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1.
Frugivorous animals play a major role in dispersing tropical, and to a lesser extent, temperate tree species. In order to attract potential seed dispersers, plants generally offer a reward of fleshy fruit pulp. Criteria for fruit choice by avian frugivores are influenced by a number of non-nutritive (e.g. fruit size and colour) factors; and nutritional composition of the fruit. There is a paucity of nutritional composition and other fruit trait data of indigenous South African fruit. This information is necessary in order to determine which frugivores are likely to ingest which fruits and consequently act as potential seed dispersal agents. This information would provide us with an understanding of the inter-relationships between indigenous fruit and frugivores in South Africa. Consequently nutritional composition was investigated in various indigenous fruit species that avian frugivores feed on. Fruits were collected from 38 indigenous tree species found in KwaZulu-Natal Afromontane and coastal forests. Pulp was freeze-dried to constant mass and then analysed for sugar, lipid and protein content; and for water content determination. Fruit width in this study ranged from 4 mm (Searsia rehmanniana and Trema orientalis) to 40 mm (Annona senegalensis, Ficus sur and Xylotheca kraussiana). Of the fruits examined in this study 29% were black and 43% were red when ripe. Most (84%) fruit species analysed for sugar content were hexose dominant with 50% being fructose and 34% being glucose dominant. Only 16% of the fruit species analysed were sucrose dominant. Fruits in this study were generally observed to be high (mean: 68.1 ± 3.3%; n = 30) in water content; and low in protein and lipid content respectively (mean: 8.2 ± 0.5%; 9.3 ± 2.2%; n = 30) indicating that these fruit species could be considered as nutrient-dilute. Future studies need to determine the nutritional composition of the remaining indigenous South African fruit in order to develop a comprehensive database as well as examining non-nutritive factors.  相似文献   

2.
Thermoregulatory behavior in temperate bats is influenced by gender, food availability, ambient temperature and reproduction. Ecologically and morphologically similar bat species (Myotis bechsteinii, M. nattereri, and Plecotus auritus; Vespertilionidae) facing similar diurnal conditions should therefore not differ in their thermoregulatory behavior. Identified day roosts (n = 23) of radio-tagged bats (n = 30) were spread over an area of 33.1 ha, but ambient temperature did not differ between roosting sites. Furthermore, there was no significant difference in cardinal direction, roost height, canopy coverage, and breast height diameter between day roosts used by the three species. Minimum roost temperatures and isolation values, however, differed significantly between our species with lowest values in P. auritus. The range of skin temperatures (min–max) recorded by temperature-sensitive transmitters was not species-specific with the lowest ranges in late pregnancy (mean ± SD: 7.1 ± 1.1 °C) and highest in post-lactation (mean ± SD: 13.1 ± 1.1 °C). The minimum skin temperature, however, was species-specific with the lowest values in P. auritus (mean ± SD: 20.2 ± 1.1 °C), intermediate in M. nattereri (mean ± SD: 23.4 ± 1.0 °C), and the highest in M. bechsteinii (mean ± SD: 26.8 ± 1.0 °C). Species-specific usage of energy-saving mechanisms might represent an important niche differentiation of species. Different mechanisms might allow, e.g. one species to occupy colder roosts with higher temperature variations or to shorten foraging times due to distinct thermoregulatory behavior.  相似文献   

3.
《Biological Control》2007,40(3):300-312
The response of generalist egg parasitoids to alternative natural hosts that are present simultaneously is not well known. We investigated the behavior of Trichogramma pretiosum Riley (Hymenoptera: Trichogrammatidae) in relation to two field hosts Helicoverpa armigera Hübner and Spodoptera litura Fabricius, in choice and no choice tests. We quantified the effects of natal host species and post-emergence adult age on the oviposition preference of the parasitoids. H. armigera eggs were consistently preferred over S. litura eggs, regardless of the natal host and adult age. When only S. litura eggs were available as hosts, they were parasitized at statistically similar rates to H. armigera eggs (average of 17 ± 2.7 vs. 13 ± 3.0, H. armigera to S. litura). The adult lifespan and lifetime fecundity of T. pretiosum were variable but were affected by natal host species and/or host species to which they were exposed. Mean lifespan and fecundity of parasitoids that had developed in H. armigera eggs and were exposed to H. armigera eggs for oviposition were 13.9 ± 1.8 days and 98.7 ± 11.0 adult offspring. By contrast, those that developed in S. litura eggs and were exposed to S. litura eggs for oviposition lived for 7 ± 0.9 days and produced 53.8 ± 8.0 adult offspring. The ovigeny index (OI) was significantly lower in the parasitoids exposed to H. armigera eggs than in those exposed to S. litura eggs, regardless of the natal host, indicating that H. armigera eggs sustain the adult parasitoids better than S. litura eggs. These results are used to predict parasitoid behavior in the field when both hosts are available.  相似文献   

4.
The reduction of insect herbivory is one of the services provided by tree diversity in forest ecosystems. While it is increasingly acknowledged that the compositional characteristics of tree species assemblages play a major role in triggering associational resistance to herbivores, underlying mechanisms are less well known. We addressed this question in the ORPHEE experiment by assessing pine processionary moth infestations (Thaumetopoea pityocampa) across a tree diversity gradient from pine monocultures to five species mixtures. We showed that tree species richness per se had no effect on the probability of attack by this pest. By contrast, the infestation rate was strongly dependent on plot composition. Mixtures of pines (Pinus pinaster) and birches (Betula pendula) were less prone to T. pityocampa infestations, whereas mixtures of pines and oaks (Quercus spp.) were more often attacked than pine monocultures. By taking into account the relative height of pines and associated broadleaved species, this effect could be explained by pine apparency. Pines were on average 343 ± 5 cm height. Birches, as fast growing trees, were slightly taller than pines (363 ± 6 cm), while oak trees were significantly smaller (74 ± 1 cm). Host trees of T. pityocampa were then partly hidden in mixtures of pines and birches but more apparent in mixtures with oaks. We suggest that reduced pine apparency disrupted visual cues used by female moths to select host trees prior to oviposition. This study highlights the need to take into account tree traits such as growth rate when selecting the tree species that have to be associated in order to improve forest resistance to pest insects.  相似文献   

5.
Man made ecosystems of dry lands are key habitats due to their ecological characteristics to survey biodiversity. This study investigated bird diversity in three oases of the Northern Algerian Sahara (i.e., Biskra in 2006, Oued Souf in 2008 and Ouargla in 2009), by using the spot-mapping method. Bird density “D” (pairs/10 ha), species richness “S” (number species), diversity (Shannon index) “H′” (in bits), and evenness “E” varied from one oasis to another (Biskra: D = 98.5, S = 47, H′ = 4.49, E = 0.81; Oued Souf: D = 96, S = 33, H′ = 3.9, E = 0.77; Ouargla: D = 91.5, S = 44, H′ = 4.39, E = 0.80). Differences in bird diversity between the monitored palm groves are due to the ecological characteristics of each environment. Documented literature outlined close taxonomic similarities between bird assemblages of the study area with many Northern Saharan oases. The Hybrid Sparrow Passer domesticus x Passer. hispaniolensis and some Columbidae species including Columba livia, Streptopelia turtur, Streptopelia senegalensis, and Streptopelia decaocto were the abundant species throughout surveyed oases in which they represented more than half (55.6%) of the sum of species densities (D = 286 pairs/10 ha). These synthropic species have known a huge expansion of their distribution range throughout Algerian oases. The correspondence analysis allowed the aggregation of both families and species into oasis they belong to. One-way ANOVA was tested to analyse variations of both family and species densities between studied oases. The ANOVA revealed there was no significant variation either in family densities (p = 0.937) or in bird densities (p = 0.622) between the surveyed oases because of the small size of bird populations.  相似文献   

6.
We compared daily visitation frequency indices by 4 large (> 150 g), 7 medium-size (50–150 g), 5 small (30–50 g) and 8 and tiny (< 30 g) frugivorous bird species on fleshy fruits of two native shrubs (Olea europaea subsp. africana and Chrysanthemoides monilifera subsp. monilifera), two established alien shrubs (Solanum mauritianum and Lantana camara) and two emerging alien shrubs (Myoporum tenuifolium and Pittosporum undulatum) at nine different sites in the Cape Floristic Region. Large, medium-size and tiny birds as groups displayed significantly higher visitation frequency indices on fruits of both emerging alien shrub species than the other shrub species. Small birds as a group displayed insignificantly different visitation frequency indices on fruits of both emerging and established alien shrub species but significantly higher visitation frequency indices on fruits of both emerging and established alien shrub species than on fruits of the native shrub species. However, there were significant differences in foraging frequency indices of the bird species included within each of these body size groups on fruits of the different shrub species. Among the large birds, Columba guinea and among the medium size birds Sturnus vulgaris, Streptopelia senegalensis, Turdus olivaceus and Onychognathus morio all exhibited significantly higher visitation frequency indices on fruits of both emerging alien shrub species than on fruits of the other shrub species. These findings indicate that alien plant control measures should be focused on eradicating localised populations of emerging aliens to limit preferential consumption of their fruits by birds and consequent dispersal of their seeds that germinate readily into natural areas.  相似文献   

7.
8.
《Acta Oecologica》2006,29(2):155-164
We studied three species of columnar cacti in the genus Neobuxbaumia which differ in their degree of rarity: Neobuxbaumia macrocephala (the rarest), Neobuxbaumia tetetzo (intermediate), and Neobuxbaumia mezcalaensis (the most common). To investigate the ecological factors that limit their distribution and abundance, we surveyed 80 localities within the region of Tehuacan-Cuicatlán, in Central Mexico. At each locality we measured several environmental variables, and the density of the Neobuxbaumia populations present. We used a principal component analysis (PCA) to identify the factors that are associated to the presence/absence of each species. Additionally, we carried out multiple regressions between environmental variables and population density to test whether the variation in these variables was related to changes in abundance. The results show that factors significantly affecting the distribution of these species are mean annual temperature, altitude, rainfall, and soil properties such as texture and organic matter content. N. mezcalaensis reaches maximum population densities of 14,740 plants per ha (average density = 3943 plants per ha) and is associated with localities with relatively abundant rainfall. N. tetetzo shows maximum population densities of 14,060 plants per ha (average = 3070 plants per ha), and is associated with sites located at high latitudes and with high phosphorous content in the soil. The rarest species, N. macrocephala, shows maximum densities of 1180 plants per ha (average = 607 plants per ha) and is associated with localities with high soil calcium content. The distribution of this species is limited to sites with specific values of the environmental variables recorded, conferring it a high habitat specificity which accounts for its rarity.  相似文献   

9.
Protected areas are the basis of modern conservation systems, but current climate change causes gaps between protected areas and the species distribution ranges. To mitigate the impact of climate change on species distribution ranges, revision of protected areas are necessary. Alternatively, active management such as excluding competitive species or transplanting target species would be effective. In this study, we assessed optimal actions (revision of protected areas or active management) in each geographical region to establish an effective spatial conservation plan in Japan. Gaps between the protected areas and future potential habitats were assessed using species distribution models and 20 future climate simulations. Fagus crenata, an endemic and dominant species in Japan, was used as a target species. Potential habitats within the protected areas were predicted to decrease from 22,122 km2 at present to 12,309 km2 under future climate conditions. Sustainable potential habitats (consistent potential habitats both at present and in future) without the protected areas extended to 13,208 km2, and were mainly found in northeast Japan. These results suggest that, in northeast Japan, revisions to protected areas would be effective in preserving sustainable potential habitats under future climate change. However, the potential habitats of southwestern Japan, in which populations were genetically different from northeastern populations, were predicted to virtually disappear both within and outside of protected areas. Active management is thus necessary in southwestern Japan to ensure intraspecific genetic diversity under future climate change.  相似文献   

10.
We used 474 European plant species to analyse the impacts of climate and land-use change on the composition of habitat-specific species pools in Germany. We quantified changes in the probability of occurrence of species in a grid cell using an ensemble of three statistical modelling techniques, namely generalized linear models (GLMs), generalized additive models (GAMs) and random forests (RFs), under three scenarios (average change +2.2, +2.9, and +3.8 °C up to 2080). We evaluated the impact on single species occurrence and resulting species pools considering their affiliation to ten major terrestrial habitat types in both current (1961–90) and future projections (2051–80). Current habitat-specific species pools declined in size across all scenarios, e.g. by 24 ± 13% (mean ± s.d.) under the most severe scenario. We show that species responses may strongly vary among scenarios and different habitats with a minimum average projected range loss of 14% (±18%; species typical to urban habitats under moderate climate change assumptions, average temperature increase +2.2 °C) to a maximum average projected range loss of 56% (±29%; species assemblages from mountain communities below the alpine zone at +3.8 °C). A separate analysis of species composition in habitat-specific species pools revealed a significant interaction between the scenario and the major habitat classes. We found a higher risk for habitat types with high conservation value characterised by a significant association between number of nationally endangered species and projected range loss in major habitats. Thus, habitat-specific management and application of measures favouring dispersal are required for mitigation of climate change impacts.  相似文献   

11.
《Mammalian Biology》2014,79(5):313-317
Coexistence has been widely studied in small mammals and frequently is assumed to be facilitated by habitat segregation. Using live trapping and spool-and-line experiments, we analyzed habitat selection and segregation across multiples scales for Peromyscus leucopus and Ochrotomys nuttalli. At the habitat scale of a forest stand (∼1–100s ha) P. leucopus co-occurred at all sites where O. nuttalli was found, and we did not detect evidence of positive or negative associations or habitat segregation. However, O. nuttalli was restricted to early successional forests, and P. leucopus had significantly lower abundances in early successional forests than in other habitats. We found similar patterns at the mesohabitat scale of the study site (400 m2). O. nuttalli abundance increased with increasing shrub and tree densities, while increases in P. leucopus abundance were associated with open understories. At the microhabitat scale of the individual movement trail, we found vertical segregation. Movement trails for O. nuttalli were at significantly higher elevation (mean height = 142.93 ± 37.10 cm) than P. leucopus trails (mean height = 15.4 ± 4.98 cm; F-value = 35.29, p < 0.001). We concluded that microhabitat segregation was driven by differential use of vertical space for movement and foraging. We suggest O. nuttalli is superior to P. leucopus in its ability to acquire food especially in shrubby subcanopies where few acorns are available. However, P. leucopus is superior in its ability to forage and avoid predators.  相似文献   

12.
《农业工程》2014,34(4):219-224
Large ungulate population monitoring is a crucial wildlife management tool as ungulates help in structuring and maintaining the large carnivore populations. Reliable data on population status of major ungulate prey species are still non-existent for most of the protected areas in the Indian part of the eastern Himalayan biodiversity hotspot. Twenty transects were monitored over a period of three years (2009–2011) totaling 600 km with an average length of 2 km. The estimated mean density of ungulates was 17.5 km−2 with overall density of 48.7 km−2. The wild pig Sus scrofa had the highest density (6.7 ± 1.2 km−2) among all the prey species followed by barking deer Muntiacus muntjak (3.9 ± 0.6 km−2), sambar Rusa unicolor (3.8 ± 0.5) and gaur Bos gaurus (3.5 ± 0.9 km−2). The estimated total ungulate biomass density was 2182.56 kg km−2. This prey biomass can support up to 7.2 tigers per 100 km−2. However, with two other sympatric carnivores sharing the same resources, the actual tiger numbers that can be supported will be lower. The estimated minor prey species was 31 km−2 significantly 30.6% crop damages were reported by wild pig (p = 0.01) and 35.4% was elephant (p = 0.004). This data on ungulate densities and biomass will be crucial for carnivore conservation in this understudied globally significant biodiversity hotspot.  相似文献   

13.
Afrotropical ant-following birds are vulnerable to forest loss and disturbance, but critical habitat thresholds regarding their abundance and species richness in human-dominated landscapes, including industrial oil palm plantations, have never been assessed. We measured forest cover through Landsat imagery and recorded species richness and relative abundance of 20 ant-following birds in 48 plots of 1-km2, covering three landscapes of Southwest Cameroon: Korup National Park, smallholder agroforestry areas (with farms embedded in forest), and an industrial oil palm plantation. We evaluated differences in encounter frequency and species richness among landscapes, and the presence of critical thresholds through enhanced adaptive regression through hinges. All species were detected in Korup National Park and the agroforestry landscape, which had similar forest cover (>85%). Only nine species were found in the oil palm plantation (forest cover = 10.3 ± 3.3%). At the 1-km2 scale, the number of species and bird encounters were comparable in agroforests and the protected area: mean species richness ranged from 12.2 ± 0.6 in the park and 12.2 ± 0.6 in the agroforestry matrix to 1.0 ± 0.4 in the industrial oil palm plantation; whereas encounters decreased from 34.4 ± 3.2 to 26.1 ± 2.9 and 1.3 ± 0.4, respectively. Bird encounters decreased linearly with decreasing forest cover, down to an extinction threshold identified at 24% forest cover. Species richness declined linearly by ca. one species per 7.4% forest cover lost. We identified an extinction threshold at 52% forest cover for the most sensitive species (Criniger chloronotus, Dicrurus atripennis, and Neocossyphus poensis). Our results show that substantial proportions of forests are required to sustain complete ant-following bird assemblages in Afrotropical landscapes and confirm the high sensitivity of this bird guild to deforestation after industrial oil palm development. Securing both forest biodiversity and food production in an Afrotropical production landscape may be best attained through a combination of protected areas and wildlife-friendly agroforestry.  相似文献   

14.
《Aquatic Botany》2007,86(4):309-315
The influence of the amplitude of cyclic water level fluctuations on the growth of four species of emergent macrophyte (Cyperus vaginatus, Phragmites australis, Triglochin procerum and Typha domingensis) was studied in a controlled, pond-based experiment. The amplitudes of water level fluctuations were static, ±15, ±30 and ±45 cm, each cycling over a forty-day period. In all treatments the water level fluctuated around an initial water depth of 60 cm. Within each amplitude treatment, plants were grown at three elevations with the sediment surface at 20, 40 or 60 cm. Only T. domingensis and P. australis showed a significant response to amplitude. Biomass of T. domingensis was similar in the static, ±15 and ±30 cm amplitude treatments but dropped by ca. 52% when grown in amplitudes of ±45 cm. In contrast, the largest biomass for P. australis occurred in the ±30 cm amplitude treatment suggesting this species prefers moderately fluctuating water levels. The response of P. australis to amplitude was contingent upon elevation with plants growing in the ±45 cm amplitude, low elevation treatment having particularly low biomasses. C. vaginatus biomass increased with increasing elevation but did not respond to amplitude while T. procerum did not respond to either amplitude or elevation likely due to the ability of the species to photosynthesise under water. The relative growth rate and the average emergent surface area were logarithmically related in C. vaginatus suggesting flooding of the photosynthetic canopy was limiting the ability of this species to acquire atmospheric carbon. No clear relationship was found for T. domingensis or P. australis indicating that a factor other than access to atmospheric carbon was restricting the growth of these species.  相似文献   

15.
Smoke stimulates seed germination of a range of species from ecosystems that may or may not be fire prone. We evaluated the effects of smoke-water on germination of ten tree species of economic value in the Amazon region. Two materials were burnt to produce smoke-water: germination paper and the wood of Cecropia palmata Willd. Seven dilutions of the solutions were tested. Seeds of nine forest trees were germinated under controlled laboratory conditions (25 °C ± 2 °C) in the laboratory. Bertholletia excelsa Humb. & Bonpl., was tested in the nursery (approximately 25–36 °C) because of its large seeds. Irrespective of the material burned, smoke-water significantly increased seed germination of three species: Cordia goeldiana Hub., Ochroma pyramidale (Cav. ex Lam.) Urb. and Jacaranda copaia (Aubl.) D. Don. and there was a significant inhibitory effect on Swietenia macrophylla King. Germination was accelerated by smoke in J. copaia, B. excelsa and Bellucia grossularioides (L.) Triana. The most pronounced effect was observed in B. excelsa, as the mean germination time of 108 d (control) was reduced to 76 d with smoke-water made from germination paper (dilution of 1:25) and to 61 d with the one from Cecropia wood (dilution of 1:250). For five of the ten species studied, smoke-water either increased or accelerated seed germination, irrespective of the materials used for its production. Seeds with low vigour and prolonged germination time seemed to be more receptive to smoke.  相似文献   

16.
The thermal energetics of rodents from cool, wet tropical highlands are poorly known. Metabolic rate, body temperature and thermal conductance were measured in the moss-forest rat, Rattus niobe (Rodentia), a small murid endemic to the highlands of New Guinea. These data were evaluated in the context of the variation observed in the genus Rattus and among tropical murids. In 7 adult R. niobe, basal metabolic rate (BMR) averaged 53.6±6.6 mL O2 h−1, or 103% of the value predicted for a body mass of 42.3±5.8 g. Compared to other species of Rattus, R. niobe combines a low body temperature (35.5±0.6 °C) and a moderately low minimal wet thermal conductance cmin (5.88±0.7 mL O2 h−1 °C−1, 95% of predicted) with a small size, all of which lead to reduced energy expenditure in a constantly cool environment. The correlations of mean annual rainfall and temperature, altitude and body mass with BMR, body temperature and cmin were analyzed comparatively among tropical Muridae. Neither BMR, nor cmin or body temperature correlated with ambient temperature or altitude. Some of the factors which promote high BMR in higher latitude habitats, such as seasonal exposure to very low temperature and short reproductive season, are lacking in wet montane tropical forests. BMR increased with rainfall, confirming a pattern observed among other assemblages of mammals. This correlation was due to the low BMR of several desert adapted murids, while R. niobe and other species from wet habitats had a moderate BMR.  相似文献   

17.
Terminalia bellerica Roxb. (Belleric Myrobalan, Vern. — Baheda, Sanskrit-Vibhitaki, Family: Combretaceae) is among multipurpose tree species in India. The dried pulp of the seeds being used for the preparation of an ancient herbal formulation called Triphala (in Hindi). Seed size is considered a useful attribute for the propagation of valuable trees. The effect of seed size on seedling emergence in T. bellerica was studied under nursery conditions. Emergence of seedlings from large (mean dry weight1.18 ± 0.02 g), medium (0.95 ± 0.03 g) and small seeds (0.76 ± 0.03 g) varied significantly (LSDSin p < 0.05 = 4.12, Sin = 0.52). Higher numbers of seedlings emerged from the large seeds compared with medium and small seeds. Seed weight also correlated positively with seedling emergence in T. bellerica (r = 0.967, significant α = 0.01, df = 7). Findings of this study will be useful for mass propagation of T. bellerica and reintroduction of elites in different habitats.  相似文献   

18.
This research is the first to record the complete life history of the aquatic firefly Luciola ficta (Olivier) using a unique individual rearing method. Transparent containers (250 ml; height: 6 cm; bottom diameter: 8 cm; mouth diameter: 9.5 cm) were used to rear individuals from egg to adult in the laboratory, so that they could be observed throughout the whole life cycle. Larvae were fed on the meat of the water snail Cipangopaludina chinensis (Gray). Temperature ranged from 18 °C to 30 °C, relative humidity (RH) was 80 ± 5%, and the light:dark (L:D) ratio was 10:14. Of 80 eggs, 35 individuals completed their life cycle under these laboratory conditions in Jiji, Nantou County, Taiwan. The external morphological characteristics of each growing stage were described. Egg hatching rate was 95%. On average, one generation spanned 388.2 ± 25.7 days. The durations of egg, larva, climbing larva, cocoon, and adult stages were 19.1 ± 1.5 days, 328.9 ± 33.2 days, 10.9 ± 7.8 days, 14.7 ± 5.3 days, and 15.7 ± 5.2 days, respectively. The number of larval instars ranged from five to seven, with a modal value of six instars for males and seven instars for females. Female larval duration averaged 337.1 ± 31.2 days, which was higher than the 307.6 ± 34.1 days of the males. From January to December 2002, adult emergence peaked twice, with the main high peak appearing in April and the second peak occurring in August. The results of indoor rearing and of field investigations in Jiji, Nantou County, suggested that L. ficta is univoltine. Adult body length is negatively correlated with larval duration (P < 0.01). The life history traits of L. ficta show plasticity in adult occurrence, egg size, egg duration, larval duration, larval instars, and adult body length. Some variations were discussed in the context of survivorship in field habitats.  相似文献   

19.
Solitary felids are commonly associated with structurally complex habitats, where their foraging success is attributed to stealth and remaining undetected by competitive scavengers. Research in North America suggests that pumas (Puma concolor), a wide-ranging species found throughout the Americas, conform to the general characteristics of solitary felids and avoid open grasslands with aggregating prey. Researchers hypothesize that pumas are limited to structurally complex habitats in North America because of pressures from other large, terrestrial competitors. We explored the spatial ecology of pumas in open habitat with aggregating prey in Chilean Patagonia, where pumas lack large, terrestrial competitors. We tracked 11 pumas over 30 months (intensive location data for 9 pumas with GPS collars for 9.33 ± 5.66 months each) in an area where mixed steppe grasslands composed 53% of the study area and carried 98% of available prey biomass, to track resource use relative to availability, assess daily movements, quantify home ranges and calculate their density. As determined by location data and kill sites, Patagonia pumas were primarily associated with open habitats with high prey biomass, but at finer scales, preferentially selected for habitat with complex structure. On average, pumas traveled 13.42 ± 2.50 km per day. Estimated 95% fixed kernel home ranges averaged 98 ± 31.8 km2 for females and 211 ± 138.8 km2 for males, with high spatial overlap within and between the sexes. In a multivariate analysis, available prey biomass was the strongest predictor of variation in the size of an individual puma's home range. Finally, we determined a total puma density of 3.44 pumas/100 km2, a significantly smaller estimate than previously reported for Patagonia, but similar to densities reported for North America.  相似文献   

20.
Genetic diversity and genetic differentiation of narrowly endemic Sinocalycanthus chinensis Cheng et S.Y. Chang, an endangered species of China, were analyzed using random amplified polymorphic DNA (RAPD) markers. Totally, 165 stable and clearly scored RAPD bands were achieved from 12 primers. The genetic diversity of S. chinensis was high (P% = 68.84; h = 0.2421 ± 0.1978; I = 0.3615 ± 0.2789), whereas that at the population level was relatively low (P% = 14.49; h = 0.0578 ± 0.0167; I = 0.0843 ± 0.0236). High genetic differentiation among populations was detected based on Shannon's information index (0.7668), Nei's gene diversity (0.7613) and AMOVA (0.8183). This might be explained by its survival in refugia during the last glaciation in southeastern China with origin from a widespread continental progenitor. The 10 populations from different geographical sites could be clustered into two groups. Low gene flow due to mixed mating system and anthropogenic activities likely played important roles in shaping the population genetic structure of the species.  相似文献   

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