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Table 1 A review of available publications on the most frequently investigated digit ratio (2D:4D) in amphibians, with the main results and additional information. Results for which significant sexual dimorphism in digit ratio was detected are indicated in bold. The effect sizes (to two decimal places) are included in parentheses where reported in parentheses. For values of other digit ratios (2D:3D and 3D:4D) in the common toad Bufo bufo, see Tables 2, 3, and S2

From: Digit ratio in the common toad Bufo bufo: the effects of reduced fingers and of age dependency

Order Sample size Adult SVL Specimen type 2D:4D References
Family, Species M F FL FR BL BR  
Anura
 Bufonidae
  Bufo bufoa 158 143 F > M Live ns ns    this study
      (−0.08) (0.02) ns ns  
      ns# M < F# (− 0.08) (− 0.01) this study
      (0.15) (−0.53)    
  Rhinella marina 24 28 F > M Live ns ns ns ns [27]
  R. marina 14 5 F > M Live ns ns ns ns [27]
 Craugastoridae
  Craugastor bransfordii 46 42 F > M Live F < M ns ns ns [26]
      (0.62) (0.12) (0.33) (0.1)  
 Dendrobatidae
  Oophaga pumilio 40 44 F = M Live ns ns F < M F < M [25]
  O. pumilio 36 48 F = M Live F < M F < M ns ns [26]
      (0.93) (0.7) (0.05) (0.2)  
 Leiopelmatidae
  Leiopelma pakeka    F > M Live ns ns [24]
 Leptodactylidae
  Engystomops pustulosus 107 52 F > M   M < F M < F ns ns [27]
  Leptodactylus podicipinusb 128 191 F > M Preserved F < M F < M [5]
  Leptodactylus fuscusc 24 25 F = M Live ns ns [5]
 Ranidae
  Pelophylax ridibundusc 30 20 F > M Live M < F ns [29]
Caudata
 Salamandridae
  Salamandra salamandra 35 31 F > M Preserved ns ns ns ns [28]
  Triturus cristatus 25 20 F = M Preserved ns ns ns ns [17]
      (−0.18) (−0.3) (−0.2) (−0.18)  
  Ichthyosaura (Mesotriton) alpestris 42 39 F > M Preserved M < F M < F M < F M < F [17]
      (−0.34) (−0.37) (− 0.48) (− 0.33)  
  Lissotriton montandoni 42 33 F > M Preserved ns ns M < F M < F [17]
      (−0.01) (− 0.03) (− 0.26) (−0.32)  
  Lissotriton vulgaris 42 41 F > M Preserved ns ns M < F M < F [17]
      (−0.13) (−0.03) (− 0.4) (− 0.29)  
  1. Abbreviations: M Male, F Female; SVL Snout-vent length; FL Left forelimbs, FR Right forelimbs, BL Left hindlimbs, BR Right hindlimbs, ns No significant differences. Number of study populations: a – three populations, b–6 populations; c – two populations. # - variant II, according to numbering protocol for forelimb fingers reflecting the hypothesis that the first digit was reduced during phylogenesis in Anura. In other cases, the digit ratio was calculated for variant I (reflecting that the fifth digit was reduced) [24,25,26,27, 29]. For more details see Fig. 1