Comparison of molecular and paleontological data in diatoms suggests a major gap in the fossil record

Comparison of molecular and paleontological data in diatoms suggests a major gap in the fossil... Diatoms, unicellular eukaryotic algae with a siliceous skeleton, offer the rare advantage of displaying both an extensive fossil record and numerous extant species, thus providing the opportunity of confronting molecular and paleontological data in a protist group. A portion of the 28S ribosomal RNA was sequenced from 5 diatoms, the divergence times of which are well known. The nucleotide substitution rate was estimated in these unicellular eukaryotes and compared with the rate of multicellular eukaryotes, using a broad data base comprising metazoans and metaphytes. When using fossil record derived divergence times, our results show that the nucleotide substitution rate is about 5 times faster in diatoms than in chordates. But, when using the relative rate test, it is observed that, over a long time period, the nucleotide substitution rate may in fact have been slightly slower in diatoms than in chordates. For this contradiction, two possible explanations are proposed: (i) a failure of the relative rate test, (ii) a gap in the pre‐Jurassic diatom fossil record. We have checked that our results concerning the relative rate test were valid. Thus, the second hypothesis, which implies pre‐Jurassic diatom evolution, in fact already suggested by some non‐molecular evidences, is favoured. Decoupling of morphological differentiation from genetic speciation also appears to have occurred and may account in part for the underestimation of the dates of recent cladogenesis events. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Journal of Evolutionary Biology Wiley

Comparison of molecular and paleontological data in diatoms suggests a major gap in the fossil record

Loading next page...
 
/lp/wiley/comparison-of-molecular-and-paleontological-data-in-diatoms-suggests-a-YDlzOp1C0Q
Publisher
Wiley
Copyright
Copyright © 1994 Wiley Subscription Services, Inc., A Wiley Company
ISSN
1010-061X
eISSN
1420-9101
DOI
10.1046/j.1420-9101.1994.7020247.x
Publisher site
See Article on Publisher Site

Abstract

Diatoms, unicellular eukaryotic algae with a siliceous skeleton, offer the rare advantage of displaying both an extensive fossil record and numerous extant species, thus providing the opportunity of confronting molecular and paleontological data in a protist group. A portion of the 28S ribosomal RNA was sequenced from 5 diatoms, the divergence times of which are well known. The nucleotide substitution rate was estimated in these unicellular eukaryotes and compared with the rate of multicellular eukaryotes, using a broad data base comprising metazoans and metaphytes. When using fossil record derived divergence times, our results show that the nucleotide substitution rate is about 5 times faster in diatoms than in chordates. But, when using the relative rate test, it is observed that, over a long time period, the nucleotide substitution rate may in fact have been slightly slower in diatoms than in chordates. For this contradiction, two possible explanations are proposed: (i) a failure of the relative rate test, (ii) a gap in the pre‐Jurassic diatom fossil record. We have checked that our results concerning the relative rate test were valid. Thus, the second hypothesis, which implies pre‐Jurassic diatom evolution, in fact already suggested by some non‐molecular evidences, is favoured. Decoupling of morphological differentiation from genetic speciation also appears to have occurred and may account in part for the underestimation of the dates of recent cladogenesis events.

Journal

Journal of Evolutionary BiologyWiley

Published: Mar 1, 1994

There are no references for this article.

You’re reading a free preview. Subscribe to read the entire article.


DeepDyve is your
personal research library

It’s your single place to instantly
discover and read the research
that matters to you.

Enjoy affordable access to
over 18 million articles from more than
15,000 peer-reviewed journals.

All for just $49/month

Explore the DeepDyve Library

Search

Query the DeepDyve database, plus search all of PubMed and Google Scholar seamlessly

Organize

Save any article or search result from DeepDyve, PubMed, and Google Scholar... all in one place.

Access

Get unlimited, online access to over 18 million full-text articles from more than 15,000 scientific journals.

Your journals are on DeepDyve

Read from thousands of the leading scholarly journals from SpringerNature, Wiley-Blackwell, Oxford University Press and more.

All the latest content is available, no embargo periods.

See the journals in your area

DeepDyve

Freelancer

DeepDyve

Pro

Price

FREE

$49/month
$360/year

Save searches from
Google Scholar,
PubMed

Create folders to
organize your research

Export folders, citations

Read DeepDyve articles

Abstract access only

Unlimited access to over
18 million full-text articles

Print

20 pages / month

PDF Discount

20% off