Germán Mora

Cenozoic Plant Diversity in the Neotropics

Several mechanisms have been proposed to explain the high levels of plant diversity in the Neotropics today, but little is known about diversification patterns of Neotropical floras through geological time. Here, we present the longest time series compiled for palynological plant diversity of the Neotropics (15 stratigraphic sections, 1530 samples, 1411 morphospecies, and 287,736 occurrences) from the Paleocene to the early Miocene (65 to 20 million years ago) in central Colombia and western Venezuela. The record shows a low-diversity Paleocene flora, a significantly more diverse early to middle Eocene flora exceeding Holocene levels, and a decline in diversity at the end of the Eocene and early Oligocene. A good correlation between diversity fluctuations and changes in global temperature was found, suggesting that tropical climate change may be directly driving the observed diversity pattern. Alternatively, the good correspondence may result from the control that climate exerts on the area available for tropical plants to grow.

Effects of Rapid Global Warming at the Paleocene-Eocene Boundary on Neotropical Vegetation

Hot Tropical Explosion The Paleocene-Eocene Thermal Maximum (PETM), 55 million years ago, was a unique episode of rapid global warming (∼5°C), often used as an ancient analog for future global climate change. Climate alteration during the PETM has been extensively studied in the marine realm, and from a few temperate to polar terrestrial localities, but little is known about how the tropics responded to the high temperatures and high levels of CO2. Using evidence from pollen analysis, Jaramillo et al. (p. 957) show that rapid tropical forest diversification occurred during the PETM, without plant extinction or regional aridity. Unexpectedly, diversity seemed to increase at higher temperatures, contradicting previous assumptions that tropical flora will succumb if temperatures become excessive. Palynology shows that tropical forests persisted under conditions of rapid climate warming 55 million years ago. Temperatures in tropical regions are estimated to have increased by 3° to 5°C, compared with Late Paleocene values, during the Paleocene-Eocene Thermal Maximum (PETM, 56.3 million years ago) event. We investigated the tropical forest response to this rapid warming by evaluating the palynological record of three stratigraphic sections in eastern Colombia and western Venezuela. We observed a rapid and distinct increase in plant diversity and origination rates, with a set of new taxa, mostly angiosperms, added to the existing stock of low-diversity Paleocene flora. There is no evidence for enhanced aridity in the northern Neotropics. The tropical rainforest was able to persist under elevated temperatures and high levels of atmospheric carbon dioxide, in contrast to speculations that tropical ecosystems were severely compromised by heat stress.

Peer Instruction and Lecture Tutorials Equally Improve Student Learning in Introductory Geology Classes

Although active learning methodologies have been implemented in geoscience classes successfully, no direct comparison between these different instructional techniques exists to date. For that reason, the purpose of this study was to compare the effectiveness in student learning of two active learning methods: peer instruction and lecture tutorials. In particular, this study focuses on a first implementation of these active learning teaching methods in small- to medium -size introductory physical geology classes. Evaluation of their effectiveness was measured through the Geoscience Concept Inventory, which was administered at the beginning (pre-test) and at the end (post-test) of each course. In addition, students were asked to evaluate the contribution of these techniques to their own learning using a Likert like survey. A comparison of pre- and post-test results indicates that both methods provided statistically significant cognitive knowledge and understanding gains. A comparison of the post-test results for both methods reveals no statistical distinction, indicating a similar level of effectiveness for both peer instruction and lecture tutorials. Similarly, the vast majority of students indicated that these teaching techniques were instrumental in helping them learn different geologic concepts. The combined results of this study are consistent with others studies showing an improvement in cognitive knowledge and understanding gains whenever active learning instructional techniques are first implemented in science classes. A detailed analysis of the obtained data revealed that most of the gains were made by students having little prior knowledge of geology relative to those having some prior knowledge of geologic concepts. Given the relatively easy use of these techniques, their proven effectiveness, and the recognition by students of their effectiveness, it is then recommended that a wider implementation of these techniques should be used in introductory geology classes.

The Need for Geologists in Sustainable Development

The challenges facing our society to become more sustainable are large and require interand trans-disciplinary approaches. Although geologists possess specialized problem-solving skills that make us well-suited to help society move toward more sustainable practices, we tend to be underrepresented in relation to other disciplines in national and global debates on sustainable development. This underrepresentation calls for broad-scale educational and professional training opportunities to increase our engagement with these issues, and sustainability science, in particular, provide a means to advance the involvement of geologists in these discussions. Societal problems related to the preservation of the environment in particular and to sustainable development in general are inherently complex. This complexity is partly due to the nonlinear response of environmental and societal systems to actions rooted in historical contexts that were precipitated by multiple groups of people who can be autonomous and adaptive (Levin, 1999). Further complexity results from lag times between the initiation of an action by these autonomous individuals and the occurrence of measurable responses by environmental and societal systems, as well as feedback mechanisms that could either amplify or dampen these responses. This complexity requires innovative approaches and solutions involving multiple disciplines in the technological, natural, and social sciences. Although some important steps have recently been taken, geologists tend not to be engaged in these discussions, despite skills and proficiencies that permit us to tackle these complex issues. One mechanism that could address this gap is the inclusion of sustainability science in geology curricula and in professional development opportunities to facilitate the emergence of a new generation of professionals well-versed in understanding and addressing sustainability issues. Sustainability science is a fairly new field of study that started in the mid-1980s and reached consensus in terms of its goals and approaches by the early 2000s (Bettencourt and Kaurc, 2011). Some researchers initially defined it as the study of the interactions between human and environmental (earth) systems, but more recently scholars have defined it as a type of applied science, in the vein of agricultural and health sciences, that seeks societal action to preserve environmental integrity through the use and application of scientific knowledge (e.g., Kates, 2011). Rather than being characterized by distinct methodologies, approaches, or questions, what differentiates sustainability science from other academic fields is its search for solutions to sustainability issues. Consequently, sustainability The Need for Geologists in Sustainable Development