Inferring Evolutionary Timescales without Independent Timing Information: An Assessment of “Universal” Insect Rates to Calibrate a Collembola (Hexapoda) Molecular Clock

Previous estimates of nucleotide substitution rates are routinely applied as secondary or “universal” molecular clock calibrations for estimating evolutionary timescales in groups that lack independent timing information. A major limitation of this approach is that rates can vary considerably among...

Full description

Bibliographic Details
Main Author: Aron D. Katz
Format: Article
Language:English
Published: MDPI AG 2020-10-01
Series:Genes
Subjects:
Online Access:https://www.mdpi.com/2073-4425/11/10/1172
id doaj-1a7385b80cb64f92853c6582a63e4618
record_format Article
spelling doaj-1a7385b80cb64f92853c6582a63e46182020-11-25T03:51:56ZengMDPI AGGenes2073-44252020-10-01111172117210.3390/genes11101172Inferring Evolutionary Timescales without Independent Timing Information: An Assessment of “Universal” Insect Rates to Calibrate a Collembola (Hexapoda) Molecular ClockAron D. Katz0Engineer Research Development Center, 2902 Newmark Dr., Champaign, IL 61826, USAPrevious estimates of nucleotide substitution rates are routinely applied as secondary or “universal” molecular clock calibrations for estimating evolutionary timescales in groups that lack independent timing information. A major limitation of this approach is that rates can vary considerably among taxonomic groups, but the assumption of rate constancy is rarely evaluated prior to using secondary rate calibrations. Here I evaluate whether an insect mitochondrial DNA clock is appropriate for estimating timescales in Collembola—a group of insect-like arthropods characterized by high levels of cryptic diversity. Relative rates of substitution in cytochrome oxidase subunit 1 (COI) were inferred via Bayesian analysis across a topologically constrained Hexapod phylogeny using a relaxed molecular clock model. Rates for Collembola did not differ significantly from the average rate or from the rates estimated for most other groups (25 of 30), suggesting that (1) their apparent cryptic diversity cannot be explained by accelerated rates of molecular evolution and (2) clocks calibrated using “universal” insect rates may be appropriate for estimating evolutionary timescales in this group. However, of the 31 groups investigated, 10 had rates that deviated significantly from the average (6 higher, 4 lower), underscoring the need for caution and careful consideration when applying secondary insect rate calibrations. Lastly, this study exemplifies a relatively simple approach for evaluating rate constancy within a taxonomic group to determine whether the use of secondary rates are appropriate for molecular clock calibrations.https://www.mdpi.com/2073-4425/11/10/1172cryptic diversitycytochrome oxidase subunit I (COI)molecular evolutionphylogenyrate constancyrelative rates
collection DOAJ
language English
format Article
sources DOAJ
author Aron D. Katz
spellingShingle Aron D. Katz
Inferring Evolutionary Timescales without Independent Timing Information: An Assessment of “Universal” Insect Rates to Calibrate a Collembola (Hexapoda) Molecular Clock
Genes
cryptic diversity
cytochrome oxidase subunit I (COI)
molecular evolution
phylogeny
rate constancy
relative rates
author_facet Aron D. Katz
author_sort Aron D. Katz
title Inferring Evolutionary Timescales without Independent Timing Information: An Assessment of “Universal” Insect Rates to Calibrate a Collembola (Hexapoda) Molecular Clock
title_short Inferring Evolutionary Timescales without Independent Timing Information: An Assessment of “Universal” Insect Rates to Calibrate a Collembola (Hexapoda) Molecular Clock
title_full Inferring Evolutionary Timescales without Independent Timing Information: An Assessment of “Universal” Insect Rates to Calibrate a Collembola (Hexapoda) Molecular Clock
title_fullStr Inferring Evolutionary Timescales without Independent Timing Information: An Assessment of “Universal” Insect Rates to Calibrate a Collembola (Hexapoda) Molecular Clock
title_full_unstemmed Inferring Evolutionary Timescales without Independent Timing Information: An Assessment of “Universal” Insect Rates to Calibrate a Collembola (Hexapoda) Molecular Clock
title_sort inferring evolutionary timescales without independent timing information: an assessment of “universal” insect rates to calibrate a collembola (hexapoda) molecular clock
publisher MDPI AG
series Genes
issn 2073-4425
publishDate 2020-10-01
description Previous estimates of nucleotide substitution rates are routinely applied as secondary or “universal” molecular clock calibrations for estimating evolutionary timescales in groups that lack independent timing information. A major limitation of this approach is that rates can vary considerably among taxonomic groups, but the assumption of rate constancy is rarely evaluated prior to using secondary rate calibrations. Here I evaluate whether an insect mitochondrial DNA clock is appropriate for estimating timescales in Collembola—a group of insect-like arthropods characterized by high levels of cryptic diversity. Relative rates of substitution in cytochrome oxidase subunit 1 (COI) were inferred via Bayesian analysis across a topologically constrained Hexapod phylogeny using a relaxed molecular clock model. Rates for Collembola did not differ significantly from the average rate or from the rates estimated for most other groups (25 of 30), suggesting that (1) their apparent cryptic diversity cannot be explained by accelerated rates of molecular evolution and (2) clocks calibrated using “universal” insect rates may be appropriate for estimating evolutionary timescales in this group. However, of the 31 groups investigated, 10 had rates that deviated significantly from the average (6 higher, 4 lower), underscoring the need for caution and careful consideration when applying secondary insect rate calibrations. Lastly, this study exemplifies a relatively simple approach for evaluating rate constancy within a taxonomic group to determine whether the use of secondary rates are appropriate for molecular clock calibrations.
topic cryptic diversity
cytochrome oxidase subunit I (COI)
molecular evolution
phylogeny
rate constancy
relative rates
url https://www.mdpi.com/2073-4425/11/10/1172
work_keys_str_mv AT arondkatz inferringevolutionarytimescaleswithoutindependenttiminginformationanassessmentofuniversalinsectratestocalibrateacollembolahexapodamolecularclock
_version_ 1724485438521999360