Demography and competition in Hyrax : A 17 years study.


:This study investigates the demography and interspecific interactions of 6 Heterohyrax brucei and 4 Procavia johnstoni populations, which inhabited 6 kopjes (rock outcrops) in the Serengeti National Park, Tanzania over a period of 17 years. On three kopjes (H1, O2 and PH2) both species lived sympatrically, while on the other three (H2, H3 and P1) either one or the other species occurred allopatrically. The rainfall pattern between 1971/1972 and 1981/1982 had undergone major changes. There was significantly less precipitation in the wet season and the dry season had become extremer and longer. The kopje vegetation, recorded as percentage crown cover of browse from bushes and trees, had changed also, decreasing between 1971/72 and 1982 on 5 kopjes. In three kopjes (H1, O2 and PH2), which were shared by both hyrax species, an increase in the number of P. johnstoni, a decrease (H1 and O2) and extinction (PH2) of H. brucei took place between the time periods 1971-1976 ("good browse years") and 1982-1984 ("poor browse years"). These changes are probably the result of indirect interspecific competition (exploitative competition) for browse material, which is the main food source for both species during the dry season. When the browsing resources are abundant coexistence on sympatric kopjes between both species is possible, but when browse is scarce the result is competitive exclusion of H. brucei by P. johnstoni. It is also argued, that P. johnstoni by being the larger species and by also being a grazer had several ecological advantages over H. brucei. In kopjes H2, H3 and P1 where H. brucei occurred allopatrically the population increased (H2, P1) or decreased (H3) during the same time period. Natural extinction was observed in kopje P1 in the allopatrically living P. johnstoni group through mange. Dispersal of 7 females and 7 males H. brucei as well as 1 female and 4 male P. johnstoni were recorded in kopjes H1, H2 and P1. One female H. brucei that immigrated successfully into kopje H2 reached an age of over 11 years. One H. brucei family group (H2) shifted its birth season from December-January to May-August. Successful natural colonization was recorded for H. brucei in kopje P1 and for P. johnstoni in H1. Two kopjes (PH2 and H3), which had no hyrax and are located far away from other hyrax populations, were experimentally colonized in 1971 and 1972 respectively. The P. Johnstoni on PH2 and the H. brucei group on H3 had been under breeding isolation for 16 years. Under such conditions P. johnstoni males can reach an age of over 8.5 years. These long-term observations have shown that the occupancy of the kopjes by both species is a dynamic process depending on the combination of several abiotic (rainfall and availability of holes and hiding places) and biotic factors (interspecific and intraspecific competition for food, interspecific cooperation, predation and parasites) as well as the degree of inbreeding dependent on the geographic isolation of the kopje.






Hoeck HN




Has Abstract


1989-05-01 00:00:00












  • Parasites alter the topology of a stream food web across seasons.

    abstract::Relatively few published food webs have included parasites, and in this study we examined the animal community in a stream across eight contiguous seasons to test how inclusion of helminth parasites alters the topology or structure of the food web. Food webs constructed for each season and analyzed using common binary...


    pub_type: 杂志文章


    authors: Hernandez AD,Sukhdeo MV

    更新日期:2008-06-01 00:00:00

  • Local and regional dynamics of a specialist herbivore: overexploitation of a patchily distributed host plant.

    abstract::This study reports a rare example where a native herbivorous insect frequently overexploits local populations of its perennial host. Local dynamics of a flightless weevil (Hadramphus spinipennis, Curculionidae) and its host plant (Aciphylla dieffenbachii, Apiaceae) were assessed for one discrete patch. In this main st...


    pub_type: 杂志文章


    authors: Schöps K

    更新日期:2002-07-01 00:00:00

  • Long-distance dispersal helps germinating mahogany seedlings escape defoliation by a specialist caterpillar.

    abstract::Herbivores and pathogens with acute host specificity may promote high tree diversity in tropical forests by causing distance- and density-dependent mortality of seedlings, but evidence is scarce. Although Lepidoptera larvae are the most abundant and host-specific guild of herbivores in these forests, their impact upon...


    pub_type: 杂志文章


    authors: Norghauer JM,Grogan J,Malcolm JR,Felfili JM

    更新日期:2010-02-01 00:00:00

  • Seasonal changes in photosynthetic characteristics of Anemone raddeana, a spring-active geophyte, in the temperate region of Japan.

    abstract::Seasonal changes in the photosynthetic characteristics of intact involucral leaves of Anemone raddeana were investigated under laboratory conditions. Net photosynthesis and constant water vapor pressure deficit showed almost the same seasonal trend. They increased rapidly from mid-April immediately after unfolding of ...


    pub_type: 杂志文章


    authors: Yoshie F,Yoshida S

    更新日期:1987-05-01 00:00:00

  • Quantitative food web analysis supports the energy-limitation hypothesis in cave stream ecosystems.

    abstract::Energy limitation has long been the primary assumption underlying conceptual models of evolutionary and ecological processes in cave ecosystems. However, the prediction that cave communities are actually energy-limited in the sense that constituent populations are consuming all or most of their resource supply is unte...


    pub_type: 杂志文章


    authors: Venarsky MP,Huntsman BM,Huryn AD,Benstead JP,Kuhajda BR

    更新日期:2014-11-01 00:00:00

  • Numerical and functional response of predators to a long-term decline in mammalian prey at a semi-arid Neotropical site.

    abstract::Occurrence and diet of ten carnivorous predators (four falconiforms, four owls, and two foxes), and population levels of their mammalian prey, were monitored over 45 months at a semi-arid site in north-central Chile. Early in this period, small mammals irrupted and then declined markedly to a density 7% of that at pea...


    pub_type: 杂志文章


    authors: Jaksié FM,Jiménez JE,Castro SA,Feinsinger P

    更新日期:1992-01-01 00:00:00

  • Amino acid abundance and proteolytic potential in North American soils.

    abstract::Studies of nitrogen (N) cycling have traditionally focused on N mineralization as the primary process limiting plant assimilation of N. Recent evidence has shown that plants may assimilate amino acids (AAs) directly, circumventing the mineralization pathway. However, the general abundance of soil AAs and their relativ...


    pub_type: 杂志文章


    authors: Hofmockel KS,Fierer N,Colman BP,Jackson RB

    更新日期:2010-08-01 00:00:00

  • Diet shifts by adult flightless dung beetles Circellium bacchus, revealed using DNA metabarcoding, reflect complex life histories.

    abstract::Life history changes may change resource use. Such shifts are not well understood in the dung beetles, despite recognised differences in larval and adult feeding ability. We use the flightless dung beetle Circellium bacchus to explore such shifts, identifying dung sources of adults using DNA metabarcoding, and compari...


    pub_type: 杂志文章


    authors: Kerley GIH,Landman M,Ficetola GF,Boyer F,Bonin A,Rioux D,Taberlet P,Coissac E

    更新日期:2018-09-01 00:00:00

  • Effects of dung and seed size on secondary dispersal, seed predation, and seedling establishment of rain forest trees.

    abstract::Seeds dispersed by tropical, arboreal mammals are usually deposited singly and without dung or in clumps of fecal material. After dispersal through defecation by mammals, most seeds are secondarily dispersed by dung beetles or consumed by rodents. These post-dispersal, plant-animal interactions are likely to interact ...


    pub_type: 杂志文章


    authors: Andresen E,Levey DJ

    更新日期:2004-03-01 00:00:00

  • The influence of omnivorous elaterid larvae on the microbial carbon cycle in different forest soils.

    abstract::Data are presented on the influence of Athous subfuscus larvae (Coleoptera, Elateridae) on the microbial carbon cycle in the biotically most active horizons of three contrasting beech forest soils: the Ah horizon of a mull soil on limestone (Göttinger Wald, FRG), the F/H horizon of a moder soil on new red sandstone (S...


    pub_type: 杂志文章


    authors: Wolters V

    更新日期:1989-08-01 00:00:00

  • Growth, photosynthesis and acclimation by two submerged macrophytes in relation to temperature.

    abstract::In this study we examine the influence of temperature on growth, photosynthetic performance and acclimation of two submerged macrophyte species, Elodea canadensis L.C. Rich and Ranunculus aquatilis (L.) Wimmer. The plants were grown at 5, 10 and 15°C and a photon flux density of 300 μmol m-2 s-1 (PAR) in a medium with...


    pub_type: 杂志文章


    authors: Madsen TV,Brix H

    更新日期:1997-04-01 00:00:00

  • Plant stress and larval performance of a dipterous gall former.

    abstract::According to the plant vigour hypothesis, galling insects should respond positively and perform better on vigorous plants or plant parts, the opposite of the predictions of the plant stress hypothesis. I carried out field experiments to analyse the effects of sustained abiotic stress on the interactions between the co...


    pub_type: 杂志文章


    authors: De Bruyn L

    更新日期:1995-04-01 00:00:00

  • A phylogenetically controlled analysis of the roles of reproductive traits in plant invasions.

    abstract::Reproductive traits are tightly linked to plant fitness and may therefore be mechanisms driving biological invasions, including the greater success of more phylogenetically novel introduced species in some systems. We present a phylogenetic comparative analysis of "Baker's law'', that introduced plants with the abilit...


    pub_type: 杂志文章


    authors: Burns JH,Ashman TL,Steets JA,Harmon-Threatt A,Knight TM

    更新日期:2011-08-01 00:00:00

  • Responses of wild plants to nitrate availability : Relationships between growth rate and nitrate uptake parameters, a case study with two Bromus species, and a survey.

    abstract::Two annual species of Bromus, an invader (B. hordeaceus, ex B. mollis) and a non-invader (B. intermedius), were grown for 28 days in growth chambers, at 5 and 100 μM NO 3- in flowing nutrient solution. No differences between the two species were observed at either NO 3- level, in terms of relative growth rate (RGR) or...


    pub_type: 杂志文章


    authors: Garnier E,Koch GW,Roy J,Mooney HA

    更新日期:1989-06-01 00:00:00

  • Environmental and genetic variation in the haematocrit of fledgling pied flycatchers Ficedula hypoleuca.

    abstract::We report a field study of the haematocrit of pied flycatcher (Ficedula hypoleuca) nestlings when close to fledging. First a descriptive study was conducted of both fledgling and adult haematocrit over 2 years to analyse correlates of variation in this trait. Then a swapping experiment was performed to see whether var...


    pub_type: 杂志文章


    authors: Potti J,Moreno J,Merino S,Frías O,Rodríguez R

    更新日期:1999-07-01 00:00:00

  • Competitive mechanisms in a food-limited species: relative importance of interference and exploitative interactions among labyrinth spiders (araneae: Araneidae).

    abstract::Field experiments were conducted to clarify the relationship between the extent of food limitation and the amount and nature of intraspecific competition in an orb weaver, the labyrinth spider Metepeira labyrinthea. In one experiment agonistic encounters between marked adult females were induced at natural web sites. ...


    pub_type: 杂志文章


    authors: Wise DH

    更新日期:1983-04-01 00:00:00

  • Resurrection grasses in India.

    abstract::A search for desiccation tolerant grasses in India revealed nine grass species (in the genera Eragrostiella, Oropetium and Tripogon) whose ability to recover from airdryness had not previously been reported. Dry leaves of these species recover uninjured within 24 h of plants receiving water. Desiccation tolerance limi...


    pub_type: 杂志文章


    authors: Gaff DF,Bole PV

    更新日期:1986-12-01 00:00:00

  • The seasonal dynamics of leaf resin, nitrogen, and herbivore damage in Eriodictyon californicum and their parallels in Diplacus aurantiacus.

    abstract::The chaparral shrub Eriodictyon californicum produces a flavonoid leaf resin with a chemically similar composition to that previously reported for the sympatric shrub Diplacus aurantiacus. We determined the phenology, resin content, and nitrogen content of Eriodictyon leaves and the leaf area lost to herbivores. Nitro...


    pub_type: 杂志文章


    authors: Johnson ND,Chu CC,Ehrlich PR,Mooney HA

    更新日期:1984-03-01 00:00:00

  • Summer water relations of the desert phreatophyte Prosopis glandulosa in the Sonoran Desert of southern California.

    abstract::Prosopis is a genus of phreatophytic trees inhabiting hot deserts and semiarid grasslands of the world. Although desert trees are exposed to unusual environmental temperature and water stress, few investigations have evaluated their water relations. This is particularly true for Prosopis species growing in areas where...


    pub_type: 杂志文章


    authors: Nilsen ET,Rundel PW,Sharifi MR

    更新日期:1981-08-01 00:00:00

  • Food level and sex shape predator-induced physiological stress: immune defence and antioxidant defence.

    abstract::Despite the potential impact on prey fitness and predator-prey interactions, most studies of predation risk ignore physiological responses and their dependence upon food level and sex. Therefore, we reared male and female larvae of the damselfly Lestes viridis under predator stress (dragonfly larvae) at high and low f...


    pub_type: 杂志文章


    authors: Slos S,De Meester L,Stoks R

    更新日期:2009-09-01 00:00:00

  • Physical factors driving intertidal macroalgae distribution: physiological stress of a dominant fucoid at its southern limit.

    abstract::Climate change is driving species range shifts worldwide. However, physiological responses related to distributional changes are not fully understood. Oceanographers have reported an increase in ocean temperature in the northwest Iberian Peninsula that is potentially related to the decline in some cold-temperate inter...


    pub_type: 杂志文章


    authors: Martínez B,Arenas F,Rubal M,Burgués S,Esteban R,García-Plazaola I,Figueroa FL,Pereira R,Saldaña L,Sousa-Pinto I,Trilla A,Viejo RM

    更新日期:2012-10-01 00:00:00

  • Aggressive behavior of adult meadow voles (Microtus pennsylvanicus) towards young.

    abstract::Field evidence indicates that adult microtines, especially females, may be a major cause of poor juvenile survival and this may be instrumental in their population regulation. This suggests that males and females behave differently towards young animals. To examine how adult males, nonlactating females, and lactating ...


    pub_type: 杂志文章


    authors: Boonstra R

    更新日期:1984-04-01 00:00:00

  • Asymmetric indirect interactions mediated by a shared parasitoid: connecting species traits and local distribution patterns for two chrysomelid beetles.

    abstract::This paper reports on an asymmetric indirect interaction between two chrysomelid beetles where one species (Galerucella tenella) experiences higher parasitization, and the other species (Galerucella calmariensis) lower parasitization, in mixed compared with monospecific populations. This pattern is likely to be a cons...


    pub_type: 杂志文章


    authors: Hambäck PA,Stenberg JA,Ericson L

    更新日期:2006-06-01 00:00:00

  • Life history consequences of sterol availability in the aquatic keystone species Daphnia.

    abstract::The absence of essential biochemical nutrients, such as polyunsaturated fatty acids or sterols, has been considered as a mechanism determining trophic interactions between the herbivore Daphnia and its phytoplankton food source. Here, we experimentally quantify the sensitivity of two Daphnia species to decreasing amou...


    pub_type: 杂志文章


    authors: Martin-Creuzburg D,Wacker A,von Elert E

    更新日期:2005-07-01 00:00:00

  • [Adaptations of Pterostichus nigrita F. (Col., Carab.) to subarctic conditions].

    abstract::Two physiological races of the carabid beetle, Pterostichus nigrita, are compared. The larvae from the northern Scandinavian population (polar circle) develop faster in all temperature regimens, have a reduced mortality in lower temperatures and an increased growth rate in high temperatures compared with the central E...


    pub_type: 杂志文章


    authors: Ferenz HJ

    更新日期:1975-03-01 00:00:00

  • The production of Cyprideis torosa Jones 1850 (Crustacea, Ostracoda).

    abstract::The ostracod Cyprideis torosa Jones, 1850 is a dominant species in the meiofauna of brackish water habitats. Its production in the field over a five-year period has been calculated using two production models. The first model uses the age-distribution of shells preserved in the sediment to assess the stage-specific mo...


    pub_type: 杂志文章


    authors: Herman PM,Heip C,Vranken G

    更新日期:1983-06-01 00:00:00

  • Comparing demographic parameters for philopatric and immigrant individuals in a long-lived bird adapted to unstable habitats.

    abstract::Theoretical models about the benefits of philopatry predict that immigrant fitness can be higher, lower or similar to that of philopatrics depending on habitat heterogeneity, dispersal costs, distance between patches or population densities. In this study, we compared transience rates, local survival and recruitment a...


    pub_type: 杂志文章


    authors: Oro D,Tavecchia G,Genovart M

    更新日期:2011-04-01 00:00:00

  • Metacommunity patterns in larval odonates.

    abstract::The growth of metacommunity ecology as a subdiscipline has increased interest in how processes at different spatial scales structure communities. However, there is still a significant knowledge gap with respect to relating the action of niche- and dispersal-assembly mechanisms to observed species distributions across ...


    pub_type: 杂志文章


    authors: McCauley SJ,Davis CJ,Relyea RA,Yurewicz KL,Skelly DK,Werner EE

    更新日期:2008-11-01 00:00:00

  • Short-term variability of plant populations within a regularly disturbed habitat.

    abstract::The changing populations of weeds during 13 years of the Broadbalk continuous wheat experiment were analysed to investigate the extent of differences in shortterm variability of cover between species. The data were from two sections of the experiment where winter wheat was grown continuously under herbicide treatment ...


    pub_type: 杂志文章


    authors: Firbank LG

    更新日期:1993-06-01 00:00:00

  • The significance of ant and plant traits for ant pollination in Leporella fimbriata.

    abstract::Ant metapleural glands secrete surface antibiotics that affect pollen as well as bacteria and fungi. This may be one reason why ant pollination is rare. It is predicted that pollination by ants is possible only in the presence of certain ant and/or plant traits. Two traits are investigated; first, absence of the metap...


    pub_type: 杂志文章


    authors: Peakall R,Angus CJ,Beattie AJ

    更新日期:1990-10-01 00:00:00