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The Ghosts Of Evolution: Nonsensical Fruit, Missing Partners, and Other Ecological Anachronisms

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Abstract

Review in Publisher's Weekly: In 1982, respected ecologists Dan Janzen and Paul Martin published a short, provocative paper in the journal Science, asserting that many fruits found in Central American forests "are adapted primarily for animals that have been extinct for thirteen thousand years." As those species went the way of the dodo, the fruits lost their initial means of dispersal, but continued to eke out a system of procreation, Janzen and Martin explained. Their insight led to the methodological realization that to fully understand the evolutionary forces shaping these fruits, scientists must first determine the behavior of the extinct animals. Science writer Barlow (From Gaia to Selfish Genes) extends this compelling idea into a narrative stretching from the Pleistocene era up through the inception, rejection and gradual, partial acceptance of this theory by the ecological science community. The large, pendulous seedpods of a honey locust, Barlow shows, evoke the ghosts of mammoths that used to disperse the seeds. . .

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December 2015
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December 2015
... Evolutionary anachronisms are attributes of living species that are best explained at the light of interrelationships with taxa that have become extinct. Nowadays, those attributions lack apparent benefits to the species, and can even result prejudicial for its survival (see Barlow, 2000). This was early recognized by Janzen and Martin (1982) that recognized anachronisms in the context of seed dispersal and passive defense strategies exhibited by plants that had evolved alongside disappeared Pleistocene megaherbivores. ...
... However, plant anachronisms are not only restricted to past interaction between plants and megamammals. In this regard, Janzen (1986) and Barlow (2000) proposed that the diverse extinct tortoises in North America may be the responsible of some (Rick and Bowman, 1960;Janzen, 1986). Further, recent studies indicate that tortoise may be important landscape engineers and may replace mammalian frugivores in selected woodlands (Sobral-Souza et al., 2017). ...
... This may be indicative that tortoise driven the evolution of Galápagos wild tomatoes (see Janzen, 1986). In this line of thought, Barlow (2000) analyzed the North American silver leaf nightshade (Solanum elaegnifolium Cav., 1794). This wild species is toxic for mammals, but not for reptiles, including tortoises. ...
... In Cameroon, forest elephants (Loxodonta cyclotis) seek papaya fruits beyond their protected reserve and disperse the seeds (Tchamba and Seme, 1993;Barlow, 2000). Wild Carica papaya seems to have many characteristics that fit the hypothesised megafaunal dispersal syndrome (Janzen and Martin, 1982;Barlow, 2000). ...
... In Cameroon, forest elephants (Loxodonta cyclotis) seek papaya fruits beyond their protected reserve and disperse the seeds (Tchamba and Seme, 1993;Barlow, 2000). Wild Carica papaya seems to have many characteristics that fit the hypothesised megafaunal dispersal syndrome (Janzen and Martin, 1982;Barlow, 2000). The non-domesticated fruits are fairly large (5-8 cm in diameter) and visually nondescript (greenish unless fully ripened) but with a penetrating aroma, and are held high up on a trunk with suppressed branching. ...
... Non-domesticated Vasconcellea fruits can be larger. Such unusual species may have evolved in response to consumption of fruits whole and seed dispersal by large (now extinct) mammals such as ground sloths (Eremotherium) and mastodon-like gomphotheres (Cuvieronius) (Simpson, 1969(Simpson, , 1980Barlow, 2000). ...
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A review of the biology and taxonomy of Carica papaya, with emphasis on agriculture.
... Las tunas (especies del género Opuntia) y otros cactus también se trasladan enganchándose en el pelaje de los mamíferos (Figura 5). Debido a que estas especies se reproducen asexualmente, no necesitan trasladar sus semillas, sino solo partes de la misma planta (Barlow, 2008). Por ejemplo, en la actualidad, las vacas asilvestradas en el sur de Entre Ríos son el principal el único agente de dispersión de una especie de cactus endémica de los bosques secos de esa zona, la tuna Opuntia aurantiaca, y otro tanto ocurre con un endemismo de Sierra de la Ventana, en el sur de la provincia de Buenos Aires: Opuntia ventanensis. ...
... Además, la superficie está cubierta por pelos glandulares pegajosos que refuerzan el agarre. Estas semillas, como bien lo sospechó la sagaz divulgadora científica y periodista norteamericana Connie Barlow (2008), habrían sido trasladadas por integrantes de la megafauna hoy extintos. Luego de su desaparición, el traslado de estas semillas quedó a cargo del ganado actual, e incluso de nosotros mismos. ...
... Las espinas en muchas de esas plantas se ubican en la zona superior, que es donde las jirafas y grandes herbívoros ramonean, mientras que en partes bajas son mucho más escasas. Yucas, acacias, algarrobos y nopales son muy altos, pero tienen defensas especialmente ubicadas en la parte superior de las plantas, en lugares que únicamente se encuentran al alcance de la megafauna (Barlow, 2008). ...
... Anachronisms are morphological or behavioural traits that are not ecologically effective today, but reflect past ecological interactions (Janzen & Martin, 1982;Barlow, 2002). Recurrent examples are overbuilt fleshy fruits with inefficient present-day seed dispersal mechanisms (Janzen & Martin, 1982), and the presence of spines, prickles and thorns (Janzen, 1986) in plants that protect themselves against large herbivores that no longer exist (Greenwood & Atkinson, 1977;Bond & Silander, 2007). ...
... The best-studied case of megafauna-related anachronism is morphological traits of fleshy fruits associated with the dispersal of seeds by large mammals (Janzen & Martin, 1982;Barlow, 2002;Guimarães, Galetti & Jordano, 2008). Because there is a strong correlation of fruit and seed size with disperser size (Wheelwright, 1985;Chen & Moles, 2015;Federman et al., 2016), the occurrence of overbuilt fruits in megafauna-deprived continents such as the Americas and Australia suggests that large vertebrates were an important selective agent for the evolution and distribution of such large fruits. ...
... Megafauna fruit representatives of 16 plant families occur only in South America, five families are exclusive to Australasia, 15 families occur only in Africa, three families in South East Asia and one family is restricted to Madagascar (Fig. 3). It is likely that many megafauna fruit plants in the Americas and Australia have lacked efficient dispersal agents since megafauna extinction, with likely negative effects on the effectiveness of their seed dispersal (regeneration and distribution) (Barlow, 2002;Guimarães et al., 2008;Weber, 2013). Currently, cassowaries in Australia and tapirs, large primates and rheas in South America are the largest endozoochorous seed dispersers of these fruits, with kangaroo rats, agoutis and other scatter-hoarding rodents being secondary short-distance seed dispersers (Forget & Vander Wall, 2001). ...
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Full-text available
For hundreds of millions of years, large vertebrates (megafauna) have inhabited most of the ecosystems on our planet. During the late Quaternary, notably during the Late Pleistocene and the early Holocene, Earth experienced a rapid extinction of large, terrestrial vertebrates. While much attention has been paid to understanding the causes of this massive megafauna extinction, less attention has been given to understanding the impacts of loss of megafauna on other organisms with whom they interacted. In this review, we discuss how the loss of megafauna disrupted and reshaped ecological interactions, and explore the ecological consequences of the ongoing decline of large vertebrates. Numerous late Quaternary extinct species of predators, parasites, commensals and mutualistic partners were associated with megafauna and were probably lost due to their strict dependence upon them (co-extinctions). Moreover, many extant species have megafauna-adapted traits that provided evolutionary benefits under past megafauna-rich conditions, but are now of no or limited use (anachronisms). Morphological evolution and behavioural changes allowed some of these species partially to overcome the absence of megafauna. Although the extinction of megafauna led to a number of co-extinction events, several species that likely co-evolved with megafauna established new interactions with humans and their domestic animals. Species that were highly specialized in interactions with megafauna, such as large predators, specialized parasites, and large commensalists (e.g. scavengers, dung beetles), and could not adapt to new hosts or prey were more likely to die out. Partners that were less megafauna dependent persisted because of behavioural plasticity or by shifting their dependency to humans via domestication, facilitation or pathogen spill-over, or through interactions with domestic megafauna. We argue that the ongoing extinction of the extant megafauna in the Anthropocene will catalyse another wave of co-extinctions due to the enormous diversity of key ecological interactions and functional roles provided by the megafauna.
... Keywords: disperser assemblages, ectozoochory, extinct megafauna, livestock, oversized fruits, parrots, palms, tapir INTRODUCTION Trade-offs between fruit size and seed dispersal ability have been repeatedly highlighted as governing plant-frugivore mutualistic interactions (Wheelwright, 1985;Lord, 2004, Bruun andPoschlod, 2006;Burns, 2013). A number of extant plants show fruit size, phenological patterns and other traits that have been argued to better reflect adaptations to past than present-day ecological conditions (Barlow, 2000). These "anachronisms" are generally suggested to explain traits that are unexpected or not understood based on their interactions with extant assemblages of fruit-eating vertebrates (Janzen and Martin, 1982;Barlow, 2000). ...
... A number of extant plants show fruit size, phenological patterns and other traits that have been argued to better reflect adaptations to past than present-day ecological conditions (Barlow, 2000). These "anachronisms" are generally suggested to explain traits that are unexpected or not understood based on their interactions with extant assemblages of fruit-eating vertebrates (Janzen and Martin, 1982;Barlow, 2000). In particular, the megafaunal seed dispersal hypothesis states that some extant plants show "overbuilt" fruits apparently adapted for seed dispersal by very large mammals such as elephant-like gomphotheres and giant ground sloths that went extinct during the Pleistocene in the Neotropics (Janzen and Martin, 1982). ...
... In particular, the megafaunal seed dispersal hypothesis states that some extant plants show "overbuilt" fruits apparently adapted for seed dispersal by very large mammals such as elephant-like gomphotheres and giant ground sloths that went extinct during the Pleistocene in the Neotropics (Janzen and Martin, 1982). These "anachronistic" fruits were assumed to be ecologically ineffective today because of the lack of presentday seed dispersal mechanisms (Janzen and Martin, 1982).This argument implies that the extinction of megafrugivores resulted in marked shifts in the patterns of seed dispersal observed today in extant plants with oversized fruits (Janzen and Martin, 1982;Howe, 1985;Barlow, 2000), with important implications in the ecology, evolution, and conservation of biodiversity. However, this hypothesis has remained controversial given its vagueness, the discrepancies in its assumptions and the limited or contrary evidence for many of its predictions (Howe, 1985;Hunter, 1989). ...
Article
Full-text available
The dispersal of many large-seeded plants is thought to have been handicapped by the extinction of megafauna in the late Pleistocene, and due to the ongoing defaunation of the largest of the extant dispersers. Oversized fruits defined as “megafaunal” provide variable amounts of flesh even though many of them cannot be ingested entirely, nor their seeds defecated, by any extant vertebrate. This apparent mismatch lead to the hypothesis of anachronisms involving extinct megafauna as dispersal-mediated selective agents on fruit traits shaped through endozoochory. It has been suggested that free-ranging livestock partially supply the dispersal functions previously provided by those globally or regionally extinct species. However, there is little knowledge on the role of livestock as a surrogate for megafauna dispersal agents relative to living wild dispersers. Here, we focus on seed dispersal of six palm species (Attalea eichleri, Attalea barreirensis, Attalea speciosa, Attalea princeps, Mauritia flexuosa, Acrocomia totai) with large fruits that conform to the so-called “megafaunal syndrome”. Data on seed dispersal were obtained by observations and camera trapping in the Cerrado, Pantanal and Amazonia biomes in Bolivia and Brazil. Rich communities of wild seed dispersers differing among palm species and study areas were recorded, including rodents, monkeys, canids, and a wide variety of birds, especially parrots. Long-distance primary dispersal was mainly conducted by parrots, while multiple species acted as short- and medium-distance secondary dispersers. Among livestock, dispersal was limited to seeds of A. totai and A. princeps moved by several species through stomatochory and endozoochory (mainly regurgitation). These results show that the large seeds can be efficiently dispersed externally by a wide array of present-day vertebrates of variable size but much smaller than extinct megafauna and livestock. A knowledge gap of the natural history of these and other plants with oversized fruits assumed to be maladapted for contemporary dispersal may have been partially favored by neglecting some key disperser guilds (e.g., parrots) and dispersal mechanisms (e.g., ectozoochory). The evaluation of historic and ongoing defaunation of key external dispersers is advocated to understand the influence of actual (rather than putative) dispersers on contemporary frugivore-plant mutualistic interactions.
... A variety of evidence indicates that the functional roles of large carnivores and megaherbivores are often significant (Owen-Smith 1988;Soulé et al. 1988;Estes et al. 1998;Terborgh et al. 1999Terborgh et al. , 2001Berger et al. 2001;Jackson et al. 2001;Sinclair et al. 2003;Ray et al. 2005) and that degraded systems may both cause and result from the loss of these species (Springer et al. 2003;Terborgh et al. 2006;Terborgh and Feeley, forthcoming). It follows that many extinct large mammals must have shaped the life histories of extant species and ecosystem characteristics through the selective forces of strong species interactions (Greenwood and Atkinson 1977;Janzen and Martin 1982;Zimov et al. 1995;Byers 1997;Barlow 2000). The likely consequence of so much large vertebrate-induced change in functionality is ecosystem dysfunction (Jackson 1997;Pandolfi et al. 2003;Terborgh and Feeley, forthcoming), driven in part by anachronistic attributes of the surviving species (Janzen and Martin 1982) and ecological chain reactions that lead to further extinctions (Springer et al. 2003;Koh et al. 2004;Terborgh et al. 2006;Donlan et al., forthcoming). ...
... Various North American species have characteristics that in modern landscapes appear to be anachronistic, probably having coevolved with large native vertebrates that became extinct in the late Pleistocene (for South American examples, see Guix et al. 2005). We briefly describe two of the many suspected anachronisms for which detailed experimental studies are sorely needed (Barlow 2000). ...
... The interglacial Pleistocene fossil plant record reveals several species of Maclura throughout North America, while the pre-European historical record documents only Osage orange (M. pomifera) in the Red River floodplains of Arkansas (Barlow 2000;Schambach 2000). The loss of proboscideans and other megaherbivores capable and suspected of dispersing the large fruits of these trees may have caused or contributed to the extinction of the other Maclura species, whereas Osage orange fortuitously survived as a small remnant and spread because of dispersal by modern humans (Barlow 2000). ...
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Large vertebrates are strong interactors in food webs, yet they were lost from most ecosystems after the dispersal of modern humans from Africa and Eurasia. We call for restoration of missing ecological functions and evolutionary potential of lost North American megafauna using extant conspecifics and related taxa. We refer to this restoration as Pleistocene rewilding; it is conceived as carefully managed ecosystem manipulations whereby costs and benefits are objectively addressed on a case‐by‐case and locality‐by‐locality basis. Pleistocene rewilding would deliberately promote large, long‐lived species over pest and weed assemblages, facilitate the persistence and ecological effectiveness of megafauna on a global scale, and broaden the underlying premise of conservation from managing extinction to encompass restoring ecological and evolutionary processes. Pleistocene rewilding can begin immediately with species such as Bolson tortoises and feral horses and continue through the coming decades with elephants and Holarctic lions. Our exemplar taxa would contribute biological, economic, and cultural benefits to North America. Owners of large tracts of private land in the central and western United States could be the first to implement this restoration. Risks of Pleistocene rewilding include the possibility of altered disease ecology and associated human health implications, as well as unexpected ecological and sociopolitical consequences of reintroductions. Establishment of programs to monitor suites of species interactions and their consequences for biodiversity and ecosystem health will be a significant challenge. Secure fencing would be a major economic cost, and social challenges will include acceptance of predation as an overriding natural process and the incorporation of pre‐Columbian ecological frameworks into conservation strategies.
... Much of its physiology, morphology and life history reflect an optimization for being swift; pronghorn have oversized hearts and lungs, a 320° field of vision, hollow hair and overlong gestation for their size (Byers 1997). Understanding the selective pressures that led to such specialized adaptations is difficult without the knowledge that the pronghorn co-evolved with a suite of now extinct predators, including the American cheetah (Micracinonyx trumani) (Byers 1997, Barlow 2001. As the only surviving member of the once speciose North American family Antilocapridae, the pronghorn no longer has effective natural predators. ...
... Ecologists recognize the anachronistic nature of animals like the pronghorn, but more as a curiosity rather than as a concrete example of the substantial alteration of ecosystems that occurred in the late Quaternary. Although work investigating the ecology and life-history characteristics of tropical and temperate plants has proposed that numerous adaptations for dispersal or regrowth arose in response to foraging by now-extinct megafauna (Janzen and Martin 1982, Wing and Tiffney 1987, Barlow 2001, in general, the implications of the prehistoric loss of megafauna in the late Pleistocene have been overlooked. Yet, these animals undoubtedly played key roles in terms of ecosystem structure and function; their abrupt disappearance some 11,000 years ago must have profoundly influenced ecosystem dynamics (Martin 1967, Donlan et al. 2005. ...
... Some gymnosperm pollen, such as that of pine, will readily germinate on standard pollen germination medium [i.e. Brewbaker and Kwack medium (Brewbaker and Kwack, 1963); Varis et al., 2010], whereas larch and Douglas-fir pollen require high concentrations of carbohydrates to germinate in vitro (Fernando et al., 1998;Dumont-Béboux et al., 1999, 2000, levels that are much higher than those that we found in their ovular secretions. Ephedra pollen is reported to germinate at high sugar concentration (Bhatnagar and Moitra, 1996), more comparable to the TSC found in secretions of Ephedra species here. ...
... Alternatively, Ginkgo may have coevolved with insect assemblages early in its evolution, developing ambophilous pollination, and later may have lost its ancient pollinators (Labandeira et al., 2007). The persistence of pollination drops that fit the chemical profile of insect pollination could be considered an evolutionary anachronism (Barlow, 2000). The existence of a diverse herbivore community (16 taxa) on well-documented ginkgoalean foliage from the Late Triassic (i.e. ...
Article
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Background and aims: Gymnosperms are either wind-pollinated (anemophilous) or both wind- and insect-pollinated (ambophilous). Regardless of pollination mode, ovular secretions play a key role in pollen capture, germination and growth; they are likely also involved in pollinator reward. Little is known about the broad-scale diversity of ovular secretions across gymnosperms, and how these may relate to various reproductive functions. This study analyses the sugar and amino acid profiles of ovular secretions across a range of ambophilous (cycads and Gnetales) and anemophilous gymnosperms (conifers) to place them in an evolutionary context of their possible functions during reproduction. Methods: Ovular secretions from 13 species representing all five main lineages of extant gymnosperms were sampled. High-performance liquid chromatography techniques were used to measure sugar and amino acid content. Multivariate statistics were applied to assess whether there are significant differences in the chemical profiles of anemophilous and ambophilous species. Data were compared with published chemical profiles of angiosperm nectar. Chemical profiles were placed in the context of phylogenetic relationships. Key results: Total sugar concentrations were significantly higher in ovular secretions of ambophilous species than wind-pollinated taxa such as Pinaceae and Cupressophyta. Ambophilous species had lower amounts of total amino acids, and a higher proportion of non-protein amino acids compared with anemophilous lineages, and were also comparable to angiosperm nectar. Results suggest that early gymnosperms likely had ovular secretion profiles that were a mosaic of those associated with modern anemophilous and ambophilous species. Ginkgo, thought to be anemophilous, had a profile typical of ambophilous taxa, suggesting that insect pollination either exists in Gingko, but is undocumented, or that its ancestral populations were insect-pollinated. Conclusions: Chemical profiles of ovular secretions of ambophilous gymnosperms show a clear signal of pollinator-driven selection, including higher levels of carbohydrates than anemophilous taxa, lower levels of amino acids, and the presence of specific amino acids, such as β-alanine, that are known to influence insect feeding behaviour and physiology.
... For instance, Janzen (1986) proposed that the very spiny cacti of America reflect the extinct megafauna that disappeared several millennia ago. Similarly, various tropical fruits are adapted to large, extinct mammalian frugivores (Janzen and Martin 1982;Barlow 2000). Another proposed anachronistic defensive adaptation is divaricate branching, spininess, camouflage, and aposematic coloration in New Zealand trees and shrubs as defense against the extinct moas (Greenwood and Atkinson 1977;Diamond 1990;Bond et al. 2004;Fadzly et al. 2009;Burns 2010;Fadzly and Burns 2010) and in similar plants in Madagascar as defense against the extinct elephant birds (Bond and Silander 2007). ...
... Another proposed anachronistic defensive adaptation is divaricate branching, spininess, camouflage, and aposematic coloration in New Zealand trees and shrubs as defense against the extinct moas (Greenwood and Atkinson 1977;Diamond 1990;Bond et al. 2004;Fadzly et al. 2009;Burns 2010;Fadzly and Burns 2010) and in similar plants in Madagascar as defense against the extinct elephant birds (Bond and Silander 2007). In all these cases, the plants may currently use the anachronistic adaptations as functional solutions in a different biological or environmental setting (Janzen and Martin 1982;Janzen 1986;Barlow 2000;Fadzly et al. 2009). There is no reason to assume that the cited cases of defensive and other botanical anachronisms are the only ones, and I propose here that the white bark of temperate/boreal trees may be explained partly as visual defense via camouflage from extinct megafauna during the snowy winter and partly as camouflage from smaller extinct and current mammalian herbivores. ...
... On all but these two continents, megafaunal fruit can now be considered 'overbuilt' (Barlow, 2000) -diaspores that owing to their large size and/or degree of mechanical and chemical protection are illfitted for effective dispersal by the extant frugivore communities. They are ecological anachronisms: fruits that evolved in the presence of megaherbivores but have remained long after their demise (Janzen & Martin, 1982;Barlow, 2000;Guimarães et al., 2008). ...
... On all but these two continents, megafaunal fruit can now be considered 'overbuilt' (Barlow, 2000) -diaspores that owing to their large size and/or degree of mechanical and chemical protection are illfitted for effective dispersal by the extant frugivore communities. They are ecological anachronisms: fruits that evolved in the presence of megaherbivores but have remained long after their demise (Janzen & Martin, 1982;Barlow, 2000;Guimarães et al., 2008). In Africa, we are in the unique position of being able to study megafaunal fruits in areas with an intact megaherbivore community. ...
Article
Full-text available
Large specialized fruit (megafaunal fruit) have evolved alongside megaherbivores to take advantage of their unparalleled seed dispersal service. Megaherbivores were widespread and abundant in the Pleistocene but due to multiple extinction events have been extirpated from all continents except Africa and small pockets of South East Asia. In Africa, we are in the unique position of being able to study megafaunal fruits where there are still areas with a largely intact megaherbivore community. The megafaunal fruits of the African forests have been examined but those of the African savannas have been largely overlooked. We use an operational definition of megafaunal fruit developed in the Neotropics to identify megafaunal fruit in the South African tree flora. Thirty-one species were identified as megafaunal fruit-bearers, representing only 3% of the tree flora. Megafaunal tree species are well represented in the families Mimosoideae, Arecaceae, Strychnaceae and Caesalpinoideae. We explored the factors underlying the distribution of these megafaunal tree species. We found that the historical distribution of megaherbivores in South Africa does not explain the distribution of these fruit. Megaherbivores have historically been found throughout South Africa while megafaunal fruit tree species occur almost exclusively in the northern tropical reaches of the country. Abiotic factors such as precipitation and temperature appear to best explain the distribution of megafaunal fruit species in the region. We conclude that megafaunal fruit are a tropical phenomenon and their tropical origins now limit their distribution. ADDITIONAL KEYWORDS: abiotic environment-African savanna elephant-historical distribution-megaherbivores-megafauna-megafaunal fruit-savannas-seed dispersal-seed dispersal guilds-tropical biota.
... Broken coevolutionary links have also been invoked to explain the prominence of light-demanding trees and thorny shrubs in the European flora (Bakker et al., 2004), and ontogenetic trends in spinescence (Janzen & Martin, 1982;Clark & Burns, 2015). These patterns attributed to now-defunct coevolutionary interactions have been termed 'ecological anachronisms' (Barlow, 2002). ...
... Moreover, the frequent hybridization of divaricates with non-divaricate congeners (Rattenbury, 1962;Godley, 1985) suggests most divaricates diverged only recently from broadleaved ancestors ( Fig. 1), consistent with a Plio-Pleistocene origin (McGlone & Webb, 1981); this evidence of a relatively recent origin is difficult to reconcile with an explanation based solely on browsing by moa, whose ancestors apparently reached the New Zealand landmass at least 60 Ma (Phillips et al., 2010). Although this debate remains unresolved, the moa-browsing hypothesis has resonated internationally, and divaricate plants have been widely reported as a legacy of extinct vertebrate herbivores (Barlow, 2002;Johnson, 2009;Hansen et al., 2010). ...
Article
Puzzling features of plants are sometimes explained as legacies of co-evolution with extinct herbivores. One example is the convergent evolution of a small-leaved, twiggy ‘divaricate’ form in > 50 woody species in New Zealand. This growth form was first interpreted as a response to the Plio-Pleistocene onset of frosty, droughty environments, but opinion now favours the hypothesis that it arose as a defence against large herbivorous birds (moa). It has been argued that the extinction of moa during the last millennium has left divaricate plants at risk of being out-competed by faster growing broadleaved competitors, yet their current abundance in some habitats suggests this growth form might confer other advantages besides protection against avian browsing. We aimed to clarify the adaptive significance of the divaricate growth form by identifying environmental correlates of its geographic distribution in New Zealand.
... On all but these two continents, megafaunal fruit can now be considered 'overbuilt' (Barlow, 2000) -diaspores that owing to their large size and/or degree of mechanical and chemical protection are illfitted for effective dispersal by the extant frugivore communities. They are ecological anachronisms: fruits that evolved in the presence of megaherbivores but have remained long after their demise (Janzen & Martin, 1982;Barlow, 2000;Guimarães et al., 2008). ...
... On all but these two continents, megafaunal fruit can now be considered 'overbuilt' (Barlow, 2000) -diaspores that owing to their large size and/or degree of mechanical and chemical protection are illfitted for effective dispersal by the extant frugivore communities. They are ecological anachronisms: fruits that evolved in the presence of megaherbivores but have remained long after their demise (Janzen & Martin, 1982;Barlow, 2000;Guimarães et al., 2008). In Africa, we are in the unique position of being able to study megafaunal fruits in areas with an intact megaherbivore community. ...
Article
Large specialized fruit (megafaunal fruit) have evolved alongside megaherbivores to take advantage of their unparalleled seed dispersal service. Megaherbivores were widespread and abundant in the Pleistocene but due to multiple extinction events have been extirpated from all continents except Africa and small pockets of South East Asia. In Africa, we are in the unique position of being able to study megafaunal fruits where there are still areas with a largely intact megaherbivore community. The megafaunal fruits of the African forests have been examined but those of the African savannas have been largely overlooked. We use an operational definition of megafaunal fruit developed in the Neotropics to identify megafaunal fruit in the South African tree flora. Thirty-one species were identified as megafaunal fruit-bearers, representing only 3% of the tree flora. Megafaunal tree species are well represented in the families Mimosoideae, Arecaceae, Strychnaceae and Caesalpinoideae. We explored the factors underlying the distribution of these megafaunal tree species. We found that the historical distribution of megaherbivores in South Africa does not explain the distribution of these fruit. Megaherbivores have historically been found throughout South Africa while megafaunal fruit tree species occur almost exclusively in the northern tropical reaches of the country. Abiotic factors such as precipitation and temperature appear to best explain the distribution of megafaunal fruit species in the region. We conclude that megafaunal fruit are a tropical phenomenon and their tropical origins now limit their distribution.
... There is ample redundancy in ecosystems and multiple alternative ways to perform particular processes. For example, the extinction of the mammalian megafauna in most continents, and in the largest world islands, necessarily affected in a negative way the system of dispersal of large fruits of many plants (Barlow, 2000). These plants may now (a) have their reproduction restricted to vegetative reproduction, (b) be dispersed by introduced megafauna (such as livestock), or (c) find alternative dispersers among present-day non-megafaunal species (see e.g. ...
... Blanco et al., 2019). The ghost of past extinction (Barlow, 2000) is by force a feature influencing the current functioning of ecosystems worldwide, because extinction is a natural process over evolutionary time. Hence, ecosystem functions need to be perceived as dynamic rather than immutable or pre-defined processes. ...
Article
Some authors consider that apex predators that cannot regulate prey populations are not a complete conservation target. We argue that this image originates in northern latitudes where cultural models of wildness have developed further due to contingent historical and social reasons. In southern European ecosystems apex predators usually cannot regulate prey populations, acting as scavengers or vegetarian. As a consequence, prey are often regulated by bottom-up mechanisms, such as density-dependent disease or food availability. This should not be seen as a downgrading of predator functionality in ecosystems, but just as another type of ecosystem organization. Actually, the species that we now call apex predators were part of much richer predator communities in the Pleistocene, where they behaved as mesopredators (wolf) or already had vegetarian diets (southern brown bear). Species functionality shows spatiotemporal heterogeneity, and this variability needs to be taken into account and incorporated to conservation plans on a case by case basis, to improve their success rates and human-wildlife coexistence.
... While these remain overlooked in landscape planning, we highlight C. cujete, which is already ubiquitous in Brazilian cities, as a first important component in allowing the existence of nectar bats in urban habitats. Due to a temporal anachronism caused by the absence of megafauna capable of dispersing its large and hard-husked fruits (Barlow, 2008), C. cujete is dispersed mostly by humans and could be sporadically dispersed by water (Barlow, 2008;Howe, 1985). Because the species has low consumable value and is used mostly for ornamentation, it is very unlikely to become invasive, and therefore does not pose a direct threat to native communities. ...
... While these remain overlooked in landscape planning, we highlight C. cujete, which is already ubiquitous in Brazilian cities, as a first important component in allowing the existence of nectar bats in urban habitats. Due to a temporal anachronism caused by the absence of megafauna capable of dispersing its large and hard-husked fruits (Barlow, 2008), C. cujete is dispersed mostly by humans and could be sporadically dispersed by water (Barlow, 2008;Howe, 1985). Because the species has low consumable value and is used mostly for ornamentation, it is very unlikely to become invasive, and therefore does not pose a direct threat to native communities. ...
Article
Pollinator-friendly plants are often a necessary component of the management of urban ecosystem that aim to reduce the impact of the artificial urban matrix on natural pollinator populations. Nectarivorous bats are neglected components of the urban pollinator community and there is a paucity of assessments on pollinator-friendly plants that may provide urban bats with reliable, year-long resources. Crescentia cujete is a bat-pollinated Bignoniaceae with very distinctive chiropterophilous features that is often used as an ornamental species in tropical urban areas worldwide. Its flowers are large and produce copious amounts of nectar, which accumulates in the flower’s storage-shaped flowers. Thus, the species is a potential bat-friendly urban plant. We assessed the species’ year-round flower emission and nightly nectar production dynamics in a green area in northeastern Brazil, and described the behavior of its floral visitors. C. cujete showed a steady, year-round flowering pattern, with no significant seasonality. Its flowers secreted copious amounts of diluted nectar and were visited exclusively by the Pallas long-tongued bat Glossophaga soricina throughout the night at high visiting frequencies, delivering successive visits to individual flowers spaced by short intervals. Our results suggest overexploitation of floral resources from C. cujete by urban bats. Moreover, its continuous flowering and copious nectar production may become a reliable resource in an artificial environment generally lacking bat-pollinated plants, thus mitigating the effects of food shortage for urban nectar bats.
... The disappearance of large mammals (e.g., mastodons) at the end of the Pleistocene (13,000-10,000 ya) also meant the loss of facilitative dispersers capable of ingesting and spreading the seed-bearing propagules of many large-fruited trees in North and South America [30,62,63]. With their key dispersers gone, the fruits of trees such as G. triacanthos L. were left to accumulate beneath parent trees-subject to heavy predation by insects and rodents [21] and lacking the seed coat scarification required for standard germination [64,65]. ...
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A long-term assumption in ecology is that species distributions correspond with their niche requirements, but evidence that species can persist in unsuitable habitat for centuries undermines the link between species and habitat. Moreover, species may be more dependent on mutualist partners than specific habitats. Most evidence connecting indigenous cultures with plant dispersal is anecdotal, but historical records suggest that Native Americans transported and cultivated many species, including Gleditsia triacanthos ("Honey locust"). Gleditsia triacanthos was an important medicinal/culinary (e.g., sugar), cultural (e.g., game sticks) and spiritual tree for the Cherokee (southeastern U.S. Native Americans). This study tests the hypothesis that a Cherokee cultivation legacy drives current regional G. triacanthos distribution patterns. Gleditsia triacanthos occurs in rocky uplands and xeric fields, but inexplicably also occurs in mesic riverine corridors and floodplains where Cherokee once settled and farmed. I combined field experiments and surveys in the Southern Appalachian Mountain region (U.S.) to investigate G. triacanthos recruitment requirements and distribution patterns to determine whether there is a quantifiable G. triacanthos association with former Cherokee settlements. Moreover, I also investigated alternate dispersal mechanisms, such as stream transport and domestic cattle. The results indicate that a centuries-old legacy of Native American cultivation remains intact as G. triacanthos' current southern Appalachian distribution appears better explained Cherokee settlement patterns than habitat. The data indicate that the tree is severely dispersal limited in the region, only moving appreciable distances from former Cherokee settlements where cattle grazing is prevalent. Human land use legacy may play a long-term role in shaping species distributions, and pre-European settlement activity appears underrated as a factor influencing modern tree species distributions.
... This selective extinction left Holocene South America almost entirely devoid of megaherbivores, a unique situation given the continent's long history of such animals. It has been argued that some modern South American ecosystems are filled with floral anachronisms: plants that coevolved with large herbivores such as mastodonts and sloths, but now produce redundant fruits too large to be successfully exploited by surviving species (Barlow 2000). In view of these extinctions, it should be understood that even the South America of pre-Columbian times had been strongly affected by human hunting and habitat change and that the modern South American mammal fauna is already depauperate. ...
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... The past 50,000 years has been a period of major environmental change across the globe (Barnosky et al., 2004;Burney and Flannery, 2005). Human dispersal, climate change, shifts in vegetation communities, altered fire frequencies and major faunal extinction events have all had (though not necessarily independently) significant consequences for global ecosystems and ecological processes over a geologically short time frame (Janzen and Martin, 1982;Barlow, 2002;Johnson, 2009;Levy, 2012;Cooper et al., 2015). By determining the cause and effect relationships between these events we can gain a better understanding of the relative contributions of humans and environmental drivers to Late Quaternary extinctions of megafauna (Barnosky et al., 2004;Cooper et al., 2015;Bartlett et al., in press), examine the effects that these extinctions had on terrestrial ecosystems, and better predict the potential consequences of future environmental change and re-wilding projects. ...
... The large fruit produced by this species appears to be ignored by present day North American wildlife; however, Janzen and Martin (1982) suggest that the fruit could have been a food source for the Gomphotheres of the Pleistocene. Barlow (2000) further added the Pleistocene equines to this list. Some suggest that only Gomphotheres could have dispersed viable seeds (Boone et al. 2015). ...
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Range extensions to Butler County (Albizia julibrissin, Maclura pomifera and Magnolia kobus), Mercer County (Bellis perennis), Venango County (Lespedeza cuneata), and both Allegheny and Lawrence Counties (Arundinaria gigantea) are reported. All species are non-native to Pennsylvania, and L. cuneata and A. julibrissin are considered invasive species in the commonwealth. The occurrence of M. kobus from a wet lowland forest in Butler County represents the first naturalized report of the species from the western half of the commonwealth. The reports of A. gigantea from Allegheny and Lawrence Counties are notable as they represent the second known occurrences of naturalized populations in Pennsylvania.
... Finalmente, el tamaño de las semillas puede asociarse con megafauna extinta que pudo realizar su dispersión por endozoocoria (Janzen y Martin, 1982;Janzen, 1986), como también se ha sugerido para M. lucida (Snow y Walter, 2007). La antigüedad de las Cycadales sugiere que en otros periodos pudieron mantenerse prolongadas interacciones con dispersores ahora extintos, como se ha sugerido para un amplio conjunto de especies vegetales neotropicales que mantienen aparentes anacronismos ecológicos entre sus frutos y las poblaciones de animales que podrían dispersarlos (Janzen y Martin, 1982;Janzen, 1986;Barlow, 2000). ...
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We compiled observations from six populations of Dioon merolae (Zamiaceae) located in the Central Depression (530- 600 m) and the Sierra Madre of Chiapas (1,100-1,200 m). More than 800 individuals of different size and in all phenological stages were visited during 1997 and 2010. A revision of the phylogenetical relationships and distribution of D. merolae is included, along with a botanical description complemented with original observations. The growth of stems is described from seedlings up to adult plants, as well as the production of basal suckers, root growth, and the production of leaves, strobili and seeds. Plant-animal interactions involved in pollination, herbivory, and seed dispersal and predation are described. The effects of occasional wild fires on survival and reproduction are discussed, as well as the longevity and age estimation of this long-lived species. D. merolae populations are severely threatened due to a local religious ceremony in which adult plants are heavily or almost completely (sometimes partially) defoliated. The conservation implications of this practice are discussed.
... It is generally difficult to reconstruct ecological properties of species and ecosystems that do not exist anymore. However, the ecological properties of still existing tree and shrub species like oak and hazel can also tell us a lot about the prevailing ecological conditions in the past (Janzen & Martin 1982, Barlow 2000, Bakker et al. 2004. Bialowieza in Poland; and the Suserup Skov in Denmark (Emborg et al. 1996, Vera 2000. ...
... Each sample with a membership probability above 0.5 is shown in yellow (cluster 1), blue (cluster 2) or purple (cluster 3) The combination of the limited breeding that has occurred in cultivated cherimoya in Central and South America with the longevity of fruit trees lead us to assume that cultivated cherimoya is only separated a few generations of human selection from its wild ancestor; this situation is shared with most other fruit tree crops that usually retain a very high percentage of the genetic diversity found in their wild relatives (Miller & Gross, 2010). We therefore propose that for cherimoya, the centre of crop diversity coincides with its geographical centre of origin in line with Vavilov's classic hypothesis on centres of crop diversity (Dvorak, Luo, & Akhunov, 2011 America, similar to the case in other tropical species that produce even bigger seeds (Persea americana, Manilkara zapota or Spondias purpurea), already took place by the extinct megafauna that was present until the Pleistocene (Barlow, 2000;Janzen & Martin, 1982) and was then dispersed by humans to South America, first in north- in this work has been reported for Phaseolus vulgaris, the common bean, in which a Mesoamerican origin has also been proposed although most of the current improved varieties have an Andean origin (Bitocchi et al., 2012(Bitocchi et al., , 2013. Central America (Bost, Smith, & Crane, 2013;Chen et al., 2009;Hernandez-Bermejo & Leon, 1994;Miller & Schaal, 2005) but are also present in South America probably since pre-Columbian times. ...
Article
Knowledge on the structure and distribution of genetic diversity is a key aspect in order to plan and execute an efficient conservation and utilization of the genetic resources of any crop as well as for determining historical demographic inferences. In this work, a large data set of 1765 accessions of cherimoya (Annona cherimola Mill, Annonaceae), an underutilized fruit tree crop native to the neotropics and used as a food source by pre-Columbian cultures, was collected from 6 different countries across the American continent and amplified with 9 highly informative microsatellite markers. The structure analyses, fine representation of the genetic diversity and an ABC approach suggest a Mesoamerican origin of the crop, contrary to previous reports, with clear implications for the dispersion of plant germplasm between Central and South America in pre-Columbian times. These results together with the potential distribution of the species in a climatic change context using two different climate models provide new insights for the history and conservation of extant genetic resources of cherimoya that can be applied to other currently underutilized woody perennial crops.
... The occurrence of large, overbuilt fruits in Central American dry forests led researchers to suggest that such fruit traits are the outcome of past selective pressures imposed by large, albeit extinct, megafauna (Janzen and Martin 1982). The so-called anachronic fruits have also been found in other megafauna-deprived ecosystems (Janzen 1986, Barlow 2000, Guimarães et al. 2008). ...
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Pleistocene extinctions affected mainly large-bodied animals, determining the loss or changes in numerous ecological functions. Evidence points to a central role of many extinct megafauna herbivores as seed dispersers. An important step in understanding the legacy of extinct mutualistic interactions is to evaluate the roles and effectiveness of megafauna herbivores in seed dispersal. Here we use morphological and ecophysiological allometries to estimate both quantitative and qualitative aspects of seed-dispersal services likely provided by extinct megafauna. We developed a mechanistic model that encompasses four stages of seed dispersal – seed ingestion, gut retention, animal movement, and seed deposition. We estimate seed-dispersal kernels through simulations to infer the role of Pleistocene megafauna in promoting long-distance dispersal and examine how seed dispersal was affected by extinctions. Simulations suggest extinct large-bodied frugivores would frequently disperse large seeds over a thousand meters, whereas smaller-bodied frugivores are more likely to deposit the seeds over a few hundred meters. Moreover, events of long-distance seed dispersal by the extinct megafauna would be up to ten times longer than long-distance dispersal by smaller-sized extant mammals. By estimating the combined distribution of seed dispersal distances considering all large-bodied mammalian frugivores in specific South American Pleistocene assemblages we found that long-distance dispersal contracted by at least two thirds after the megafauna died out. The disruption of long-distance dispersal is expected to have consequences for recruitment, spatial and genetic structure of plant populations, population persistence and community composition. Promoting long-distance seed dispersal was one among other salient features of extinct Pleistocene megafauna that reveal their influence on natural ecosystems. Modeling the consequences of megafaunal extinctions can offer quantitative predictions on the consequences of ongoing defaunation to plant populations and ecological communities. This article is protected by copyright. All rights reserved.
... The presence and loss of megafauna might also have longterm impacts on biotic communities that are still ongoing and witnessed by current plant traits that coevolved with megafauna, which may be less adaptive in modern landscapes (e.g., ecological anachronisms) (89). For example, woody species that are adapted to megafauna dispersal (67) may still be experiencing slow declines (90), depending on whether megafauna have been substituted by smaller wild animals, domestic livestock, or humans. ...
Article
Until recently in Earth history, very large herbivores (mammoths, ground sloths, diprotodons, and many others) occurred in most of the World's terrestrial ecosystems, but the majority have gone extinct as part of the late-Quaternary extinctions. How has this large-scale removal of large herbivores affected landscape structure and ecosystem functioning? In this review, we combine paleo-data with information from modern exclosure experiments to assess the impact of large herbivores (and their disappearance) on woody species, landscape structure, and ecosystem functions. In modern landscapes characterized by intense herbivory, woody plants can persist by defending themselves or by association with defended species, can persist by growing in places that are physically inaccessible to herbivores, or can persist where high predator activity limits foraging by herbivores. At the landscape scale, different herbivore densities and assemblages may result in dynamic gradients in woody cover. The late-Quaternary extinctions were natural experiments in large-herbivore removal; the paleoecological record shows evidence of widespread changes in community composition and ecosystem structure and function, consistent with modern exclosure experiments. We propose a conceptual framework that describes the impact of large herbivores on woody plant abundance mediated by herbivore diversity and density, predicting that herbivore suppression of woody plants is strongest where herbivore diversity is high. We conclude that the decline of large herbivores induces major alterations in landscape structure and ecosystem functions.
... Indeed, grazing by megaherbivores may have been crucial for maintaining the vast 'mammoth steppe' of the Pleistocene (Zimov et al. 1995, Johnson 2009), a biome absent today. And work investigating the ecology and life history characteristics of tropical and temperate plants has proposed that numerous adaptations for dispersal or regrowth arose in response to foraging by now extinct megafauna (Janzen and Martin 1982, Wing and Tiffney 1987, Barlow 2001. ...
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Recent studies connecting the decline of large predators and consumers with the disintegration of ecosystems often overlook that this natural experiment already occurred. As recently as 14 ka, tens of millions of large-bodied mammals were widespread across the American continents. Within 1000 yr of the arrival of humans, ∼80% were extinct including all > 600 kg. While the cause of the late Pleistocene (LP) extinction remains contentious, largely overlooked are the ecological consequences of the loss of millions of large-bodied animals. Here, we examine the influence of the LP extinction on a local mammal community. Our study site is Hall’s Cave in the Great Plains of Texas, which has unparalleled fine-grained temporal resolution over the past 20 ka, allowing characterization of the community before and after the extinction. In step with continental patterns, this community lost 80% of large-bodied herbivores and 20% of apex predators at the LP extinction. Using tightly constrained temporal windows spanning full glacial to modern time periods and comprehensive faunal lists, we reconstruct mammal associations and body size distributions over time. We find changes in alpha and beta diversity, and in the statistical moments associated with periods of climate change as well as with the LP extinction event. Additionally, there is a fundamental change in the composition of herbivores, with grazers being replaced by frugivores/granivores starting about 15 ka; the only large-bodied grazer remaining today is the bison Bison bison. Moreover, the null model program PAIRS reveals interesting temporal patterns in the disassociation or co-occurrence of species through the terminal Pleistocene and Holocene. Extinct species formed more significant associations than modern ones, and formed more aggregated pairs than do modern species. Further, negative species associations were about three times stronger than positive.
... S. langsdorffii seeds are not covered by a thick and hard endocarp or seed coat, quite the opposite; fruit ripening occurs in the same time of year (and only once a year); and there are no reports for consumption by introduced large herbivores, such as horses, pigs or cattle. Barlow (2000) added several fruit traits related to megafaunal dispersal syndrome and wrote: "…If seeds are large but not physically protected, they will be chemically protected by bitter, peppery, or nauseating toxins. Big mammals quickly learn not to chew such seeds…". ...
Article
• Diaspore structure has been hypothesized to play a role in seed viability and/or germination of recalcitrant seeds, especially for Swartzia langsdorffii. Thus, this work aims to (1) investigate in situ contribution of pericarp and aril on seed viability and germination, and (2) identify morphoanatomical traits of Swartzia langsdorffii diaspores that aid its desiccation-sensitive seed to remain viable. • The role of the pericarp and aril in seed survival and germination was investigated by placing the whole fruit, whole seeds (arillate seed) and bare seeds (without aril) on the soil in the forest understory, assessing germination, emergence, dead, firm and predated seeds; and water content (WC) of pericarps, arils and seeds. Correlation analysis was performed between environmental variables and physiological parameters. Histochemical features of diaspores were also investigated. • Pericarp WC was reduced after several months, while the aril maintained its WC, even covering seeds for justone month. Seeds did not lose water even without the presence of the pericarp and aril. However, the presence of pericarp promoted seed WC, viability and germination long after dispersal. The embryo presented a thickened outer periclinal cell wall. • Pericarp and aril are not essential to prevent water loss in seeds, but help to retain seed moisture, favouring viability maintenance and promoting germination during the rainy season. Morphoanatomical features of seeds are suggested as main factors to reduce water loss. Survival of these desiccation-sensitive seeds upon dispersal during the dry season appears to be facilitated by multiple diaspore features that prevent viability loss.
... The avocado fruit accumulates oil instead of sugar unlike most fruits, probably as a consequence of co-evolutionary processes developed with ancient neotropical megafauna that became extinct about 30,000-11,000 years ago [5]. Avocado has been described as the most nutritious of all fruits [3], as the mature fruit flesh of avocado contains about 20 % beneficial fatty acids, 6 % carbohydrates, 2 % protein, and vitamin precursors and antioxidants such as carotenoids and vitamins E, C, B2, B12, B1, K and D [6]. ...
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Avocado (Persea americana) is an economically important tropical fruit considered to be a good source of fatty acids. Despite its importance, the molecular and cellular characterization of biochemical and developmental processes in avocado is limited due to the lack of transcriptome and genomic information. The transcriptomes of seeds, roots, stems, leaves, aerial buds and flowers were determined using different sequencing platforms. Additionally, the transcriptomes of three different stages of fruit ripening (pre-climacteric, climacteric and post-climacteric) were also analyzed. The analysis of the RNAseqatlas presented here reveals strong differences in gene expression patterns between different organs, especially between root and flower, but also reveals similarities among the gene expression patterns in other organs, such as stem, leaves and aerial buds (vegetative organs) or seed and fruit (storage organs). Important regulators, functional categories, and differentially expressed genes involved in avocado fruit ripening were identified. Additionally, to demonstrate the utility of the avocado gene expression atlas, we investigated the expression patterns of genes implicated in fatty acid metabolism and fruit ripening. A description of transcriptomic changes occurring during fruit ripening was obtained in Mexican avocado, contributing to a dynamic view of the expression patterns of genes involved in fatty acid biosynthesis and the fruit ripening process.
... Both large fruits and large thorns are believed to be adaptations to the former presence of large herbivores, namely of the late Pleistocene. The species is therefore thought to be shaped by past evolutionary forces and fit for a biological environment that no longer exists (Barlow, 2001(Barlow, , 2002Bronaugh, 2010). ...
Article
Object-based learning is an approach that aims to foster observational skills and sensory awareness. Paradoxical plant objects that do not lend themselves to all-too-easy explanations and interpretations can be used to practice the search for ecological explanations and the formation of evolutionary hypotheses. They can be the basis of particularly fruitful and rewarding learning experiences. Gleditsia triacanthos, the honey locust, is a commonly planted ornamental tree. It exhibits striking structures of defense against – and fruit that point to a mutualism with – large animals. These structures, possibly developed in coevolution with Pleistocene faunas, invite a discussion of the complex, neither fully antagonistic nor fully mutualistic, relationships between plants and animals. © 2019 National Association of Biology Teachers. All rights reserved.
... Speciation may be influenced by dispersal dynamics as the basis of gene flow within and between populations (Loveless & Hamrick, 1984;Herrera, 1989;Eriksson & Bremer, 1992;Dodd et al., 1999;Kisel & Barraclough, 2010;Theim et al., 2014), although the impacts of seed dispersal must be separated from those of gamete dispersal via pollination (Grant, 1949). Dispersal dynamics may also affect extinction susceptibility, via the potential impact on conspecific competition and pest/disease exposure (Janzen, 1970;Connell, 1971), the well-documented link between extinction risk and geographic range size (Gaston, 2003 and references therein), and vector reliability (Janzen & Martin, 1982;Barlow, 2000;Donatti et al., 2007;Guimarães et al., 2008;Johnson, 2009). If these relationships among geographic range, gene flow, speciation, and extinction risk are strong, then plant clades with different types of dispersal are expected to exhibit differences in macroevolutionary patterns through differential diversification. ...
Article
As a primary determinant of spatial structure in angiosperm populations, fruit dispersal may impact large-scale ecological and evolutionary processes. Essential to understanding these mechanisms is an accurate reconstruction of dispersal mode over the entire history of an angiosperm lineage. A total-evidence phylogeny is presented for most fossil fruit and all extant genera in Fagales over its c. 95 million yr history. This phylogeny - the largest of its kind to include plant fossils - was used to reconstruct an evolutionary history directly informed by fossil morphologies and to assess relationships among dispersal mode, biogeographic range size, and diversification rate. Reconstructions indicate four transitions to wind dispersal and seven to biotic dispersal, with the phylogenetic integration of fossils crucial to understanding these patterns. Complexity further increased when more specialized behaviors were considered, with fluttering, gliding, autorotating, and scatter-hoarding evolving multiple times across the order. Preliminary biogeographic analyses suggest larger range sizes in biotically dispersed lineages, especially when pollination mode was held constant. Biotically dispersed lineages had significantly higher diversification rates than abiotically dispersed lineages, although transitions in dispersal mode alone cannot explain all detected diversification rate shifts across Fagales. © 2015 The Authors. New Phytologist © 2015 New Phytologist Trust.
... Carpenter et al. (2018a) compared the seeds present in moa gizzards and coprolites to show that large seeds (> 3.3 mm) appear to have been destroyed during passage through the digestive tract. This likely explains why there are no large anachronistic 'moa' fruits, such as those seen on other landmasses with extinct herbivores (Barlow 2000), and in extant associations such as with the southern cassowary (Casuarius casuarius) in the rainforests of north Queensland, Australia (Stocker & Irvine 1983). The largest fruit in the New Zealand flora can be dispersed by the extant kererū (Hemiphaga novaeseelandiae; Clout & Hay 1989) and probably other birds such as weka (Gallirallus australis; Carpenter et al 2018b). ...
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For tens of millions of years the ratite moa (Aves: Dinornithiformes) were the largest herbivores in New Zealand’s terrestrial ecosystems. In occupying this ecological niche for such a long time, moa undoubtedly had a strong influence on the evolution of New Zealand’s flora and played important functional roles within ecosystems. The extinction of moa in the 15th century ce therefore marked a significant event in New Zealand’s biological history, not only in terms of biodiversity loss, but in the loss of an evolutionarily and ecologically distinct order of birds. Understanding the full extent and magnitude of this loss, and its implications for New Zealand ecosystems, depends upon a detailed knowledge of moa diets. Over the past 100 years, periodic discoveries of preserved moa gizzard content and coprolites (ancient preserved dung) have gradually begun to shed light on the diets of moa and their roles within New Zealand ecosystems. Here, we review how the study of such samples has shaped our understanding of moa diets through time. We then provide a synthesis of current knowledge about moa diets, including summarising 2755 records of plant remains from 23 moa gizzard contents and 158 moa coprolites. A clear picture is now emerging of distinct differences between the feeding ecologies of moa species, which together with differences in habitat preferences facilitated niche partitioning. Such insights provide empirical data to inform the debate surrounding the role of moa herbivory in the evolution of distinctive plant traits within the New Zealand flora. These data also help identify specific ecological functions and roles that have been lost due to the extinction of moa, and resolve to what extent these could be replaced via surrogate taxa.
... According to Janzen and Martin (1982), domestic megafauna may replicate some of the interactions between fruit trees and extinct megafauna. The introduction of such domestic animals from Europe to America provided suitable dispersers for megafaunal fruits and seeds (Janzen and Martin, 1982;Barlow, 2000). Livestock may have increased guava dispersal by favoring the establishment of the guava populations in areas where the species previously did not occur and enhancing gene flow. ...
Article
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Guava (Psidium guajava L., Myrtaceae) is a Neotropical fruit that is widely consumed around the world. However, its evolutionary history and domestication process are unknown. Here we examine available ecological, taxonomic, genetic, archeological, and historical evidence about guava. Guava needs full sunlight, warm temperatures, and well-distributed rainfall throughout the year to grow, but tolerates drought. Zoochory and anthropochory are the main forms of dispersal. Guava’s phylogenetic relationships with other species of the genus Psidium are unclear. A group of six species that share several morphological characteristics are tentatively accepted as the Psidium guajava complex. DNA analyses are limited to the characterization of crop genetic diversity within localities and do not account for possible evolutionary and domestication scenarios. A significant amount of archeological information exists, with a greater number and older records in South America than in Mesoamerica, where there are also numerous historical records. From this information, we propose that: (1) the guava ancestor may have originated during the Middle or Late Miocene, and the savannas and semi-deciduous forests of South America formed during the Late Pleistocene would have been the most appropriate ecosystems for its growth, (2) the megafauna were important dispersers for guava, (3) dispersal by humans during the Holocene expanded guava’s geographic range, including to the southwestern Amazonian lowlands, (4) where its domestication may have started, and (5) with the European conquest of the Neotropics, accompanied by their domestic animals, new contact routes between previously remote guava populations were established. These proposals could direct future research on the evolutionary and domestication process of guava.
... Many paleontologists now recognize that the seed dispersers for plants that produce large fleshy fruits, such as cucurbits and many trees, were now-extinct megafaunal herbivores (Janzen and Martin, 1982;Kistler et al., 2015). Barlow (2002); following Janzen and Martin (1982) referred to these large fruits as evolutionary anachronisms. Notably, paleontologists working in the tropical forests of South America have argued that these large-seed dispersers were gomphotheres and other Pleistocene megafauna (Janzen and Martin, 1982). ...
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The apple (Malus domestica [Suckow] Borkh.) is one of the most economically and culturally significant fruits in the world today, and it is grown in all temperate zones. With over a thousand landraces recognized, the modern apple provides a unique case study for understanding plant evolution under human cultivation. Recent genomic and archaeobotanical studies have illuminated parts of the process of domestication in the Rosaceae family. Interestingly, these data seem to suggest that rosaceous arboreal crops did not follow the same pathway toward domestication as other domesticated, especially annual, plants. Unlike in cereal crops, tree domestication appears to have been rapid and driven by hybridization. Apple domestication also calls into question the concept of centers of domestication and human intentionality. Studies of arboreal domestication also illustrate the importance of fully understanding the seed dispersal processes in the wild progenitors when studying crop origins. Large fruits in Rosaceae evolved as a seed-dispersal adaptation recruiting megafaunal mammals of the late Miocene. Genetic studies illustrate that the increase in fruit size and changes in morphology during evolution in the wild resulted from hybridization events and were selected for by large seed dispersers. Humans over the past three millennia have fixed larger-fruiting hybrids through grafting and cloning. Ultimately, the process of evolution under human cultivation parallels the natural evolution of larger fruits in the clade as an adaptive strategy, which resulted in mutualism with large mammalian seed dispersers (disperser recruitment).
... rodent, lagomorphs and others). this behavior is generally used for nutrition (geophagy) and sharpening of the teeth with continuous growth (Brain 1981, Johnson 1985, Barlow 2000, Sabatini and Costa 2001, Borrini et al. 2012). Yet, geophagy and gnawing cannot be identified based only on tooth traces. ...
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We describe the first occurrence of biogenic traces made by mammals within an iron formation cave located in the Serra da Ferrugem Ridge, in Southeastern Brazil. These bioerosions are tooth traces produced in boulders, walls and floor within the cave. The traces occur as sets of two or more grooves, which are highly variable in size. The grooves were compared to tooth traces artificially produced by imprinting the incisors of different mammal species collected in the cave region on soft clay. Among those, the following taxa are potential tracemakers: Akodon sp., Oligoryzomys sp., Necromys lasiurus, Rhipidomys mastacalis, Oecomys gr. concolor, Trinomys moojeni, and Hydrochoerus hydrochaeris. The age of the traces is unknown; therefore, any discussion on its fossil nature is circumstantial. Regardless of its relevance to paleontology, the presence of ichnological features should be considered as an additional cave value, according to the current Brazilian legislation regarding cave protection.
... Ecological anachronisms are adaptations present in living organisms that evolved in response to past interactions with extinct species (Barlow, 2002). One classic example of an ecological anachronism is the large, fleshy fruits of many neotropical trees in Central and South America (Janzen and Martin, 1982). ...
Article
Herbivory is an important ecological process than has influenced the evolution of grassland-savannah systems. The evolutionary history of herbivory largely determines how resilient plant communities are to herbivory, with communities evolving with a long history generally possessing plant adaptations that make them able to cope with such disturbance. Thus, the evolutionary history of herbivory can serve as an indicator of a system’s resilience to modern grazing. Determining this history, however, is problematic because quantitative measures of herbivory and knowledge of plant origin are needed over appropriate evolutionary time frames. Paleoecology offers a useful framework for assessing this evolutionary history of plant-herbivore interactions. The Patagonian steppe is a phytogeographic province of South America whose evolutionary history of herbivory has been debated. Past discussions have focused completely on the abundance of its sole large ungulate herbivore–the guanaco (Lama guanicoe Müller 1776)–since European colonization of the continent. Here we use a paleoecological approach to reconstruct the evolutionary history of herbivory and plant evolution in the Patagonian steppe over a much broader, geologic time frame (Cenozoic) to shed light on the matter. We examine the role of past climate, ancient megafauna, and guanaco in shaping the vegetation and briefly discuss how present land use may be misaligned with the steppe’s evolutionary history of herbivory.
... As such, it was hypothesised that divaricate 521 species may not be adapted to the current browsing pressure of introduced mammals because their 522 costly ratite-resistant architecture was thought to be useless against mammals (Bond et al. 2004). 523 Diamond (1990) imported the concept of "ghost" from overseas cases of anachronisms (later 524 reviewed by Barlow 2000) when defending the hypothesis that divaricates are adapted to a now-525 extinct fauna. However, the conclusions of Pollock et al. (2007) about the preferences of ungulates 526 for New Zealand woody plants, as well as a study by Lusk (2014) on the regeneration of divaricate 527 and non-divaricate species in a forest remnant that had been subject to ungulate browsing for 528 decades, indicate that the divaricate habit may also be effective in deterring mammal browsing. ...
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The evolution of divaricate plants in New Zealand has been the subject of long-running debate among botanists and ecologists. Hypotheses about this remarkable case of convergent evolution have focused mainly on two different types of selective pressures: the Plio-Pleistocene advent of cool, dry climates, or browsing by now-extinct moa. Here, we review the scientific literature relating to the New Zealand divaricates, and present a list of 81 taxa whose architectures fall on the divaricate habit spectrum. We recommend a series of standardised terms to facilitate clear communication about these species. We identify potentially informative areas of research yet to be explored, such as the genetics underlying the establishment and control of this habit. We also review work about similar plants overseas, proposing a list of 47 such species as a first step towards more comprehensive inventories; these may motivate further studies of the ecology, morphology and evolutionary history of these overseas plants which could help shed light on the evolution of their New Zealand counterparts. Finally, we compile published divergence dates between divaricate species and their non-divaricate relatives, which suggest that the divaricate habit is fairly recent (< 10 My) in most cases.
... Nonetheless, such changes do not always result in evolutionary transition in that one species. Thus, we cannot assume that a species' traits at any time of its evolutionary history necessarily reflect selective forces that acted on it at (or shortly before) that time [55,56]. Plant adaptations to herbivory are not an exception. ...
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Herbivory is fundamental in ecology, being a major driver of ecosystem structure and functioning. Plant Si and phytoliths play a significant antiherbivory role, the understanding of which and of its evolutionary context will increase our understanding of this phenomenon, its origins, and its significance for past, extant, and future ecosystems. To achieve this goal, we need a superdisciplinary evolutionary framework connecting the role of Si in plant–herbivore interactions, in global processes, and in plant and herbivore evolution. To do this properly, we should acknowledge and incorporate into our work some basic facts that are too often overlooked. First, there is great taxonomic variance both in plant Si contents, forms, and roles, but also in herbivore responses, dietary preferences, and in fossil evidence. Second, species and their traits, as well as whole ecosystems, should be seen in the context of their entire evolutionary history and may therefore reflect not only adaptations to extant selective factors but also anachronistic traits. Third, evolutionary history and evolutionary transitions are complex, resulting in true and apparent asynchronisms. Fourth, evolution and ecology are multiscalar, in which various phenomena and processes act at various scales. Taking these issues into consideration will improve our ability to develop this needed theoretical framework and will bring us closer to gaining a more complete understanding of one of the most exciting and elusive phenomena in plant biology and ecology.
... Surprisingly, there are no known predators, including insects, which attack Gy. dioica seeds in its native range (Dardenne et al. 1972b;Janzen 1976). The predator absence in Gy. dioica could be an evolutionary anachronism (Barlow 2000;Gill 2014); the tough seeds are too difficult for most animals and insects to chew through, in addition to the chemical defense. As the seeds are too heavy for either wind or water dispersal, they might have been eaten by large mammals, such as mammoths and mastodons, that could have helped their germination. ...
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Chapter
The strongest advocate of the defensive role of red and yellow autumn leaf coloration as a case of Zahavi’s handicap principle was Dr. Marco Archetti. After the unexpected death of Professor Bill Hamilton in the year 2000, Marco Archetti was practically left by himself to carry the red/yellow autumn leaf handicap flag. As a Post Doc at Oxford University, he arranged a small conference on the autumn leaf color issue in Oxford’s St. John’s College in March 2008. In that conference, attended by plant physiologists, plant and animal ecologists, and several scientists that specialised in the sensory systems of herbivorous insects, the various and even contrasting views concerning the biology of autumn leaf coloration were presented. Two days of focused discussions vividly illuminated the need for a well-balanced multidisciplinary understanding, and that such a review had to be written and published by the group, and indeed, a year later it was published in Trends in Ecology and Evolution (Archetti et al. 2009a). Among other things, it became clear to all the scientists involved that yellow and red autumn leaves are in a way two different strategies (although not always and not concerning all defensive aspects) and that at least concerning the co-evolutionary hypothesis, they should be treated separately. Moreover, it also became clear that both physiology and ecolgy are involved and that the gains from autumn coloration do not stem from only one of these very different function types, and also that aposematic signaling is involved as well. This understanding was an important step to lower the flames that blazed in the arena of investigating the evolution and functions of colorful autumn leaves, but this critical understanding and even later progress did not eliminate the need for an even better understanding of the complicated scientific question of the evolution of autumn leaf colors.
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