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1.
I conducted the first long- term study of the life history patterns of Propithecus diadema edwardsi—Milne- Edward’s sifaka— in the rain forests of southeastern Madagascar, beginning in 1986. I report behavioral observations on a total of 33 individuals from three groups over a 9- year span. We captured,marked, and released 21 individuals. Individual group size ranged from three to nine sifakas. Two breeding females lived in groups I and II until 1993. A newly formed group (III) had one breeding female. Age at first reproduction is 4 years for females and 5 years for males. Gestation length is 179 days (n =2). Most births occurred in June (n = 17), but infants were also born in May (n = 2) and July (n =2). Nine of 21 (43%) infants born died before the age of 1 year, and 15 (67%) died before the age of reproduction. One female bred in her natal group after the death of the resident male and the immigration of an adult male. Another two females disappeared at 4 and 5 years of age;they could have emigrated or died. All 5- to- 6- year- old males (n = 4) have emigrated from their natal groups to adjacent groups. Two have committed infanticide. Five or more individuals were killed by Cryptoprocta ferox.Despite high mortality and offspring dispersal, the number of individuals in the two main groups remained nearly the same over the 9- year study.  相似文献   

2.
Aiming to explain individual variation in gonadosomatic index (testicular volume per body weight), we examined the relationship between gonadosomatic index (GI), age, and season in a wild, seasonally breeding lemur—the Milne-Edwards' sifaka (Propithecus diadema edwardsi). Between 1987 and 2000, we captured and measured male lemurs from Ranomafana National Park in Madagascar 69 times. We used linear and polynomial regressions and residuals to examine the effect of season on GI and the effect of age on GI, after accounting for the effect caused by season among males of breeding age. As the breeding season approached, GI increased significantly, and all individuals measured in both the breeding and nonbreeding season had larger GI values in the breeding season. Among males of breeding age, we found no relationship between age and GI, after accounting for seasonal effects. Age, season and body weight fail to explain the variation remaining in GI. We discuss sperm competition, breeding-group composition, and the presence of parents as additional sources of variation in GI.  相似文献   

3.
The R-banded karyotypes of two Indriidae, Propithecus diadema and Indri indri, are described and compared with each other and with those of the other species of this family, previously reported, Avahi laniger and Propithecus verreauxi. These comparisons show that 30 chromosomal rearrangements, including 21 Robertsonian translocations and eight pericentric inversions, differentiate these karyotypes. A phylogenic diagram is proposed, showing the early separation of Avahi and the relatively late divergence of the three other species. A populational evolution has occurred between the three other species, but Indri is clearly separated from the two other species by at least five complex rearrangements, although it shares four Robertsonian translocations with P. verreauxi but not P. diadema.  相似文献   

4.
Infanticide might be described as a reproductive strategy employed by anthropoid primate males when they immigrate into new groups. But infanticide has rarely been observed in wild prosimian primates. For the Malagasy lemurs this may reflect one or more of the following: strict breeding seasons; relative monomorphism in canine tooth and body size; small group sizes; male–female dominance relations; and male–female dyads within groups. We addressed the following questions: Do prosimian males commit infanticide in circumstances similar to those in which anthropoids do? and Is there any reproductive advantage for a highly seasonal breeder to commit infanticide? To help answer these questions, we describe the death of a 24-hr-old infant male Propithecus diadema edwardsi from wounds received during a fight between his mother, her adult daughter, and a newly immigrant male. Interbirth intervals between surviving offspring are 2 years for Propithecus diadema edwardsi; therefore, a male could dramatically shorten the time between reproductive windows by killing an infant. Whether this tactic would be favored by sexual selection cannot be addressed until more information has been collected on the length of interbirth interval due to infanticide relative to that of infant death by other causes; how social factors such as stability of breeding relationships affect long-term male reproductive success; how effective female counterstrategies are to prevent infanticide and/or whether they choose to mate with males that commit infanticide; and how often males that kill infants subsequently sire infants, particularly in groups that contain a resident male.  相似文献   

5.
The silky sifaka, Propithecus candidus, considered one of the rarest and most endangered primates in the world, exists in only a few fragmented forests in northeastern Madagascar. This species faces increasing pressures as a direct result from loss of habitat in the form of tavy (slash and burn agriculture), illegal logging and mining along with hunting for subsistence, even within protected areas. We report a marker suite of 21 loci developed from genomic DNA from a silky sifaka collected in 2003 from Anjanaharibe-Sud Special Reserve. Polymorphism of each locus evaluated in 18 individuals pooled from Marojejy National Park and Anjanaharibe-Sud Special Reserve. The number of observed alleles per locus ranges from 2 to 7. The observed and expected heterozygosity were 0.389–0.889 and 0.322–0.789, respectively. The information revealed in this study will provide useful tools for further study of the social structure and population dynamics of the silky sifaka to facilitate conservation management in the imminent future.  相似文献   

6.
A group of Colobus polykomosat Tiwai, Sierra Leone, demonstrated seasonal flexibility in its diet, with seeds, young leaves, and mature leaves each dominating the diet at different times. Comparison of food consumption with phenological data indicates that seeds are eaten whenever available and are preferred to other foods, while young leaves are preferred to mature leaves. Colobus polykomosalso prefer liane to tree leaves, despite the relatively high quality of mature tree foliage at the Tiwai site. Analysis of protein, fiber, and energy values of foods selected and items available, but not eaten, suggests that preference is related to protein and energy maximization. Leguminous plants, especially Papilionaceae and Mimosaceae, are highlighted as important food sources for C. polykomos;seeds and leaves from these families have a high nitrogen content, and the protein content of leguminous seeds often equals or exceeds that found in leaves. It is predicted, therefore, that colobines living in habitats with a high density of legumes will feed heavily on seeds, subject to constraints such as seasonal availability. Where suitable leguminous species are less common, a mixture of fruits, seeds, and young or mature leaves or both is likely to be selected. The results of this and other recent studies of colobines do not support the notion that colobines are specialist folivores.  相似文献   

7.
Using focal animal samples, the social organization of sifakas was studied in two forests for 2500 hr spread over 18 months. Data were also obtained on the size and composition of groups at two other sites. The size and adult sex ratio of groups varied widely within populations, although population-wide sex ratios approached unity. During the brief annual mating season, some males mated with females belonging to other groups. The response of both male and female group members to the approach of a nongroup male appeared to depend on his identity. It is argued that while group size may be constrained by the availability of resources, group composition reflects the effects of small-sample demographic variations rather than the outcome of reproductive competition among or between males and females. Spatial boundaries of groups do not coincide with social or reproductive boundaries even within a single breeding season; further study is needed of the processes whereby relationships are established and maintained between individuals from different groups.  相似文献   

8.
I examined dietary selection by Yakushima macaques (Macaca fuscata yakui)in relation to food availability and air temperature. Multiple regression analysis indicates that both food availability and temperature influenced the selection of foods. Feeding on young leaves, seeds, and flowers was affected more by availability, while feeding on fruits, mature leaves, and fallen seeds was affected more by temperature. Feeding on insects is strongly correlated with temperature,perhaps because availability of insects increased with temperature. These results suggest that temperature influences dietary selection of Yakushima macaques by changing the energy expenditure required for thermoregulation and through its influence on the accessibility to insects, which are an important protein source for the monkeys.  相似文献   

9.
The golden-crowned sifaka (Propithecus tattersalli) is one of the most critically endangered species of Propithecus endemic to a limited area in the Daraina region of north-eastern Madagascar. This species is endangered due to habitat loss and fragmentation, a consequence of deforestation. Twenty nuclear microsatellite loci were isolated from genomic DNA derived from a Propithecus tattersalli from the Daraina area in north-eastern Madagascar. Population genetic parameters were estimated on 20 individuals from two Daraina forest fragments to determine the potential utility of this marker suite for future studies on the golden-crowned sifaka.  相似文献   

10.
Studies in anthropoid primates and other mammals suggest that reproductive season, rank, reproductive skew, aggression received, and social support are the major factors influencing glucocorticoid output. In which way these are also affecting adrenal function in lemurid primates has been studied rarely. Here, we examine the influence of reproductive season and rank on glucocorticoid output in male sifakas (Propithecus verreauxi), a species characterized by high breeding seasonality, a hierarchy among males and extreme reproductive skew towards dominant males. We established a fecal assay for non-invasively monitoring adrenal activity and collected 315 fecal samples during the reproductive and birth season from 10 male sifakas living in 5 groups in Western Madagascar. We found a significant effect of season on glucocorticoid output, with males exhibiting higher fecal glucocorticoid levels during the reproductive compared to the birth season in conjunction with an increase in overall aggression rates during the former period. Moreover, our data indicate a significant effect of rank on adrenocortical activity with dominant males exhibiting higher glucocorticoid levels than subordinate males in the reproductive season. However, dominant males did not differ significantly in rates of initiated or received aggression and rates of affiliative behavior from subordinates but showed significantly lower rates of submission. Given their highly formalized dominance relationships, we conclude that higher glucocorticoid output in dominant males during the 4-month reproductive season is likely related to higher energetic demands necessary to cope with the challenges of male reproduction rather than to physical demands of increased fighting frequency to maintain dominance status. High rank in sifakas may thus carry high costs, which, however, may be outweighed by monopolization of almost all paternities. In sum, our data generally support the findings on the relationship between environmental and social factors and glucocorticoid output found in non-lemurid primates.  相似文献   

11.
12.
Diet of Southern Muriquis in Continuous Brazilian Atlantic Forest   总被引:1,自引:0,他引:1  
We systematically collected data on feeding behavior for one group of 33–39 southern muriquis (Brachyteles arachnoides) in Parque Estadual Carlos Botelho (PECB), São Paulo State, Brazil (37,432.45 ha of continuous Atlantic Forest), between January and December 1995. We determined food item consumption from instantaneous scans of behavior. Fruits were the most eaten food items in all 12 mo (40–80% of scan in every mo, average = 71.3%). Muriquis ate young leaves more than mature leaves or flowers. Our results are consistent with previous findings at the same and neighboring forest sites that southern muriquis have a consistently frugivorous diet when inhabiting less disturbed habitats, but contrast with previous observations on oppportunistic frugivory in muriqui populations inhabiting fragmented forests. Sustained high levels of frugivory probably result from year-round availability of fruit within large continuous forests.  相似文献   

13.
Quantitative characters of the flowering head of a garden population ofMicroseris laciniata were scored during the second, third, and fourth season of growth. Number of achenes per head, number of phyllaries per head and the average number of pappus parts per achene in single heads show significant plant to plant variation. Achenes per head and pappus parts per achene were scored in identical plants in two subsequent seasons. The number of pappus parts per achene varies freely between five and ten. This contrasts with annual species ofMicroseris in which either five or ten pappus parts are found, depending on the species. In spite of a clear plant-specific average of pappus parts, both high and low pappus part determination can be demonstrated in all specimens. The number of pappus parts depends on the position of an achene on the receptacle, marginal achenes usually having fewer pappus parts than central ones. This gradient is not closely correlated with the position of an achene on the genetic spiral.  相似文献   

14.
Forest fragmentation is viewed as a serious threat to primates, yet whether or not it can disrupt food resources and cause energetic stress remains largely untested. I present the results of a 12-mo study of the feeding ecology of Propithecus diadema in fragmented and continuous forest at Tsinjoarivo, eastern Madagascar. Two continuous forest groups had higher dietary diversity and ate more fleshy fruit, but during the dry season, diversity was reduced and they relied heavily on mistletoe (Bakerella clavata). In contrast, 2 groups in fragments employed the lean season strategy of eating mistletoe year-round; the fruiting tree species that sustain continuous forest groups through the rainy season were largely absent. As expected, intersite dietary overlap was highest in the dry season. The level of specialization was high: fragment groups devoted 30–40% of feeding time to Bakerella clavata, compared to 28–30% in continuous forest. The major characteristic of Bakerella clavata enabling it to be an important fallback or staple resource, or both, is its extended phenology. The difference in resource utilization between sites may have important implications for nutritional status, as well as ranging and social behavior, largely owing to the small size and high abundance of feeding patches of Bakerella. Understanding resource shifts in fragments can shed light on socioecological questions by providing comparisons between continuous forest and fragment populations with differing diets and resource distributions. In addition, understanding dietary shifts in fragments can aid in species-specific conservation efforts, while contributing to a better understanding of the considerable interspecific variability of primates in responses to fragmentation.  相似文献   

15.
The Coquerel's sifakas were chosen for this study on hand preference because little is known about handedness in Indriidae. Fifteen Coquerel's sifakas were observed at the Duke University Primate Center as they fed on chopped fruit, vegetables, and primate chow. Analysis of age, sex, and hand preference indicated that the adult males both individually and as a group tended toward left-handedness. Adult females as a group did not show a trend in the direction of handedness. However, individual adult females showed consistent right- or left-hand preference. Younger sifakas tended toward ambipreference, suggesting that lateralization of hand preference is gradual, becoming more stable in adulthood. These findings suggest that sex and age may be strong indicators for lateralization of hand preference in Coquerel's sifakas. Duke University Primate Research Center Publication 292  相似文献   

16.
Studies so far have correlated the variation in the composition of snake venoms with the target prey population and snakes diet. Here we present the first example of an alternative evolutionary link between venom composition and dietary adaptation of snakes. We describe a dinucleotide deletion in the only three finger toxin gene expressed in the sea snake Aipysurus eydouxii (Marbled Sea Snake) venom and how it may have been the result of a significant change in dietary habits. The deletion leads to a frame shift and truncation with an accompanying loss of neurotoxicity. Due to the remarkable streamlining of sea snake venoms, a mutation of a single toxin can have dramatic effects on the whole venom, in this case likely explaining the 50- to 100-fold decrease in venom toxicity in comparison to that of other species in the same genus. This is a secondary result of the adaptation of A. eydouxii to a new dietary habit — feeding exclusively on fish eggs and, thus, the snake no longer using its venom for prey capture. This was parallel to greatly atrophied venom glands and loss of effective fangs. It is interesting to note that a potent venom was not maintained for use in defense, thus reinforcing that the primary use of snake venom is for prey capture.Nucleotide sequence data reported here have been deposited in the GenBank database under accession number AY559317.Reviewing Editor: Dr. Martin Kreitman  相似文献   

17.
According to optimal foraging theory, herbivores can base food choice mainly on the quality or the quantity of food, or both. Among herbivorous primates, folivorous lemurs living in the highly seasonal environment of Madagascar have to cope with the shortage of high-quality food during the dry season, at least in deciduous forests. We studied (Verreaux's sifaka) in Kirindy, western Madagascar, to understand the influence of dry season and food quality and quantity on behavioral patterns and feeding strategy (qualitative vs. quantitative dietary choice) of a folivorous lemur in a deciduous forest. We followed 7 groups (4 groups/period; 3 individuals/group/month) during 4 periods of the year (wet season: February–March; early/middle/late dry season: May–June; July–September; October–November). We collected samples of plants eaten and examined behavioral and feeding patterns, considering food quality (macronutrients, proteins/fibers ratio, and tannins) and abundance. We found 1) a significant reduction of home range, core area, and daily path length from the wet to the dry season, possibly related to dietary change and 2) a daily period of inactivity in the dry season for energy conservation. Regarding the feeding strategy, Kirindy sifakas showed 1) high variation and selection in choosing food items and 2) a dietary choice based mainly on quality: Kirindy sifakas fed on plant species/families independently from their abundance and tannins represented a feeding deterrent during the dry season. Overall, behavioral and dietary adaptations allow Kirindy sifakas to overcome the shortage of high-quality food in the lean period.  相似文献   

18.
The population biology of Maculinea rebeli Hirschke, 1904, on dry grassland biotypes in different successional stages was investigated in the summers of 1990 and 1991 in the district of Höxter (North Rhine–Westphalia, Germany). The population characteristics of M. rebeli were studied by mark-recapture and eggshell counts on the larval host plant Gentiana cruciata. Pitfall traps, ant baits, excavating and counting of ant nests were used to examine the Formicidae community and the nest density of Myrmica sabuleti. In 1990, the total population of M. rebeli was estimated as 528 individuals, with subpopulations varying from 2 to 273 individuals. Populations existed in areas differing in size and vegetation structure. However, the limiting factor for population size was the density of the host ant population. The differences in population size did not depend on the size of the habitat or the density of the larval food plant. The butterflies can switch their host. In the absence of M. schenki, the colonies of M. sabuleti can maintain M. rebeli populations. Adult males and females have a maximum life expectancy of 13 days. The females prefer to oviposit on G. cruciata plants of 10–30cm height. Only plants which stuck out of the surrounding vegetation were oviposited on. The average number of eggs deposited per female was 100–150. Low density populations are probably most threatened. Therefore, future protective measures should work towards further maintaining and optimizing the habitats of the small populations, as well as creating the prerequisites so that dense stable populations of M. rebeli can develop.  相似文献   

19.
Spatial and temporal variation in the diet of anadromous Arctic charr, Salvelinus alpinus, was determined from over 2500 prey-containing stomachs collected from three stock complex areas in northern Labrador. Based on the percent wet mass, sand lance, Ammodytes spp., capelin, Mallotus villosus, and sculpins, Triglops spp. and Myoxocephalus spp., were the most important components of the diet in the Voisey stock complex, with capelin, sand lance, and hyperiid amphipods, Parathemisto spp., dominating in the Nain region. In contrast, hyperiid amphipods and sculpins were the main prey items in the more northern Hebron–Saglek complex indicating that diet differs among stocks, and at times over limited spatial scales. The relative importance of prey varied with size of predator. Mean weight of charr has declined over time (p < 0.01), and for one stock complex, is highly correlated with the average quantity of capelin found in the stomachs (r = 0.66, p < 0.001). Dietary shifts observed in anadromous charr in some areas of northern Labrador could be associated, in part, with changes in the distribution of capelin in the northwest Atlantic Ocean, possibly as a result of anomalous ocean climate conditions.  相似文献   

20.
Subclass and ordinal relationships ofLoasaceae, a small predominately New World family, are examined usingrbcL sequence data. Sequences were examined for eight of the fifteen genera of theLoasaceae and the morphologically anomalous aquatic genusHydrostachys (Hydrostachyaceae). Parsimony analyses of these sequences, combined with previously publishedrcbL data, indicate thatLoasaceae belong in theCornales, and are the sister group ofHydrangeaceae. This agrees with phylogenies based on chloroplast DNA inverted repeat restriction site, morphological and chemical data. TherbcL trees support the monophyly of theLoasaceae and most generic relationships correspond to current subfamily divisions. TherbcL phylogeny also provides the first suggestion thatHydrostachys is allied with theHydrangeaceae in theCornales.  相似文献   

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