We investigated the molecular phylogenetic divergence and historical biogeography of the gall-inducing micromoth Eucecidoses minutanus Brèthes (Cecidosidae) in the Neotropical region, which inhabits a wide range and has a particular life history associated with Schinus L. (Anacardiaceae). We characterize patterns of genetic variation based on 2.7 kb of mitochondrial DNA sequences in populations from the Parana Forest, Araucaria Forest, Pampean, Chacoan and Monte provinces. We found that the distribution pattern coincides with the Peripampasic orogenic arc, with most populations occurring in the mountainous areas located east of the Andes and on the Atlantic coast. The phylogeny revealed a marked geographically structured differentiation, which highlights a first split into two major clades: western (Monte and Chacoan) and eastern (Pampean and coastal forests). Together with AMOVA and network analysis, phylogeny revealed the existence of six well-defined lineages, which are isolated by distance. The TMRCA for Eucecidoses was estimated at ca. 65 Mya, and the divergence among major clades occurred by the Plio-Pleistocene ca. 20–25 Mya, with the extant six lineages emerging about 0.9 to 5.7 Mya (later than the rise of Schinus). These results are associated with a diversification pattern of either a late burst of speciation or early extinction. Population range expansion for some lineages concurring with major climatic changes that occurred during the wet–dry events of the Pleistocene in the region was recovered in both neutrality tests and past dynamics through time analysis. A possible biogeographic scenario reconstructed suggests that Eucecidoses likely emerged from a central meta-population in the south and later dispersed (ca. 38 Mya) using western and eastern as two major routes. Thus, a combination of dispersal and vicariance events that occurred in the ancestral populations might have shaped the current distribution of extant lineages. Speciation driven by host plant shift is potentially involved in the evolutionary history of Eucecidoses.
Pleistocene climatic oscillations favoured the expansion of grassland ecosystems and open vegetation landscapes throughout the Neotropics, and influenced the evolutionary history of species adapted to such environments. In this study, we sampled populations of the rodent Oxymycterus nasutus endemic to open areas in the Pampas and Atlantic Forest biomes to assess the tempo and mode of population divergence using an integrative approach, including coalescence theory, ecological niche models, and morphometry. Our results indicated that these O. nasutus populations exhibited high levels of genetic structure. Six major mtDNA clades were found, structuring these biomes into distinct groups. Estimates of their divergence times was indicated to be 0.571 myr. The high degree of genetic structure is reflected in the analyses of geometric morphometric; skull differences between lineages in the two ecoregions were detected. During the last glacial maximum, there was a strong increase in suitable abiotic conditions for O. nasutus. Distinct molecular markers revealed a population expansion over time, with a possible demographic retraction during the post-glacial period. Considering that all clades coalesce with the last interglacial maximum, our results indicated that reduction in suitable conditions during this period may have resulted in a possible vicariance associated with refuge isolation.
Resumo: As características químicas do sedimento em conjunto com a estrutura de bosques de mangue são informações fundamentais para compreender a dinâmica deste ambiente. O objetivo foi analisar parâmetros químicos e a estrutura de bosque em manguezais com diferentes graus de pressão antrópica. Foram estudados dois manguezais em Paranaguá, PR, um localizado próximo a um complexo industrial e ao porto de Paranaguá, e outro localizado na Unidade de Conservação na Floresta Estadual do Palmito. Foram avaliados os teores de fósforo, matéria orgânica, amônio, nitrato e nitrogênio disponível, assim como a densidade e perímetro a altura do peito das espécies Rizhophorae mangle, Laguncularia racemosa e Aviscenia schaueriana. O manguezal da Vila Becker, com maior interferência antrópica, teve maiores concentrações de fósforo, amônio e nitrogênio total, indicando ser um sedimento com melhor fertilidade. Não houve diferenças entre os manguezais com relação a estrutura de bosque, mas a Rizophorae mangle teve a maior densidade entre as espécies avaliadas, independente do manguezal. A proximidade destes ambientes ao meio urbano e industrial pode estar alterando as características químicas do sedimento o que futuramente pode alterar a estrutura de bosque destes manguezais.Palavras-chave: Antropização; nutrientes; vegetação; estuário. Abstract:The chemical characteristics in conjunction with the mangrove forest structure are key information to understand the dynamics of this environment. The objective was to analyze chemical parameters and forest structure in mangroves under different anthropogenic stresses. Two mangroves were studied in Paranaguá, PR, one located near an industrial complex and the port of Paranaguá, and another one located in the Conservation Unit in Palmito State Forest. The levels of phosphorus, organic matter, ammonium, nitrate and nitrogen available were evaluated as well as the density and perimeter of the breast height of the species Rizhophorae mangle, Laguncularia racemosa and Aviscenia schaueriana. The Vila Becker mangrove, with greater anthropogenic interference, had higher concentrations of phosphorus, ammonia and total nitrogen, indicating a sediment with better fertility. There were no differences among mangroves in relation to forest structure, but Rizophorae mangle had the highest density among the evaluated species, independent of the mangrove. The proximity of these environments to the urban and industrial environment may be altering the chemical characteristics of the sediment, which in the future may alter the forest structure of these mangroves.
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