Table 2.

Within-ejaculate, cross-environment phenotypic covariances (±s.e.; lower left) and correlations (±s.e.; upper right) of curvilinear sperm velocity of 10 908 spermatozoa from 582 video takes from 84 video recordings of 28 experimental willow warbler Phylloscopus trochilus experimental ejaculates/males in three experimental media of different viscosities (cellulose concentrations). Estimates are from a multi-response mixed model under a character-state approach (see methods for details).

cellulose (w/v)	0%	1%	2%
0%	—	0.168 ± 0.255	0.467 ± 0.215
1%	7.40 ± 11.56	—	0.876 ± 0.108
2%	19.18 ± 11.12	20.11 ± 7.29	—