DOI: 10.5061/dryad.3n5tb2rw4
title: Why are telomeres the length that they are? Insight from a phylogenetic comparative analysis

description: Telomeres are short repeating nucleotide sequences at the ends of
 chromosomes that shorten with every cellular replication. Despite the
 importance of keeping telomere length within a critical homeostatic range,
 adult telomere length can differ by two orders of magnitude across
 vertebrate species. Why telomere length varies so widely remains unknown,
 though popular hypotheses suggest that body size, lifespan, and endothermy
 are key variables that have coevolved with telomere length. To test the
 relationship among telomere length, telomerase activity (which extends
 telomeres), and these variables, we modeled the evolution of telomere
 length across 122 vertebrate species. We failed to find an influence of
 body mass, lifespan, or baseline metabolism on telomere length. However,
 we found a significant interactive effect between baseline metabolism and
 body mass. The presence of telomerase activity was positively correlated
 with telomere length across the 58 species where data for both existed.
 Taken together, our findings suggest that body mass may have
 differentially influenced the evolution of telomere length in endotherms
 and ectotherms and indicate that telomerase activity and telomere length
 may have coevolved.
description: # Why are telomeres the length that they are? Insight from a phylogenetic
 comparative analysis Dataset DOI:
 [10.5061/dryad.3n5tb2rw4](10.5061/dryad.3n5tb2rw4) ## Description of the
 data and file structure Data for was collected for "*EVO-24-0205.R3:
 Why are telomeres the length that they are? Insight from a phylogenetic
 comparative analysis*." ### Files and variables #### File:
 index\_for\_EVO-24-0205.R3.Rmd **Description:**  Complete workflow for the
 analyses and results #### File: spp.tree.nwk **Description:** Phylogenetic
 tree used for the analyses #### File:
 Supplementary\_table\_1\_references.docx **Description:** References for
 Supplementary table 1 #### File: Supplementary\_table\_1.csv
 **Description:** Source data file for all analyses. Missing values are
 marked as "NA" ##### Variables * Common.name: Common names of
 the species utilized in the analyses * Scientific_name: Genus and species
 separated by an underscore * Domain: Domain of the specific species *
 Kingdom: Kingdom of the specific species * Phylum: Phylum of the specific
 species * Class: Class of the specific species * Order: Order of the
 specific species * Family: Family of the specific species * Genus: Genus
 of the specific species * Species: Species name of the specific species *
 Endo_ectotherm: Binary variable indicating whether the species is an
 endotherm or ectotherm * Adult_mass_grams: Adult mass of the species in
 grams * Lifespan_years: Lifespan of the species in years *
 Average_Telomere_Length_kb: Telomere length of the species in kilobases *
 Telomerase_activity: Binary variable of whether the species displays
 telomerase activity in somatic, non-germline cells in adulthood * Tissue
 type for TA: The source tissue that telomerase activity was measured in *
 Source for TA: The study which measured telomerase activity * Tissue type
 for TL: The source tissue that telomere length was measured in *
 Tissue_coded: Renaming the column tissue type and organizing the different
 tissues for ease of analysis. Tissue type from "multiple somatic
 tissues" is marked as "NA" * Methodology for TL: Whether
 the methodology used for measuring telomere length did or did not denature
 the DNA, or if the methodology was unclear/used a combination  * method:
 Renaming the column methodology for TL for ease of analysis. Methodology
 unclear or combined is marked as "NA" * Source for TL: The
 source for the reported telomere length value * Source for Lifespan: The
 source for the reported lifespan value * Source for Mass: The source for
 the reported mass value * Captivity: Binary variable describing whether or
 not the species had a long history of captivity/domestication. All species
 are marked as 0. * Notes: Additional clarification for specific cells and
 values ## Code/software All analyses were run on R version 4.3.0.  ##
 Access information Data was derived from the following sources: * A full
 list of the sources for the data can be found in supplementary table 1, as
 well as the supplementary table 1 references document.