Density and recruitment
Population numbers in the two treatments increased progressively following the trapping sessions in 2012 and 2015 (Fig. 1A, 1C). We found effects of treatment (F 1, 36 = 294.38, P< 0.001 for 2012 and F 1, 42 = 30.41,P < 0.001 for 2015), time (F 5, 36 = 128.06, P < 0.001 for 2012 andF 6, 42 = 66.36, P < 0.001 for 2015), and treatment × time (F 5, 36 = 17.16,P < 0.001 for 2012 and F 6, 42 = 9.34, P < 0.001 for 2015). The mean estimated population numbers in the low- and high-density treatments at the end of the experiments were 38.07 ± 4.67 and 107.99 ± 8.73 in 2012 and 42.76 ± 7.25, and 111.86 ± 18.47 in 2015, respectively.
Founder numbers in the two treatments decreased progressively following the trapping sessions in both years (Fig. 1B, 1D). For founder numbers in 2012 (Fig. 1B), we found effects of treatment (F 1, 72 = 433.37, P < 0.001), sex (F 1, 72 = 94.10, P < 0.001), time (F 5, 72 = 11.53, P < 0.001), treatment × time (F 5, 72 = 4.81, P= 0.001), and sex × treatment × time (F 5, 72 = 3.30, P = 0.010); however, no effects were found for sex × treatment (F 1, 72 = 2.40, P = 0.126) or sex × time (F 5, 72 = 0.56, P = 0.733). For founder numbers in 2015 (Fig. 1D), we found effects of treatment (F 1, 84 = 1814.78, P < 0.001), sex (F 1, 84 = 6.11, P = 0.015), time (F 6, 84 = 18.61, P < 0.001), and treatment × sex (F 1, 84 = 7.92, P = 0.006); however, no effects were found for treatment × time (F 6, 84 = 0.80, P = 0.573), sex × time (F 6, 84 = 0.14, P = 0.990), or treatment × sex × time (F 6, 84 = 0.75, P = 0.612). The mean estimated numbers of founder males and females in the low-density treatment during the experiment were 2.50 ± 0.65 and 3.00 ± 1.11 in 2012, 3.75 ± 0.88 and 3.75 ± 0.88 in 2015. The mean numbers in the high-density treatments were 5.24 ± 0.82 and 14.50 ± 1.67 in 2012, 15.00 ± 0.88 and 12.75 ± 0.88 in 2015.
For recruitment in 2012 (Fig. 2A), we verified an effect of treatment (F 1, 24 = 10.25, P = 0.004), but no effects on time (F 3, 24 = 0.64, P = 0.600) or treatment × time (F 3, 24 = 0.43, P = 0.736). For recruitment in 2015 (Fig. 2B), we found effects of treatment (F 1, 30 = 9.22, P = 0.005) and treatment × time (F 4, 30 = 4.22, P = 0.008), but not for time (F 4, 30 = 1.38, P = 0.264). Populations in low-density enclosures in 2012 and 2015 had 131% and 97% higher recruitment than those in high-density enclosures, respectively.
For the proportion of reproductive females and males in 2012 (Fig. 2C, 2E), we found effects of treatment (F 1, 36 = 7.72, P = 0.009 for females and F 1, 35 = 7.52, P = 0.010 for males) and time (F 5, 36 = 5.42, P = 0.001 for females and F 1, 35 = 434.54, P < 0.001 for males), and marginal interaction between treatment and time (F 5, 36 = 2.45,P = 0.052) for females, but not for males (F 5, 35 = 0.87, P = 0.515). For 2015 (Fig. 2D, 2F), we verified effects of treatment (F 1, 42= 10.25, P = 0.003 for females, F 1, 42 = 25.60, P < 0.001 for males) and time for males (F 6, 42 = 11.70, P < 0.001), but not for females (F 6, 42 = 0.73, P = 0.627). Interactions between treatment and time were not found (F 6,42 = 0.54, P = 0.773 for females andF 6, 42 = 0.67, P = 0.677 for males). Populations in low-density enclosures in 2012 and 2015 had 70% and 107% higher proportions of reproductive females and 38% and 69% higher proportions of reproductive males than populations in high-density enclosures, respectively.