FUNCTIONAL DIVERSITY LOSS AT THE TERMINAL PLEISTOCENE: A SITE-SPECIFIC ANALYSIS

Functional diversity is increasingly being used to study ecosystem function and community structure in a variety of taxa. During periods of biodiversity decline, the magnitude of functional diversity loss often differs from that of species richness loss, providing more insight into how ecosystems are affected in these scenarios. Given the alarmingly high rate of current global biodiversity loss, it is becoming increasingly important to understand how biodiversity and ecosystem function are related across taxa.

The Hall’s Cave site on the Edwards Plateau of Texas provides a unique opportunity to study the ecological effects of the Late Pleistocene (LP) extinction event which occurred roughly 14ka. This extinction is exceptional in the fossil record due to the extreme size selectivity; over 80% of all large bodied mammals went extinct including all species over 600kg. The remarkably abundant and diverse fossil assemblage at Hall’s Cave spans this extinction event and continues to modern, providing a continuous record of the mammalian community over this interval.

This study seeks to quantify the loss of functional diversity over the LP megafaunal extinction compared to random species loss. Functional trait data was gathered from literature searches for all 80 mammalian taxa present in the Hall’s Cave community prior to the LP extinction event. Traits included in this analysis are body size, diet, annual methane emissions, range size, social group size, degree of cursoriality, arboreality and soil disturbance, activity period, and migratory behavior. Trait data was additionally informed by unpublished stable isotope and morphology data measured from Hall’s Cave specimens to make compiled traits as characteristic of the site as possible. Functional diversity before and directly after the LP extinction was quantified using Gower’s Distance and following the methods of Petchey and Gaston (2002). Preliminary results suggest that functional diversity loss over the LP extinction was significantly different than random species loss of the same magnitude, likely due to the proportionally greater effect large bodied taxa have on ecosystems. Further, the mammalian community following the loss of megafauna was less functionally redundant, potentially making it less resilient to continued loss of biodiversity.