Influence of habitat structure on a streamside small mammal Community in a Brazilian rural area

Gentile, Rosana; Fernandez, Fernando A. S.

doi:10.1515/mamm.1999.63.1.29

Cited by 63 publications

(56 citation statements)

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“…cursor Winge, 1887 are cursorial rodents and have diurnal behaviour (Emmons and Feer, 1997) while Oligoryzomys nigripes Olfers, 1818 is a scansorial rodent with nocturnal behaviour. The three species living in sympatric conditions in the Atlantic Forest (Gentile and Fernandez, 1999), and share soil resources. Simões et al (2011) observed using numeric descriptors that sympatric rodents phylogenetically related have a different community structure although it presented a similar component community.…”

Section: Introductionmentioning

confidence: 99%

Helminth communities in three sympatric rodents from the Brazilian Atlantic Forest: contrasting biomass and numerical abundance

Maldonado-Júnior²,

Luque

2012

Braz. J. Biol.

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The study of parasite body size is an important approach to understand the different patterns of helminth community structure, once it is usually analysed using only numerical descriptors which do not capture size heterogeneity among parasite species. In the present study, we compared the pattern in the helminth community of three sympatric wild rodent species Akodon cursor, A. montensis and Oligoryzomys nigripes using numerical abundance and biomass approaches. The cestode Rodentolepis akodontis was the worm with highest biomass in the three rodents. The trichostrongylid Stilestrongylus lanfrediae presented highest biomass in O. nigripes and represented 70% of the total numeric abundance of parasites. Interestingly, for Akodon spp. the species with more biomass represented less than 10% of the total numerical abundance. Parasites with the higher numeric abundance do not have the largest body size. Although the biomass pattern is different from numeric abundance, this difference does not influence in the helminth distribution community among the three sympatric hosts. The status change of a helminth species within the community due to its volumetric dominance might justify a new approach since parasites belonging to different taxa obtain resources from the host in different ways.Keywords: biomass, abundance, helminth community structure, sympatric rodents, Atlantic Forest. Comunidades de helmintos de três roedores simpátricos da Mata Atlântica brasileira:contrastando biomassa e abundância numérica ResumoA utilização do tamanho do corpo do parasita é uma importante abordagem para compreender diferentes padrões na estrutura da comunidade helmíntica, uma vez que são utilizados apenas descritores numéricos que não necessariamente detectam a heterogeneidade no tamanho entre as espécies de parasitos. No presente estudo, comparou-se o padrão da comunidade helmíntica de três roedores silvestres simpátricos (Akodon cursor, A. montensise e Oligoryzomys nigripes), usando uma abordagem com abundância numérica e biomassa. O cestoide Rodentolepis akodontis foi o helminto com maior biomassa nos três roedores. O tricostrongilídeo Stilestrongylus lanfrediae apresentou uma alta biomassa em O. nigripes e representou 70% da abundância numérica total dos parasitas. Interessantemente, em Akodon spp., a espécie com maior biomassa, representou menos de 10% da abundância total. Parasitas com maior abundância numérica não foram aqueles com maior tamanho do corpo. Embora o padrão de biomassa determinado tenha sido diferente da abundância numérica, essa diferença não influenciou na distribuição das comunidades de helmintos nos três hospedeiros simpátricos. A mudança do status de uma espécie de helminto dentro da comunidade em função da sua dominância volumétrica pode justificar uma nova abordagem, uma vez que parasitas pertencentes a diferentes táxons podem obter recursos de seu hospedeiro de forma diferente.Palavras-chave: biomassa, abundância, estrutura da comunidade de helmintos, roedores simpátricos, Mata Atlântica.

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Section: Introductionmentioning

confidence: 99%

Helminth communities in three sympatric rodents from the Brazilian Atlantic Forest: contrasting biomass and numerical abundance

Maldonado-Júnior²,

Luque

2012

Braz. J. Biol.

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“…02'37"S -42 o 37'13"). The rodents were live-caught in wire-mesh live-traps (Tomahawk and Sherman) placed on the floor along the streams, which is the most important habitat of N. squamipes (Gentile & Fernandez 1999). Traps were spaced 10 m apart, and baited with peanut butter mixed with banana, oat, and bacon on manioc pieces.…”

Section: Methodsmentioning

confidence: 99%

An ecological field study of the water-rat Nectomys squamipes as a wild reservoir indicator of Schistosoma mansoni transmission in an endemic area

Gentile

Costa-Neto

Gonçalves³

et al. 2006

Mem. Inst. Oswaldo Cruz

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Small mammals are found naturally infected by Schistosoma mansoni, becoming a confounding factor for control programs of schistosomiasis in endemic areas. The aims of this study were: to investigate the infection rates by S. mansoni on the water-rat Nectomys squamipes during four years in endemic areas of Sumidouro, state of Rio de Janeiro, using mark-recapture technique; to compare two diagnostic methods for schistosomiasis; and to evaluate the effects of the chemotherapy in the human infected population on the rodent infection rates. The rodent infection rates of S. mansoni increased when rodent population sizes were lower. Coprology and serology results presented the same trends along time and were correlated. Serology could detect recent infection, including the false negatives in the coprology. The chemotherapy in the humans could not interrupt the rodent infection. Rodents can increase the schistosomiaisis transmission where it already exists, they probably maintain the transmission cycle in the nature and can be considered as biological indicators of the transmission sites of this parasite since they are highly susceptible to infection. The water-rats may present different levels of importance in the transmission dynamics of S. mansoni infection cycle for each area, and can be considered important wild-reservoirs of this human disease.Key words: diagnostic methods -population ecology -rodents -schistosomiasis Small mammals are found naturally infected by Schistosoma mansoni, becoming a confounding factor for control programs of schistosomiasis in endemic areas (Barbosa et al. 1958, Antunes et al. 1971, Rey 1993. Among the extra-human definitive hosts of this parasite, rodents of the genera Nectomys and Holochilus are the most probable wild reservoirs taking into account: (1) their semiaquatic habits (Ernest & Mares 1986), which make them highly exposed to infection; (2) their wide geographic distribution (Bonvicino 1994) coincident with the distribution of schistosomiasis in Brazil; (3) presence of infected individuals in most of the endemic areas where they were investigated, despite of the low human prevalence -rodents frequently showing higher infection rates in relation to human populations (Rey 1993); (4) rodent tolerance to human presence, occurring near human dwellings. Several experimental studies also support the hypothesis that water-rats are probable wild reservoirs of S. mansoni, showing high susceptibility to infection (Borda 1972, Souza et al. 1992, Maldonado Jr. et al. 1994, Ribeiro et al. 1998, somatic development hypertrophy of adult worms , elimination of viable eggs with high infectivity potential (Picot 1992), high infection persistence , low pathogenicity with efficient peri-ovular modulation and low tissue aggression (Silva & Andrade 1989), and ability to close the transmission cycle in semi-natural conditions (Antunes et al. 1973, Carvalho et al. 1976, Kawazoe & Pinto 1983. Infection of small mammals other than Nectomys and Holochilus by S. mansoni occurs only occasionally, especial...

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“…They were distributed in seven lin e transects spread along the valley during five nights per trapping period, amounting to a total of 9478 trap-nights. A II transects were placed along steams except one, wh ich was placed on a forest fragment -see GENTILE & FERNANDEZ (1999) for a more detailed description of the study area.…”

Section: Methodsmentioning

confidence: 99%

A field comparison of two capture-mark-recapture estimators of small mammal populations

Gentile

Fernandez

1999

Rev. Bras. Zool.

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ABSTRACT. The results obtained by two estimators of population sizes, MNKA and Mh, were compared for four species of sma ll mammmais -Didelphis ol/rito Wied, 1826, Philollder /relloto (O ilers, 1818), NectolllYs sql/olllipes (Brants, 1827) and Akodon cursor (Wi nge, 1887) -during a long-te rm population study. The MNKA estimator consistently underestimated the population sizes in relation to Mh. On the other, the probabilistic estimator Mh, which reduces bias through the jackknife technique, cOllld not be used in all cases as its assumptions were not always met. Correction factors between the estimates obtained by the two methods were calculated for the last three species, for which catchability did not valY signiticantly in time and that presented positive correlation between the estimates by the two models. In order to combine the adavantages of both methods for sma ll mammal population st udies, is suggested the use of probabilistic closed popUlation models and to calculate a correction factor based in another model which al low estimates in all cases, and which provides correlated estimates. This correction factors should be used in those cases where the probabilistic model cannot be used. KEY WORDS. Capture-recapture,jackknile estimator, minimun number known alive, population size Capture-mark -reeapture population estimation models have been widely described in the li terature. For closed populations, several models have been developed whieh do not make the restrictive assumption of equa l catchability; this asssumption is a problem when estimating population size of animals of complex behaviour s uch as mammal s. There are models wh ich deal with heterogeneity of capture probabilities among individuals (BURNHAM & OVERTON 1979;CHAO 1988), a long time (DARROCIl 1958), or due to behav ioural response to traps (OTIS el af. 1978); the first and third problems can also be dealt with altogether (Mode l Mbh , OTIS el al. 1978). However, no model has been proposed which allows to deal with the three so urces of heterogeneity simultaneously; the source(s) not dealt with remain as assumptions to be fulfilled (SEBER 1986).The main dirficulty in the application of s uch probabilistic model s is to collect enough data to satisfy all the assumptions . Data co ll ected with emphasis in

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Influence of habitat structure on a streamside small mammal Community in a Brazilian rural area

Cited by 63 publications

References 0 publications

Helminth communities in three sympatric rodents from the Brazilian Atlantic Forest: contrasting biomass and numerical abundance

Helminth communities in three sympatric rodents from the Brazilian Atlantic Forest: contrasting biomass and numerical abundance

An ecological field study of the water-rat Nectomys squamipes as a wild reservoir indicator of Schistosoma mansoni transmission in an endemic area

A field comparison of two capture-mark-recapture estimators of small mammal populations

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