Fig. 2
From: Extensive variation in sperm morphology in a frog with no sperm competition
Seasonal variation in sperm length in spring peepers from 7 populations in 2 mitochondrial lineages (Interior, Eastern) and their Contact zone in southwestern Ontario (n = 86 males). Linear regression lines are shown for populations sampled on two different days (solid = significant (P ≤ 0.05), dashed = non-significant; see Additional File 1). The black curvilinear regression line is from a model (R2 = 0.17, F2,83 = 8.24, P = 0.0005) fitted to all of the data with date as a quadratic predictor, but not controlling for body condition. Overlapping data points are jittered horizontally for clarity. Sampling dates and localities are indicated by black triangles on the x-axis: Pond Mills (PM), Fingal (FI), Starkey Hill (SH), Dereham (DE), Calton Swamp (CS), Lafortune (LA), and Long Point (LP) (see [14] for details)