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Environmental change drove macroevolution in cupuladriid bryozoans
1Center for Tropical Paleoecology and Archeology, Smithsonian Tropical Research Institute, Apartado 0843-03092, Panamá, República de Panamá. odeaa@si.edu
Proceedings. Biological Sciences
|July 31, 2009
Summary
Environmental change drove macroevolutionary events in cupuladriid bryozoans. A shift to asexual reproduction occurred due to ecosystem changes, despite delayed extinctions.
Area of Science:
- Paleontology
- Marine Biology
- Evolutionary Biology
Background:
- Macroevolutionary events often correlate with environmental shifts, but direct causation is difficult to establish.
- The closure of the Isthmus of Panama significantly altered marine ecosystems, including primary productivity in the Caribbean.
Purpose of the Study:
- To investigate the cause-and-effect relationship between environmental change and macroevolutionary patterns.
- To analyze the impact of the Isthmus of Panama's closure on cupuladriid bryozoan species.
Main Methods:
- Compiled a 10-million-year record of bryozoan origination, extinction, reproduction modes, morphologies, and abundances.
- Analyzed species' responses to environmental changes, specifically the collapse of primary productivity.
Main Results:
- A dramatic shift in reproduction from clonal to asexual reproduction occurred in bryozoans.
- Originations were synchronous with environmental changes, but extinctions lagged by 1-2 million years.
- Extinct species were less adaptable, failing to reduce cloning rates in response to new conditions.
Conclusions:
- Environmental change, specifically the collapse in primary productivity, is the root cause of macroevolutionary turnover in these bryozoans.
- Delayed extinctions highlight the importance of species' adaptive capacity in the face of environmental shifts.
- The study provides mechanistic support for environmental change driving evolutionary patterns.
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