Navegando por Assunto "Macroecology"

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Artigo
Global distribution of microwhip scorpions (Arachnida: Palpigradi)
(2021-01-29) Mammola, Stefano; Souza, Maysa Fernanda Villela Rezende; Isaia, Marco; Ferreira, Rodrigo Lopes
Aim Historically, research on global distribution patterns has mostly concentrated on conspicuous organisms and thus a large proportion of biodiversity on Earth remains unmapped. We examined the global distribution of palpigrades, a poorly studied group of low dispersive arachnids specialized to subterranean life. We asked what are the ecological factors driving their distributions, and to what extent sampling bias may influence the observed patterns. Location Global. Taxon Palpigrades (Arachnida: Palpigradi) in the genus Eukoenenia. Methods We assembled a database of over 1000 localities and referring to 57 soil- and 69 cave-adapted palpigrades. We tested for differences in range sizes of soil- and cave-adapted species. We used variance partitioning analysis to explore the contribution of climate, nutrient availability and geology in driving observed distributions. Finally, we verified the potential correlation between the number of occurrence records and the number of palpigrades' researchers. Results Europe and Brazil emerged as centres of diversification of cave-adapted palpigrades. Conversely, the diversity of soil-adapted species was distributed over a broader geographical expanse, mainly in the Southern Hemisphere. Both cave and soil species had narrow distribution ranges, with a median value of 0.01 km2; only a few parthenogenetic species were distributed over multiple continents. The distribution of cave- and soil-adapted palpigrades was primarily explained by climatic conditions, and secondarily by nutrient and habitat availability. In the Alps, the distribution of cave-adapted species also bears the signature of historical events related to glaciation cycles. We observed, however, a pronounced people-species correlation, suggesting that the observed patterns are not generalizable to poorly explored areas. Main conclusions Our study highlights enormous gaps in current knowledge about the biogeography of palpigrades. Even if the information is largely incomplete and biased, we show how data can be harnessed to draw a preliminary picture of the global distribution patterns of palpigrades. Thus, we offer a jumping-off point for future studies on the macroecology and conservation of poorly known organisms.
Artigo
Network and parasitological analyses reveal latitudinal gradient in bats-ectoparasitic flies interactions across the Neotropic.
(2023-06-14) Biz, Luana S.; Bastazini, Vinicius A. G.; Carvalho, Fernando; Pereira, Maria João Ramos
Ecological interactions between parasites and their hosts play a fundamental role in evolutionary processes. Selection pressures are exerted on parasites and their hosts, usually resulting in high levels of specificity. Such is the case of ectoparasitic bat-flies, but how large-scale spatial gradients affect the dynamics of their interactions with their bat hosts is still unknown. In the present study, we investigated interaction patterns between bats and their ectoparasitic flies (Streblidae and Nycteribiidae), both presenting their peak of diversity in the Neotropical region, along a latitudinal gradient. Using network analyses and parasitic indices, grounded on the latitudinal diversity gradient theory, we evaluated how spatial gradients affect species interactions and parasitic indices at the macroscale level, predicting that interaction networks should become richer in species, leading to increases in network modularity, size, and specialization, and to a decrease in nestedness and connectance. We conducted a literature review, focusing on studies done in the Neotropical region, and data of our own authorship. We obtained a richness of 97 species of bats parasitized by 128 species of ectoparasitic flies, distributed into 57 interaction networks between latitudes 29ºS and 19ºN in the Neotropic. Network metrics and parasitic indices varied along the latitudinal gradient, with changes in richness of bats and their ectoparasitic flies and in the structure of their interactions; network specialization, modularity and connectance increase with latitude, while network size decreases with latitude. Regions closer to the equator had higher parasite loads. Our results show that interaction networks metrics present a latitudinal gradient and that such interactions, when observed at a local scale, hide variations that only become perceptible at larger scales. In this way, ectoparasites such as bat flies are not only influenced by the ecology and biology of their hosts, but by other environmental factors acting directly on their distribution and survival.