Origin of the foraminifera
C G Wray1, M R Langer, R DeSalle
1Department of Entomology, American Museum of Natural History, New York, NY 10024.
Summary
The evolutionary origins of foraminifera, crucial marine protists in geologic studies, remain unknown. Our study reveals their DNA sequences suggest a divergent "alveolate" lineage, challenging previous assumptions about their amoebalike ancestry.
Area of Science:
- Protistology
- Molecular Evolution
- Paleontology
Background:
- Foraminifera are abundant marine protists vital for geologic studies.
- The evolutionary ancestry of foraminifera has been previously unknown.
- Purifying foraminiferal DNA and preventing PCR contamination are significant challenges.
Purpose of the Study:
- To determine the evolutionary origins of benthic foraminifera.
- To verify DNA sequence data using novel techniques.
- To establish the phylogenetic position of foraminifera within eukaryotes.
Main Methods:
- Sequencing of nuclear small-subunit ribosomal DNA (rDNA) from two Ammonia species.
- Development of DNA.DNA in situ hybridization techniques for data verification.
- Phylogenetic analysis of verified DNA sequences.
Main Results:
- Nuclear small-subunit rDNA sequences were obtained for two Ammonia species.
- DNA.DNA in situ hybridization confirmed the accuracy of sequence data.
- Phylogenetic analysis identified foraminifera as a divergent "alveolate" lineage.
Conclusions:
- Foraminifera do not appear to be derived from an amoebalike ancestor.
- Cytological features and DNA sequences suggest a heterokaryotic flagellated marine protist origin.
- The evolutionary divergence of foraminifera likely occurred in the later Proterozoic era.
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