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111.
Dioon edule (Zamiaceae) is an endemic Mexican cycad. Nineteen microsatellite loci were isolated from three enriched genomic libraries of D. edule var. angustifolium, D. tomasellii, and D. caputoi. Seven of these loci showed polymorphisms in D. edule. Levels of polymorphism were assessed using 16 individuals from each of seven populations throughout the range of this species. The number of alleles per locus ranged from two to five and the observed and expected heterozygosities ranged from 0.0 to 0.9821 and from 0.0088 to 0.6318, respectively. All loci show significant linkage disequilibrium. Three loci depart significantly from Hardy–Weinberg equilibrium. 相似文献
112.
If resource availability shapes population distribution, changes in resource abundance should cause parallel changes in population numbers. However, tracking ability may be disrupted by different environmental and behavioural factors that act at different spatial and temporal scales. Here we analyse the ability of wintering Blackcap Sylvia atricapilla populations to track spatio-temporal variation in fruit availability in southern Spain in two habitats (forests and shrublands) with different population structure. Former studies had shown that forests are equally used by both adult migrant and local Blackcaps, whereas shrublands are nearly monopolized by juvenile migrants. These differences might affect resource tracking: it should be disrupted in forests, as local birds remain over winter in their breeding territories, but not in shrublands where similarly competitive juvenile migrants can freely track the spatial distribution of fruits. We analysed the fruit-tracking ability of Blackcap populations among sites and years in both habitat types using a habitat-matching model, which predicts spatio-temporal changes in population abundance proportional to changes in resource availability. We counted Blackcaps and fruiting shrubs (dominated by Lentiscs Pistacia lentiscus and Wild Olives Olea europaea sylvestris ) during four winters in forest and shrubland patches. The abundance of fruits was always higher in shrublands than in forests. In shrublands, Blackcaps seemed to move freely across fruit-rich habitat patches, tracking changes in fruiting-shrub abundance among sites and years. However, such tracking was not observed in forests. This supports the view that fruit-tracking ability may be constrained by local factors, such as the social structure of populations occurring in different habitat types, which introduces spatio-temporal variation in the way fruit availability shapes the abundance distribution of these birds in their Mediterranean wintering grounds. 相似文献
113.
GONZALO NIETO FELINER Fls JAVIER FUERTES AGUILAR JOSEP ANTONI ROSSELLÓ 《Botanical journal of the Linnean Society. Linnean Society of London》2001,135(1):71-84
The taxonomic status of the populations of Armeria from the Horconera massif (Cordoba province), previously misidentified or referred to without an explicit identification, is re-examined on the basis of morphological and molecular data. A multivariate analysis indicates that they can be discriminated from morphologically and geographically close taxa using morphometric characters. According to these results, and taking into account the previous evidence that supports extensive reticulation in the genus, a new species, A. trianoi , is formally described. Molecular evidence from our previous works, in particular the nuclear ribosomal ITS sequence data, provides the frame for a discussion on the origin of the new entity. It is suggested that A. trianoi may be the result of introgression of sympatric populations of A. villosa subsp. longiaristata into a pre-existing taxon, possibly A. filicaulis var. minor presently occurring in Sierra Tejeda some 50 km apart. 相似文献
114.
JAVIER BUSTAMANTE JOSÉ ANTONIO DONÉZAR FERNANDO HIRALDO OLGA CEBALLOS ALEJANDRO TRAVAINI 《Ibis》1997,139(2):322-330
During the 1992 breeding season, we studied the habitat selection, behaviour, aggressive interactions and diet of immature and adult Grey Eagle-buzzards Geranoaetus melanoleucus in an area of the Argentinean Patagonia. Immature eagles selected areas rich in prey, had no preference for flat or rugged areas and did not avoid areas close to active nests or those used by adult eagles. The density of the European Hare Lepus europaeus was the best predictor of the distribution of immature eagles. Adult eagles preferred rugged to flat areas but were not significantly affected by prey distribution. Immature eagles used flapping flight more frequently than did adult eagles. Wing-flapping frequency of immatures did not differ when flying over slopes or plains. In contrast, adults used a more economic flight with a lower wing-flapping frequency than that of immatures, especially when flying over slopes. Adults, in contrast to immatures, tended to select slopes when flying over predominantly flat country. Only in 22% of the occasions when adult and immatures were seen together were immatures attacked by adults, a rate of aggressive encounters similar to that observed between immatures (32%). This similarity indicates that adults do not actively exclude immatures from certain areas. The main prey of both immature and adult eagles was the introduced European Hare followed by native rodents and birds. Immatures ate significantly more carrion and fewer birds than did adults. These observations suggest that differences in flight behaviour and in the flight silhouette between adult and immature eagles may be responsible for their different habitat selection in relation to topography. While immatures apparently cue on prey density for habitat selection, adults select areas that allow more economic foraging flights 相似文献
115.
JAVIER BUSTAMANTE 《Ibis》1994,136(2):176-184
I observed the natural process of family break-up in 13 families of Black Kites Milvus migrans and five families of Red Kites M. milvus in which fledglings had been individually marked. In other broods, I performed experiments which modified the parental investment fledglings received by supplementing nests of both species with food or transferring Black Kite chicks to nests with younger or older chicks of the same species.
The time of family break-up in the Black Kite is mainly an offspring decision which is not affected by an artificial increase of parental investment. The duration of the post-fledging period was not increased in Black Kites that were given supplementary food. Chicks transferred to nests with a younger chick did not extend the post-fledging period, nor did chicks transferred to nests with an older chick shorten the post-fledging period. In Red Kites, parental investment seemed to have more influence on the timing of the family break-up. Red Kite adults invested less as parents than did Black Kites during the post-fledging dependence period, and in nests where supplementary food was given, Red Kite fledglings stayed attached for a longer period. 相似文献
The time of family break-up in the Black Kite is mainly an offspring decision which is not affected by an artificial increase of parental investment. The duration of the post-fledging period was not increased in Black Kites that were given supplementary food. Chicks transferred to nests with a younger chick did not extend the post-fledging period, nor did chicks transferred to nests with an older chick shorten the post-fledging period. In Red Kites, parental investment seemed to have more influence on the timing of the family break-up. Red Kite adults invested less as parents than did Black Kites during the post-fledging dependence period, and in nests where supplementary food was given, Red Kite fledglings stayed attached for a longer period. 相似文献
116.
117.
1. The objective was to explore the regulatory mechanisms underlying the numerical dynamics of a river stock of European eel Anguilla anguilla based on a purely observational study. We used a 21-year data set on the Rio Esva (Asturias, northwestern Spain) stock of eels, encompassing eel density at an estuary site and at nine sites distributed among three tributaries selected to differ in the distance from the tidal limit and fishery data on glass eels from the nearby Rio Nalón estuary.
2. The abundance of glass eels and estuarine and in-stream densities declined simultaneously over a 15-year period. However, following a historical minimum in the abundance of glass eels around the year 2000, the density continued to decline in the estuary whereas density in the streams began an increase that has continued to the present.
3. In-stream cohort mortality rate ( Z ) varied from 0.0016 day−1 to only 0.0003 day−1 (on an annual basis from 0.57 to 0.099 year−1 ). The negative effects of intra-cohort and inter-cohort densities on mortality rate emphasized the responses of the riverine stock to compensatory density-dependence. As a consequence, the number of eels surviving to commence the silvering stage was similar in magnitude in the strongest and weakest cohorts.
4. These results suggest that, even if the low abundance of glass eels persists, in-stream density may increase towards a stable value regulated by in-stream density-dependence. 相似文献
2. The abundance of glass eels and estuarine and in-stream densities declined simultaneously over a 15-year period. However, following a historical minimum in the abundance of glass eels around the year 2000, the density continued to decline in the estuary whereas density in the streams began an increase that has continued to the present.
3. In-stream cohort mortality rate ( Z ) varied from 0.0016 day
4. These results suggest that, even if the low abundance of glass eels persists, in-stream density may increase towards a stable value regulated by in-stream density-dependence. 相似文献
118.
Kernel density estimation with spherical data 总被引:9,自引:0,他引:9
119.
Factors influencing family rupture and parent-offspring conflict in the Black Kite Milvus migrans 总被引:2,自引:0,他引:2
Juvenile and adult behaviour was studied at eight nests of Black Kites Milvus migrans within the Doñana Biological Reserve, Spain. Parental investment in vigilance and defence of offspring progressively decreased during the post-fledging dependence period. The number of feeds was also slightly reduced towards the end of the period. However, this does not seem to be the main factor which leads to juvenile independence. The fact that the family rupture is sudden and that the post-fledging dependence period tends to shorten as the season progresses suggests that juvenile and adult migratory urgency may be as important a factor as reduced parental investment in breaking the family ties. 相似文献