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. 2012 Jul 5;367(1597):1811–1828. doi: 10.1098/rstb.2011.0215

Table 1.

Factors influencing the evolution of complexity in vocal communication. SSD, sexual size dimorphism.

case-study, signal variable model, rank constrained tree
 unconstrained tree
AICc AICw r t1/2 (support region) vy (support region) AICc AICw r t1/2 (support region) vy (support region)
frogs, n = 32 species
call amplitude modulation 1. phylogeny: null 292.1 0.37 n.a. 0 (0–10) 440 (260–760) 290.5 0.37 n.a. 20 (0–140) 440 (300–∞)
2. ecology: sympatry 294.4 0.12 ∼0.16a 1 (0–10) 420 (260–720) 292.9 0.11
3. ecology: microhabitatb 294.2 0.13 292.5 0.14 −0.14 20 (0–160) 430 (280–∞)
4. ecology: noisec 294.2 0.13 292.8 0.12
5. social: SSD 294.5 0.11 293.1 0.10
6. allometry: body size 294.7 0.10 292.6 0.13
7. ecology: macrohabitat 296.7 0.04 294.8 0.04
call duration 1. ecology: microhabitatb −11.82 0.81 0.45 900 (170–∞) 30 (0–70) 57.1 0.12
2. phylogeny: null −7.20 0.08 54.6 0.42 n.a. 460 (870–∞) 10 (0–20)
3. ecology: sympatry −5.16 0.03 57.3 0.11
4. allometry: body size −5.20 0.03 57.2 0.11
5. ecology: noisec −4.63 0.02 57.3 0.11
6. social: SSD −4.59 0.02 57.3 0.11
7. ecology: macrohabitat −3.53 0.01 60.0 0.03
birds (distantly related), n = 23 species
syllable repertoire size 1. allometry: body size 46.2 0.35 0.35 75 (25–∞) 25 (0–700) 47.4 0.34 0.34 500 (25–∞) 175 (0–700)
2. phylogeny: null 46.3 0.33 n.a. 300 (25–∞) 125 (0–825) 47.4 0.34 n.a. 175 (25–∞) 75 (0–825)
3. ecology: breeding range 48.6 0.11 49.7 0.11
4. ecology: macrohabitat 48.7 0.10 50.0 0.09
5. social: extra-pair paternity 48.9 0.09 49.9 0.10
6. social: mating system 52.1 0.02 53.0 0.02
song repertoire size 1. phylogeny: null 55.0 0.46 n.a. 975 (0–∞) 600 (0–∞) 56.3 0.46 n.a. 975 (0–∞) 575 (0–∞)
2. ecology: breeding range 57.0 0.17 0.21 950 (0–∞) 550 (0–∞) 58.3 0.17 0.20 975 (0–∞) 575 (0–∞)
3. allometry: body size 57.9 0.11 59.2 0.11
4. social: extra-pair paternity 58.0 0.10 59.2 0.11
5. ecology: macrohabitat 58.0 0.10 59.1 0.11
6. social: mating system 59.2 0.06 61.3 0.04
birds (closely related), n = 23 species
syllable repertoire 1. ecology: migration −41.4 0.42 ∼0.52d ∞ (630–∞) 10 (0–20) −37.5 0.13
2. phylogeny: null −41.1 0.36 n.a. 940 (500–∞) 10 (0–30) −40.5 0.57 n.a. 910 (480–∞) 10 (0–30)
3. ecology: macrohabitat −38.7 0.11 −37.8 0.15
4. allometry: body size −38.7 0.11 −38.0 0.16
syllable duration 1. phylogeny: null −64.1 0.66 n.a. ∞ (830–∞) 10 (0–20) −64.2 0.66 n.a. ∞ (830–∞) 10 (0–20)
2. ecology: macrohabitat −61.2 0.15 −61.3 0.16
3. allometry: body size −61.2 0.15 −61.2 0.15
4. ecology: migration −57.9 0.03 −58.1 0.03
song duration 1. phylogeny: null −57.8 0.64 n.a. ∞ (780–∞) 10 (0–20) −52.2 0.11
2. allometry: body size −55.2 0.27 −55.0 0.43 0.28 ∞ (780–∞) 10 (0–20)
3. ecology: macrohabitat −54.9 0.15 −54.6 0.35 0.05 ∞ (780–∞) 10 (0–20)
4. ecology: migration −52.1 0.06 −52.2 0.11

aThere are several prominent outliers making direct interpretation of this coefficient misleading (figure 1a).

bMicrohabitat was defined as the height (m) of call sites above ground.

cThe level of background noise potentially experienced by a species was determined by whether species were reported to call near streams.

dThe standard errors of parameter values for migration were very large making biological interpretation difficult.