University of California Research Seminar Network: A Prospectus

By webcasting the hundreds of seminars presented in the University of California system each week, UC educators hope to enhance the exchange of scientific information for their campuses and create the foundation for an international research seminar network

Effect of Resting Patterns of Tamarins (Saguinus fuscicollis and Saguinus mystax) on the Spatial Distribution of Seeds and Seedling Recruitment

The spatial distributions of dispersed seeds have important evolutionary consequences for plants. Repeated defecations in sites frequently used by seed dispersers can result in high seed concentrations. We observed the resting behavior of a mixed-species group of tamarins in Peru and recorded the occurrence of seed dispersal (over 8 mo) and seed fate (over 11–22 mo) to determine whether the location and use of resting sites influenced the spatial distribution of dispersed seeds and seedlings. The tamarins rested mostly on trees (Saguinus fuscicollis: 60.6%, S. mystax: 89.2%) and dead trunks (S. fuscicollis: 24.4%) and used 61% of their resting sites repeatedly. During both the dry and wet seasons, tamarins dispersed significantly more seeds within resting areas (0.00662 and 0.00424 seeds/m2, respectively) than outside them (0.00141 and 0.00181 seeds/m2). Seed survival and seedling recruitment did not differ significantly between resting and other areas, resulting in a higher seedling concentration around the resting sites. Seed density did not increase with the duration or the frequency of use of the resting sites but did increase when we pooled the seasonal resting sites together in 50 m × 50 m quadrats, ultimately causing a clumped distribution of dispersed seeds. The use of resting sites in secondary forest, particularly during the dry season, allows the creation of seedling recruitment centers for species coming from the primary forest. Our findings show that tamarin resting behavior affects the spatial distribution of dispersed seeds and seedlings, and their resting sites play an important role in plant diversity maintenance and facilitate forest regeneration in degraded areas

Seed Dispersal Anachronisms: Rethinking the Fruits Extinct Megafauna Ate

Background: Some neotropical, fleshy-fruited plants have fruits structurally similar to paleotropical fruits dispersed by megafauna (mammals.10 3 kg), yet these dispersers were extinct in South America 10–15 Kyr BP. Anachronic dispersal systems are best explained by interactions with extinct animals and show impaired dispersal resulting in altered seed dispersal dynamics. Methodology/Principal Findings: We introduce an operational definition of megafaunal fruits and perform a comparative analysis of 103 Neotropical fruit species fitting this dispersal mode. We define two megafaunal fruit types based on previous analyses of elephant fruits: fruits 4–10 cm in diameter with up to five large seeds, and fruits.10 cm diameter with numerous small seeds. Megafaunal fruits are well represented in unrelated families such as Sapotaceae, Fabaceae, Solanaceae, Apocynaceae, Malvaceae, Caryocaraceae, and Arecaceae and combine an overbuilt design (large fruit mass and size) with either a single or few (,3 seeds) extremely large seeds or many small seeds (usually.100 seeds). Within-family and within-genus contrasts between megafaunal and non-megafaunal groups of species indicate a marked difference in fruit diameter and fruit mass but less so for individual seed mass, with a significant trend for megafaunal fruits to have larger seeds and seediness. Conclusions/Significance: Megafaunal fruits allow plants to circumvent the trade-off between seed size and dispersal b

Anastrozole versus tamoxifen for the prevention of locoregional and contralateral breast cancer in postmenopausal women with locally excised ductal carcinoma in situ (IBIS-II DCIS): a double-blind, randomised controlled trial

Background Third-generation aromatase inhibitors are more effective than tamoxifen for preventing recurrence in postmenopausal women with hormone-receptor-positive invasive breast cancer. However, it is not known whether anastrozole is more effective than tamoxifen for women with hormone-receptor-positive ductal carcinoma in situ (DCIS). Here, we compare the efficacy of anastrozole with that of tamoxifen in postmenopausal women with hormone-receptor-positive DCIS. Methods In a double-blind, multicentre, randomised placebo-controlled trial, we recruited women who had been diagnosed with locally excised, hormone-receptor-positive DCIS. Eligible women were randomly assigned in a 1:1 ratio by central computer allocation to receive 1 mg oral anastrozole or 20 mg oral tamoxifen every day for 5 years. Randomisation was stratified by major centre or hub and was done in blocks (six, eight, or ten). All trial personnel, participants, and clinicians were masked to treatment allocation and only the trial statistician had access to treatment allocation. The primary endpoint was all recurrence, including recurrent DCIS and new contralateral tumours. All analyses were done on a modified intention-to-treat basis (in all women who were randomised and did not revoke consent for their data to be included) and proportional hazard models were used to compute hazard ratios and corresponding confidence intervals. This trial is registered at the ISRCTN registry, number ISRCTN37546358. Results Between March 3, 2003, and Feb 8, 2012, we enrolled 2980 postmenopausal women from 236 centres in 14 countries and randomly assigned them to receive anastrozole (1449 analysed) or tamoxifen (1489 analysed). Median follow-up was 7·2 years (IQR 5·6–8·9), and 144 breast cancer recurrences were recorded. We noted no statistically significant difference in overall recurrence (67 recurrences for anastrozole vs 77 for tamoxifen; HR 0·89 [95% CI 0·64–1·23]). The non-inferiority of anastrozole was established (upper 95% CI <1·25), but its superiority to tamoxifen was not (p=0·49). A total of 69 deaths were recorded (33 for anastrozole vs 36 for tamoxifen; HR 0·93 [95% CI 0·58–1·50], p=0·78), and no specific cause was more common in one group than the other. The number of women reporting any adverse event was similar between anastrozole (1323 women, 91%) and tamoxifen (1379 women, 93%); the side-effect profiles of the two drugs differed, with more fractures, musculoskeletal events, hypercholesterolaemia, and strokes with anastrozole and more muscle spasm, gynaecological cancers and symptoms, vasomotor symptoms, and deep vein thromboses with tamoxifen. Conclusions No clear efficacy differences were seen between the two treatments. Anastrozole offers another treatment option for postmenopausal women with hormone-receptor-positive DCIS, which may be be more appropriate for some women with contraindications for tamoxifen. Longer follow-up will be necessary to fully evaluate treatment differences

Averting biodiversity collapse in tropical forest protected areas

The rapid disruption of tropical forests probably imperils global biodiversity more than any other contemporary phenomenon¹⁻³. With deforestation advancing quickly, protected areas are increasingly becoming final refuges for threatened species and natural ecosystem processes. However, many protected areas in the tropics are themselves vulnerable to human encroachment and other environmental stresses⁴⁻⁹. As pressures mount, it is vital to know whether existing reserves can sustain their biodiversity. A critical constraint in addressing this question has been that data describing a broad array of biodiversity groups have been unavailable for a sufficiently large and representative sample of reserves. Here we present a uniquely comprehensive data set on changes over the past 20 to 30 years in 31 functional groups of species and 21 potential drivers of environmental change, for 60 protected areas stratified across the world’s major tropical regions. Our analysis reveals great variation in reserve ‘health’: about half of all reserves have been effective or performed passably, but the rest are experiencing an erosion of biodiversity that is often alarmingly widespread taxonomically and functionally. Habitat disruption, hunting and forest-product exploitation were the strongest predictors of declining reserve health. Crucially, environmental changes immediately outside reserves seemed nearly as important as those inside in determining their ecological fate, with changes inside reserves strongly mirroring those occurring around them. These findings suggest that tropical protected areas are often intimately linked ecologically to their surrounding habitats, and that a failure to stem broad-scale loss and degradation of such habitats could sharply increase the likelihood of serious biodiversity declines.Keywords: Ecology, Environmental scienc

Occupation de l’espace par deux Bovidés sympatriques de la forêt dense africaine Cephalophus callipygus. Influence du rythme d’activité

The two sympatric duikers, the Peters’ Duiker Cephalophus callipygus and the Bay Duiker C. dorsalis are very similar in morphology (body-weight, 20-22 kg ; height at shoulder, 52-55 cm). They share the same forest areas and have a similar diet, but they display opposite activity rhythms : Peters’ Duiker is strictly diurnal, whereas Bay Duiker is nocturnal. The activity rhythm of 17 individuals was followed by radio-tracking during a 28 months study period. It shows a bimodal pattern, with short rest periods in the middle of the day for C. callipygus, and during the first half of the night for C. dorsalis. The inactive period of the latter is longer than that of C. callipygus. The density of the undergrowth and visibility at the animal level were estimated, using an objective technique, and three undergrowth categories were distinguished. Peters’ Duiker prefers a dense undergrowth both for its diurnal rest and for its long activity period. On the contrary, the Bay Duiker can forage in a more open undergrowth when active by night, but always conceals itself in some protected place (tree falls, hollow logs, between tree butresses, ...) during itsFeer F. Occupation de l’espace par deux Bovidés sympatriques de la forêt dense africaine Cephalophus callipygus. Influence du rythme d’activité. In: Revue d'Écologie (La Terre et La Vie), tome 44, n°3, 1989. pp. 225-248

Observations écologiques sur le Néotrague de Bates (Neotragus batesi du Nord-Est du Gabon

Bates’s Pygmy Antelope Neotragus batesi was studied for 15 consecutive months in North East Gabon. Fourteen animals were individually marked and six of them (5 ♀ ♀ and 1 ♂) monitored by radio-tracking. During the same period, 128 specimens were collected outside the study area, to examine the stages of growth of their jugal teeth, tooth wear and reproductive condition. Four age-categories can be recognized among young animals, and five among adults. In the mature rain forest Neotragus batesi is commonly found in tree falls and along riversides. It thrives in secondary growth vegetation and native plantations where it reaches its highest population densities. Both its morphology and habits are well adapted to locomotion through dense undergrowth. Bates’s Pigmy Antelope is active by day as well as by night, with peaks in the morning and the evening. It rests in the middle of the day, and in the beginning and middle of the night. The home ranges are small (1 to 3 ha for females ; 2 to 4 ha for males). This area is not used evenly throughout the year ; the core-area of the range changes in keeping with the seasons. Furthermore, every home range includes areas which are used only by day and others which are visited only by night, vegetation structure differing accordingly. The more regularly tended native plantations are those which produce the most food for Neotragus batesi, but periodical clearing of the undergrowth also disturbs the animals. Bates’s Pygmy Antelope has therefore to make use of both well managed native plantations and neglected ones or secondary growth to ensure its food supply and shelter. About 200 species of plants are eaten by Neotragus batesi in N.E. Gabon. Usually this pigmy antelope makes use of a given area when its plant food is most readily available, thus quickly adapting to new situations. Some of the most actively sought plant species, however, may definitely be scarce. On the whole this animal tends to browse upon the most nutritious parts of the plants it selects. Bates’s Pigmy Antelope is a solitary animal ; 76 % of the individuals encountered were alone. More than one female can share a single home range, whereas males never do so. Interindividual communication is mostly achieved through short groans (between a young animal and its mother, or between adult males and females), and through olfactory marking by the secretion of males’ anteorbital glands. Females do not display any territorial behaviour, whereas males might do so. Males are apparently polygamous, their large home ranges overlapping those of several females. Females give birth throughout the year, with peaks at the end of each of the two rainy seasons. In this way the young animals are weaned at a time when fresh grass is readily available. Mortality rate among males apparently increases at the M² stage, when the young leave their mothers’ ranges, and also among the oldest adults. Among females mortality seems to be the highest amongst subadults, at the onset of the reproductive period. Females, as usual, outlive males. Competition with sympatric ungulates is avoided by differences in size, a protracted activity rythm, and a strictly folivorous diet.Feer F. Observations écologiques sur le Néotrague de Bates (Neotragus batesi du Nord-Est du Gabon. In: La Terre et La Vie, Revue d'Histoire naturelle, tome 33, n°2, 1979. pp. 159-239