TITLE PAGE - acumen - The University of Alabama

streams, while the obligate-cave species are adapted to survive in the energy-poor cave
environment. These differences in evolutionary history likely contributed to the differential
response to the corn litter amendment. While cave communities per se have the ability to exploit
short-term increases in energy availability, species-specific responses are dictated by differing
selective pressures and resulting life-history traits.
Introduction
Community ecologists have identified several mechanisms that influence the structure
and function of ecosystems, including predator-prey interactions, disturbance regime, and
resource quantity and quality (Morin 2011). Likewise, evolutionary biologists have identified
many of the same mechanisms as important drivers in both morphological and life history
evolution (see Stearns 2000, Reznick et al. 2001). Thus, an understanding of evolutionary history
can provide insight into the factors that influence species abundance, diversity, or composition
within communities. This study illustrates how cave ecosystems are an ideal setting to examine
the interplay between evolutionary history and contemporary community structure.
In cave ecosystems, there is no photosynthetic primary production and
chemolithoautotrophy appears to be limited to relatively few systems (Sarbu et al. 1996; Engel et
al. 2004), making most communities entirely reliant on allochthonous sources of organic matter
(100% donor-control; Polis and Strong 1996). Limited surface connectivity reduces the quantity
of detrital inputs, while their quality is diminished by prior biologic processing in soil horizons
and transport flow paths. Thus, limitation mediated by the availability of organic carbon, as
opposed to via nitrogen (N) or phosphorus (P) supply, has historically been considered the
primary factor influencing both ecological and evolutionary processes in cave ecosystems
(Culver et al. 1995; Graening and Brown 2003; but see Schneider et al, 2010).
40