Redução do esforço amostral de ácaros do solo (Acari: Oribatida) em fragmentos de floresta da região de Alter do Chão, Pará, Brasil
The high diversity and abundance of edaphic invertebrates results in high costs in biodiversity studies, mainly in tropical regions. The highest issue related to sampling protocols is its efficiency for ecological studies that is reduced in studies with small organisms. With oribatid mites commun...
| Autor principal: | Ferreira, Raimundo Nonato Costa |
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| Grau: | Dissertação |
| Idioma: | por |
| Publicado em: |
Instituto Nacional de Pesquisas da Amazônia - INPA
2020
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| Assuntos: | |
| Acesso em linha: |
https://repositorio.inpa.gov.br/handle/1/12495 http://lattes.cnpq.br/9543377874658570 |
| Resumo: |
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The high diversity and abundance of edaphic invertebrates results in high costs in
biodiversity studies, mainly in tropical regions. The highest issue related to sampling
protocols is its efficiency for ecological studies that is reduced in studies with small
organisms. With oribatid mites community, this issue must take in consideration the
large investment in time necessary to sort and identify the individuals, because of the
high abundance and diversity, and also the necessary techniques to indentify these
small organisms. Therefore, as time investment increases, higher will be the costs of
the protocol, and the higher will be the time necessary for publication of the results.
We aimed to evaluate the efficiency of reduced effort in sorting subsamples, and to
demonstrate which one possesses better cost-benefits relationship in identifying
oribatid mites. We are also comparing two levels of taxonomical identification:
species and genera. Litter and soil were sampled in 16 plots in fragments of forest,
and the apparatus of Berlese-Tullgren was used for extraction of the invertebrates.
Using the apparatus of Santos-Yano, reduction of the initial proportion of the sub-
samples, containing the extracted mites from the Berlese-Tullgren and preserved in
alcohol, were done in fractions of 50, 25, 12.5 e 6.25 % of the initial content. For
each effort reduction dissimilarities matrixes were generated using abundance (Bray-
Curtis index), and presence absence data (Sørensen index). Using Mantel
correlation, we evaluated the similarity among each reduced effort, considering ≥ 07
as a satisfactory value. For eight of the 16 plots, the similarity index among the
maximum effort (100%) and effort reductions to 50% were higher than 70% for
species and genera. Therefore, for the others eight plots, the calculations were done
to compare the reduced effort of 50% with 25, 12.5 and 6.25%. For each effort, the
community composition was reduced to two axes using Principal Component
Analysis (PCoA). The axes of the PCoA were submitted to a Multiple Multivariate
Regression with three environmental variables: amount of litter, tree density and area
of the fragment. A total of 7,318 individuals of adult oribatid mites, distributed in 156
species, being 61% composed by morphospecies, 96 genera and 51 families was
recorded. The most abundant species were: Rostrozetes ovulum e Archegozetes
longisetosus. Due the high number of monotypic genera, the relation between
species and genera is about 2:1 in the higher efforts. This ratio is reduced when the
effort is being reduced. In general, the influence patterns of the environmental
variables detected with higher efforts were also captured in reduced efforts. This
pattern was similar between the two levels of identification, meaning that genera as a
surrogate of species is viable. The costs per each species in the protocol were
reduced in smaller efforts. The costs and time in the identification of oribatid mites
can be reduced with lower loss of ecological and taxonomic information. With this
strategy, oribatid mites can be used in medium or large spatial scale surveys in
Amazonia. |