Limits...
Seed dispersal anachronisms: rethinking the fruits extinct megafauna ate.

Guimarães PR, Galetti M, Jordano P - PLoS ONE (2008)

Bottom Line: Some neotropical, fleshy-fruited plants have fruits structurally similar to paleotropical fruits dispersed by megafauna (mammals > 10(3) kg), yet these dispersers were extinct in South America 10-15 Kyr BP.We introduce an operational definition of megafaunal fruits and perform a comparative analysis of 103 Neotropical fruit species fitting this dispersal mode.These effects could be extended to other plant species dispersed by large vertebrates in present-day, defaunated communities.

View Article: PubMed Central - PubMed

Affiliation: Departamento de Física da Matéria Condensada, Instituto de Física Gleb Wataghin, Universidade Estadual de Campinas, Campinas, São Paulo, Brazil.

ABSTRACT

Background: Some neotropical, fleshy-fruited plants have fruits structurally similar to paleotropical fruits dispersed by megafauna (mammals > 10(3) kg), yet these dispersers were extinct in South America 10-15 Kyr BP. Anachronic dispersal systems are best explained by interactions with extinct animals and show impaired dispersal resulting in altered seed dispersal dynamics.

Methodology/principal findings: We introduce an operational definition of megafaunal fruits and perform a comparative analysis of 103 Neotropical fruit species fitting this dispersal mode. We define two megafaunal fruit types based on previous analyses of elephant fruits: fruits 4-10 cm in diameter with up to five large seeds, and fruits > 10 cm diameter with numerous small seeds. Megafaunal fruits are well represented in unrelated families such as Sapotaceae, Fabaceae, Solanaceae, Apocynaceae, Malvaceae, Caryocaraceae, and Arecaceae and combine an overbuilt design (large fruit mass and size) with either a single or few (< 3 seeds) extremely large seeds or many small seeds (usually > 100 seeds). Within-family and within-genus contrasts between megafaunal and non-megafaunal groups of species indicate a marked difference in fruit diameter and fruit mass but less so for individual seed mass, with a significant trend for megafaunal fruits to have larger seeds and seediness.

Conclusions/significance: Megafaunal fruits allow plants to circumvent the trade-off between seed size and dispersal by relying on frugivores able to disperse enormous seed loads over long-distances. Present-day seed dispersal by scatter-hoarding rodents, introduced livestock, runoff, flooding, gravity, and human-mediated dispersal allowed survival of megafauna-dependent fruit species after extinction of the major seed dispersers. Megafauna extinction had several potential consequences, such as a scale shift reducing the seed dispersal distances, increasingly clumped spatial patterns, reduced geographic ranges and limited genetic variation and increased among-population structuring. These effects could be extended to other plant species dispersed by large vertebrates in present-day, defaunated communities.

Show MeSH
Bivariate plots of fleshy fruit traits for megafauna and non-megafauna species.Dots, megafauna-fruit species; +, non-megafauna fruited species. (A) dry mass of seeds per fruit and fruit mass. Intrafamilial comparisons are indicated by connecting lines between dots and +s; (B) individual seed mass and number of seeds per fruits.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2258420&req=5

pone-0001745-g004: Bivariate plots of fleshy fruit traits for megafauna and non-megafauna species.Dots, megafauna-fruit species; +, non-megafauna fruited species. (A) dry mass of seeds per fruit and fruit mass. Intrafamilial comparisons are indicated by connecting lines between dots and +s; (B) individual seed mass and number of seeds per fruits.

Mentions: Megafaunal fruits are characteristically heavy (Table 1), varying in form between spheroid drupaceous designs and elongate legume-like forms up to 50–1000 g total fruit mass. This results in very high seed loads/fruit, with total seed(s) mass/fruit increasing with fruit mass (Fig. 4a) (R2 = 0.9221, F = 65.12, P<0.0001, d.f. = 2, 11); a trend also patent when comparing intra-familial contrasts (Fig. 4a). The slope of the relationship between seed load/fruit and fruit mass (Fig. 4a) does not depart significantly from a 1∶1 trend, suggesting seed load is an isometric function of fruit mass for these species. In addition, they typically show a larger seed load/fruit relative to non-megafaunal species. The mass of seeds/fruit ranges for megafaunal species between 0.2%–97.4% of the total fresh fruit mass, while the comparable range for non-megafaunal species is 0.1%–8.9%. However, this is the simple result of increasing total fruit mass, not increasing the relative seed load/fruit (Fig. 4a); thus, there are no differences between megafaunal and non-megafaunal species in seed(s) mass/fruit when accounting for variation in fruit mass (F = 2.11, P = 0.17, d.f. = 2, 11 for the a posteriori contrast with fruit mass as the covariate).


Seed dispersal anachronisms: rethinking the fruits extinct megafauna ate.

Guimarães PR, Galetti M, Jordano P - PLoS ONE (2008)

Bivariate plots of fleshy fruit traits for megafauna and non-megafauna species.Dots, megafauna-fruit species; +, non-megafauna fruited species. (A) dry mass of seeds per fruit and fruit mass. Intrafamilial comparisons are indicated by connecting lines between dots and +s; (B) individual seed mass and number of seeds per fruits.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2258420&req=5

pone-0001745-g004: Bivariate plots of fleshy fruit traits for megafauna and non-megafauna species.Dots, megafauna-fruit species; +, non-megafauna fruited species. (A) dry mass of seeds per fruit and fruit mass. Intrafamilial comparisons are indicated by connecting lines between dots and +s; (B) individual seed mass and number of seeds per fruits.
Mentions: Megafaunal fruits are characteristically heavy (Table 1), varying in form between spheroid drupaceous designs and elongate legume-like forms up to 50–1000 g total fruit mass. This results in very high seed loads/fruit, with total seed(s) mass/fruit increasing with fruit mass (Fig. 4a) (R2 = 0.9221, F = 65.12, P<0.0001, d.f. = 2, 11); a trend also patent when comparing intra-familial contrasts (Fig. 4a). The slope of the relationship between seed load/fruit and fruit mass (Fig. 4a) does not depart significantly from a 1∶1 trend, suggesting seed load is an isometric function of fruit mass for these species. In addition, they typically show a larger seed load/fruit relative to non-megafaunal species. The mass of seeds/fruit ranges for megafaunal species between 0.2%–97.4% of the total fresh fruit mass, while the comparable range for non-megafaunal species is 0.1%–8.9%. However, this is the simple result of increasing total fruit mass, not increasing the relative seed load/fruit (Fig. 4a); thus, there are no differences between megafaunal and non-megafaunal species in seed(s) mass/fruit when accounting for variation in fruit mass (F = 2.11, P = 0.17, d.f. = 2, 11 for the a posteriori contrast with fruit mass as the covariate).

Bottom Line: Some neotropical, fleshy-fruited plants have fruits structurally similar to paleotropical fruits dispersed by megafauna (mammals > 10(3) kg), yet these dispersers were extinct in South America 10-15 Kyr BP.We introduce an operational definition of megafaunal fruits and perform a comparative analysis of 103 Neotropical fruit species fitting this dispersal mode.These effects could be extended to other plant species dispersed by large vertebrates in present-day, defaunated communities.

View Article: PubMed Central - PubMed

Affiliation: Departamento de Física da Matéria Condensada, Instituto de Física Gleb Wataghin, Universidade Estadual de Campinas, Campinas, São Paulo, Brazil.

ABSTRACT

Background: Some neotropical, fleshy-fruited plants have fruits structurally similar to paleotropical fruits dispersed by megafauna (mammals > 10(3) kg), yet these dispersers were extinct in South America 10-15 Kyr BP. Anachronic dispersal systems are best explained by interactions with extinct animals and show impaired dispersal resulting in altered seed dispersal dynamics.

Methodology/principal findings: We introduce an operational definition of megafaunal fruits and perform a comparative analysis of 103 Neotropical fruit species fitting this dispersal mode. We define two megafaunal fruit types based on previous analyses of elephant fruits: fruits 4-10 cm in diameter with up to five large seeds, and fruits > 10 cm diameter with numerous small seeds. Megafaunal fruits are well represented in unrelated families such as Sapotaceae, Fabaceae, Solanaceae, Apocynaceae, Malvaceae, Caryocaraceae, and Arecaceae and combine an overbuilt design (large fruit mass and size) with either a single or few (< 3 seeds) extremely large seeds or many small seeds (usually > 100 seeds). Within-family and within-genus contrasts between megafaunal and non-megafaunal groups of species indicate a marked difference in fruit diameter and fruit mass but less so for individual seed mass, with a significant trend for megafaunal fruits to have larger seeds and seediness.

Conclusions/significance: Megafaunal fruits allow plants to circumvent the trade-off between seed size and dispersal by relying on frugivores able to disperse enormous seed loads over long-distances. Present-day seed dispersal by scatter-hoarding rodents, introduced livestock, runoff, flooding, gravity, and human-mediated dispersal allowed survival of megafauna-dependent fruit species after extinction of the major seed dispersers. Megafauna extinction had several potential consequences, such as a scale shift reducing the seed dispersal distances, increasingly clumped spatial patterns, reduced geographic ranges and limited genetic variation and increased among-population structuring. These effects could be extended to other plant species dispersed by large vertebrates in present-day, defaunated communities.

Show MeSH