Epizoochory Ranking Index
EPIZOOCHORY RANKING INDEX allows an assessment how well a certain species is adapted to epizoochory (external animal dispersal) in comparison to other species and dispersal modes.
EPIZOOCHORY RANKING INDEX is an index that ranges from 0 to 1, with 0 addressing species with the lowest and 1 addressing species with the highest potential for epizoochory. We use a combination of attachment potential (ATP; Will et al., 2007) and retention potential (RTP; Römermann et al., 2005; Tackenberg et al., 2006) as an indicator of epizoochory potential. This potential can be interpreted as the proportion of seeds that are transported by an animal over a longer time period that principally allows long distance dispersal. The index was computed for the transport in woolly hair. Based on our experience the difference between various fur types in EPIZOOCHORY RANKING INDEX is negligible for many applications, although some differences exist (cf. Römermann et al., 2005; Tackenberg et al., 2006).
Specifically, EPIZOOCHORY RANKING INDEX is calculated as the percentile rank of (ascending) ATP*RTP of the respective species in relation to the values of all species for which data were available.
A value of e.g. 0.7 means that 30 % of the species possess a higher (or identical) epizoochory potential and a higher (or identical) proportion of seeds are transported by animal furs for a significant time period, respectively.
EPIZOOCHORY RANKING INDEX is calculated for all species with relevant data available.
Hintze, C., Heydel, F., Hoppe, C., Cunze, S., König, A. & Tackenberg, O. (2013). D³: The Dispersal and Diaspore Database - Baseline data and statistics on seed dispersal. Perspect. Plant Ecol. Evol. Syst. 15, 180-192.
Römermann, C. et al. (2005): How to predict attachment potential of seeds to sheep and cattle coat from simple morphological seed traits. Oikos 110, 219-230.
Tackenberg, O., Römermann, C., Thompson, K. & Poschlod, P. (2006): What does seed morphology tell us about external animal dispersal? Results from an experimental approach measuring retention times. Basic and Applied Ecology 7, 45-58.
Will, H., Maussner, S., Tackenberg, O. (2007): Experimental studies of diaspore attachment to animal coats: Predicting epizoochorous dispersal potential. Oecologia 153, 331-339.