(C) 2011 Adelita M. Linzmeier. This is an open access article distributed under the terms of the Creative Commons Attribution License 3.0 (CC-BY), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
For reference, use of the paginated PDF or printed version of this article is recommended.
Body size is correlated with many species traits such as morphology, physiology, life history and abundance as well; it is one of the most discussed topics in macroecological studies. The aim of this paper was to analyze the body size distribution of Chrysomelidae, caught with Malaise traps during two years in four areas with different levels of conservation in the Araucaria Forest, Paraná, Brazil, determining if body size is a good predictor of abundance, and if body size could be used to indicate environmental quality. Body size was considered the total length of the specimen from the anterior region of head to the apex of abdomen/elytron. Measurements were taken for up to ten specimens of each species for each area and for all specimens of those species represented by fewer than ten individuals. The highest abundance and richness of Chrysomelidae were obtained in the lowest body size classes. This herbivorous group showed a trend toward a decrease in body size with increasing abundance, but body size was not a good predictor of its abundance. There was a trend toward a decrease in body size from the less to the most conserved areas; however, the definition of a pattern in successional areas not seems to be entirely clear.
Abundance, biodiversity, body length, macroecology, Neotropical region, richness
Potential ecological relationships between body size and structure of animal communities have been one of main focuses in ecological studies (
The relationship between body size and abundance is an essential link between individual and population level traits and the structure and dynamics of ecological communities (
Controversy has arisen regarding how body size and abundance are related, and concerning the ecological and evolutionary implications of these relationships. In this way, an early step in elucidating the factors that structure animal assemblages may be to understand how the body sizes of their component species are distributed (
Another aspect about the body size that has been widely discussed is its use in the assessment of environmental quality. In general, richness and abundance are the variables most used to measure not only the diversity but also to assess the environmental quality of areas in different successional stages. Studies have shown that habitat type, management, succession and degradation level have a great influence on the body size of insects increasing or decreasing species body size along succession (
Phytophages represent about 45% of all described insect species (
The data came from the project Vila Velha (PROVIVE), which was developed in the Parque Estadual of Vila Velha (25°13'5.0"S; 50°2'26.9"W). This park is a conservation unit in the state of Paraná with an area of 3.122 ha, mainly covered by natural fields (steppe, grassy-woody) (
Of the five areas sampled during the PROVIVE project, the material from four areas was used in this study, one edge area and three with increasing conservation level. A brief description of these areas is as follows. More information could be found in
In each sampling area, a Malaise trap was placed and the caught material removed weekly from September 1999 to August 2001. As Malaise is a selective trap collecting flying insects, in this study Chrysomelidae assemblage is composed by species that fly from ground to 2m high and, because of the sampling effort, it was assumed that this trap sampled all species that occur in each sampling area.
The Coleoptera were mounted, labeled, and the chrysomelids identified to the lowest taxonomic level possible. The material is deposited in the Coleção de Entomologia Pe. J. S. Moure, Departamento de Zoologia, Universidade Federal do Paraná (DZUP).
All Chrysomelidae species sampled in each area were measured. The size was considered the total length of the specimen from the anterior region of the head (excluding antennae) to the apex of the abdomen or elytra (
According to
The length values were grouped in arbitrarily established size classes (class 1: 1.0 to 2.99 mm, class 2: 3.0 to 4.99 mm, class 3: 5.0 to 6.99 mm and so on) and adjusted on a logarithmic scale, following
Correlation analyses were performed between size classes and abundance and, between size classes and richness.
A regression analysis was performed to determine the influence of body size on the abundance of Chrysomelidae. The dependent variable was the abundance of each species and the independent variable its average size. The slope obtained was visually compared to that proposed by
To examine if there were differences in body size of the Chrysomelidae community in each area, ANOVA (5% significance) was performed based on all measured values. This analysis was also used only for those species recorded in all areas. In addition, ANOVA was used to determine if the size of species varied in areas with different succession levels. For this, species that occurred at least in two areas and that had at least six specimens sampled were selected. Each species was analyzed separately, totaling 15 species that met these prerequisites.
The normality of data was previously tested by the Kolmogorov-Smirnov test and data were log transformed. The analyses were performed using the STATISTICA program 8.0 (
During the two years 2, 650 specimens of 254 Chrysomelidae species were sampled and, 1, 217 specimens were measured (Table 1).
Body size (mm) (mean ± SD) of the Chrysomelidae community, trapped with Malaise in four areas with different conservation levels, in Ponta Grossa, Paraná, Brazil. Values followed by the same letter do not differ significantly (P < 0.05). (n) number of specimens measured, (S) richness and (N) abundance.
Body size | n | S | N | |
---|---|---|---|---|
Border | 6.23 ± 2.42a | 391 | 134 | 484 |
Phase 1 | 5.63 ± 2.86b | 267 | 78 | 742 |
Phase 2 | 4.75 ± 1.94c | 317 | 88 | 1010 |
Phase 3 | 5.38 ± 2.50b | 242 | 70 | 414 |
Total | - | 1, 217 | 254 | 2, 650 |
The Chrysomelidae size class histogram showed a tendency toward a decrease in abundance with increase in body size (Fig. 1), where the pattern of Chrysomelidae distribution of abundance was a polygonal type with a tail to the right. The same pattern was observed for the richness distribution. The highest frequencies of both abundances and richness were in class 2, with chrysomelids measuring from 3.0 to 4.99 mm.
Size Frequency of specimens (N) and species (S) of Chrysomelidae total and in each area, with different conservation levels, in Ponta Grossa, Paraná, Brazil.
The distribution of abundance in each area also showed a tendency toward a decrease in abundance with increasing body size, with the highest frequencies in class 2. However, in Phase 1 a higher abundance of Chrysomelidae was in class 3, from 5.0 to 6.99 mm and, in Phase 3, unlike the other, showed the highest abundance in class 6, from 11.0 to 12.99 mm (Fig. 1).
Regarding species richness, this followed the distribution pattern of abundance, with the largest number of species occurring in smaller size classes. Border area had the same number of species in classes 2 and 3. Notice that class 6 to all Chrysomelidae and class 5 of Phase 2 (Fig. 1) there are no values of richness. It happened because there are no species that fit in these size classes, i.e., the average species size fitted in other size class. However, as the specimens have a range of size, some values fitted in different size classes.
In all areas, there was a negative correlation between body size and abundance and between body size and richness, but only in Phase 1 and Phase 2 these correlations were significant (Table 2).
Correlation between size class and abundance (N) and between size class and richness (S) of Chrysomelidae trapped with Malaise in four areas with different conservation levels, in Ponta Grossa, Paraná, Brazil. Values followed by * showed significant correlation (P < 0.05).
Areas | N | S |
---|---|---|
Border | -0, 47 | -0, 49 |
Phase 1 | -0, 70* | -0, 67* |
Phase 2 | -0, 67* | -0, 64* |
Phase 3 | -0, 53 | -0, 52 |
Studying the influence of body size on abundance, it was possible to show that the model was significant (b = -0.46, r = 0.16, P < 0.01) only when data from all areas are included (Fig. 2). Even so, body size explained only 2.56% of Chrysomelidae abundance. Moreover, the slope was -0.46.
Relation between body size (log) and abundance (log) of Chrysomelidae, trapped with Malaise in four areas with different conservation levels in Ponta Grossa, Paraná, Brazil (closed circles = observed data, line = linear model adjusted).
The Border area, which is an ecotone between a field and Araucaria Forest and which is influenced more by human activity, was the place where the species reached the highest body sizes, 6.23 mm on average, and it was the only area with size class 7, with chrysomelids measuring from 13.0 to 15.0 mm. In this same area was sampled the higher number of species. In contrast, Phase 2 which is an intermediate stage of conservation, showed the smallest size, 4.75 mm on average, with the maximum size occurring in class 5 and, where was registered the higher abundance. The lowest richness as well as the lowest abundance was in Phase 3 (Table 1).
There was a significant decrease (F3, 1213 = 28.7, P < 0.05) in chrysomelid body size in areas less conserved, Border and Phase 1 to Phase 2 (Table 1). However, in Phase 3, which is the best conserved area, size was significantly greater than that of Phase 2 and did not differ significantly from that of Phase 1. There was no difference in body size of the Chrysomelidae community when only the species common to all areas were analyzed.
While determining if species common to at least two of the studied areas showed variation in body size, it was found that of the 15 species examined, eight had an increase in body size from an area less conserved to one better conserved, but for only two of them, Trichaltica elegantula Baly, 1876 and Hispini sp.9, this increase was significant. Four species showed a decrease in body size from an area less conserved to a better conserved, but this difference was not significant in any of the cases. Acanthonycha costatipennis Jacoby, 1905 and Eumolpinae sp.1 showed a significant increase in body size from the edge area to an area of intermediate level of conservation, followed by a significant decrease in size in the most conserved area, Phase 3, regarding to compared to the edge (Table 3).
Body size (mm) (mean ± SD) of Chrysomelidae species common to at least two of the four areas with different levels of conservation and which have at least six specimens collected in Ponta Grossa, Paraná, Brazil. Averages followed by the same letter in line do not differ significantly (P < 0.05).
Border | Phase 1 | Phase 2 | Phase 3 | |
---|---|---|---|---|
Acanthonycha chloroptera | 5, 19±0, 80a | 5, 65±0, 46a | ||
Acanthonycha costatipennis | 4, 96±0, 72a | 5, 84±0, 28b | 5, 07±0, 59b | |
Dinaltica gigia | 5, 15±0, 31a | 4, 89±0, 29a | ||
Heikertingerella ferruginea | 3, 74±0, 36a | 3, 68±0, 21a | 3, 78±0, 16a | |
Monoplatus ocularis | 3, 92±0, 25a | 3, 82±0, 22a | 3, 72±0, 14a | |
Neothona prima | 2, 20±0, 13a | 2, 33±0, 11a | ||
Omophoita octoguttata | 10, 11±0, 77a | 10, 41±0, 62a | ||
Phyllotrupes violaceomaculatus | 7, 80±0, 52a | 7, 96±0, 64a | ||
Trichaltica elegantula | 2, 40±0, 18a | 2, 65±0, 15b | ||
Hispini sp.7 | 6, 90±0, 44a | 7, 04±0, 41a | ||
Hispini sp.9 | 5, 97±0, 30a | 6, 25±0, 19b | ||
Eumolpinae sp.1 | 5, 00±0, 40a | 5, 80±0, 31b | 5, 47±0, 25b | |
Eumolpinae sp.6 | 4, 88±0, 33a | 5, 05±0, 40a | ||
Eumolpinae sp.14 | 8, 29±0, 52a | 8, 22±0, 53a | ||
Eumolpinae sp.15 | 7, 73±0, 49a | 7, 63±0, 55a | 7, 33±0, 58a |
The highest richness and abundance was recorded in smaller size classes, with the highest number of species and specimens ranging from 3.0 to 4.99 mm in length (Fig. 1). This value was very near to that found for Chrysomelidae fauna by different authors using different collecting methods and in different habitats.
According to
In fact, according to
According to
However, the fractal structure of environment cannot alone explain the shape of the size distribution, since the smallest size class is not always the most numerous, but this may be a mechanism that accounts for the shape of distribution (
Size is a poor predictor of Chrysomelidae abundance. Other variables such as availability and quality of food resources, presence of predators/parasitoids, intra- and interspecific competition and climatic factors should have a greater influence on the abundance of this group.
Several authors have found that body size is a poor predictor of population densities on a local scale (
It is important to stress that EER as calculated here is not recommended by
Many features of organisms are correlated with animal body size, but especially life history, ability of dispersion and efficiency, and feeding specialization are linked to succession, so that changes in body size during plant succession may be an important indicator of environmental changes (
In the literature, there are different results, some of them show the same tendency as in this study, such as those of
There are environmental changes that could favor different species at different stages of succession. In early succession, plants have few defenses, high growth rates and low proportion of carbon and nitrogen in their tissues (
Other studies, however, have found opposite results.
As these results conflict with those obtained here and mainly do not deal with herbivorous insects but predators, it appears that the efficiency-specialization hypothesis proposed by
Among the 15 species examined, only four showed significant variations in body size among the different areas, and consequently, it was not possible to establish a consistent pattern between body size and level of conservation when species were analyzed separately. However, interesting information was obtained. Unlike what was determined for the entire Chrysomelidae community where the edge area had the highest average body size, for three species that showed significant differences in body size among areas (Acanthonycha costatipennis, Hispini sp.9 and Eumolpinae sp.1), the Border was the area where these species had the smallest body size. These species did not contribute to explaining the Chrysomelidae pattern, where it was not possible to know which species most influenced the pattern.
ConclusionsThe Chrysomelidae, an essentially phytophagous group, showed a trend toward a decrease in abundance with increasing body size, in a negative polygonal relation. Furthermore, a greater number of chrysomelid species collected by Malaise traps occurred in smaller body size classes; species ranged from 1.0 to 15.0 mm in length and most of them measured between 3.0 and 4.99 mm.
The results presented here seem to follow the pattern found for several animal groups, where body size is a poor predictor of abundance. Other factors such as availability of food, metabolic efficiency, host plant specificity and/or parts of the plant, predation, parasitism and climate should act more on the Chrysomelidae community determining the size of species populations.
It was demonstrated that there is a change in body size of Chrysomelidae communities in areas with different levels of conservation. There was a trend toward a decrease in body size of the less to the most conserved areas. The Border area, which is an ecotone and more influenced by human activity, had larger chrysomelid body sizes. However, the definition of a pattern in successional areas did not seem to be entirely clear, due to significant increase in body size of a later succession stage in relation to one of the others areas in an intermediate successional stage. Nevertheless, the results suggest that degrading the habitats, the small and specialized species would be at risk of disappearing.
The fractal characteristic of the environments, mainly the plants, may be one of the operating mechanisms in Chrysomelidae community. It would explain the higher richness and abundance of this group into smaller size classes, but it should not be considered the only explanation. Other factors, such as those already mentioned could be interfering in the ecological processes that generate such patterns.
We would like to thank Conselho Nacional de Desenvolvimento Científico e Tecnológico, for the Doctoral Fellowship awarded to the first author and the Research Fellowship to the second author. This research represents contribution Nº 1.834 from the Departamento de Zoologia, Universidade Federal do Paraná, Curitiba, Brazil. We are also grateful to Dr Luciano de Azevedo Moura for providing valuable suggestions and Dr A. Leyva for English editing of the manuscript.