Effects of Global Warming on Ancient Mammalian Communities and Their Environments

Abstract

BackgroundCurrent global warming affects the composition and dynamics of mammalian communities and can increase extinction risk; however, long-term effects of warming on mammals are less understood. Dietary reconstructions inferred from stable isotopes of fossil herbivorous mammalian tooth enamel document environmental and climatic changes in ancient ecosystems, including C3/C4 transitions and relative seasonality.Methodology/Principal FindingsHere, we use stable carbon and oxygen isotopes preserved in fossil teeth to document the magnitude of mammalian dietary shifts and ancient floral change during geologically documented glacial and interglacial periods during the Pliocene (∼1.9 million years ago) and Pleistocene (∼1.3 million years ago) in Florida. Stable isotope data demonstrate increased aridity, increased C4 grass consumption, inter-faunal dietary partitioning, increased isotopic niche breadth of mixed feeders, niche partitioning of phylogenetically similar taxa, and differences in relative seasonality with warming.Conclusion/SignificanceOur data show that global warming resulted in dramatic vegetation and dietary changes even at lower latitudes (∼28°N). Our results also question the use of models that predict the long term decline and extinction of species based on the assumption that niches are conserved over time. These findings have immediate relevance to clarifying possible biotic responses to current global warming in modern ecosystems.

Dental microwear texture as a proxy for diet in xenarthrans

“…Nonetheless, all macropods with sample sizes appropriate for analysis demonstrate a significant decline in δ 13 C values with increased aridity (p < 0.05). Declining δ 13 C values are contrary to expectations, as increased aridity is likely to result in greater (i.e., water-stressed; Tieszen 1991) δ 13 C values and/or an increase of C 4 vegetation on the landscape (as seen in DeSantis et al 2009). Significant declines in δ 13 C values, coupled with aridity, suggest that macropods were shifting their diets to compensate for changing climatic conditions.…”

“…Bulk samples were taken parallel to the growth axis of the tooth, while serial samples were taken perpendicular to the growth axis. Enamel powder was pretreated with 30% hydrogen peroxide for 24 h and 0.1 N acetic acid for 12 h to remove organics and secondary carbonates, respectively (Koch et al 1997;DeSantis et al 2009). These samples (~1 mg per sample) were then run on a VG Prism stable isotope ratio mass spectrometer with an in-line ISOCARB automatic sampler in the Department of Geological Sciences at the University of Florida.…”

“…All statistical analyses follow the same methods of a priori geochemical and DMTA analysis (Ungar et al 2003;DeSantis et al 2009DeSantis et al , 2013Prideaux et al 2009 (Dunn 1964) to conduct multiple comparisons (between extant and/or extinct taxa) absent of the Bonferroni correction. As the Bonferroni correction is meant to reduce the likelihood of false positives (type I errors) by taking into consideration the number of comparisons being made, it also increases the probability of false negatives (type II errors; Cabin and Mitchell 2000;Nakagawa 2004).…”

“…18 O values of~2.4‰ (ranging from 1.8 to 2.9‰; DeSantis et al 2009). For Cuddie Springs, SU6 formed during a period of enhanced aridity (ca.…”

The Late Pleistocene (Rancholabrean) Viko vijin Local Fauna from La Mixteca Alta, northwestern Oaxaca, southern Mexico

“…Forty four percent of the mammalian genera identified in the Viko vijin L. F., were mainly grazers, while the rest were mixed feeders or browsers (MacFadden & Cerling, 1996;Koch et al, 1998;Feranec, 2004;Prado et al, 2005;Rivals et al, 2007;DeSantis et al, 2009). This suggests Hibbard, 1955;Mooser & Dalquest, 1975;Miller & Carranza-Castañeda, 1984;Webb & Perrigo, 1984;Montellano-Ballesteros, 1992;Lucas et al, 1997;Cisneros, 2005;Pearson, 2005;Meade et al, 2006;Laurito & Aguilar, 2007;Lucas et al, 2008).…”