Spatial patterns of seed predation by harvester ants ( Messor Forel) in Mediterranean grassland and scrubland

Azcárate, Francisco M.; Peco, Begoña

doi:10.1007/s00040-003-0635-y

Cited by 51 publications

(45 citation statements)

References 45 publications

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“…Therefore, densely aggregated groups of seeds were much more attractive for ants than sparse seeds, and the probability to be predated decreased with increasing reciprocal distance of seeds. Although this tendency was already recorded for Messor (Hensen 2002;Azca´rate and Peco 2003) and other ants (Kaspari 1993), it has been here statistically demonstrated for the first time.…”

Section: Resultscontrasting

confidence: 42%

“…All other things being equal, they tend to gather seeds of the kinds that are more abundant, passing from one set to the next across the growing season when those usually favoured become less available (Hahn and Maschwitz 1985;Cerdan et al 1986;Neumayer 1994;Detrain and Pasteels 2000). Messor species recruit foraging trails and harvest seeds mainly from clumps with higher seed densities (Hensen 2002;Azca´rate and Peco 2003). However, a large variety of Mediterranean species are exposed to seed predation by these ants (Hensen 2002;Mossa et al 2004).…”

Section: Introductionmentioning

confidence: 98%

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A stochastic model of seed dispersal pattern to assess seed predation by ants in annual dry grasslands

2005

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A combined field experiment and modelling approach has been used to provide evidence that ants may be responsible for an observed lower patchiness and higher plant diversity in the neighbourhood of ant nests, within Mediterranean dry grasslands belonging to the phytosociological class Tuberarietea guttatae. The hypothesis was that seeds occurring in clumps may have an higher probability to be harvested than seeds having a scattered distribution. In order to test this hypothesis, four analysis steps have been performed. First, the seed productivity and dispersal pattern was recorded for four plant species found, either more abundant beside the ant nests (Tuberaria guttata, Euphorbia exigua) or away from the ant nests (Bromus scoparius and Plantago bellardi). Second, a stochastic model was developed to simulate the observed dispersal patterns of each studied species. Third, ten seed arranges in accordance to the distribution patterns created by the model were offered to the ants and the positions of the predated seeds was recorded. Finally, the observed pattern of seed predation was matched to models performed by different distributions of probability. Results confirmed the initial hypothesis, showing that the probability of being predated decreases with the increase of the reciprocal distance of seeds. It was concluded that the preference of ants for high concentrations of food items holds down the dominant species sufficiently to allow the subordinates to survive. The observed higher frequency of small-seeded, small-sized, or creeping therophytes close to the ant nests can be therefore seen as an example of indirect mirmecophily

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Section: Resultscontrasting

confidence: 42%

Section: Introductionmentioning

confidence: 98%

A stochastic model of seed dispersal pattern to assess seed predation by ants in annual dry grasslands

2005

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“…) colonies have also been recorded in the study area, but the activity of this species is restricted to scrub communities. The density of M. barbarus nest-holes varies between 200 and 300 per hectare, concentrated on the ecotones and adjacent scrub areas (Azca´rate and Peco 2003). At distances higher than fifty meters from the ecotone, M. barbarus is almost absent (Azca´rate 2003).…”

Section: Study Areamentioning

confidence: 99%

“…) have found high Lavandula seed availability in the scrubland, and almost none in the adjacent grassland as a result of the low dispersal range through autochory . The high density of M. barbarus colonies in the ecotones between scrubland and grasslands (Azca´rate and Peco 2003) could accentuate seed limitation in the potential expansion area of Lavandula, as ants collect seeds from a number of species from both the grassland and the adjacent scrub communities (Azca´rate and Peco 2003). At the same time, M. barbarus activity may influence seed dispersal if some of the predated seeds are accidentally returned to the soil surface at points impossible to reach by autochory.…”

Section: Introductionmentioning

confidence: 98%

Effects of harvester ants on seed availability and dispersal of Lavandula stoechas subsp. pedunculata in a Mediterranean grassland-scrubland mosaic

2006

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The role of harvester ants in Mediterranean grassland and scrubland has mostly focused on seed consumption. However, recent studies have reported their role as accidental dispersal agents of some of the collected seeds via refuse piles. The objective of this study is to examine the effect of the ant Messor barbarus on seed availability and dispersal of one of its major diet components, Lavandula stoechas subsp. pedunculata, in scrubland, grassland and the ecotones between them. After confirming and quantifying the Lavandula contribution to M. barbarus diet, we described the spatial and temporal patterns of pre-and post-dispersal seed predation, seed content and seedling occurrence in the refuse piles. Our results show that: (1) Lavandula propagules constitute a high proportion of the prey items collected by M. barbarus, with particularly intense collection activity in mid-summer, spring and autumn, in decreasing order. (2) Predispersal predation rate was significantly higher in the ecotone than in the scrubland (76% and 13.5% of total seed production lost respectively). (3) Season and propagule type (seed vs. fruit) were the most significant variables explaining the post-dispersal predation probability, which approached 100% of seeds after 48 h in mid-summer. (4) Viable Lavandula seeds were found in refuse piles at densities of 0.06-0.2 per g of refuse pile material, or 58.8-207.2 per refuse pile. On the one hand, these results indicate that the ecotones are most affected by M. barbarus pre-dispersal consumption, which may locally limit Lavandula colonisation. On the other hand, the small proportion of consumed seeds that is dispersed to refuse piles may be relevant at the population level, as this dispersal implies arrival at potentially favourable sites for establishment.

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“…Being major seed consumers in xeric habitats (Azcárate and Peco, 2003), these keystone species infl uence the vegetation by depleting and dispersing seeds (e.g., Pacini, 1990;MacMahon et al, 2000) to an extent disproportionate to their numbers or biomass (Hölldobler and Wilson, 1990). Despite their ecological impact, little is known about the life history of Central European Messor ants.…”

Section: Introductionmentioning

confidence: 99%

Life history traits of a European Messor harvester ant

Schlick-Steiner

Steiner

Stauffer³

et al. 2005

Insect. Soc.

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We present life history traits of a Central European harvester ant, Messor cf. structor, determined by gyne and male dissections, behavioural assays, standardised brood photography and laboratory rearing of brood. Messor cf. structor is polygynous and builds up unicolonial populations. Sexuals develop from hibernated larvae in a univoltine cycle and become adult from late summer to late autumn. Neither intra-nor extranidal mating was observed in autumn, even though gynes and males were mature. In spring, after hibernation, intranidal mating without swarming fl ight took place, even though the fl ight muscles of alate sexuals were still fully developed.

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Spatial patterns of seed predation by harvester ants ( Messor Forel) in Mediterranean grassland and scrubland

Cited by 51 publications

References 45 publications

A stochastic model of seed dispersal pattern to assess seed predation by ants in annual dry grasslands

A stochastic model of seed dispersal pattern to assess seed predation by ants in annual dry grasslands

Effects of harvester ants on seed availability and dispersal of Lavandula stoechas subsp. pedunculata in a Mediterranean grassland-scrubland mosaic

Life history traits of a European Messor harvester ant

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