Endozoochory of seeds and invertebrates by migratory waterbirds in Oklahoma, USA (original) (raw)
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Darwiniana Nueva Serie, 2008
Se estudiaron diferentes atributos funcionales de 2 pajonales de Schoenoplectus californicus (C. A. Mey) Sójak que son muy similares en su estructura y especie dominante, pero aparecen en los extremos opuestos a lo largo de un gradiente de influencia fluvial-mareal en el Bajo Delta del río Paraná. Los resultados mostraron una productividad primaria neta aérea (PPNA) significativamente más alta en el pajonal afectado directamente por la marea (1999.41 ± 211.97 g m-2 año-1). En el sitio aguas arriba, menos proclive a la inundación por mareas, S. californicus tuvo una menor PPNA (1299.17 ± 179.48 g m-2 año-1) y el sistema mostró una mayor capacidad para retener la biomasa producida dentro del pajonal, con cantidades significativamente mayores de biomasa muerta en pie (1316.00 ± 336.01 vs. 112.40 ± 55.05 g m-2) y mayores contenidos de materia orgánica en el suelo (16.20 ± 0.12 % vs. 0.70 ± 0.08 %). Los resultados obtenidos en este trabajo sugieren que los flujos superficiales de alta energía pueden cambiar el funcionamiento de estos pajonales, de un sistema estable acumulador de materia orgánica a un pajonal de rápido crecimiento, con altas tasas de acumulación de sedimentos minerales. Palabras clave. Delta del río Paraná, humedales mareales de agua dulce, productividad primaria neta, Schoenoplectus.
Hydrobiologia (2010) 654, 125–136
The objective of this study was to evaluate the influences of detritus from the leaves of different species, and of exposure time on invertebrate colonization of leaves in a shaded Cerrado stream. We hypothesized that the exposure time is the main factor that influences the colonization of leaves by invertebrates. We used leaves of five tree species native to the Brazilian Cerrado: Protium heptaphyllum and Protium brasiliense (Burseraceae), Ocotea sp. (Lauraceae), Myrcia guyanensis (Myrtaceae), and Miconia chartacea (Melastomataceae), which are characterized by their toughness and low-nutritional quality. Litter bags, each containing leaves from one species, were placed in a headwater stream and removed after 7, 15, 30, 60, 90, and 120 days. The dominant taxon was Chironomidae, which comprised ca. 52% of all organisms and ca. 20% of the total biomass. The taxonomic richness of colonizing organisms did not vary among the leaf species. However, the density and biomass of the associated organisms varied differently among the kinds of detritus during the course of the incubation. The collector-gatherers and shredders reached higher densities in the detritus that decomposed more rapidly (Ocotea sp. and M. guyanensis), principally in the more advanced stages of colonization. The collector-filterers reached higher densities in the detritus that decomposed more slowly (P. heptaphyllum, P. brasiliense, and M. chartacea), principally in the initial stages of incubation. A cluster analysis divided the detritus samples of different leaf species according to the exposure time (initial phase: up to 7 days; intermediate phase: 7-30 days; advanced phase: 30-120 days), suggesting some succession in invertebrate colonization, with differences in taxon composition (indicator taxa analysis). These results suggest that regardless of the leaf-detritus species, exposure time was the main factor that influenced the colonization process of aquatic invertebrates.
Freshwater Biology, 2023
1. We review progress in our understanding of the importance of waterbirds as dispersal vectors of other organisms, and identify priorities for further research. 2. Waterbirds are excellent for long-distance dispersal (LDD), while other vectors such as fish and mammals disperse similar propagules, but over shorter distances. Empirical studies of internal and external transport by waterbirds have shown that the former mechanism is generally more important. Internal transport is widely recognized for aquatic plants and aquatic invertebrates with resting eggs, but is also important for other organisms (e.g. terrestrial flowering plants not dispersed by frugivores, bryophytes, tardigrades, fish eggs). 3. Waterbird vectors are also important in terrestrial habitats, and provide connectivity across terrestrial-aquatic boundaries. There are important differences in the roles of different waterbird species, especially those using different habitats along the aquatic-terrestrial gradient. Early attempts to predict zoochory based on propagule morphology have been found wanting, and more research is needed into how the traits of vectors and vectored organisms (including life-history, dormancy and growth traits) explain dispersal interactions. Experimental studies have focused on the potential of propagules to survive internal or external transport, and research into factors determining the establishment success of propagules after dispersal is lacking. 4. Recent spatially explicit models of seed dispersal by waterbirds should be expanded to include invertebrate dispersal, and to compare multiple bird species in the same landscape. Network approaches have been applied to plant-waterbird dispersal interactions, and these are needed for invertebrates. Genetic studies support effective LDD of plants and invertebrates along waterbird flyways, but there remains a lack of examples at a local scale. Next Generation Sequencing and genomics should be applied to waterbird-mediated dispersal across the landscape. More studies of biogeography, community ecology, or population genetics should integrate waterbird movements at the design stage. 5. Zoochory research has paid little attention to the dispersal of non-pathogenic microbes (both eukaryotic and prokaryotic). Nevertheless, there is evidence that dispersal via avian guts can be central to the connectivity of aquatic microbial metacommunities. More work on microbial dispersal by waterbirds should explore its implications for biogeochemistry, and the interchange with gut flora of other aquatic organisms. In the Anthropocene, the role of migratory waterbirds in LDD of plants and other organisms is particularly important, e.g. compensating for loss of large migratory mammals and fish, allowing native species to adjust their distributions under global heating, and spreading alien species along flyways after their initial introductions by human vectors. Recent technological advances have opened exciting opportunities that should be fully exploited to further our understanding of dispersal by waterbirds.
CARACTERIZACIÓN DEL SUELO EN COLONIAS DE Cynomys mexicanus Merriam, 1892 EN EL NOROESTE DE MÉXICO
Revista Mexicana de Ciencias Forestales, 2018
El perrito de las praderas mexicano (Cynomys mexicanus) es endémico del noreste de México y uno de los mamíferos en riesgo de extinción. A pesar de numerosos estudios sobre la especie, se carece de datos ecológicos, en particular en lo referente a las relaciones que establecen con su hábitat. Recientemente se ha destacado que los pastizales halofíticos de esa región del país están pasando por un proceso de degradación y muestran una baja productividad, como se evidencia por los cambios en la estructura y fisonomía del paisaje. Sin embargo, aunque existe una relación entre la fisonomía de la vegetación y el sustrato subyacente, no hay estudios cabales de las propiedades edáficas de sus colonias. Se planteó la hipótesis de que el perrito de las praderas mexicano ocupa diversos hábitats que son identificados a partir de diferentes características del suelo. En este estudio se analizaron las propiedades físicas y químicas del suelo de 36 colonias de ellos localizad...
Journal of Biogeography, 2015
Aim The bipolar disjunction, a biogeographical pattern defined by taxa with a distribution at very high latitudes in both hemispheres (> 61° N; > 54° S), is only known to occur in about 30 vascular plant species. Our aim was to use the bipolar species Carex arctogena to test the four classic hypotheses proposed to explain this exceptional disjunction: convergent evolution, vicariance, mountain-hopping and direct long-distance dispersal. Location Arctic/boreal and temperate latitudes of both hemispheres. Methods A combination of molecular and bioclimatic data was used to test phylogeographical hypotheses in C. arctogena. Three chloroplast markers (atpF-atpH, matK and rps16) and the nuclear ITS region were sequenced for all species in Carex sections Capituligerae and Longespicatae; Carex rupestris, C. obtusata and Uncinia triquetra were used as outrgroups. Phylogenetic relationships, divergence-time estimates and biogeographical patterns were inferred using maximum likelihood, statistical parsimony and Bayesian inference. Results Carex sections Capituligerae and Longespicatae formed a monophyletic group that diverged during the late Miocene. Two main lineages of C. arctogena were inferred. Southern Hemisphere populations of C. arctogena shared the same haplotype as a widespread circumboreal lineage. Bioclimatic data shows that Southern and Northern Hemisphere populations currently differ in their ecological regimes. Main conclusions Two of the four hypotheses accounting for bipolar disjunctions may be rejected. Our results suggest that direct long-distance dispersal, probably southwards and mediated by birds, best explains the bipolar distribution of C. arctogena.
Editorial: Animal-Mediated Dispersal in Understudied Systems
Frontiers in Ecology and Evolution, 2020
Editorial on the Research Topic Animal-Mediated Dispersal in Understudied Systems Animals disperse many smaller organisms by ingesting, transporting and egesting propagules (endozoochory) or by carrying propagules attached to their exterior (epizoochory). Both forms of animal-mediated dispersal are generally well-studied, but most previous work focused only on a few kinds of species interactions. For example, seed dispersal by frugivorous birds and mammals, scatter-hoarding by small mammals, seed dispersal by ants, and dispersal of grasses and herbs by large herbivores have been investigated in detail. In contrast, other kinds of zoochory remain relatively unexplored, such as dispersal of propagules of aquatic invertebrates, or dispersal by vectors such as granivorous birds, fish, and reptiles. Our current knowledge on zoochory may be biased, overlooking important yet unidentified species interactions. This Research Topic provides 14 new studies on zoochory in understudied dispersal systems to fill this gap. This collection includes reviews, statistical modeling, network analyses, field observations, and analyses of historical data. This identifies new interactions, and presents new methods and ideas for future work. The publications in this Research Topic highlight seven key points or lessons. First, much of the plant dispersal literature is dominated by dispersal syndromes assigned based on the morphology of seeds and fruits. However, many of the studies collected here show that syndromes are not reliable and should not be assumed to reflect actual dispersal mechanisms in the absence of field studies. The "endozoochory syndrome" is generally applied exclusively to plants with a fleshy fruit and equated with "frugivory, " thereby ignoring that many non-fleshy fruits may also be dispersed by endozoochory. This collection demonstrates how a wide variety of plant species generally assumed to rely on abiotic dispersal can be dispersed by endozoochory: Corvids (Green et al.), Cyprinidae fish (Boedeltje et al.), and ungulates (Baltzinger et al.) all disperse seeds without fleshy fruits. Additionally, the epizoochory syndrome often fails to predict what plants are actually dispersed via epizoochory by mammals (Baltzinger et al.). Second, our dispersal topic shows that zoochory is not exclusive to plants, but also applies to an understudied range of other organisms-including animal propagules. Hessen et al. remind us how important zoochory of invertebrates such as cladocerans and copepods by migratory birds is, especially in areas such as the Arctic where species need to shift their distributions quickly due to climate change. Okamura et al. show us in their review that bryozoans have proved to be an excellent model of invertebrate zoochory by waterbirds, since these organisms are detected with
Biological invasions and the study of vertebrate dispersal of plants: Opportunities and integration
Acta Oecologica, 2011
Biological invasions are a key threat to natural ecosystems and consequently a major focus of ecological research. Even though it is dispersal processes that result in the movement of invasive populations through landscapes, dispersal ecology has played a relatively minor role in invasion ecology research. This is particularly true for vertebrate-dispersed plants. To encourage thinking around these issues and a greater involvement of dispersal ecologists in invasion research, we review contributions made to invasion ecology by dispersal ecology and highlight opportunities that the study of biological invasions offers for improving our understanding of dispersal processes. We suggest that by working in the context of invasions dispersal ecologists are not only able to contribute to the development of process-based management but also gain new opportunities for developing and testing predictions in their field. Because biological invasions are perturbations of natural systems they provide excellent opportunities for both natural and manipulative experimentation with potential for a range of forms of replication. Significantly, the need to develop a predictive understanding of population-level patterns of spread in order to manage invasives demands a shift away from studying individual vectors to developing predictions that integrate across all vectors and processes in the dispersal loop. This is a significant development for dispersal ecology and is a major opportunity for dispersal ecologists to contribute to a current environmental issue.
Endozoochory of aquatic ferns and angiosperms by mallards in Central Europe
Journal of Ecology, 2018
1. Modern literature on plant dispersal by birds focuses mainly on the importance of frugivory and scatter-hoarding, yet recent studies show that endozoochory by migratory waterbirds is an important mechanism of long-distance dispersal for a broad range of plants. Nevertheless, there is a lack of empirical field studies that identify the plants dispersed by waterbirds in a comprehensive manner. In particular , so far there are no detailed studies of the level of spatial variation in the plant taxa dispersed by a waterbird vector, and no clear demonstration that aquatic ferns can be dispersed by endozoochory. Consequently, we remain ignorant of the networks of dispersal interactions between granivorous waterbirds and plants. 2. Five sets of faecal samples (total n = 215) were collected from mallards Anas platy-rhynchos on autumn migration in the Hevesi-holm and Balaton regions in Hungary, central Europe. Intact diaspores were extracted, identified and their germinability assessed under standard conditions. The plant communities recorded at different sites were compared with PERMANOVA and other multivariate methods. 3. Macrospores of the floating watermoss Salvinia natans were recorded in 32 samples , and a total of 16 macrospores germinated, providing the first field demonstration of endozoochory of ferns by birds. Of 21 angiosperm taxa recorded (of which eight germinated), 13 were terrestrial species, although the most abundant taxa were aquatic species such as the alkali bulrush Bolboschoenus maritimus and the sago pondweed Potamogeton pectinatus. Two naturalized alien species, the common fig Ficus carica and the hackberry Celtis occidentalis were also recorded. Only four of the taxa had an endozoochory syndrome. The plant taxa dispersed varied at two different spatial scales, with minor but significant differences between samples from sites separated by less than 1 km, and major differences between the two regions separated by c. 220 km. 4. Synthesis. This is a unique study of the spatial variation in plants dispersed by endo-zoochory by a migratory waterfowl species, with a high taxonomic resolution and the first demonstration of avian endozoochory of ferns. We recorded eight taxa not previously reported as dispersed by mallards, showing how more empirical studies are essential, so we can understand which plants are dispersed by migratory birds. We found evidence that networks of interactions between granivorous waterbird vectors and dispersed plants vary spatially.
We evaluated the seed dispersal of Bursera longipes by birds along a successional gradient of tropical dry forest (TDF) in southwestern Mexico. B. longipes is an endemic tree to the TDF in the Balsas basin. The relative abundance of frugivorous birds, their frequency of visits to B. longipes and the number of removed fruits were recorded at three study sites with different stages of forest succession (early, intermediate and mature) characterized by distinct floristic and structural elements. Flycatchers of the Myiarchus and Tyrannus genera removed the majority of fruits at each site. Overall, visits to B. longipes were less frequent at the early successional site. Birds that function as legitimate dispersers by consuming whole seeds and regurgitating or defecating intact seeds in the process also remove the pseudoaril from seeds, thereby facilitating the germination process. The highest germination percentages were recorded for seeds that passed through the digestive system of two migratory flycatchers: M. cinerascens and M. nutingii. Perch plants, mainly composed of legumes (e.g., Eysenhardtia polystachya, Acacia cochliacantha, Calliandra eryophylla, Mimosa polyantha), serve also as nurse plants since the number of young individuals recruited from B. longipes was higher under these than expected by chance. This study shows that Myiarchus flycatchers are the most efficient seed dispersers of B. longipes across all successional stages. This suggests a close mutualistic relationship derived from adaptive processes and local specializations throughout the distribution of both taxa, as supported by the geographic mosaic theory of coevolution.
It was proposed previously that passive dispersal by migratory aquatic birds explain the widespread distribution of many wetland organisms. Several experimental studies have shown that many widespread wetland plant species can be readily dispersed within the guts of Anatidae. However, it is unclear whether plants with a more restricted distribution are able to disperse via waterbirds. This paper addresses the dispersal ability and germination ecology of the little-known Hungarian milkvetch Astragalus contortuplicatus, which occurs on banks of continental rivers and has a limited and unpredictable distribution. To test whether limited capacity for endozoochory by waterfowl could explain the sporadic appearance of this species, we force-fed ten captive mallards (Anas platyrhynchos) with 100 milkvetch seeds each. Droppings were collected for up to 45 h after feeding. Intact and viable seeds were found in the droppings of each mallard, and altogether 24.7% of seeds fed were recovered intact. The proportion of retrieved seeds that germinated (27.0%) was significantly higher than that of untreated control seeds (0.5%), but significantly lower than that of mechanically scarified seeds (96.0%). Retrieved seeds that germinated developed into healthy mature plants. Given the average flight velocity of mallards, seeds of A. contortuplicatus may travel up to 1600 km inside the digestive tract of migrating individuals. Our results suggest that avian vectors may be more important for the dispersal of rare higher plants (especially those with a hard seed-coat) than hitherto considered. Moreover, they suggest that rarity does not necessarily indicate limited dispersal ability, and may instead be explained by specific habitat requirements.