Diving as a lifestyle has evolved on multiple occasions when air-breathing terrestrial animals invaded the aquatic realm, and diving performance shapes the ecology and behaviour of all air-breathing aquatic taxa, from small insects to great whales. Using the largest dataset yet assembled, we show that maximum dive duration increases predictably with body mass in both ectotherms and endotherms. Compared to endotherms, ectotherms can remain submerged for longer, but the mass scaling relationship for dive duration is much steeper in endotherms than in ectotherms. These differences in diving allometry can be fully explained by inherent differences between the two groups in their metabolic rate and how metabolism scales with body mass and temperature. Therefore, we suggest that similar constraints on oxygen storage and usage have shaped the evolutionary ecology of diving in all air-breathing animals, irrespective of their evolutionary history and metabolic mode. The steeper scaling relationship between body mass and dive duration in endotherms not only helps explain why the largest extant vertebrate divers are endothermic rather than ectothermic, but also fits well with the emerging consensus that large extinct tetrapod divers (e.g. plesiosaurs, ichthyosaurs and mosasaurs) were endothermic.

Data on diving performance and body mass of ectotherms and endotherms were collated from the published literature. We have drawn on a previously published dataset, initially constructed by Schreer and Kovacs (1997) and subsequently updated by Halsey et al. (2006), Brischoux et al. (2008) and Hayward et al. (2016). We used the "penguiness book" to locate most of the studies used. We rechecked all records and added data from the primary literature to generate the most comprehensive dataset on dive duration to date, comprising 1,792 records for 286 species of which 62 were ectotherms and 224 endotherms.

Brischoux F, Bonnet X, Cook TR & Shine R. Allometry of diving capacities: ectothermy vs. endothermy. J. Evol. Biol. 21, 324-329 (2008).

Halsey LG, Butler PJ & Blackburn TM. A phylogenetic analysis of the allometry of diving. Am. Nat. 167, 276-287 (2006).

Hayward A, Pajuelo M, Haase CG, Anderson DM & Gillooly JF. Common metabolic constraints on dive duration in endothermic and ectothermic vertebrates. PeerJ 4, e2569 (2016).

Ropert-Coudert Y, Kato A, Robbins A, Humphries GRW. The Penguiness book. World Wide Web electronic publication (http://www.penguiness.net), version 3.0, October 2018. DOI:10.13140/RG.2.2.32289.66406

Schreer JF & Kovacs KM. Allometry of diving capacity in air-breathing vertebrates. Can. J. Zool. 75, 339-358 (1997).

there are three files:

1. dataset on dive duration

2. phylogenetic tree of the taxa in the dataset

3. R script to analyse the data using PGLS

1. Data set with records (rows) on dive duration for different species, compiled from published literature.

Column names:

1. Species: the species name of individual to which the datarecord pertains;
2. Endo.vs..Ecto: classifies the species as either an endotherm (bird or mammal) or an ectotherm (insect, amphibian or reptile);
3. Mass..kg.: body mass of the individual to which the datarecord pertains in kilograms;
4. Dive.duration..min: reported mean dive duration in minutes;
5. Maximum.dive.duration..min: reported maximum dive duration in minutes;
6. Temerature: Relevant temperature of the individual during the dive. For endotherms this is body temperature in most cases, whereas for the smaller ectotherms this is water temperature;
7. Remarks: remarks taken from the study to help identify the conditions that pertain to the datarecord. If the temperature is not obtained from the literature source, the relevant source is also stated here;
8. Literature.source: Primary source for the data record;
9. Selected: a column which indicates whether a record was used in the analysis on 95th percentile of maximum dive duration, accounting for temperature;
10. Treenames: a column with the names that are identical to those used in the phylogenetic tree

2. phylogenetic tree of the taxa in the dataset

Tree in nexus format saved as a .txt file which includes 281 taxa and has branchlengths derived from TimeTree

3. R script to analyse the data using PGLS

Rscript which reproduce the results from the PGLS analysis in Table 1 in the paper which reports on this dataset.