Ecological Archives E096-168-A4

Kunio Takatsu and Osamu Kishida. 2015. Predator cannibalism can intensify negative impacts on heterospecific prey. Ecology 96:15971608. http://dx.doi.org/10.1890/14-1616.1

Appendix D. Summary of statistical analyses comparing the four small-variation treatments.

We initially established a large-variation treatment and four small-variation treatments (i.e., small variation treatment with 20 early hatchlings, 20 late hatchlings, 10 early hatchlings, or 10 late hatchlings) at the start of the experiment. Because we expected that cannibalism would rarely occur in the four small-variation treatments, we conducted preliminary analyses of the data of those four treatments to determine whether the effects of the four treatments on the measured variables were similar. Therefore, we tested whether (1) frog tadpole mortality (Table D1), (2) behavior (i.e., frog tadpole activity; Table D2), morphology (i.e., degree of defensive morphology in frog tadpoles; Table D3), and life history (i.e., mean, Table D4, and median, Table D5, metamorphosis timing and size at metamorphosis of the frog tadpoles), (3) mortality of the salamander larvae (Table D6), or (4) morphology (i.e., largest body length, Table D7, and largest gape width, Table D8) and life history (i.e., earliest timing at metamorphosis, Table D9, and size at metamorphosis of the first metamorphs, Table D10) differed among the four small-variation treatments. We used repeated-measures ANOVA to compare activity of the frog tadpoles, performed a Kaplan-Meier analysis of the earliest timing of metamorphosis in the salamander larvae, and compared the other measurements by using Kruskal-Wallis tests. We did not find significant differences in any of these traits among the four small-variation treatments (Tables D1–10).

Table D1. Kruskal-Wallis test results for frog tadpole mortality.

Measurements

χ²3

P

Mortality of
the frog tadpoles

Day 1 to day 19

0.76

0.86

Day 19 to day 31

1.94

0.59

Day 31 to day 150

7.16

0.067

 

Table D2. Repeated-measures ANOVA results for frog tadpole activity.

Factors

df

F

P

Treatment

3

0.26

0.85

Time

2

296.65

<0.001

Treatment*Time

6

1.86

0.10

 

Table D3. Kruskal-Wallis test results for the degree of defensive morphology.

Measurements

χ²3

P

Degree of defensive morphology

day 19

2.64

0.45

day 31

6.84

0.072

 

Table D4. Kruskal-Wallis test results for mean metamorphosis timing and mean size at metamorphosis in frog tadpoles.

Measurements

χ²3

P

Mean timing of metamorphosis

2.48

0.48

Mean size at metamorphosis

5.86

0.12

 

Table D5. Kruskal-Wallis test results for median metamorphosis timing and median size at metamorphosis of the frog tadpoles.

Measurements

χ²3

P

Median timing of metamorphosis

4.44

0.22

Median size at metamorphosis

6.46

0.091

 

Table D6. Kruskal-Wallis test results for mortality of salamander larvae.

Measurements

χ²3

P

Mortality of the salamander larvae

Day 1 to day 19

2.17

0.54

Day 19 to day 31

2.11

0.55

Day 31 to day 151

7.32

0.062

 

Table D7. Kruskal-Wallis test results for largest body length.

Measurements

χ²3

P

Largest body length

day 19

7.10

0.069

day 31

0.31

0.96

 

Table D8. Kruskal-Wallis test results for largest gape width.

Measurements

χ²3

P

Largest gape width

day 19

4.67

0.20

day 31

0.96

0.062

 

Table D9. Kaplan-Meier analysis results for the earliest timing of salamander metamorphosis

Measurements

χ²3

P

Earliest timing at metamorphosis

6.53

0.089

 

Table D10. Kruskal-Wallis test results for size at metamorphosis (i.e., body length) of the first metamorphs .

Measurements

χ²3

P

Size at metamorphosis of the first metamorphs

5.92

0.12


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