NSF Org:	EAR Division Of Earth Sciences
Recipient:	UNIVERSITY OF SOUTH FLORIDA
Initial Amendment Date:	May 12, 2011
Latest Amendment Date:	June 10, 2013
Award Number:	1053517
Award Instrument:	Continuing Grant
Program Manager:	Judith Skog EAR  Division Of Earth Sciences GEO  Directorate for Geosciences
Start Date:	June 1, 2011
End Date:	December 31, 2015 (Estimated)
Total Intended Award Amount:	$82,166.00
Total Awarded Amount to Date:	$82,166.00
Funds Obligated to Date:	FY 2011 = $27,280.00 FY 2012 = $26,627.00 FY 2013 = $28,259.00
History of Investigator:	Peter Harries (Principal Investigator) harries@usf.edu
Recipient Sponsored Research Office:	University of South Florida 4202 E FOWLER AVE TAMPA FL  US  33620-5800 (813)974-2897
Sponsor Congressional District:	15
Primary Place of Performance:	University of South Florida 4202 E FOWLER AVE TAMPA FL  US  33620-5800
Primary Place of Performance Congressional District:	15
Unique Entity Identifier (UEI):	NKAZLXLL7Z91
Parent UEI:
NSF Program(s):	Sedimentary Geo & Paleobiology
Primary Program Source:	01001112DB NSF RESEARCH & RELATED ACTIVIT 01001213DB NSF RESEARCH & RELATED ACTIVIT 01001314DB NSF RESEARCH & RELATED ACTIVIT
Program Reference Code(s):	OTHR
Program Element Code(s):	745900
Award Agency Code:	4900
Fund Agency Code:	4900
Assistance Listing Number(s):	47.050

ABSTRACT

Collaborative Research: The Effects Of Broad-Scale Climate Variability on Evolutionary Pattern: Comparative Tempo and Mode in Cretaceous and Neogene Marine Molluscs.

Technical Description:

This study aims to address a central question in paleobiologic research: how variable is evolutionary tempo and mode? Although the issue has been debated for several decades, this study goes beyond earlier approaches in that it is focused on testing whether overall paleoclimatic regime ? the differences between green- and icehouse climates ? and the concomitant rates of environmental change associated with different climate phases play a role in regulating the rate and pattern of evolution. This builds on Sheldon?s (1996) ?plus ça change? model that suggests that the rate of environmental variability influences the evolutionary response. To test this over-arching hypothesis, data will be gathered from a greenhouse (the Late Cretaceous) as well as icehouse intervals (the Neogene). More specifically, we will sample Campanian-Maastrichtian units in the North American Western Interior Seaway (WIS) as well as the Miocene-Pleistocene units of Florida. The analyses will focus on various molluscan lineages that have relatively closely related Cretaceous ancestors and Neogene descendents, such as lucinid, nuculid, and venerid bivalves as well as naticid and turritellid gastropods. The collected specimens will be analyzed using traditional size measurements as well as shape analysis to investigate the nature of morphologic change through the intervals studied. Furthermore, to investigate the effects that stratigraphic architecture may have on the manner in which evolutionary patterns are recorded in the record, we will also examine the same Cretaceous taxonomic groups in the WIS, a foreland basin with relatively continuous sedimentation, with coeval deposits in the US Gulf Coast, a passive-margin setting with substantially more sedimentary breaks.


Broader Significance and Importance:
Since Darwin first published his opus that established natural selection as a prominent mechanism for producing evolutionary change, the timing (tempo) and nature (mode) of evolution has remained a persistent theme of numerous studies. The contentiousness of the issue came to the forefront with the advent of ?punctuated equilibrium?, which initiated a range of studies into examining changes in various groups. This study builds on those previous ones, but adds a new dimension to the study of tempo and mode by focusing on whether or not the rate of environmental change can influence the nature of the evolutionary response. Intellectually, the broader significance of this proposal is that this is the first study to specifically examine the influence of different climate modes on the biotas evolutionary response. Furthermore, given the multidisciplinary nature of this study, the PIs will be actively engaged in training undergraduate and graduate students in a broad spectrum of geologic approaches to collecting and analyzing data. Finally, the project involves the synergy between research universities and the Museum of the Earth, which will broaden the venues through which the results and its implications can be disseminated and used as an means of presenting evidence of the scientific evolution debate to the public.

PROJECT OUTCOMES REPORT

Disclaimer

This Project Outcomes Report for the General Public is displayed verbatim as submitted by the Principal Investigator (PI) for this award. Any opinions, findings, and conclusions or recommendations expressed in this Report are those of the PI and do not necessarily reflect the views of the National Science Foundation; NSF has not approved or endorsed its content.

This project investigated a major debate in the field of paleobiology: the nature and pattern of evolutionary change. This debate centers around one of Darwin’s primary contentions – that evolution occurs as a continual, gradual process (i.e., phyletic gradualism) – inherit in his view of how evolution occurred with other empirical evidence from the fossil record which suggested that through most of their histories organisms displayed remarkable stasis (i.e., punctuate equilibrium). The approach of this study was to examine whether the context of environmental change as well as the depositional setting influenced at least our perception of evolutionary change. This study used Sheldon’s ‘Plus ca change’ model as a starting point as his notion that if environmental change was very dynamic and changing in an unpredictable manner that volatility would negatively impact evolution. In contrast more stable conditions would favor a more consistent evolutionary response. We also considered another issue, one that Darwin had also focused on in his writings about the fossil record, which is completeness. To address the first issue, we investigated intervals representative of the two major climatic modes that characterize Earth history: green- and icehouse worlds, with climate stability more pronounced in the former. To approach this problem, we investigated one of the most common invertebrate fossils preserved in the geologic record: bivalves. This group has an excellent preservation potential and is generally the most common constituent of virtually all Meso- and Cenozoic marine deposits. Additionally, we focused on two intervals – the Late Cretaceous and the Plio-Pleistocene – that represent periods of green- and icehouse climates, respectively. Furthermore, we analyzed Late Cretaceous material from the Western Interior Seaway, a mid-continent seaway that ranged from Mexico up to the Canadian Arctic, and afrom the Gulf Coastal Plain as these represent very different depositional settings. The former, due its very high subsidence, has very expanded, highly complete sections, whereas the latter is characterized by thinner, more condensed sequences which are often truncated by unconformities. This allowed us to see how depositional setting and the completeness of the record influence the patterns seen.

 

The results to date of the study suggest that stasis is an inherent part of the bivalve groups investigated. In the case of the bivalve Chione, there is incredible consistency in shape, even with pronounced changes in size, through an interval approaching 25 Ma ranging from the mid-Miocene to the present. The Cretaceous data are still in the process of being analyzed, but initial results suggests that there is also considerable stasis, although potentially with reduced amounts of overall variability. We hope to expand this project to look at additional groups of molluscs, such as the inoceramid bivalves and ammonites, to see whether these groups that dominated Cretaceous marine environments and are characterized by very rapid evolution also show this pattern. It also appears that despite the less complete nature of the Gulf Coastal Plain setting the evolutionary patterns can be effectively determined.

 

Last Modified: 01/09/2017
Modified by: Peter J Harries

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