Relationships between Virulence, Asexual Multiplication, and Transmission Potential across Ancestral and Selection Lines

<p>Virulence, as measured by minimum red blood cell density, is plotted against maximum parasitemia in (A), and average daily gametocyte production (a measure of lifetime transmission potential) is plotted against virulence in (B). Data are all from pretransmission lines—ancestral and selected—measured in naïve (closed symbols; solid line) and immunized mice (open symbols; broken line). Regression analysis for both traits showed significant (<i>p</i> < 0.001) and similar (<i>p</i> > 0.05) slopes within both naïve and immunized mice, and significantly lower (<i>p</i> < 0.001) maximum parasitemia and gametocyte production in immunized than in naïve mice. When the two data points from naïve mice with values of above 3 × 10⁹ rbc/ml were excluded from the analyses, the slopes remained statistically similar (<i>p</i> > 0.05). Unselected ancestral populations, black squares; N-lines, green circles; I-lines, red triangles; avirulent unadapted ancestral population, small symbols; virulent preadapted ancestral population, large symbols.