In order to understand how the effects of land‐use change vary among taxa and environmental contexts, we investigate how three types of land‐use change have influenced phylogenetic diversity (PD) and species composition of three functionally distinct communities: plants, small mammals, and large mammals. We found large mammal communities were by far the most heavily impacted by land‐use change, with areas of attempted large wildlife exclusion and intense livestock grazing, respectively, containing 164 and 165 million fewer years of evolutionary history than conserved areas (~40% declines). The effects of land‐use change on PD varied substantially across taxa, type of land‐use change, and, for most groups, also across abiotic conditions. This highlights the need for taxa‐specific or multi‐taxa evaluations, for managers interested in conserving specific groups or whole communities, respectively. It also suggests that efforts to conserve and restore PD may be most successful if they focus on areas of particular land‐use types and abiotic conditions. Importantly, we also describe the substantial species turnover and compositional changes that cannot be detected by alpha diversity metrics, emphasizing that neither PD nor other taxonomic diversity metrics are sufficient proxies for ecological integrity. Finally, our results provide further support for the emerging consensus that conserved landscapes are critical to support intact assemblages of some lineages such as large mammals, but that mosaics of disturbed land‐uses, including both agricultural and pastoral land, do provide important habitats for a diverse array of plants and small mammals.
Tag: animal communities
Negative impacts of dominance on bee communities: Does the influence of invasive honey bees differ from native bees?
Invasive species can reach high abundances and dominate native environments. One of the most impressive examples of ecological invasions is the spread of the African subspecies of the honey bee throughout the Americas, starting from its introduction in a single locality in Brazil. The invasive honey bee is expected to more negatively impact bee community abundance and diversity than native dominant species, but this has not been tested previously. We developed a comprehensive and systematic bee sampling scheme, using a protocol deploying 11,520 pan traps across regions and crops for three years in Brazil. We found that invasive honey bees are now the single most dominant bee species. Such dominance has not only negative consequences for abundance and species richness of native bees but also for overall bee abundance (i.e., strong “numerical” effects of honey bees). Contrary to expectations, honey bees did not have stronger negative impacts than other native bees achieving similar levels of dominance (i.e., lack of negative “identity” effects of honey bees). These effects were markedly consistent across crop species, seasons and years, and were independent from land-use effects. Dominance could be a proxy of bee community degradation and more generally of the severity of ecological invasions.
Characteristics of a snake community in the hilly forest of Quan Son District, Northern Vietnam
The snake communities in Asian tropical forests are relatively unknown, with most studies focusing on species lists. We investigated species composition, relative abundance, and community ecology of snakes in a mature secondary hilly forest area in the Quan Son District, northern Vietnam. To our knowledge, it is one of the few field investigations focused on snake community structure to have been undertaken within the Indo-Burma Hotspot, which is one of the most biologically important regions on the planet. We surveyed snakes along random transects in forests during two time periods (10-12 d), between 500 and 1,350 m elevation. In 361.8 h of surveys, we encountered 19 species, with a clear altitudinal separation in snake assemblages and numbers. Encounter frequencies dropped with elevation but had a peak at the intermediate elevation of 600-699 m. We therefore observed a Mid Domain Effect in our snake community in terms of both species richness and number of individuals observed. Of the 19 recorded species (including one Pythonidae, 11 Colubridae, two Elapidae, one Pseudaspididae, three Viperidae, and one Xenodermidae), 78.9% were exclusively or primarily terrestrial, 42.1% were semiarboreal, and 21% were semiaquatic (with some species belonging to two guild categories). We also present new natural history observations of snakes in the region. We discuss the importance of our findings relative to other similar studies conducted in South America and Africa, in addition to those in Vietnam and SouthEast Asia.
Generalist, selective or ‘mixed’ foragers? Feeding strategies of two tropical toads across suburban habitats
Suitable habitats for anurans can be found in the ever-growing tropical urban environments but anurans’ adaptations to urban conditions, including their trophic ecology remain largely unknown. We studied the food habits of two generalist, widespread West African Sclerophrys adult toads: African common (Sclerophrys regularis) and Hallowell’s toad (Sclerophrys maculata). The first was studied in Lomé (Togo), Cotonou (Benin) and Ikeja (Nigeria), and the second in Port Harcourt and Ikeja (both Nigeria); the latter city represents the only studied sympatric occurrence. Mean dietary overlap between population pairs was relatively high, and diet composition of the two species when sympatric did not differ significantly. Food niche width was significantly positively correlated with local rainfall in both species, and diet composition changed significantly between the dry and wet seasons. Diversity metrics revealed that females had a more diversified diet, with higher evenness and lower dominance index values than males. The diet of both species was not correlated to prey type availability, in both the wet and dry season. Both toad species targeted specific food items rather than opportunistically consume prey as observed in most anurans which may be a response to high anuran diversity typically found in the tropics or an adjustment to urban habitats.
Determining the composition and structure of antelope communities in three study sites within the Niger Delta (Nigeria) based on bushmeat market data
The composition and structure of antelope assemblages were analyzed by using data from wild meat markets in three distinct study stations in the southern Niger Delta, Nigeria. The relative abundance of the different species coming into the markets was analyzed, and various diversity metrics were used to describe the different antelope communities. Sex ratios of these populations as well as the effect of season on the abundance of the various species in the markets were examined. It was observed that a single recently described species (Philantomba walteri) was the dominant species in the three localities, contributing about 70% of all the antelope individuals. The relatively low number of antelope carcasses observed in this study (less than the number of carcasses of small carnivores in the same sites) suggests that the ungulate fauna is already very depleted in the eastern Niger Delta region, with these mammals being hunted more intensely in the wet season.
Daily Activity Patterns and Co-Occurrence of Duikers Revealed by an Intensive Camera Trap Survey across Central African Rainforests
The duiker community in Central African rainforests includes a diversity of species that can coexist in the same area. The study of their activity patterns is needed to better understand habitat use or association between the species. Using camera traps, we studied the temporal activity patterns, and quantified for the first time the temporal overlap and spatial co-occurrence between species. Our results show that: (i) Two species are strongly diurnal: Cephalophus leucogaster, and Philantomba congica, (ii) two species are mostly diurnal: C.callipygus and C. nigrifrons, (iii) one species is strongly nocturnal: C.castaneus, (iv) and one species is mostly nocturnal: C.silvicultor. Analyses of temporal activities (for five species) identified four species pairs that highly overlapped (Δ^≥ 0.80), and six pairs that weakly overlapped (Δ^ between 0.06 and 0.35). Finally, co-occurrence tests reveal a truly random co-occurrence (plt > 0.05 and pgt > 0.05) for six species pairs, and a positive co-occurrence (pgt < 0.05) for four pairs. Positive co-occurrences are particularly noted for pairs formed by C.callipygus with the other species (except C. nigrifrons). These results are essential for a better understanding of the coexistence of duikers and the ecology of poorly known species (C. leucogaster and C. nigrifrons), and provide clarification on the activity patterns of C. silvicultor which was subject to controversy. Camera traps proved then to be a powerful tool for studying the activity patterns of free-ranging duiker populations.