Different solutions lead to similar life history traits across the great divides of the amniote tree of life

Shai Meiri*, Gopal Murali, Anna Zimin, Lior Shak, Yuval Itescu, Gabriel Caetano, Uri Roll

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

12 Scopus citations


Amniote vertebrates share a suite of extra-embryonic membranes that distinguish them from anamniotes. Other than that, however, their reproductive characteristics could not be more different. They differ in basic ectothermic vs endothermic physiology, in that two clades evolved powered flight, and one clade evolved a protective shell. In terms of reproductive strategies, some produce eggs and others give birth to live young, at various degrees of development. Crucially, endotherms provide lengthy parental care, including thermal and food provisioning—whereas ectotherms seldom do. These differences could be expected to manifest themselves in major differences between clades in quantitative reproductive traits. We review the reproductive characteristics, and the distributions of brood sizes, breeding frequencies, offspring sizes and their derivatives (yearly fecundity and biomass production rates) of the four major amniote clades (mammals, birds, turtles and squamates), and several major subclades (birds: Palaeognathae, Galloanserae, Neoaves; mammals: Metatheria and Eutheria). While there are differences between these clades in some of these traits, they generally show similar ranges, distribution shapes and central tendencies across birds, placental mammals and squamates. Marsupials and turtles, however, differ in having smaller offspring, a strategy which subsequently influences other traits.

Original languageEnglish
Article number3
JournalJournal of Biological Research
Issue number1
StatePublished - Dec 2021


  • Amniotes
  • Aves
  • Breeding frequency
  • Cleidoic egg
  • Clutch size
  • Ectothermy
  • Endothermy
  • Litter size
  • Mammalia
  • Metabolic rates
  • Offspring size
  • Parental care
  • Reproductive investment
  • Reptilia
  • Squamata


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