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Examination of spatial variation in demography among or within populations of the same species is a topic of growing interest in ecology. We examined whether spatial variation in demography of a tropical megaherbivore followed the “temporal paradigm” or the “adult survival paradigm” of ungulate population dynamics formulated from temperate-zone studies. We quantified spatial variation in demographic rates for giraffes (Giraffa camelopardalis) at regional and continental scales. Regionally, we used photographic capture-mark-recapture data from 860 adult females and 449 calves to estimate adult female survival, calf survival, and reproduction at 5 sites in the Tarangire ecosystem of Tanzania. We examined potential mechanisms for spatial variation in regional demographic rates. At the continental scale, we synthesized demographic estimates from published studies across the range of the species. We created matrix population models for all sites at both scales and used prospective and retrospective analyses to determine which vital rate was most important to variation in population growth rate. Spatial variability of demographic parameters at the continental scale was in agreement with the temporal paradigm of low variability in adult survival and more highly variable reproduction and calf survival. In contrast, at the regional scale, adult female survival had higher spatial variation, in agreement with the adult survival paradigm. At both scales, variation in adult female survival made the greatest contribution to variation in local population growth rates. Our work documented contrasting patterns of spatial variation in demographic rates of giraffes at 2 spatial scales, but at both scales, we found the same vital rate was most important. We also found anthropogenic impacts on adult females are the most likely mechanism of regional population trajectories.

The predation rate of artificial bird nests was measured in disturbed chaparral habitat fragments and at an unfragmented site in coastal San Diego County, California USA. Local extinctions of chaparral birds has been previously shown to occur in these fragments. The predation rate was highest at the unfragmented site. Among fragments, predation was higher at moderately disturbed than at highly disturbed sites. These results suggest that nest predator species diversity or density is reduced in disturbed chaparral fragments. Nest predation is probably not the most important cause of the observed loss of chaparral breeding bird diversity in these fragments.

We report differences in the thermal biology, elevational, temporal and geographic distributions of sympatric clones of the widespread asexual house gecko, Lepidodactylus lugubris. The two most common L. lugubris clones in Fiji, clones 2NA and 2NB, differ significantly in preferred temperature as measured in a laboratory heat gradient, but were similar in critical thermal maximum and minimum. Significant differences were found in the relative frequency of clones 2NA, 2NB, and a third Fijian clone, clone 3NB, at seven sites along an elevational gradient in Fiji. Clone 2NB was not collected at sites above 235 m, consistent with its higher preferred temperature, whereas clone 2NA was captured as high as 835 m. Clone 3NB was extremely rare at sealevel (1% of all individuals at three sites below 100 m), but predominated at the two highest-elevation sites (42% and 100%). Clones 2NA and 2NB did not differ significantly in their activity time or ambient activity temperature at low-elevation sites. Clone 3NB however, was active on significantly cooler nights at two of those sites. These significant inter-clonal differences in spatial and temporal distribution should allow a more complete utilization of resources by the assemblage of clones than by any single clonal genotype, and may promote coexistence of clones at a within-island and within-site scale. Clone 2NA, which is the most common clone in Fiji and has the broadest elevational distribution, also has the widest geographic distribution. It was the predominant clone at 27 of 34 sites surveyed in nine Pacific archipelagoes. This suggests that the ecological attributes that favor this clone in Fiji also favor it elsewhere in the Pacific despite differing environmental conditions and clonal composition in those areas.