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In territorial, socially monogamous species, the establishment and defense of a territory are an important strategy to maximize individual fitness, but the factors responsible for the duration of territory occupancy are rarely studied, especially in long‐lived mammals. A long‐term monitoring program in southeast Norway spanning over 18 years allowed us to follow the individual life histories of Eurasian beavers (Castor fiber) from adolescence in their natal family group to dispersal and territory establishment until the end of territory occupancy. We investigated whether territory size, resource availability, population density, and dispersal age could explain the duration of territory occupancy, which ranged from 1 to 11 years. The duration of territory occupancy was positively related to dispersal age, suggesting that individuals that delayed dispersal had a competitive advantage due to a larger body mass. This is in support with the maturation hypothesis, which states that an animal should await its physical and behavioral maturation before the acquisition of a territory. Further, we found that individuals that established in medium‐sized territories occupied them longer as compared to individuals in small or large territories. This suggests that large territories are more costly to defend due to an increased patrolling effort, and small territories might not have sufficient resources. The lifetime reproductive success ranged from zero to six kits and generally increased with an increasing duration of territory occupancy. Our findings show the importance of holding a territory and demonstrate that dispersal decisions and territory selection have important consequences for the fitness of an individual. 相似文献
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- Small‐scale discontinuities, formed by accumulations of wood, are recognised as a key feature of functionally intact forested streams because they promote organic matter retention, increase habitat complexity and provide flow refugia. Re‐establishing such features in physically degraded streams is therefore a common priority for restoration schemes. Ecosystem engineering by beavers in the form of dam building might offer a natural mechanism for restoring degraded streams. Despite an increase in beaver reintroductions globally, the ecosystem engineering concept has rarely been applied to restoring biodiversity and ecosystem function, especially within degraded freshwater systems.
- By comparing multiple beaver‐modified and unmodified sites on headwater streams draining 13 ha of pastureland in eastern Scotland, U.K., we investigated if hydromorphological changes caused by reintroduced beavers (Castor fiber) translate into desirable biological responses when there is a long history of physical degradation and contraction of the regional species pool due to agricultural land use.
- Beaver modified in‐stream habitat by constructing 10 dams, thus creating a series of interconnected dam pools. Organic matter retention and aquatic plant biomass increased (7 and 20 fold higher respectively) in beaver ponds relative to unmodified channels, consistent with the lower fluctuation in stream stage observed below a series of dams. Growing season concentrations of extractable P and NO3 were on average 49% and 43% lower respectively below a series of dams than above, although colour and suspended solids concentrations increased.
- Macroinvertebrate samples from beaver‐modified habitats were less taxon rich (alpha diversity on average 27% lower) than those from unmodified stream habitat. However, due to significant compositional differences between beaver versus unmodified habitats, a composite sample from all habitats indicated increased richness at the landscape scale; gamma diversity was 28% higher on average than in the absence of beaver‐modified habitat. Feeding guild composition shifted from grazer/scraper and filter feeder dominance in unmodified habitats to shredder and collector‐gatherer dominance in beaver‐created habitats.
- Dam building by beaver in degraded environments can improve physical and biological diversity when viewed at a scale encompassing both modified and unmodified habitats. By restoring ecosystem processes locally, it may also offer wider scale benefits, including greater nutrient retention and flood attenuation. These benefits should be evaluated against evidence of any negative effects on land use or fisheries.
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Katrin Hohwieler Frank Rosell Martin Mayer 《Ethology : formerly Zeitschrift fur Tierpsychologie》2018,124(8):591-599
Chemical communication by scent‐marking is widespread among mammals and can serve different purposes, such as territory demarcation, mate attraction and self‐advertisement. In this study, we examined scent‐marking behavior by subordinate Eurasian beavers (Castor fiber) in a population in southeast Norway. We conducted scent experiments in 18 family groups, simulating a territory intruder using experimental scent mounds (ESM). In total, we recorded 196 territorial reactions (destroying and/or overmarking of scent mounds). Subordinates contributed 14% of all territorial reactions and first overmarked 12% of the ESM, and the number of subordinates in the family group did not increase the total number of territorial reactions. This suggests that the contribution by subordinates plays a minor role in territorial defense. The number of territorial reactions by subordinates was positively related to the age of their parents, suggesting that subordinates might take over territorial duties with increasing parental senescence, likely because they have increased chances of inheriting the territory. Increased experience in territorial activities possibly helps subordinates to successfully gain and defend a territory of their own. 相似文献
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Lemur catta Troop D at Berenty Reserve has been studied intermittently for 35 years. During 90 hours of continuous sampling in August 1998, I observed and mapped troop movement and scent marking. I compared these observations with data from June, 1975. The core of Troop D1's 1998 home range is the same as for Troop D in 1975. Sixty-two percent of Troop D1's time in 1998 was spent in the 1975 home range, and 52% of their scent marks were placed in that 1975 home range. The remainder of their time was spent in an extension of their home range, which is now an area of confrontation with an adjacent troop. They used the same sleeping trees in the 2 years, and all of the 1998 scent marks deposited in the 1975 home range were placed in the same locations marked in 1975. The similarities in their use of space in 1975 and 1998 were remarkable. 相似文献
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Patricia Maria Graf Rory Paul Wilson Lea Cohen Sanchez Klaus Hacklӓnder Frank Rosell 《Ecology and evolution》2018,8(2):997-1008
Semi‐aquatic mammals have secondarily returned to the aquatic environment, although they spend a major part of their life operating in air. Moving both on land, as well as in, and under water is challenging because such species are considered to be imperfectly adapted to both environments. We deployed accelerometers combined with a depth sensor to study the diving behavior of 12 free‐living Eurasian beavers Castor fiber in southeast Norway between 2009 and 2011 to examine the extent to which beavers conformed with mass‐dependent dive capacities, expecting them to be poorer than wholly aquatic species. Dives were generally shallow (<1 m) and of short duration (<30 s), suggesting that the majority of dives were aerobic. Dive parameters such as maximum diving depth, dive duration, and bottom phase duration were related to the effort during different dive phases and the maximum depth reached. During the descent, mean vectorial dynamic body acceleration (VeDBA—a proxy for movement power) was highest near the surface, probably due to increased upthrust linked to fur‐ and lung‐associated air. Inconsistently though, mean VeDBA underwater was highest during the ascent when this air would be expected to help drive the animals back to the surface. Higher movement costs during ascents may arise from transporting materials up, the air bubbling out of the fur, and/or the animals’ exhaling during the bottom phase of the dive. In a manner similar to other homeotherms, beavers extended both dive and bottom phase durations with diving depth. Deeper dives tended to have a longer bottom phase, although its duration was shortened with increased VeDBA during the bottom phase. Water temperature did not affect diving behavior. Overall, the beavers’ dive profile (depth, duration) was similar to other semi‐aquatic freshwater divers. However, beavers dived for only 2.8% of their active time, presumably because they do not rely on diving for food acquisition. 相似文献
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- Mammalian herbivores that consume both aquatic and terrestrial vegetation may have important but little understood effects on freshwater ecosystems. We assessed the effects of North American moose (Alces americanus) and/or beaver (Castor canadensis) on aquatic vegetation and abiotic conditions of three types of waterbodies.
- We established year‐round aquatic exclosures and reference plots in glacial lakes, dammed lakes and riverine ponds (n = 3 in each case). Within plots, we monitored parameters including dissolved oxygen, light, plant diversity and species‐specific plant biomass.
- The effects of herbivory by beaver and moose appear to be contingent upon abiotic and plant community characteristics. Exposure to herbivory decreased biomass in riverine ponds and dammed lakes but not in glacial lakes and decreased species richness in riverine ponds and glacial lakes but not in dammed lakes. Changes in macrophyte species diversity correlated with exposure to herbivory only in glacial lakes. Disaggregating the effects of herbivory according to abiotic conditions and plant community characteristics revealed outcomes that are not detectable when results are aggregated.
- In some catchments, the response of the aquatic plant community to beaver and moose herbivory may substantially differ from the response of the surrounding terrestrial plant community. Five of the six waterbodies created by beavers (dammed lakes and riverine ponds) maintained >80% macrophyte cover, despite seasonal reduction in biomass by both moose and beaver. Herbivores appear to cause a short‐term reduction in plant biomass in dammed lakes, resulting in greater light availability, without depleting biomass over a number of years.
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Males of the agaristid moth Hecatesia thyridiondefend small patches of coastal heathland in southwestern Australia in the late afternoon. As they fly back and forth low over their territories, they produce an acoustical signal. Neighboring males commonly fly toward each other; these interactions often result in aerial duels, with the eventual departure of one of the males. Playback experiments established that males were attracted to the sounds of other males. Females were observed to fly into territories and eventually mate with the signaling occupant. Marked males sometimes returned to the same spot on consecutive days. On any given day males occupied only a fraction of the sites that were acceptable territories. The mating system of H. thyridionappears to be a dispersed lek, with males acoustically advertising territories that are used for mating and not for feeding or oviposition. 相似文献
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Eric B. Liebgold 《Ethology : formerly Zeitschrift fur Tierpsychologie》2014,120(4):388-399
Juveniles' behaviors are often influenced by the behaviors of conspecifics. Most experimental studies of the influence of conspecific behavior vary the social environment by the presence or absence of conspecifics or investigate the impact of the outcome of social encounters (winner/loser effects) but less frequently expose individuals to variation in behavioral phenotypes present in the social environment. Based on previous work showing that juveniles of the salamander Plethodon cinereus are likely to interact frequently with non‐parental adults, I hypothesized that territorial adults in the social environment alter the future behaviors of juveniles. I measured the intracohort social behaviors of juvenile salamanders collected from two geographic areas, Michigan (MI) and Virginia (VA), before and after housing with ostensibly territorial (VA) or non‐territorial (MI) adults. There were overall effects of adult territoriality and aggression on the behavior of juveniles. However, juveniles from populations in MI were especially susceptible to behavioral modification. Compared with behaviors prior to being housed with adults, MI juveniles increased investigatory and escape behaviors in juvenile–juvenile interactions after being housed with adults that displayed territorial behaviors and decreased investigatory and escape behaviors after being housed with non‐territorial adults. This study shows that not only is a specific behavior, territoriality of adult salamanders, a social environment that modifies future juvenile behaviors, but the effects of social environment may differ between populations. 相似文献
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Stefan Ziegler John E. Fa Christian Wohlfart Bruno Streit Stefanie Jacob Martin Wegmann 《Biotropica》2016,48(3):405-412
Hunting and trade of wild animals for their meat (bushmeat), especially mammals, is commonplace in tropical forests worldwide. In West and Central Africa, bushmeat extraction has increased substantially during recent decades. Currently, such levels of hunting pose a major threat to native wildlife. In this paper, we compiled published data on hunting offtake of mammals, from a number of studies conducted between 1990 and 2007 in Cameroon, Central African Republic, Democratic Republic of Congo, Equatorial Guinea, Gabon, and Republic of Congo. From these data sources, we estimated annual extraction rates of all hunted species and analyzed the relationship between environmental and anthropogenic variables surrounding each hunting rate and levels of bushmeat extraction. We defined hunting pressure as a function of bushmeat offtake and number of hunted species and confirm that hunting pressure is significantly correlated with road density, distance to protected areas and population density. These correlations are then used to map hunting pressure across the Congo Basin. We show that predicted risk areas show a patchy distribution throughout the study region and that many protected areas are located in high‐risk areas. We suggest that such a map can be used to identify areas of greatest impact of hunting to guide large‐scale conservation planning initiatives for central Africa. 相似文献
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Bryana M. Bush Cristina Stenert Leonardo Maltchik Darold P. Batzer 《Freshwater Biology》2019,64(7):1265-1274
- Beavers are ecosystem engineers known to modify the environment primarily via dam building. Beaver wetlands are complexes of newly created, mature, and abandoned beaver constructions within a stream network. Invertebrate dynamics across all habitats derived from these successional stages remains poorly explored.
- Here, we test how this natural successional gradient created by beaver affects invertebrate β‐diversity and its components (turnover and nestedness). Invertebrates were sampled in the Piedmont region of Georgia (U.S.A.) in two seasons (autumn and spring) in each of four stages of habitat succession: natural stream channels, forested wetlands created by newly formed beaver dams, mature open wetland marshes, and abandoned wetland meadows.
- In autumn, invertebrate communities were different among successional stages, apart from new versus abandoned wetlands and new versus mature wetlands, which were only marginally different, and streams versus abandoned wetlands. In spring, only the mature beaver wetland communities were unique, differing from both streams and from newly formed or abandoned wetlands. Beta‐diversity was nearly twice as high for the overall study‐system than any individual successional stage, which all had similar diversity. Additionally, turnover was significantly higher than nestedness in all stages.
- Community differences combined with high turnover among successional stages indicates that beaver wetland communities are not merely a subset of more stable mature wetlands or streams; instead, each stage has a different taxonomic make‐up. Our results strengthen the idea that beaver activity can be an important conservation tool by contributing substantially to diversity in areas where they are present. Beaver wetlands have the potential to help stabilise β‐ and regional diversity in the face of wetland loss from climate change and other human impacts.
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Andreas Jürgens Suk‐Ling Wee Adam Shuttleworth Steven D. Johnson 《Ecology letters》2013,16(9):1157-1167
Floral mimicry of decaying plant or animal material has evolved in many plant lineages and exploits, for the purpose of pollination, insects seeking oviposition sites. Existing studies suggest that volatile signals play a particularly important role in these mimicry systems. Here, we present the first large‐scale phylogenetically informed study of patterns of evolution in the volatile emissions of plants that mimic insect oviposition sites. Multivariate analyses showed strong convergent evolution, represented by distinct clusters in chemical phenotype space of plants that mimic animal carrion, decaying plant material, herbivore dung and omnivore/carnivore faeces respectively. These plants deploy universal infochemicals that serve as indicators for the main nutrients utilised by saprophagous, coprophagous and necrophagous insects. The emission of oligosulphide‐dominated volatile blends very similar to those emitted by carrion has evolved independently in at least five plant families (Annonaceae, Apocynaceae, Araceae, Orchidaceae and Rafflesiaceae) and characterises plants associated mainly with pollination by necrophagous flies and beetles. 相似文献
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Sergio Castrezana Brant C. Faircloth William C. Bridges Patricia Adair Gowaty 《Ecology and evolution》2017,7(18):7515-7526
A prominent hypothesis for polyandry says that male–male competitive drivers induce males to coerce already‐mated females to copulate, suggesting that females are more likely to be harassed in the presence of multiple males. This early sociobiological idea of male competitive drive seemed to explain why sperm‐storing females mate multiply. Here, we describe an experiment eliminating all opportunities for male–male behavioral competition, while varying females’ opportunities to mate or not with the same male many times, or with many other males only one time each. We limited each female subject's exposure to no more than one male per day over her entire lifespan starting at the age at which copulations usually commence. We tested a priori predictions about relative lifespan and daily components of RS of female Drosophila melanogaster in experimental social situations producing lifelong virgins, once‐mated females, lifelong monogamous, and lifelong polyandrous females, using a matched‐treatments design. Results included that (1) a single copulation enhanced female survival compared to survival of lifelong virgins, (2) multiple copulations enhanced the number of offspring for both monogamous and polyandrous females, (3) compared to females in lifelong monogamy, polyandrous females paired daily with a novel, age‐matched experienced male produced offspring of enhanced viability, and (4) female survival was unchallenged when monogamous and polyandrous females could re‐mate with age‐ and experienced‐matched males. (5) Polyandrous females daily paired with novel virgin males had significantly reduced lifespans compared to polyandrous females with novel, age‐matched, and experienced males. (6) Polyandrous mating enhanced offspring viability and thereby weakened support for the random mating hypothesis for female multiple mating. Analyzes of nonequivalence of variances revealed opportunities for within‐sex selection among females. Results support the idea that females able to avoid constraints on their behavior from simultaneous exposure to multiple males can affect both RS and survival of females and offspring. 相似文献
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Joshua D. Day Jackson H. Birrell Tyson J. Terry Amy Clark Phil Allen Samuel B. St. Clair 《Ecology and evolution》2019,9(10):6052-6067
Recent increases in the frequency and size of desert wildfires bring into question the impacts of fire on desert invertebrate communities. Furthermore, consumer communities can strongly impact invertebrates through predation and top‐down effects on plant community assembly. We experimentally applied burn and rodent exclusion treatments in a full factorial design at sites in both the Mojave and Great Basin deserts to examine the impact that fire and rodent consumers have on invertebrate communities. Pitfall traps were used to survey invertebrates from April through September 2016 to determine changes in abundance, richness, and diversity of invertebrate communities in response to fire and rodent treatments. Generally speaking, rodent exclusion had very little effect on invertebrate abundance or ant abundance, richness or diversity. The one exception was ant abundance, which was higher in rodent access plots than in rodent exclusion plots in June 2016, but only at the Great Basin site. Fire had little effect on the abundances of invertebrate groups at either desert site, with the exception of a negative effect on flying‐forager abundance at our Great Basin site. However, fire reduced ant species richness and Shannon's diversity at both desert sites. Fire did appear to indirectly affect ant community composition by altering plant community composition. Structural equation models suggest that fire increased invasive plant cover, which negatively impacted ant species richness and Shannon's diversity, a pattern that was consistent at both desert sites. These results suggest that invertebrate communities demonstrate some resilience to fire and invasions but increasing fire and spread of invasive due to invasive grass fire cycles may put increasing pressure on the stability of invertebrate communities. 相似文献