Dispersing Siberian flying squirrels (Pteromys volans) locate preferred habitats in fragmented landscapes

2012 ◽  
Vol 90 (7) ◽  
pp. 885-892 ◽  
Author(s):  
V. Selonen ◽  
I.K. Hanski

In fragmented landscapes, dispersal abilities determine the potential of a species to colonize temporally unoccupied habitats. For example in territorial species, even the high-quality sites will be temporally unoccupied between the death of residents and recolonization by dispersers. This has implications for conservation management, because whether or not unoccupied habitats are worthy of protecting depends on likelihood that these sites will be recolonized in the near future. We analysed the ability of dispersing Siberian flying squirrels ( Pteromys volans (L., 1758)) to locate the preferred habitats. Dispersers encountered many patches of preferred habitat and, in the end, a majority of them successfully settled in these patches. The dispersal distance increased with increasing distance between patches, but settlement in preferred patches and short-term mortality were independent of dispersal distance or distance between available patches. We conclude that dispersers were effective in locating the preferred habitat in fragmented landscapes. Indeed, large interpatch distances partly explain that dispersal distances are longer in flying squirrels than usually observed in similar-sized mammals. For conservation management, our findings encourage managers to protect temporally unoccupied, high-quality habitats in addition to occupied habitats to promote a sustainable habitat network in space and time.

2011 ◽  
Vol 278 (1716) ◽  
pp. 2257-2264 ◽  
Author(s):  
Johanna Lenz ◽  
Wolfgang Fiedler ◽  
Tanja Caprano ◽  
Wolfgang Friedrichs ◽  
Bernhard H. Gaese ◽  
...  

Frugivorous birds provide important ecosystem services by transporting seeds of fleshy fruited plants. It has been assumed that seed-dispersal kernels generated by these animals are generally leptokurtic, resulting in little dispersal among habitat fragments. However, little is known about the seed-dispersal distribution generated by large frugivorous birds in fragmented landscapes. We investigated movement and seed-dispersal patterns of trumpeter hornbills ( Bycanistes bucinator ) in a fragmented landscape in South Africa. Novel GPS loggers provide high-quality location data without bias against recording long-distance movements. We found a very weakly bimodal seed-dispersal distribution with potential dispersal distances up to 14.5 km. Within forest, the seed-dispersal distribution was unimodal with an expected dispersal distance of 86 m. In the fragmented agricultural landscape, the distribution was strongly bimodal with peaks at 18 and 512 m. Our results demonstrate that seed-dispersal distributions differed when birds moved in different habitat types. Seed-dispersal distances in fragmented landscapes show that transport among habitat patches is more frequent than previously assumed, allowing plants to disperse among habitat patches and to track the changing climatic conditions.


Oryx ◽  
2002 ◽  
Vol 36 (3) ◽  
pp. 266-271 ◽  
Author(s):  
Juan Carlos Serio-Silva ◽  
Victor Rico-Gray

We studied changes in germination rates and dispersal distance of seeds of Ficus perforata and F. lundelli dispersed by howler monkeys (Alouatta palliata mexicana), in a small (40 ha) ‘disturbed’ and a larger (>600 ha) ‘preserved’ tropical rainforest in southern Veracruz, Mexico. The interaction between A. p. mexicana and Ficus (Urostigma) spp. is beneficial for the interacting species and has important implications for their conservation. Howler monkeys gain from the ingestion of an important food source, germination rates of Ficus seeds are improved by passage through the monkeys' digestive tract, and the seeds are more likely to be deposited in a site suitable for germination and development. Seed dispersal distances are relatively larger in the preserved site, with both the size of the forest area and the spatial pattern of Ficus affecting the dispersal process. In a large forest fragment with ‘regularly’ distributed Ficus individuals the howler monkeys move away from the seed source, increasing the probability that the seeds are desposited on a tree other than Ficus, which is important for the germination and future development of a hemiepiphytic species. In a small forest fragment with trees distributed in clumps howlers repeatedly use the same individual trees, and faeces containing seeds may be dropped on unsuitable trees more often. These are key issues when addressing conservation policies for fragmented forests.


2009 ◽  
Vol 2009 ◽  
pp. 1-4 ◽  
Author(s):  
Jeffrey D. Holland

The distance from a source patch that dispersing insects reach depends on the number of dispersers, or random draws from a probability density function called a dispersal kernel, and the shape of that kernel. This can cause asymmetrical dispersal between habitat patches that produce different numbers of dispersers. Spatial distributions based on these dynamics can explain several ecological patterns including megapopulations and geographic range boundaries. I hypothesized that a locally extirpated longhorned beetle, the sugar maple borer, has a new geographical range shaped primarily by probabilistic dispersal distances. I used data on occurrence from Ontario, Canada to construct a model of geographical range in Indiana, USA based on maximum dispersal distance scaled by habitat area. This model predicted the new range boundary within 500 m very accurately. This beetle may be an ideal organism for exploring spatial dynamics driven by dispersal.


2011 ◽  
Vol 279 (1735) ◽  
pp. 1883-1888 ◽  
Author(s):  
Peter M. Buston ◽  
Geoffrey P. Jones ◽  
Serge Planes ◽  
Simon R. Thorrold

A central question of marine ecology is, how far do larvae disperse? Coupled biophysical models predict that the probability of successful dispersal declines as a function of distance between populations. Estimates of genetic isolation-by-distance and self-recruitment provide indirect support for this prediction. Here, we conduct the first direct test of this prediction, using data from the well-studied system of clown anemonefish ( Amphiprion percula ) at Kimbe Island, in Papua New Guinea. Amphiprion percula live in small breeding groups that inhabit sea anemones. These groups can be thought of as populations within a metapopulation. We use the x- and y -coordinates of each anemone to determine the expected distribution of dispersal distances (the distribution of distances between each and every population in the metapopulation). We use parentage analyses to trace recruits back to parents and determine the observed distribution of dispersal distances. Then, we employ a logistic model to (i) compare the observed and expected dispersal distance distributions and (ii) determine the relationship between the probability of successful dispersal and the distance between populations. The observed and expected dispersal distance distributions are significantly different ( p < 0.0001). Remarkably, the probability of successful dispersal between populations decreases fivefold over 1 km. This study provides a framework for quantitative investigations of larval dispersal that can be applied to other species. Further, the approach facilitates testing biological and physical hypotheses for the factors influencing larval dispersal in unison, which will advance our understanding of marine population connectivity.


The Condor ◽  
2006 ◽  
Vol 108 (3) ◽  
pp. 711-717
Author(s):  
Nikita Chernetsov ◽  
Leonid V. Sokolov ◽  
Vladislav Kosarev ◽  
Dmitry Leoke ◽  
Mikhail Markovets ◽  
...  

Abstract Over four years, nestling Pied Flycatchers (Ficedula hypoleuca) were banded and recaptured in nest boxes at a 44 km long and 1–1.5 km wide study area along the Courish Spit on the southeast Baltic coast. The return rate for males was nearly twice as high as for females. Males settled significantly closer to their natal sites than predicted by the null model, which assumed that any nest box in the study area was selected at random. For females, the frequency distribution of natal dispersal distances was not significantly different from that predicted by the null model. The difference in average dispersal distance between the sexes was highly significant. Although some individuals settled within tens of kilometers, most male Pied Flycatchers settled within several kilometers of their natal sites. We suggest that even if females settle on average farther from their natal sites than males do, both sexes imprint on a relatively small (several kilometers in diameter) area during postfledging exploration, to which they return each spring.


The Condor ◽  
2019 ◽  
Vol 121 (4) ◽  
Author(s):  
Julianna M A Jenkins ◽  
Damon B Lesmeister ◽  
Eric D Forsman ◽  
Katie M Dugger ◽  
Steven H Ackers ◽  
...  

Abstract Dispersal among breeding sites in territorial animals (i.e. breeding dispersal) is driven by numerous selection pressures, including competition and spatiotemporal variation in habitat quality. The scale and trend of dispersal movements over time may signal changing conditions within the population or on the landscape. We examined 2,158 breeding dispersal events from 694 male and 608 female individually marked Northern Spotted Owls (Strix occidentalis caurina) monitored over 28 yr on 7 study areas to assess the relative importance of individual (sex, experience), reproductive (annual productivity, mate availability), and environmental (forest alteration, presence of competitor) sources of variation in breeding dispersal distance. Median breeding dispersal distance was 3.17 km, with 99% of all breeding dispersal events &lt;37 km. Mean annual dispersal distances increased by 2.43 km in Oregon and 9.40 km in Washington between 1990 and 2017, which coincided with increases in annual detections of nonnative Barred Owl (S. varia). Frequency of breeding dispersal events, both among and within individuals, also increased over time. Female owls moved farther than males (median of 3.26 and 3.10 km, respectively), and birds with less experience (territory tenure) moved farther than those with more experience. Owls that were single in the year prior to dispersal moved 13–31% farther than those paired prior to dispersal. The greatest environmental change occurring over the course of our study was the expansion of Barred Owl populations. Breeding dispersal distance was positively related to Barred Owls in the study area and disturbance within the originating territory. While it appears that social factors continue to be important drivers of breeding dispersal distance in Spotted Owls, increased competition from Barred Owls and habitat alteration have a contributing effect. Increased breeding dispersal distances should be of concern for conservation efforts and considered in population monitoring because changing dispersal behavior may lead to higher rates of mortality and/or emigration from historical study areas.


2019 ◽  
Vol 286 (1894) ◽  
pp. 20182007 ◽  
Author(s):  
E. Rehm ◽  
E. Fricke ◽  
J. Bender ◽  
J. Savidge ◽  
H. Rogers

Frugivores play differing roles in shaping dispersal patterns yet seed dispersal distance is rarely quantified across entire communities. We model seed dispersal distance using gut passage times and bird movement for the majority (39 interactions) of known bird–tree interactions on the island of Saipan to highlight differences in seed dispersal distances provided by the five avian frugivores. One bird species was found to be a seed predator rather than a disperser. The remaining four avian species dispersed seeds but differences in seed dispersal distance were largely driven by interspecific variation in bird movement rather than intraspecific variation in gut passage times. The median dispersal distance was at least 56 m for all species-specific combinations, indicating all species play a role in reducing high seed mortality under the parent tree. However, one species—the Micronesian Starling—performed 94% of dispersal events greater than 500 m, suggesting this species could be a key driver of long-distance dispersal services (e.g. linking populations, colonizing new areas). Assessing variation in dispersal patterns across this network highlights key sources of variation in seed dispersal distances and suggests which empirical approaches are sufficient for modelling how seed dispersal mutualisms affect populations and communities.


2019 ◽  
Vol 2019 ◽  
pp. 1-22 ◽  
Author(s):  
Krzysztof Cabaj ◽  
Marcin Gregorczyk ◽  
Wojciech Mazurczyk ◽  
Piotr Nowakowski ◽  
Piotr Żórawski

Currently 5G communication networks are envisioned to offer in a near future a wide range of high-quality services and unfaltering user experiences. In order to achieve this, several issues including security, privacy, and trust aspects need to be solved so that the 5G networks can be widely welcomed and accepted. Considering above, in this paper, we take a step towards these requirements by proposing a dedicated SDN-based integrated security framework for the Internet of Radio Light (IoRL) system that is following 5G architecture design. In particular, we present how TCP SYN-based scanning activities and DHCP-related network threats like Denial of Service (DoS), traffic eavesdropping, etc. can be detected and mitigated using such an approach. Enclosed experimental results prove that the proposed security framework is effective and efficient and thus can be considered as a promising defensive solution.


2020 ◽  
pp. 147612702097904
Author(s):  
Richard J Arend

We discuss the impediments to theorizing about entrepreneurial activity, why these exist, and what to do about them. We do so because we believe that the evolution of theory in entrepreneurship has been frustratingly slow. We approach the relevant issues from an appropriate but narrow perspective—through the analysis of two pairs of recent articles published in the generalist top theory outlet—the Academy of Management Review. We consider these as exemplars of high-quality, high-visibility, likely-to-be-highly-cited, and new entrepreneurship theorizing. All four articles focus on original partial theory-building in the entrepreneurial process. These articles address different challenges facing different individual entrepreneurs, with many similarities in approach. However, each work argues its new propositions or insights from a non-entrepreneurial reference theory, which may well be one of the sacrifices that must be made to get published in top mainstream journals. We focus on the similarities of these articles to argue our points about why theorizing in our field is unlikely to improve in the near future and to identify the main impediments to such improvements. We explore the negative implications for our field’s future, and then we suggest five bold steps to better the prognostication.


2017 ◽  
Vol 8 (4) ◽  
pp. 23-29
Author(s):  
Rajaguru D. ◽  
Puviyarasi T. ◽  
Vengattaraman T.

The Internet of Things(IoT) such as the use of robots, sensors, actuators, electronic signalization and a variety of other internet-enabled physical devices may provide for new advanced smart applications to be used in construction in the very near future. Such applications require real-time responses and are therefore time-critical. Therefore, in order to support collaboration, control, monitoring, supply management, safety and other construction processes, they have to meet dependability requirements, including requirements for high Quality of Service (QoS). Dependability and high QoS can be achieved by using adequate number and quality of computing resources, such as processing, memory and networking elements, geographically close to the smart environments for handheld device computing (HDC).


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