Paulo De Marco

Defying the curse of ignorance: perspectives in insect macroecology and conservation biogeography

Abstract.  1. Despite the abundance, richness and ecological importance of insects, distribution patterns remain unknown for most groups, and this creates serious difficulties for the evaluation of macroecological patterns and the underlying drivers. Although the problem is real, we provide an optimistic perspective on insect macroecology and conservation biogeography.

Odonate biodiversity in terra‐firme forest streamlets in Central Amazonia: on the relative effects of neutral and niche drivers at small geographical extents

Abstract.  1. The Amazon region is formed primarily by a dense network of acid and nutrient‐poor streamlets. The stability of environmental conditions coupled with spatial constraints to dispersal turns these streamlets into an interesting arena to compare neutral and niche drivers for community organisation. Here, we evaluated the relative importance of local environmental conditions and regional dispersal limitation to determine beta‐diversity and distributional patterns of species richness of the adult Odonata assemblage present in the Adolpho Ducke Forest Reserve (Manaus, Amazon) river basins.

Efeito da alteração ambiental sobre comunidades de Odonata em riachos de Mata Atlântica de Minas Gerais, Brasil

The effect of riparian deforestation and stream impoundments on an odonate community was studied in areas of surviving Atlantic forest in Vicosa and in Rio Doce State Park (PERD), Marlieria, Minas Gerais, Brazil. During 1997 16 species of Libellulidae, 4 Coenagrionidae, 2 Gomphidae, 2 Calopterygidae, 1 Megapodagrionidae, 1 Aeshnidae and 3 Protoneuridae were collected. In Vicosa, the association of sampled odonates with lotic or lentic systems, and in PERD for areas with or without riparian vegetation were compared. The results suggest that although overall odonate taxonomic richness is high in areas without riparian vegetation. Likely, because productivity increase of such areas and its invasion by lentic Odonata species.

The influence of habitat integrity and physical-chemical water variables on the structure of aquatic and semi-aquatic Heteroptera

This work aimed to assess the effect of certain physical-chemical variables and the Habitat Integrity Index (HII) have on an aquatic and semi-aquatic heteropteran community. We collected in five streams (from 1st to 4th order) that differed in habitat integrity, in order to test 1) whether heteropteran richness decreases with the Habitat Integrity Index; and 2) whether richness responds to alterations in water physical-chemical variables, since these influence community structure. In each stream, linear transects of 100 m were demarcated. A total of 1425 specimens from 10 families, 30 genera and 67 morphospecies were collected. Species richness was correlated with the Habitat Integrity Index (HII), showing a positive relationship only for Gerromorpha. This may be due to the fact that streams with greater integrity offer nearby marginal vegetation where prey and shelter can be easily found, representing optimal places for oviposition and hunting. Species adapted to such conditions are more sensitive to alterations in the physical structure of rivers. Significant differences in the composition of Heteroptera and studied infra-orders were also observed, which suggests that the anthropic disturbances over these sites have changed these insect communities. Our results indicate that the alteration in riparian areas can lead to significant changes in Heteroptera composition, even though species richness was not affected. The physical-chemical variables showed no influence on the distribution of species. This result suggests that the environment presented insufficient variation that could cause changes in the investigated community, which implies that factors other than those analyzed here may explain such variation. Three species Rhagovelia trailli (White, 1879), Rhagovelia sp. 4 and Tenagobia incerta (Lundblad, 1928) were considered to be indicators of pristine sites. The results indicate that aquatic and semi-aquatic Heteroptera and more specifically the sub-order Gerromorpha can be an important tool to assess environmental habitat integrity and enhance conservation actions of riparian forests.

Odonate assemblage structure in relation to basin and aquatic habitat structure in Pantanal wetlands

Structural properties of aquatic habitats are the basis of several theories produced to explain the functioning of aquatic environments. We predicted a longitudinal change of ecosystem properties along the river, and also that potamal areas of the river are similar to lakes. In rivers with periodic floods we also expect a high degree of similarity due to increased environmental similarity and increase dispersal of component species. Otherwise, rivers must be conceived as a landscape element with an intrinsic hierarchical nature and dispersal among its parts are constrained by this structure. Under this view, we also could expect that different basin or different “micro-basin” could present communities that are historically different in their general properties. Here, we aimed to describe odonate larval communities in the Pantanal Mortes-Araguaia river basin in Brazil comparing the composition, species richness and community structure between lakes and rivers, and also the possible differences among river basins. The field work was done in three rivers and three lakes chosen to conform to a paired experiment, each pair in a different river basin. An aggregated sampling unit was used based on Ekman dredge and D-nets replicated on each site. We sampled 936 individuals distributed in 30 genera and a total of 34 morphotypes. There was no difference in species richness among lakes and rivers, but a marked difference among basins. Samples from the same basin present a higher similarity of the species abundance relations than among river or lake samples. We also did not observed differences in composition and community structure between large rivers and lakes, in the same basin. The results supported the concept of structural similarity between large rivers and lakes and the differences observed among basins could indicate historical events in colonization that are shaping communities characteristics.

Challenges and perspectives for species distribution modelling in the neotropics

The workshop ‘Species distribution models: applications, challenges and perspectives’ held at Belo Horizonte (Brazil), 29–30 August 2011, aimed to review the state-of-the-art in species distribution modelling (SDM) in the neotropical realm. It brought together researchers in ecology, evolution, biogeography and conservation, with different backgrounds and research interests. The application of SDM in the megadiverse neotropics—where data on species occurrences are scarce—presents several challenges, involving acknowledging the limitations imposed by data quality, including surveys as an integral part of SDM studies, and designing the analyses in accordance with the question investigated. Specific solutions were discussed, and a code of good practice in SDM studies and related field surveys was drafted.

Niche modelling and landscape genetics of Caryocar brasiliense ("Pequi" tree: Caryocaraceae) in Brazilian Cerrado: an integrative approach for evaluating central-peripheral population patterns.

Complex and integrative approaches may be necessary to understand the abundant-centre model and the patterns in genetic diversity that may be explained by this model. Here we developed an integrated framework to study spatial patterns in genetic diversity within local populations, coupling genetic data, niche modelling and landscape genetics, and applied this framework to evaluate population structure of Caryocar brasiliense, an endemic tree from the Brazilian Cerrado. We showed different geographical patterns for genetic diversity, allelic richness and inbreeding levels, estimated using microsatellite data for ten local populations. Ecological suitability was estimating by combining five niche modelling techniques. Genetic diversity tend to follow a central-periphery model and is associated with ecological variables. On the other hand, inbreeding levels may be alternatively explained by isolation processes and habitat fragmentation more related to intense recent human occupation in the southern border of the biome, or by deeper historical patterns in the origin of the populations. Although still suffering from some of the problems of central-periphery analysis (small number of local populations), our analyses show how these patterns can be better investigated and offering a better understanding of the processes structuring genetic diversity within species’ geographic ranges.

Amazonian species within the Cerrado savanna: new records and potential distribution for Aglae caerulea (Apidae: Euglossini)

Given human-related changes, quality distributional data are required for consistent conservation. Still, the lack of proper biogeographic information is a major setback for many groups. Here, we use new occurrences for Aglae caerulea in the Cerrado to model its potential distribution. We used Maximum Entropy (MaxEnt) and Genetic Algorithm for Rule-Set Production (GARP) algorithms in different modeling runs and both previous and new A. caerulea occurrences to predict this species distribution. Models which used only the previous A. caerulea’s records did not predicted the new Cerrado records, while those where we used the latter did predict the new ones as minimally suitable. A. caerulea distribution significantly increased towards the Cerrado according to both MaxEnt and GARP algorithms. Gallery forests are important dispersal alternatives for several species dwelling the Amazon and the Atlantic forest. Niche models of other rare Euglossini bees are advised to better evaluate their distributions.

Thermoregulatory constraints on behavior: patterns in a neotropical dragonfly assemblage

As libelulas sao classificadas comportamentalmente em voadoras e pousadoras com relacao a sua capacidade de termoregulacao. Libelulas de grande tamanho corporal devem termoregular de forma mais eficiente em locais com elevada irradiacao solar, ao passo que libelulas menores dependem da temperatura ambiente. Neste estudo, foram realizadas analises de orcamento temporal de uma assembleia de libelulas para determinar como o tamanho corporal pode restringir a defesa de territorios e outros comportamentos. Baseado no orcamento temporal, foram observados tres grupos de especies. O primeiro e o segundo grupos abrangem especies que permaneceram pousadas grande parte do tempo de atividade, entretanto especies do primeiro grupo realizaram voos de transicao mais frequentemente. O terceiro grupo conteve as especies que foram observadas frequentemente patrulhando seus territorios ou executando atividades reprodutivas. As especies maiores permaneceram mais tempo em atividades de patrulha e defesa de seus territorios enquanto as especies menores ficaram mais tempo pousadas. Libelulas maiores com maior habilidade de termoregulacao puderam gastar mais tempo em atividades reprodutivas. A classificacao das libelulas em voadoras e pousadoras e considerada extremamente util, mas simplifica os padroes comportamentais observados entre especies que tem grande variacao de tamanho corporal. E provavel que o continuo comportamental associado com a variacao de tamanho corporal, nos pousadores, possa explicar os padroes de interacoes entre especies em comunidades de libelulas.

Patterns in the organization of Cerrado pond biodiversity in Brazilian pasture landscapes

There is a worldwide concern on the loss of pond biodiversity in human dominated landscapes. Nevertheless, agricultural activities appear to increase pond number in the Brazilian Cerrado through damming streams for cattle raising. These man-made ponds may represent important landscape features, but their importance to regional biodiversity has not yet been studied. Here, we evaluated differences in alpha and beta diversity under a multi-taxonomic approach, as well as tested pond size as the main driver of local species richness. We also assessed the importance of environmental heterogeneity through the analysis of the regional species accumulation curves (SAC). The overall result suggests that species turnover was the major component of regional biodiversity for all groups. Major physical and chemical water conditions had no effects on algae, macrophytes, water bugs, and birds species richness. Pond size had a significant effect on Odonata and fish species richness, while water beetles and amphibians were influenced by trophic conditions. Results from regional SAC show variations among different taxonomic groups regarding landscape heterogeneity: only algae, fish, and birds do not reached to an asymptote and had higher z-values. Our results highlight the importance of ponds for biodiversity conservation in increasingly agricultural landscapes in central Brazil.