1. Aquino , J. Enzmann , D. Schwartz , M. Jain , N. Kraft , S. 2016 descr: Descriptive statistics. R package version 1.1.3 http://cran.r-project.org/package=descr
2. Auguie , B. 2016 gridExtra: Miscellaneous functions for “Grid” graphics. R package version 2.2.1 https://cran.r-project.org/package=gridExtra
3. Global patterns in predator-prey size relationships reveal size dependency of trophic transfer efficiency;Barnes;Ecology,2010
4. Becker , R. A. Wilks , A. R. Brownrigg , R. 2016 mapdata: Extra map databases. R package version 2 https://cran.r-Project.org/package=mapdata
5. Brownrigg , R. Minka , T. P. Becker , R. A. Wilks , A. R. 2010 maps: Draw geographical maps. R package version 2 https://cran.r-Project.org/package=maps