Selection for Optimal Fruit-Crop Size in Bird-Dispersed Plants

Murray, K. Greg

doi:10.1086/284620

Cited by 87 publications

(69 citation statements)

References 19 publications

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“…Both within and among species, we found a positive correlation between crop size and removal rate (fruit per day). In this respect, our data are consistent with most (Howe and DeSteven 1979;Howe and Vande Kerckhove 1979;Murray 1987;Gryj and Dominguez 1996), but not all (Bronstein and Hoffman 1987) studies.…”

Section: Fruit Production and Removal In Panamanian Strangler Figssupporting

confidence: 92%

“…Furthermore, we use these data to assess the effect of various factors on fruit removal. For example, some authors (Howe and DeSteven 1979;Howe and Vande Kerckhove 1979;Murray 1987;Gryj and Dominguez 1996; but see Fleming 1981), report that there is a positive relationship between crop size and number of individual frugivores attracted, resulting in increased fruit removal. Finally, using published information on the dietary requirements of bats, we estimate the number that feed on the ripe fruits of a fig tree and disperse its seeds to assess the relative importance of figs as a keystone resource.…”

Section: Introductionmentioning

confidence: 99%

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Fruit characteristics and factors affecting fruit removal in a Panamanian community of strangler figs

2000

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We describe fruiting characteristics for 12 species in a community of strangler figs (Moraceae: Urostigma) studied in Panama. We quantify diurnal and nocturnal removal rates and proportions of fruits removed, and relate them to the activities of the main dispersers of the figs: bats and birds. These results combined with previous studies show that there are clear differences between fig species with fruit that ripen red and those with fruit that remain green(ish). In the red-fruited species, the fruit are small, ripen asynchronously over relatively long periods, produce little scent, and are mainly taken during the day by birds. In contrast, in the green(ish)-fruited species, the fruits are larger, span a range of sizes, ripen relatively synchronously, produce very distinctive aromas, and are mainly taken at night by bats. This dichotomy in fruiting characteristics suggests coadaptive links between groups of dispersers and different species within the genus Ficus. All fig species produce a range of fruit crop sizes (10-155 fuits/m canopy area) of which a high proportion were removed by seed dispersers (>80%). Removal rates (fruit removed per day) were positively correlated with crop size, suggesting that trees with large crop size attract more frugivores. Removal rates of green-fruited figs were significantly lower and persistence and abortion of ripe fruit were significant higher around full moon, apparently due to the reduced activity of bats. We further estimate the number of bats that are sustained by a tree fruit crop and account for the observed fruit removal. We then discuss the evidence for coadaptation between different groups of figs and their seed dispersers, Finally, we consider the conservation implications for figs as keystone resources in tropical forests.

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Section: Fruit Production and Removal In Panamanian Strangler Figssupporting

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Fruit characteristics and factors affecting fruit removal in a Panamanian community of strangler figs

2000

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“…The "rates-versus-numbers" problem illustrated in this paper is not unique to the study of the maternal component of reproduction, but presumably applies also to some other fields in plant reproductive ecology where rate-based, relative measures have been frequently used (e.g., seed dispersal, seed predation; De Steven 1981, Murray 1987, Herrera 1 9 8 8~) .…”

Section: Short-term Vs Lifetime Fecunditymentioning

confidence: 99%

“…Plants producing large numbers of flowers often receive fewer pollinator visits, and have a lower fruit set, on a per flower basis than conspecifics producing fewer flowers, yet individuals with the largest floral displays are still those producing most seeds (Wyatt 1980, Andersson 1988, Klinkhamer et al 1989. Similarly, in some bird-dispersed plants the proportion of seeds that is dispersed depends on traits like fruit size, crop size, and fruit seediness, yet absolute numbers are often unrelated to individual variation in these traits (Murray 1987, Herrera 1988a, Obeso 1989.…”

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confidence: 99%

Dissecting Factors Responsible For Individual Variation in Plant Fecundity

Herrera¹

1991

Ecology

142

131

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Abstract. This paper analyses, on an individual plant basis, the various components determining seed production in the evergreen shrub Lavandula latifolia (Labiatae), in order to estimate their relative contributions to individual differences in fecundity. The relationships between fecundity and age, size, and growth rate are also examined. Experimental pollination and watering were done in an attempt to alter natural patterns of partial fecundity components. Fecundity of individual plants is partitioned into its absolute (number of inflorescences, number of flowers per inflorescence) and relative (fruits/flower and seeds/ fruit) partial components, and the following questions are addressed: (1) Are there individual differences in relative components of fecundity? (2) What are the proportional contributions of relative and absolute components of fecundity to individual variation in seed production? (3) Are relative measures of reproductive success reliable predictors of individual differences in fecundity? (4) When induced experimentally, do changes in partial fecundity components translate into modifications of the population's ranking of absolute fecundities?Fecundity depended more on plant size than age, was unrelated to growth rate, and was limited by water, but not pollen, availability. Individual plants differed in all components of fecundity examined, and differences were consistent among years. The proportional contributions of the various components to individual differences in fecundity were very unequal. Almost all variation among plants in seed production (-90% of variance) was explained by the variances and covariances of number of inflorescences and number of flowers per inflorescence. Variation among plants in the two relative components (fruit and seed set), even though statistically significant, had a negligible influence on individual differences in fecundity. These patterns remained invariant despite significant modification of flower production and fruit set induced by artificially watering a part of the study population. Fruit and seed set alone are unreliable indicators of individual differences in the maternal component of fitness in L. latifolia, and a review of relevant literature indicates that this probably applies to other polycarpic plants as well. Plant reproductive biology studies may make erroneous inferences if they consider exclusively data on relative fruit and seed set, and neglect the absolute components of individual differences in fecundity. It is proposed that, to circumvent these potential problems, demographic aspects and absolute estimates of seed output on a per individual basis should be examined in addition to the customarily employed fruit and seed set measures.Key words: fecundity components; flower production; fvuit set; individual variation; Lavandula latifolia; Mediterranean scrublands; plant demography; reproductive biology; seed production; size hierarchy; water limitation. contributions in Bentley and Elias 1983, Jones andRecent studies on plant reproductive ...

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“…5B). Several studies show that bird visitation and fruit removal are positively correlated with fruit crop size, both at the habitat level and the individual plant level (Murray 1987;Sargent 1990; but see Davidar and Morton 1986). Del Rio et al (1996) found that avian seed dispersal of mistletoes was strongly dependent on the prevalence of mistletoe on individual plants.…”

Section: Conditional Outcomesmentioning

confidence: 99%

Changes in interactions between juniper and mistletoe mediated by shared avian frugivores: parasitism to potential mutualism

Ommeren

Whitham

2002

Oecologia

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Although mistletoe is typically viewed as a parasite of juniper in a two-way interaction, its role may become neutral or even mutualistic when their common avian seed dispersing agents are considered as a three-way interaction. In the study area, wintering avian frugivores forage on both one-seed juniper (Juniperus monosperma) berries and on the fruit of its associated mistletoe (Phoradendron juniperinum). Three major findings emerged from our studies that support a three-way interaction and the hypothesis of conditional interactions. First, mistletoes provide a stable resource for shared avian seed dispersers; junipers do not. Whereas juniper berry production varied 10- to 15-fold over the 3 years of our study, mistletoe fruit abundance did not vary significantly. Second, the abundance of avian seed dispersal agents, such as Townsend's solitaires (Myadestes townsendi), is strongly tied to the abundance of juniper berries in mast years and mistletoe fruits in all years. In fact, the best overall predictor of their common avian seed dispersal agents was the abundance of mistletoe; stands with mistletoe attracted up to 3 times more avian frugivores than stands with little or no mistletoe. Thus, mistletoe berries can serve as the main attractor for birds that disperse juniper berries. Third, in agreement with the hypothesis that mistletoe can benefit junipers by attracting and supporting greater populations of avian seed dispersal agents, the number of juniper seedlings was more than 2-fold greater in stands with high mistletoe density compared with stands that had little or no mistletoe. Results suggest that the occurrence of a three-way interaction, in the presence of environmental variation (in this case, annual variation in juniper berry crops), may change the ecological roles of associated species. A conceptual model is presented to illustrate how the role of mistletoe may range from parasitic to mutualistic, while the role of avian seed dispersers may conversely range from mutualistic to parasitic, the latter by acting as vectors for the spread of mistletoe.

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Selection for Optimal Fruit-Crop Size in Bird-Dispersed Plants

Cited by 87 publications

References 19 publications

Fruit characteristics and factors affecting fruit removal in a Panamanian community of strangler figs

Fruit characteristics and factors affecting fruit removal in a Panamanian community of strangler figs

Dissecting Factors Responsible For Individual Variation in Plant Fecundity

Changes in interactions between juniper and mistletoe mediated by shared avian frugivores: parasitism to potential mutualism

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