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Effects of frugivore preferences and habitat heterogeneity on seed rain: a multi-scale analysis.

Rodríguez-Pérez J, Larrinaga AR, Santamaría L - PLoS ONE (2012)

Bottom Line: Shrub cover was positively correlated with habitat preference at the three scales of analysis, whereas slope was negatively correlated at the home-range scale.Model scenarios indicated that spatially-aggregated seed rain emerged when we incorporated the joint effect of habitat preference at the two largest (home-range and within home-range) scales.We conclude that, in order to predict seed rain in animal dispersed plants, it is important to consider the multi-scale effects of habitat preference by frugivores.

View Article: PubMed Central - PubMed

Affiliation: Institut Mediterrani d'Estudis Avançats, IMEDEA, Mallorca, Balearic Islands, Spain. jvr.rodriguez@gmail.com

ABSTRACT
Seed rain mediated by frugivores is influenced by (1) the seed-deposition distances following fruit ingestion, (2) the disperser activity, as determined by its behaviour and habitat preferences, and (3) the structure of the habitat within the landscape. Here, we evaluated such components using the fleshy-fruited shrub Ephedra fragilis and the frugivorous Balearic lizard Podarcis lilfordi. We estimated seed-deposition patterns based on the displacements and habitat preferences of lizards, derived from visual surveys and telemetry data. The influence of variables potentially determining lizard habitat preference (i.e., height, slope, four measures of habitat abundance and four measures of habitat fragmentation) was evaluated at three spatial scales: 'home-range' (c. 2.5-10*10(3) m(2); telemetry data), 'within home-range' (c. 100 m(2); telemetry data) and 'microhabitat' (<100 m(2); visual survey). Cumulative lizard displacement (from each telemetric location to the initial capture point) saturated before the peak of seed defecation (seed-retention time), indicating that lizard home-range size and habitat preferences were the main determinants of the spread and shape of seed shadows. Shrub cover was positively correlated with habitat preference at the three scales of analysis, whereas slope was negatively correlated at the home-range scale. Model scenarios indicated that spatially-aggregated seed rain emerged when we incorporated the joint effect of habitat preference at the two largest (home-range and within home-range) scales. We conclude that, in order to predict seed rain in animal dispersed plants, it is important to consider the multi-scale effects of habitat preference by frugivores.

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Cumulative frequency of defecation of Ephedra seeds ingested by lizards over time (i.e., proportion of ingested seeds defecated during such time interval; left axis), and net displacement (i.e., maximum net distance from the last relocation to the release location) of radio-tagged lizards over time (right axis).Lines represent accumulative log-normal fits. Symbols represent daily averages (±SE) each two hours of both variables (see material & methods); note, however, that fits were based on all measured values (not shown for clarity).
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pone-0033246-g002: Cumulative frequency of defecation of Ephedra seeds ingested by lizards over time (i.e., proportion of ingested seeds defecated during such time interval; left axis), and net displacement (i.e., maximum net distance from the last relocation to the release location) of radio-tagged lizards over time (right axis).Lines represent accumulative log-normal fits. Symbols represent daily averages (±SE) each two hours of both variables (see material & methods); note, however, that fits were based on all measured values (not shown for clarity).

Mentions: Retention time experiments showed that most seeds were defecated in the second and third day after ingestion (Fig. 2). Seed retention time did not vary with seed weight (F1,74 = 0.02, p = 0.884) or lizard sex (not included in the best model). Overall, ingested and non-ingested seeds showed similar (F1,12 = 1.03, p = 0.330) and fairly high (c. 80%) germination rates. However, germination probability decreased with increasing retention time and decreasing seed weight (loge(p/1−p) = −0.032*RT+0.290*SW+2.90; F1,73 = 5.53, p = 0.021 and F1,73 = 5.53, p = 0.021, respectively) and did not differ between sexes (F1,73 = 2.20, p = 0.142). Lizard net displacement saturated rapidly, reaching a maximum of approx. 72 m after 24 hours – i.e., before the peak of seed defecation (Fig. 2).


Effects of frugivore preferences and habitat heterogeneity on seed rain: a multi-scale analysis.

Rodríguez-Pérez J, Larrinaga AR, Santamaría L - PLoS ONE (2012)

Cumulative frequency of defecation of Ephedra seeds ingested by lizards over time (i.e., proportion of ingested seeds defecated during such time interval; left axis), and net displacement (i.e., maximum net distance from the last relocation to the release location) of radio-tagged lizards over time (right axis).Lines represent accumulative log-normal fits. Symbols represent daily averages (±SE) each two hours of both variables (see material & methods); note, however, that fits were based on all measured values (not shown for clarity).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3306386&req=5

pone-0033246-g002: Cumulative frequency of defecation of Ephedra seeds ingested by lizards over time (i.e., proportion of ingested seeds defecated during such time interval; left axis), and net displacement (i.e., maximum net distance from the last relocation to the release location) of radio-tagged lizards over time (right axis).Lines represent accumulative log-normal fits. Symbols represent daily averages (±SE) each two hours of both variables (see material & methods); note, however, that fits were based on all measured values (not shown for clarity).
Mentions: Retention time experiments showed that most seeds were defecated in the second and third day after ingestion (Fig. 2). Seed retention time did not vary with seed weight (F1,74 = 0.02, p = 0.884) or lizard sex (not included in the best model). Overall, ingested and non-ingested seeds showed similar (F1,12 = 1.03, p = 0.330) and fairly high (c. 80%) germination rates. However, germination probability decreased with increasing retention time and decreasing seed weight (loge(p/1−p) = −0.032*RT+0.290*SW+2.90; F1,73 = 5.53, p = 0.021 and F1,73 = 5.53, p = 0.021, respectively) and did not differ between sexes (F1,73 = 2.20, p = 0.142). Lizard net displacement saturated rapidly, reaching a maximum of approx. 72 m after 24 hours – i.e., before the peak of seed defecation (Fig. 2).

Bottom Line: Shrub cover was positively correlated with habitat preference at the three scales of analysis, whereas slope was negatively correlated at the home-range scale.Model scenarios indicated that spatially-aggregated seed rain emerged when we incorporated the joint effect of habitat preference at the two largest (home-range and within home-range) scales.We conclude that, in order to predict seed rain in animal dispersed plants, it is important to consider the multi-scale effects of habitat preference by frugivores.

View Article: PubMed Central - PubMed

Affiliation: Institut Mediterrani d'Estudis Avançats, IMEDEA, Mallorca, Balearic Islands, Spain. jvr.rodriguez@gmail.com

ABSTRACT
Seed rain mediated by frugivores is influenced by (1) the seed-deposition distances following fruit ingestion, (2) the disperser activity, as determined by its behaviour and habitat preferences, and (3) the structure of the habitat within the landscape. Here, we evaluated such components using the fleshy-fruited shrub Ephedra fragilis and the frugivorous Balearic lizard Podarcis lilfordi. We estimated seed-deposition patterns based on the displacements and habitat preferences of lizards, derived from visual surveys and telemetry data. The influence of variables potentially determining lizard habitat preference (i.e., height, slope, four measures of habitat abundance and four measures of habitat fragmentation) was evaluated at three spatial scales: 'home-range' (c. 2.5-10*10(3) m(2); telemetry data), 'within home-range' (c. 100 m(2); telemetry data) and 'microhabitat' (<100 m(2); visual survey). Cumulative lizard displacement (from each telemetric location to the initial capture point) saturated before the peak of seed defecation (seed-retention time), indicating that lizard home-range size and habitat preferences were the main determinants of the spread and shape of seed shadows. Shrub cover was positively correlated with habitat preference at the three scales of analysis, whereas slope was negatively correlated at the home-range scale. Model scenarios indicated that spatially-aggregated seed rain emerged when we incorporated the joint effect of habitat preference at the two largest (home-range and within home-range) scales. We conclude that, in order to predict seed rain in animal dispersed plants, it is important to consider the multi-scale effects of habitat preference by frugivores.

Show MeSH
Related in: MedlinePlus