Corresponding author: Vivian Flinte (
Academic editor: M. Schmitt
Species richness and abundance of seven
The majority of
It is believed that multiple factors, operating across a hierarchy of spatial and temporal scales, shape species distributions (
On tropical mountains, abiotic factors are likely to have even greater effects on community structure, so patterns of population fluctuation similar to subtropical and even temperate regions may emerge, with occurrence periods of insects well defined throughout the year. Increasing altitude brings lower temperatures, increased precipitation (rain or snow), lower partial pressure of gases, higher wind speed and turbulence, and greater extremes in radiation input (
There are only few studies with Brazilian
Our study was conducted in Serra dos Órgãos National Park (
Surveys were conducted at six sites of different altitudes (approximately 1300 m, 1500 m, 1600 m, 1700 m, 1800 m and 2050 m) in Teresópolis County, specifically on the
Within a wider project on
Species studied at the Serra dos Órgãos National Park:
To describe species richness on each plant species and altitude, only adults were considered because eggs, larvae and pupae of the studied
Adult individuals of the focal
Host plant records based on larval “no choice” feeding tests for the seven
Host plants / Cassidines |
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Because the host plants
Beetles were deposited in the collection of the Laboratório de Ecologia de Insetos at the Federal University of Rio de Janeiro, but some specimens were also deposited in the collection of the Department of Biodiversity and Evolutionary Taxonomy, Institute of Zoology, University of Wroclaw, Poland. After curation, plants were deposited in the Herbarium of the Federal University of Rio de Janeiro and in the Rio de Janeiro Botanical Garden.
Surveys were conducted every two months from June 2006 to June 2007 by Sama de Freitas and one additional of four undergraduation students. At each site, two transects of 200 m × 0.5 m (length × width) were made, one at each side of the border of the trail. Within each transect, host plants were carefully surveyed for adults of the focal
To obtain mean plant density for each altitude, we summed the number of plant individuals of each species in the transect per month, and divided that number by the number of surveys (seven months). In order to describe the temporal distribution of the species we considered the total abundance of each species per survey. Finally, beetle altitudinal distribution was calculated from the total number of adults sampled over the course of the study for each species and elevational site. Host plant quality was not considered in this study.
At no altitudinal site did all seven host plant species co-occur. Plant richness was highest with five species co-occurring at 1600 m, 1700 m and 1800 m, and lowest at 1300 m and 2050 m where only two and three species co-occurred, respectively (
Mean host plant density of the studied
Our field observations were consistent with the data presented by
Relative adult occurrence (in percentage) of the seven
Host plants / Cassidines |
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33.3 | 66.7 | ||||
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1.5* | 98.5 | ||||
3.7 * | 3.7 * | 92.6 | ||||
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70.9 | 25.5 | 2.9 | 0.7* |
* Plant species on which adult individuals were found in field during the present study, but larval feeding was not recorded in the laboratory by
Except for
Abundance of the seven focal species varied considerably along the year. The lowest values were recorded in June, gradually increasing until peaking in February and then decreasing again (
Abundance (per month and total) of the seven
Months / Cassidines | 2006 | 2007 | Total abundance | |||||
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In spite of the low number of studied species, changes in species richness could also be observed during the period; in June 2006 and 2007 and April 2007 just three of the four most abundant species were found in the field and only in October all seven species were recorded together (
Three species,
Population fluctuation of
Most insect species living in temperate zones become active during spring and summer, overwintering in diapause (
Changes in community composition per elevational site were observed with increasing altitude. Considering the small number of study species, richness showed no clear pattern with altitude, starting with three species at the three lowest sites, to four species at intermediate elevations (1700 m and 1800 m), and decreasing to two species at the highest site (
Abundance of the seven
Altitudes / Cassidines | 1300 m | 1500 m | 1600 m | 1700 m | 1800 m | 2050 m | Total abundance | Total sites |
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Significant differences occurred in the spatial distribution of
A general increase in the total abundance of beetles throughout the altitudinal gradient was recorded, the highest numbers of individuals being found at 1700 m and 1800 m, 61 and 252, respectively, followed by a sharp decrease in abundance at the highest site (
A general pattern observed within the seven study species seems to be the complete or near absence of most of the species at the highest altitudinal site. Temperatures below 0°C are commonly recorded at the highest elevations in the Park (
Since many
We are grateful to Lech Borowiec (University of Wroclaw, Poland) for identifying the beetle species, and Lucia d’Ávila Freire de Carvalho (Rio de Janeiro Botanical Garden) and Luciano Bianchetti (Embrapa/Brasília) for identifying the