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Populations, pools, and peccaries: simulating the impact of ecosystem engineers on rainforest frogs.

Ringler M, Hödl W, Ringler E - Behav. Ecol. (2015)

Bottom Line: Following the supplementation, population size almost doubled as a result of increased autochthonous recruitment driven by a higher per-capita reproduction of males and a higher proportion of reproducing females.The effect was evenly distributed across the population.Our study shows that management and conservation must consider nontrophic relationships and that human "ecosystem engineering" can play a vital role in efforts against the "global amphibian decline."

View Article: PubMed Central - PubMed

Affiliation: Department of Integrative Zoology , University of Vienna , Althanstrasse 14 , A-1090 Vienna , Austria and.

ABSTRACT

"Ecosystem engineering" describes habitat alteration by an organism that affects another organism; such nontrophic interactions between organisms are a current focus in ecological research. Our study quantifies the actual impact an ecosystem engineer can have on another species by using a previously identified model system-peccaries and rainforest frogs. In a 4-year experiment, we simulated the impact of peccaries on a population of Allobates femoralis (Dendrobatidae) by installing an array of artificial pools to mimic a forest patch modified by peccaries. The data were analyzed using a gradual before-after control-impact (gBACI) model. Following the supplementation, population size almost doubled as a result of increased autochthonous recruitment driven by a higher per-capita reproduction of males and a higher proportion of reproducing females. The effect was evenly distributed across the population. The differential response of males and females reflects the reproductive behavior of A. femoralis, as only the males use the aquatic sites for tadpole deposition. Our study shows that management and conservation must consider nontrophic relationships and that human "ecosystem engineering" can play a vital role in efforts against the "global amphibian decline."

No MeSH data available.


Density maps of males (left) and females (right) across the 4 years of the experiment; rectangles indicate treatment and control plots (cf. Figure 1); colors indicate density of males and females per hectare; kernel density calculated in ArcGIS© 9.3.1 with a search radius of 35 m and a cell size for analysis of 0.2×0.2 m.
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Figure 4: Density maps of males (left) and females (right) across the 4 years of the experiment; rectangles indicate treatment and control plots (cf. Figure 1); colors indicate density of males and females per hectare; kernel density calculated in ArcGIS© 9.3.1 with a search radius of 35 m and a cell size for analysis of 0.2×0.2 m.

Mentions: The Anova GLM (Table 2, 2a) explained 84.63% (R2) of the observed variation in the rarefied counts of individuals in the treatment and control plots. Resource supplementation significantly increased the population size from the pre- to post-intervention years (Figures 2 and 3a): population size almost doubled during the experiment (Table 1, Figures 2 and 4). In contrast, the differences among the pre- and post-treatment years were nonsignificant. The effect of the artificial pools declined significantly with increasing distance from the treatment plot, and the detached control plots were unaffected (Figures 3b and 4). During all years, individual counts varied significantly among plots and were significantly influenced by the distance from the treatment plot (Figure 3b). Males and females had significantly unequal distributions, but there was no significant differential reaction of the sexes to the supplementation (Figure 3c). The Ancova GLM with previous rainfall as a covariate (Table 2, 2b) had a marginally better fit to our data (R2 = 84.72%) and, unlike the collinear nested factor “year,” previous rainfall was a significant predictor of population size, whereas the influence of all other factors remained unchanged. The residuals in all Anova/Ancova analyses were normally distributed.


Populations, pools, and peccaries: simulating the impact of ecosystem engineers on rainforest frogs.

Ringler M, Hödl W, Ringler E - Behav. Ecol. (2015)

Density maps of males (left) and females (right) across the 4 years of the experiment; rectangles indicate treatment and control plots (cf. Figure 1); colors indicate density of males and females per hectare; kernel density calculated in ArcGIS© 9.3.1 with a search radius of 35 m and a cell size for analysis of 0.2×0.2 m.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4374131&req=5

Figure 4: Density maps of males (left) and females (right) across the 4 years of the experiment; rectangles indicate treatment and control plots (cf. Figure 1); colors indicate density of males and females per hectare; kernel density calculated in ArcGIS© 9.3.1 with a search radius of 35 m and a cell size for analysis of 0.2×0.2 m.
Mentions: The Anova GLM (Table 2, 2a) explained 84.63% (R2) of the observed variation in the rarefied counts of individuals in the treatment and control plots. Resource supplementation significantly increased the population size from the pre- to post-intervention years (Figures 2 and 3a): population size almost doubled during the experiment (Table 1, Figures 2 and 4). In contrast, the differences among the pre- and post-treatment years were nonsignificant. The effect of the artificial pools declined significantly with increasing distance from the treatment plot, and the detached control plots were unaffected (Figures 3b and 4). During all years, individual counts varied significantly among plots and were significantly influenced by the distance from the treatment plot (Figure 3b). Males and females had significantly unequal distributions, but there was no significant differential reaction of the sexes to the supplementation (Figure 3c). The Ancova GLM with previous rainfall as a covariate (Table 2, 2b) had a marginally better fit to our data (R2 = 84.72%) and, unlike the collinear nested factor “year,” previous rainfall was a significant predictor of population size, whereas the influence of all other factors remained unchanged. The residuals in all Anova/Ancova analyses were normally distributed.

Bottom Line: Following the supplementation, population size almost doubled as a result of increased autochthonous recruitment driven by a higher per-capita reproduction of males and a higher proportion of reproducing females.The effect was evenly distributed across the population.Our study shows that management and conservation must consider nontrophic relationships and that human "ecosystem engineering" can play a vital role in efforts against the "global amphibian decline."

View Article: PubMed Central - PubMed

Affiliation: Department of Integrative Zoology , University of Vienna , Althanstrasse 14 , A-1090 Vienna , Austria and.

ABSTRACT

"Ecosystem engineering" describes habitat alteration by an organism that affects another organism; such nontrophic interactions between organisms are a current focus in ecological research. Our study quantifies the actual impact an ecosystem engineer can have on another species by using a previously identified model system-peccaries and rainforest frogs. In a 4-year experiment, we simulated the impact of peccaries on a population of Allobates femoralis (Dendrobatidae) by installing an array of artificial pools to mimic a forest patch modified by peccaries. The data were analyzed using a gradual before-after control-impact (gBACI) model. Following the supplementation, population size almost doubled as a result of increased autochthonous recruitment driven by a higher per-capita reproduction of males and a higher proportion of reproducing females. The effect was evenly distributed across the population. The differential response of males and females reflects the reproductive behavior of A. femoralis, as only the males use the aquatic sites for tadpole deposition. Our study shows that management and conservation must consider nontrophic relationships and that human "ecosystem engineering" can play a vital role in efforts against the "global amphibian decline."

No MeSH data available.