Moderator:  Dr A. Márcia Barbosa

Dates
Day 1:  Tuesday, February 16, 14:00-16:30 UTC
Day 2:  Wednesday, February 17, 14:00-16:30 UTC

Description:
Species have continually changing distributions, and they occur with varying frequency across space. Categorical occurrence maps, whether observed or model-derived, are thus incomplete and oversimplified representations of species’ actual distributions. Moreover, categorical occurrence derived from model predictions normally relies on largely arbitrary but outcome-determining user-specified thresholds. Analyses that build on such categorical maps, such as most indices of diversity, overlap, (dis)similarity and change, thus omit important gradations in species occurrence and can be visibly conditioned by threshold choice. Fuzzy logic is a simple tool to eliminate the need for such thresholds and formally incorporate the location uncertainty and gradual variations that characterize natural biodiversity patterns. This workshop will show how fuzzy logic can be easily integrated into biogeographical analyses to improve the depiction and combination of species distribution patterns, with applications in macroecological interactions, global change, biotic regionalization and other biodiversity studies.

We will use presence-(pseudo)absence models that produce presence probability values (e.g. generalized linear and generalized additive models; tree-based classification and regression methods), which can be converted to favourability or fuzzy membership values. We will see how these values allow direct comparison and combination of gradual distribution patterns across species, regions and time periods; and how common indices of diversity, overlap and (dis)similarity can also be generalized to work with fuzzy (degree of) occurrence values. This allows the use of presence probability models without depending on thresholds to force them into binary predictions, thus avoiding the compounded effects of threshold choice on results and conclusions.

The workshop includes concise theoretical lessons explaining the concepts behind the described procedures, and practical hands-on sessions where participants put these procedures into practice using R. Note that we will not cover data preparation and model building; We will provide some already-made species distribution models as examples for participants to work with. Participants are also encouraged to bring their own presence-(pseudo)absence data and presence probability predictions, for different (ecologically related) species or time periods.

  • Format:  Live online lessons on Zoom, with a Slack space for workshop materials, questions and discussion.
  • Expected Background:  This workshop requires familiarity with R at the user level and basic knowledge about species distribution (or ecological niche) models.
  • Required:  A computer with recent versions of R, RStudio, and R packages ‘fuzzySim’ and ‘terra’ already installed; A good enough internet connection for live video sessions, and preferably a webcam for enhanced interactivity.
  • Total time:  5 hours spread over two days
  • Maximum attendees:  20

Fees

TIBS Members:  $80USD; registration is open now!

Non-members:  $120USD; registration opens November 1.