4  Pseudo-absences

Generate pseudo-absence or background environmental values to compare with occurrence environment

Describe various strategies for generating pseudo-absences.

• Pseudo-absences • biomod2
  • (Barbet-Massin et al. 2012)

4.1 All background

A common Maxent strategy is to feed all background points into Maxent, and then to use the resulting distribution as a null model. This is the default strategy in Maxent (Phillips et al. 2017; Phillips, Anderson, and Schapire 2006; Phillips and Dudík 2008).

4.2 Mask by FAO areas

The FAO areas applicable to species are included in the aquamapsdata, presumably from evaluating OBIS observations and the literature.

4.3 Use occurrences from same Family, different species

By using the same family, we can be sure that the pseudo-absences are ecologically similar to the species of interest.

Barbet-Massin, Morgane, Frédéric Jiguet, Cécile Hélène Albert, and Wilfried Thuiller. 2012. “Selecting Pseudo-Absences for Species Distribution Models: How, Where and How Many?” Methods in Ecology and Evolution 3 (2): 327–38. https://doi.org/10.1111/j.2041-210X.2011.00172.x.

Phillips, Steven J., Robert P. Anderson, Miroslav Dudík, Robert E. Schapire, and Mary E. Blair. 2017. “Opening the Black Box: An Open-Source Release of Maxent.” Ecography 40 (7): 887–93. https://doi.org/10.1111/ecog.03049.

Phillips, Steven J., Robert P. Anderson, and Robert E. Schapire. 2006. “Maximum Entropy Modeling of Species Geographic Distributions.” Ecological Modelling 190 (3): 231–59. https://doi.org/10.1016/j.ecolmodel.2005.03.026.

Phillips, Steven J., and Miroslav Dudík. 2008. “Modeling of Species Distributions with Maxent: New Extensions and a Comprehensive Evaluation.” Ecography 31 (2): 161–75. https://doi.org/10.1111/j.0906-7590.2008.5203.x.