Calhim & Birkhead. Testis Compensation
SUPPLEMENTARY MATERIAL
LITERATURE REVIEW
Table S1. Summary of observational studies of the relationship between testis asymmetry and male quality.
Species / Male quality traits / Relationship with testis asymmetry 1 / Relationship between (relative) testis asymmetry and the size of the larger testis 2 / ReferenceAbsolute 3 / Relative 4
House sparrow / Passer domesticus / Badge size / Positive / Møller (1994)
Barn swallow / Hirundo rustica / Tail length / Positive / Møller (1994)
Red junglefowl / Gallus gallus / Comb size, spleen size and body size / None / Kimball et al. (1997)
Domestic chicken / Gallus domesticus / Comb and spur size / None / Pizzari et al. (2004)
Sedge warbler / Acrocephalus schoenobaenus / Song rate, song length, song complexity and repertoire size / None / None / Positive / Birkhead et al. (1997)
Zebra finch / Taeniopygia guttata / Song rate and beak colour;
Body condition / None
None / None
Negative / None / Birkhead et al. (1998)
Greenfinch / Carduelis chloris / Plumage brightness and parasite load / None / Positive / Merilä and Sheldon (1999)
Tree swallow / Tachycineta bicolor / Body condition and ectoparasite load / None / None / None 5 / Kempenaers et al. (2002)
Red-billed quelea / Quelea quelea / Bill colour, body size and body condition / None / None / Dale (2001)
1 A positive relationship suggests that testis compensation occurs in low quality individuals (Møller 1994).
2 A positive relationship indicates only that the size of the smaller testis is not a constant proportion of the larger and might probably have a compensatory role (e.g. Birkhead et al. 1998). However, this is valid only for species with directional testis asymmetry.
3 Absolute asymmetry refers to the signed difference between the larger and the smaller testis size.
4 Relative asymmetry refers to absolute asymmetry controlling for mean testes size.
5 This species does not have directional testis size asymmetry (see 2).