Principal component analysis (PCA).

<p>PCA of temperature (days above 13°C), average male size, male and female aggression, mating behaviour (latency to mate and mating duration), and female fecundity (egg weight). The plot shows each trial per month of the season as a coloured dot and each variable as a vector. Vectors that are close together are highly correlated, while vectors that are orthogonal are poorly correlated. Length and direction of arrows show the strength and direction of correlation, respectively.