共查询到20条相似文献，搜索用时 31 毫秒
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Mae K. A. Johnson Oscar P. J. Johnson Reagan A. Johnson Marc T. J. Johnson 《Ecology and evolution》2020,10(3):1639-1647
- Dispersal has important ecological and evolutionary consequences for populations, but understanding the role of specific traits in dispersal can be difficult and requires careful experimentation. Moreover, understanding how humans alter dispersal is an important question, especially on oceanic islands where anthropogenic disturbance through species introductions can dramatically alter native ecosystems.
- In this study, we investigated the functional role of spines in seed dispersal of the plant caltrop (Tribulus cistoides L., Zygophyllaceae) by anthropogenic dispersal agents. We also tested whether humans or wildlife are more important seed dispersers of T. cistoides on the Galápagos.
- Tribulus cistoides is found on tropical mainland and oceanic island habitats. The dispersal structure of T. cistoides is called a mericarp, and they are typically protected by one pair of upper spines and a second pair of lower spines, but the presence and size of spines varies within and between populations. On the Galápagos, the upper and lower spines protect mericarps from seed predation by Darwin's finches. We tested whether spines play a dual role in dispersal by factorially manipulating the presence/absence of the upper and lower spines to simulate natural variation in mericarp morphology.
- The upper spines greatly facilitated seed dispersal, whereas the lower spines had no discernible effect on dispersal. The presence of upper spines increased dispersal rate on shoes by pedestrians 23‐fold, on fabrics (e.g., towels) and cars by nearly twofold, and the presence of upper spines increased dispersal distance by cars sixfold. When comparing dispersal rates in habitats with high (roads and foot paths) versus low (arid forest) anthropogenic activity, dispersal rates were demonstrably higher in the habitats with more human activity.
- These results have important implications for understanding the ecology and evolution of plant dispersal in the Anthropocene. Spines on the fruits of T. cistoides play important functional roles in anthropogenic dispersal, whereas native and introduced wildlife plays a minor role in dispersal on inhabited islands of the Galápagos. Our results imply that seed predators and humans are jointly shaping the ecology and evolution of contemporary populations of T. cistoides on the Galápagos.
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KENNETH A. KNEIDEL 《Ecological Entomology》1983,8(2):163-169
ABSTRACT.
- 1 Experiments were conducted to test for the presence of fugitive species and priority effects among the Diptera species that breed in dead slug carcasses (Limax maximus L.).
- 2 Slug carcasses exposed for only 1 day produced a community that was very similar to that bred from carcasses exposed until fully decomposed. This suggests that competitive ability and dispersal ability are positively correlated in this system.
- 3 The colonization of flies was manipulated by transferring larvae of the phorid, Megaselia scalaris Loew, to carcasses before and after they were exposed in the field. A‘priority effect’was demonstrated in that M.scalaris survived better and had a stronger impact on other species when it was the first species to colonize slug carcasses.
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M. Kotilínek T. T &#x;itelov J. Ko&#x;nar P. Fibich L. Hemrov P. Koutecký Z. Münzbergov J. Jerskov 《Plant biology (Stuttgart, Germany)》2020,22(3):522-532
- Species with vast production of dust‐like windborne seeds, such as orchids, should not be limited by seed dispersal. This paradigm, however, does not fit recent studies showing that many sites suitable for orchids are unoccupied and most seeds land close to their maternal plant. To explore this issue, we studied seed dispersal and gene flow of two forest orchid species, Epipactis atrorubens and Cephalanthera rubra, growing in a fragmented landscape of forested limestone hills in southwest Bohemia, Czech Republic.
- We used a combination of seed trapping and plant genotyping methods (microsatellite DNA markers) to quantify short‐ and long‐distance dispersal, respectively. In addition, seed production of both species was estimated.
- We found that most seeds landed very close to maternal plants (95% of captured seeds were within 7.2 m) in both species, and dispersal distance was influenced by forest type in E. atrorubens. In addition, C. rubra showed clonal reproduction (20% of plants were of clonal origin) and very low fruiting success (only 1.6% of plants were fruiting) in comparison with E. atrorubens (25.7%). Gene flow was frequent up to 2 km in C. rubra and up to 125 km in E. atrorubens, and we detected a relatively high dispersal rate among regions in both species.
- Although both species occupy similar habitats and have similar seed dispersal abilities, C. rubra is notably rarer in the study area. Considerably low fruiting success in this species likely limits its gene flow to longer distances and designates it more sensitive to habitat loss and fragmentation.
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Overcoming urban stream syndrome: Trophic flexibility confers resilience in a Hawaiian stream fish 
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下载免费PDF全文 Peter J. Lisi Evan S. Childress Roderick B. Gagne Ernie F. Hain Brad A. Lamphere Ryan P. Walter J. Derek Hogan James F. Gilliam Michael J. Blum Peter B. McIntyre 《Freshwater Biology》2018,63(5):492-502
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Reproductive biology and pollination ecology of Triplaris gardneriana (Polygonaceae): a case of ambophily in the Brazilian Chaco 下载免费PDF全文
下载免费PDF全文 - Triplaris gardneriana (Polygonaceae) is a dioecious pioneer tree reported as insect‐pollinated, despite possessing traits related to anemophily. Here, we analyse the possible roles of insects and wind on the pollination of this species to establish whether the species is ambophilous.
- We carried out observations of floral biology, as well as on the frequency and behaviour of pollinators visiting flowers in a population of T. gardneriana in the Chaco vegetation of Brazil. We conducted experimental pollinations to determine the maternal fertility of female plants and whether they were pollen‐limited, and we also conducted aerobiological experiments to provide evidence of how environmental factors influence atmospheric pollen dispersal.
- The population comprised an area of approximately 152.000 m2 and was composed of 603 female and 426 male plants (sex ratio = 0.59:0.41). We observed 48 species of insects visiting flowers of T. gardneriana, of which the bees Scaptotrigona depilis and Apis mellifera scutellata were the most effective pollinators. We recorded pollen grains dispersed by wind on 74% of the glass slides placed on females, located at different distances (1–10 m) from male plants.
- Airborne pollen concentration was negatively correlated with relative humidity and positively correlated with temperature. Our observations and experimental results provide the first evidence that T. gardneriana is an ambophilous species, with pollen dispersal resulting from both animal and wind pollination. This mixed pollination strategy may be adaptive in T. gardneriana providing reproductive assurance during colonisation of sites with different biotic and abiotic conditions.
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Daniela Lupi Serena Malabusini Silvia de Milato Alessandro Luigi Heinzl Enrico Ruzzier Luciano Bani Sara Savoldelli Costanza Jucker 《Agricultural and Forest Entomology》2023,25(4):511-521
- Psacothea hilaris hilaris is an exotic cerambycid detected in Lombardy (northern Italy) in 2005 and now established and undergoing an expansion phase. The species constitutes a serious pest for Ficus spp. and Morus spp.
- The aim of this work is to update the distribution area of the species in Italy, investigating its expansion over 16 years. Data were acquired through the authors' direct field records and community science, by data mining on national and international web platforms and social networks. Reports were analysed and GPS points plotted in ArcMap 10.8.1 to obtain distribution maps.
- Of the records collected, 34% were acquired during field surveys, 22% via e-mail and 44% through on-line forums and social networks.
- Adults of P. h. hilaris showed a long period of activity, from April to the beginning of December, with a peak of presence from June to September. The presence of the pest has been ascertained over six provinces in Lombardy covering an area estimated at more than 1750 km2 in 2021. New detections occurred within 2 km of a known infestation from the previous year in 41.6% of cases, and between 2 and 4 km away in 37.7% of cases. The mean rate of range expansion estimated from reported records was 3.17 ± 0.33 km/year from 2010 to 2021. After an initial phase of settlement, the insect is now spreading southward.
- Given the relevant phytosanitary interest that the species may have for fig plants in Italy and in the Mediterranean Basin, it is fundamental to deepen the knowledge about its flight biology, dynamics and active dispersal capabilities in order to estimate the future range expansion.
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- 1 An extensive investigation was carried out into the structure of a large, effectively continuous population of Yponomeuta padellus Latreille, feeding on hawthorn, Crataegus monogyna, and blackthorn, Prunus spinosa.
- 2 Mark—recapture studies were used to obtain direct estimates of the male dispersal rate, σ, in two successive years.
- 3 Dispersal was found to be extremely localized with respect to the total area of the study population. Estimates of u ranged from a minimum of 2.47 m to a maximum of 12.5 m.
- 4 Limited dispersal could be an important factor governing the genetic differentiation of Y.padellus populations, and its implications for the supposed existence of host races in this species are discussed.
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- Alpine rivers are, despite anthropogenic water flow regulation, still often highly dynamic ecosystems. Plant species occurring along these rivers are subject to ecological disturbance, mainly caused by seasonal flooding. Gypsophila repens typically grows at higher altitudes in the Alps, but also occurs at lower altitudes on gravel banks directly along the river and in heath forests at larger distances from the river. Populations on gravel banks are considered non‐permanent and it is assumed that new individuals originate from seed periodically washed down from higher altitudes. Populations in heath forests are, in contrast, permanent and not regularly provided with seeds from higher altitudes through flooding. If the genetic structure of this plant species is strongly affected by gene flow via seed dispersal, then higher levels of genetic diversity in populations but less differentiation among populations on gravel banks than in heath forests can be expected.
- In this study, we analysed genetic diversity within and differentiation among 15 populations of G. repens from gravel banks and heath forests along the alpine River Isar using amplified fragment length polymorphisms (AFLP).
- Genetic diversity was, as assumed, slightly higher in gravel bank than in heath forest populations, but genetic differentiation was, in contrast to our expectations, comparable among populations in both habitat types.
- Our study provides evidence for increased genetic diversity under conditions of higher ecological disturbance and increased seed dispersal on gravel banks. Similar levels of genetic differentiation among populations in both habitat types can be attributed to the species' long lifetime, a permanent soil seed bank and gene flow by pollinators among different habitats/locations.
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Evolutionary divergence in freshwater insects with contrasting dispersal capacity across a sea of desert 下载免费PDF全文
下载免费PDF全文 Emma Razeng Amy E. Smith Katherine A. Harrisson Alexandra Pavlova Thuy Nguyen Adrian Pinder Phil Suter Jeff Webb Michael G. Gardner Jayne Brim Box Ross Thompson Jenny Davis Paul Sunnucks 《Freshwater Biology》2017,62(8):1443-1459
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Patrick Heidbüchel Maria Sachs Nadia Hamzehian Andreas Hussner 《Freshwater Biology》2020,65(11):1936-1949
- The dispersal of aquatic plant propagules is highly facilitated in streams due to flow. As many aquatic plants predominantly spread through vegetative propagules, the specific retention and thus drift distance of dispersed plant fragments largely contribute to the rapid spread along the course of a stream.
- We determined fragment retention for four aquatic plant species (Elodea canadensis, Myriophyllum spicatum, Ceratophyllum demersum, Salvinia natans; representing four different common morpho-structural groups) in sections of small to medium-sized German streams with different levels of stream sinuosity.
- The number of fragments showed a logistic decline over drift distance. In two small streams, 90% of drifting fragments were retained at distances (D90) of only 5–9 m and 19–70 m, while higher D90 values of 116–903 m and 153–2,367 m were determined for sections of a medium-sized stream. The likelihood of retention thereby decreased significantly with increasing stream size and was reduced in straightened stream sections.
- Differences in retention were more strongly related to fragment buoyancy rather than fragment size and morphology. Increasing buoyancy significantly lowered the likelihood of fragment retention over drift distance by a factor of 3–8, whereas contrasting effects were documented for size and morphology of fragments.
- The relevance of different obstacles was highly stream section-specific and depended on obstacle abundance, distribution, and the degree of submergence/emergence.
- Our findings elucidate the dynamic retention patterns of plant fragments and highlight the strong interplay between extrinsic (stream) and intrinsic (fragment) properties. We conclude that straightened lowland streams of intermediate size promote the rapid dispersal of invasive aquatic plants and are particularly prone to invaders producing large amounts of small and highly buoyant plant fragments. Information on the species-specific fragment colonisation dynamics in the field is further required to improve our understanding of the vegetative dispersal capacity of invasive aquatic plants in stream ecosystems.