Ecological fidelity of functional traits based on species presence-absence in a modern mammalian bone assemblage (Amboseli, Kenya)

Abstract

Comparisons between modern death assemblages and their source communities have demonstrated fidelity to species diversity across a variety of environments and taxonomic groups. However, differential species preservation and collection (including body-size bias) in both modern and fossil death assemblages may still skew the representation of other important ecological characteristics. Here, we move beyond live-dead taxonomic fidelity and focus on the recovery of functional ecology (how species interact with their ecosystem) at the community level for a diverse non-volant mammal community (87 species; Amboseli, Kenya). We use published literature to characterize species, using four functional traits and their associated categorical attributes (i) dietary mode (11 attributes; e.g., browser, grazer), (ii) preferred feeding habitat (16 attributes; e.g., grassland, woodland), (iii) preferred sheltering habitat (17 attributes; e.g., grassland, underground cavity), and (iv) activity time (7 attributes; e.g., diurnal, nocturnal, nocturnally dominated crepuscular). For each functional ecological trait we compare the death assemblage's recovered richness and abundance structure of constituent functional attributes with those of the source community, using Jaccard similarity, Spearman's rho, and the Probability of Interspecific Encounter (evenness). We use Monte Carlo simulations to evaluate whether these empirical comparisons are significantly different from expectations calculated from randomized sampling of species from the source community. Results indicate that although the Amboseli death assemblage is significantly overrepresented by large-bodied species relative to the Amboseli source community, it captures many functional dimensions of the ecosystem within expectations of a randomized collection of species. Additional resampling simulations and logistic regressions further illustrate that the size bias inherent to the Amboseli death assemblage is not a major driver of deviations between the functional ecological properties of the death assemblage and its source community. Finally, the Amboseli death assemblage also enhances our understanding of the mammal community by adding nine species and two functional attributes previously unknown from the ecosystem.

Owl pellets: a more effective alternative to conventional trapping for broad‐scale studies of small mammal communities

“…Given these advantages, owl pellets can be used as a powerful tool to investigate broad‐scale small mammal community composition (Miller et al . ), including compositional changes in response to landscape‐level climatic variation (Hadly ; Heisler, Somers & Poulin ), species–habitat associations and habitat change (Pena et al . ; Heisler et al .…”

“…Considerable time and expense are required to quantify mammal remains; however, single pellet collections include hundreds to thousands of individuals spatiotemporally averaged across habitats within the foraging ranges of individual owls, providing a unique perspective on species-habitat associations across entire biogeographic regions. Given these advantages, owl pellets can be used as a powerful tool to investigate broad-scale small mammal community composition (Miller et al 2014), including compositional changes in response to landscape-level climatic variation (Hadly 1999;Heisler, Somers & Poulin 2014), species-habitat associations and habitat change (Pena et al 2003;Heisler et al 2013), species distributional changes, as well as monitoring distributions of endangered or exotic species (Clark & Bunck 1991).…”

The fossil record of the sixth extinction

“…For example, the death assemblage at Amboseli, Kenya has a body size distribution with a larger mean and median than is typical of the live mammal community (Miller et al . ).…”

“…These same factors impact the preservation potential of these animals; that is, to a first approximation larger, more widely distributed and locally abundant mammals should have a higher probability of being recovered as fossils (Behrensmeyer & Chapman 1993;Liow et al 2008). For example, the death assemblage at Amboseli, Kenya has a body size distribution with a larger mean and median than is typical of the live mammal community (Miller et al 2014).…”

Potential evolutionary body size reduction in a Malagasy primate (Propithecus verreauxi) in response to human size-selective hunting pressure

“…While this result is consistent with the hypothesis of recent phyletic dwarfism in response to size-selective hunting pressures by humans, our finding alone does not necessarily demonstrate a history of adaptive evolution for smaller body sizes in this population. As an alternative explanation, the archaeological sample could be biased by assemblage and/or taphonomic processes [48]. For example, if past people were preferentially hunting larger sifaka with projectiles such as slingshots or blowguns [49,50], then individuals who ended up in the archaeological sample may have been larger than the average for the overall population at the time.…”