Table 2. Multiple regression analyses controlling for phylogeny (GLS) of sperm quantity and quality in relation to combined testis mass and body mass across eight species of Australian Maluridae.
predictor | slope | t | P | λ | |
(a) Sperm quantity | |||||
CP volume | testis mass | 58.37 | 2.89 | 0.03 | <0.001 1.0; 0.09 |
body mass | −45.39 | −1.34 | 0.24 | ||
Seminal glomera mass | testis mass | 0.04 | 4.32 | 0.007 | <0.001 1.0; 0.04 |
body mass | −0.03 | −1.94 | 0.11 | ||
Sperm stores | testis mass | 152.33 | 3.14 | 0.02 | <0.001 1.0; 0.07 |
body mass | −172.23 | −2.11 | 0.09 | ||
Ejaculate sperm count | testis mass | 31.05 | 2.44 | 0.07 | <0.001 1.0; 0.04 |
body mass | −40.69 | −2.23 | 0.09 | ||
(b) Sperm quality | |||||
Motile sperm in ejaculates | testis mass | 0.24 | 2.94 | 0.04 | <0.001 1.0; 0.02 |
body mass | 0.05 | 0.45 | 0.67 | ||
Viable sperm in sperm reserves | testis mass | 0.15 | 2.99 | 0.03 | <0.001 1.0; 0.007 |
body mass | −0.04 | −0.47 | 0.66 | ||
Morphologically normal sperm in sperm reserves | testis mass | 0.18 | 4.23 | 0.008 | <0.001 0.14; 0.5 |
body mass | −0.36 | −4.95 | 0.004 |
The model including the maximum-likelihood value of λ was compared against the models including λ = 0 and λ = 1, and superscripts following the λ estimates indicate significance levels of the likelihood-ratio testes (first position: against λ = 0; second position: against λ = 1).