latitude and temperature
could better explain the global bird richness ranking, while the second-power
effectof latitude was
the best predictor for amphibianand mammalian richness rankings, as evidenced by
the AIC model selection and comparison among the regression models. In conclusion,
the inclusion of high-order and interaction terms of environmental and spatial
variables could offer more insights into the understanding of global species
diversity patterns.