Latitudinal life history gradients in two Pliocene species of Glycymeris (Bivalvia)

ABSTRACT

Modern bivalves display a latitudinal life history gradient (LLHG): tropical bivalves tend to grow fast and die young, whereas mid- and high-latitude bivalves typically grow more slowly and may live much longer. Environmental factors such as temperature and seasonal food availability, both of which affect metabolic rates, are thought to be partially responsible for this pattern. Given that temperature influences life histories, we predict that the expression of individual life history gradients should vary over time with changes in global climate. Here, we use internal growth increments to constrain lifespans and growth rates in populations of Glycymeris americana and Glycymeris subovata along the Pliocene and Pleistocene Atlantic continental shelf of North America. We find that G. americana was long-lived (up to 93 years) and follows the expected pattern of longer life and slower growth at higher latitudes, whereas the shorter-lived (up to 36 years) G. subovata does not. G. americana life history data lend preliminary support for a change in the slope of the LLHG from the Pliocene to the Pleistocene. While G. americana is currently living along the U.S. Atlantic Coast, we were unable to obtain sufficient samples for our analysis; this represents a future area of research.

KEYWORDS:

• Lifespan
• growth rate
• temperature
• sclerochronology
• plio-pleistocene
• Bivalvia

Acknowledgments

Undergraduate students Steven Harris (Syracuse University) and Emily Artruc (SUNY College of Environmental Science and Forestry) helped to process the initial samples for this work. Robert Silver in the SU Department of Biology provided invaluable assistance with microscopy. Funding from NSF to Ivany (NSF-PLR-1543031) and Surge (NSF-EAR-1656974) supported aspects of this work. Fancher was funded by the UNC IDEA 2.0 program to assist with this project. SHSU undergraduate student Stephen Casper was funded by an SHSU EURECA grant to Moss. Finally, Roger Portell of the Florida Museum of Natural History and Alexander Hastings and Adam Pritchard of the Virginia Museum of Natural History facilitated loans of many specimens for this study, including some for sectioning. We thank them for their support of this research.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

Will be submitted to Pangaea upon acceptance.

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/08912963.2024.2357608.

Additional information

Funding

This work was supported by Sam Houston State University [EURECA]; the University of North Carolina IDEA 2.0; the National Science Foundation of the United States [NSF-PLR-1543031 and NSF-EAR-1656974].