Electronic supplementary material: Methods and Statistics




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Electronic supplementary material: Methods and Statistics

Time to First Heartbeat (TFH)

To the best of our knowledge, we have included all species for which there were data available on TFH, along with sizes and temperatures at this stage. In a few cases, embryo mass was estimated based on length-weight regressions, or based on linear dimensions assuming that biomass density is equal to the density of water. Wet-mass values were converted to dry mass by assuming 90% body water at TFH (references 20-21 below).


Time to hatching (TH) and time to maturity (TM)

TH data were taken from the same studies as the TFH data, when available, so the TH data represent a subset of the species used for TFH. We used TH because it was a late stage in development having the most available data for this group of species. However, TH is not an ideal late-stage measure because larger species tend to hatch at earlier stages of development (see reference 19 of Online Supplement 2). The TM data include all the data compiled by Savage et al. (2003) for heterotrophic eukaryotes (excluding endotherms). These data represent a diverse assortment of ectothermic invertebrates and vertebrates, and do not include species listed in Table 1. For the TH and TM data, wet masses of hatchlings and adults were converted to dry masses, when necessary, by assuming 75% body-water content (Gillooly et al. 2002).


Statistical Analyses

We chose Model I regression, rather than Model II regression, in evaluating the relationship of time to first heartbeat with size and temperature for three reasons. First, Model I assumes a causal relationship between the independent and dependent variables such that size and temperature control developmental times (as assumed by our model), and not vice versa. Second, since all of the body size and temperature values were direct measures taken at the time to first heartbeat, we assume the error in measuring the independent variables of these plots (i.e. size and temperature) is negligible relative to variability among taxa in the time to first heartbeat, Third, we therefore assume that most of the variability about the fitted lines is due to biological factors that operate through their effects on Em and bo. Model I (and not Model II) regression yields the corrected size- and temperature-corrected slopes regardless of variability about the fitted lines attributable to variation among taxa in Em and bo.

With respect to the issue of possible phylogenetic effects, note that our analyses include a diverse set of taxonomic groups (birds, amphibians, fish, invertebrates), and that species are generally distantly related even within taxonomic groups. Thus, it is unlikely that a phylogenetic correction would change the slopes or intercepts of the relationships in Table 1. Still, to address this issue, we performed ANCOVA analyses on the TFH and TH data, assuming differences in intercepts among taxonomic groups. For all four models (the two size-corrected models and the two temperature-corrected models), the slope remains significant (P < 0.05), but the differences in intercepts among groups are not statistically significant. These findings are consistent with other recent work indicating that size- and temperature-corrected rates of growth (i.e. bo/Em) are similar across varied taxonomic groups (Gillooly et al. 2002; Ernest et al. 2003; Savage et al. 2004). Thus, the chance that these relationships are a spurious result due to differences among groups is very small. Unfortunately, we had insufficient statistical power to simultaneously test for differences in slopes and intercepts among groups using ANCOVA.
Ernest, S. K. M., Enquist, B. J., Brown, J. H., Charnov, E. L., Gillooly, J. F., Savage, V. M., White, E. P., Smith, F. A., Hadly, E. A., Haskell, J. P., Lyons, S. K., Maurer, B. A., Niklas, K. J. & Tiffney, B. 2003. Thermodynamic and metabolic effects on the scaling of production and population energy use. Ecology Letters 6, 990-995.
Gillooly, J. F., Charnov, E. L., West, G. B., Savage, V. M. & Brown, J. H. 2002 Effects of size and temperature on developmental time. Nature 417, 70-73.
Savage, V. M., Gillooly, J. F., Brown, J. H., West, G. B. & Charnov, E. L. 2004 Effects of body size and temperature on population growth. The American Naturalist 163, 429-441.
Data and sources from Figure 1


Table 2. Data compiled on times to first heartbeat (TFH) and times to hatching (TH) for diverse taxa.

The term “NA” is used to indicate no data available.
















Time to first Heartbeat




Time to Hatching







Taxon

Species

Temperature (°C)




mass at TFH (g dry)

time (h)




mass at TH (g dry)

time (h)




Source

fish

Clupea harengus

12




1.00x10-4

97




1.10x10-4

168.0




1,2

fish

Phoxinus phoxinus

25




1.70x10-4

48




5.00x10-4

52.0




3

fish

Raja erinacea

17




2.00x10-3

648




1.09x100

3456.0




4

fish

Salmo gairdneri

10




1.21x10-3

360




7.50x10-3

592.8




5,6

fish

Salmo gairdneri

7




1.17x10-3

535




7.50x10-3

NA




5,6

fish

Salmo gairdneri

13




9.62x10-4

240




6.80x10-3

520.8




5,6

amphibian

Ascaphus truei

15




2.34x10-2

276




2.13x10-2

432.0




7

amphibian

Bryobatrachus nimbus

10




1.20x10-3

969




1.92x10-3

1809.6




8

amphibian

Bryobatrachus nimbus

15




1.20x10-3

569




1.92x10-3

1060.8




8

amphibian

Eleutherodactylus coqui

25




3.00x10-4

151




5.73x10-3

NA




9, 10

amphibian

Heleioporus eyrei

21




1.40x10-3

172




1.90x10-2

240.0




11

invertebrate

Artemia franciscana

20




1.34x10-5

63




NA

NA




12

invertebrate

Daphnia magna

20




4.74x10-6

70




1.10x10-5

76.1




12

invertebrate

Procambarus clarkia

25




4.40x10-4

312




1.25x10-3

528.0




13

bird

Coturnix chinensis

38




1.00x10-4

48




9.84x10-1

372.0




14

bird

Gallus gallus

38




2.00x10-3

48




8.55x100

504.0




15

bird

Larus schistisagus

38




7.00x10-3

58




2.08x101

648.0




16

bird

Tyto alba

37




4.20x10-1

168




3.70x100

480.0




17,18

1. Johnston, I. A., V. L. A. Vieira, and M. Abercromby. 1995. Temperature and myogenesis in embryos of the atlantic herring Clupea harengus. Journal of Experimental Biology 198:1389-1403.


2. Eldridge, M. B., T. Echeverria, and J. T. Whipple. 1977. Energetics of Pacific herring (Clupea harengus) embryos and larvae exposed to low concentrations of benzene, a monoaromatic compound of crude oil. Trans. Am. Fish Soc. 106:452-461.
3. Schonweger, G., T. Schwerte, and B. Pelster. 2000. Temperature-dependent development of cardiac activity in unrestrained larvae of the minnow Phoxinus phoxinus. Am. J. Physiol. Regulatory Integrative Comp. Physiol. 279:1634-1640.
4. Pelster, B., and W. E. Bemis. 1991. Ontogeny of heart function in the little skate Raja enrinacea. Journal of Experimental Biology 156:387-398.
5. Ballard, W. W. 1973. Normal embryonic stages for Salmonid fishes, based on Salmo gairdneri richardson and Salvelinus fontinalis. Journal of Experimental Zoology 184:7-26.
6. Rombough, P. J. 1988. Growth, aerobic metabolism, and dissolved-oxygen requirements of embryos and alevins of steelhead, Salmo gairdneri. Canadian Journal of Zoology 66:651-660.

7. Brown, H. A. 1977. Oxygen consumption of a large, cold-adapted frog egg (Ascaphus truei (Amphibia: Ascaphidae)). . Canadian Journal of Zoology 55:343-348.


8. Mitchell, N. J., and R. S. Seymour. 2000. Effects of temperature on energy cost and timing of embryonic and larval development of the terrestrially breeding moss frog, Bryobatrachus nimbus. Physiological and Biochemical Zoology 73:829-840.
9. Burggren, W. W., R. L. Infantino, and D. S. Townsend. 1990. Developmental changes in cardiac and metabolic physiology of the direct-developing tropical Frog Eleutherodactylus coqui. Journal of Experimental Zoology 152:129-147.
10. Burggren, W. W., and S. J. Warburton. 1994. Patterns of form and function in developing hearts: contributions from non-mammalian vertebrates. Cardioscience 5:183-191
11. Packer, W. C. 1966. Embryonic and larval development of Heleioporus eyrei (Amphibia: Leptodactylidae). Copeia 1996:92-97
12. Spicer, J. I., and D. Morritt. 1996. Ontogenic Changes in Cardiac Function in Crustaceans. Comparative Biochemistry and Physiology 114A:81-89.
13. Harper, S. L., and C. L. Reiber. 2006. Cardiac development in crayfish: ontogeny of cardiac physiology and aerobic metabolism in the red swamp crayfish Procambarus clarkii. Journal of Comparative Physiology B 176:405-414
14. Pearson, J. T., M. Tsudzuki, Y. Nakane, R. Akiyama, and H. Tazawa. 1998. Development of heart rate in the precocial king quail Coturnix chinensis. Journal of Experimental Biology 201:931-941.
15. Rugh, R. 1977. The chick embryo: Twenty-four hour stage, Pages 138-151 A guide to vertebrate development. Minneapolis.
16. Pearson, J. T., K. Moriya, M. Yanone, and H. Tazawa. 2000. Development and regulation of heart rate in embryos and hatchlings of gull (Larus Schistisagus and Larus crassirostris) in relation to growth. Journal of Comparative Physiology B 170:429-438.
17. Koppl, C. E. F., B. Nieder, R. Sistermann, and H. Wagner. 2005. Embryonic and posthatching development of the barn owl (Tyto alba): reference data for age determination. Developmental dynamics 233:1248-1260.
18. Nagarajan, R., K. Thiyagesan, R. Natarajan, and R. Kanakasabai. 2002. Patterns of growth in nestling indian barn owls. Condor 104:885-890.
19. Seymour, R. S. 1999. Respiration of aquatic and terrestrial amphibian embryos. American Zoologist 39: 261-270.
20. Dietz MW, van Kampen M, van Griensven MJM, van Mourik S .1998. Daily energy budgets of avian embryos: The paradox of the plateau phase in egg metabolic rate. Physiological Zoology 71(2): 147-156.
21. Ricklefs, R. E. & Cullen, J. 1973. Embryonic growth of the green iguana Iguana iguana. Copeia 2: 295-305.





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