Analysis of the functional connectivity through the characterization of movement of the species Heliconius erato

Author(s)

Julia de Lima Pinheiro

• Document type: Master's Dissertation
• Press: Piracicaba.
• Institution: Universidade de São Paulo (USP). Escola Superior de Agricultura Luiz de Queiroz (ESALA/BC)
• Defense date: 2017-08-18

Examining board members

Danilo Boscolo; André Victor Lucci Freitas; Karl Stephan Mokross; Marcus Vinícius Vieira

• Advisor: Ricardo Ribeiro Rodrigues; Danilo Boscolo

Abstract

The anthropic influence on natural habitats may cause forest loss and fragmentation. This process changes species richness, compromising their conservation. The effects of forest fragmentation depend, among other factors, on the functional connectivity, namely on how an organism perceives and responds to the landscape structure. Understanding the factors that determine the quality of the matrix for the organisms and understanding animal movement are essential steps to guide conservation initiatives on fragmented landscapes. Therefore, from the movement characterization of the butterfly species Heliconius erato, which is indicated as a good surrogate for environmental monitoring, it was possible to infer about its perception capacity and to analyze landscape functional connectivity for this species. The study was conducted in the Northern region of Batatais, São Paulo. The translocation of 78 Heliconius erato individuals was conducted to non-forested matrix at different distances from forest patches and their paths back to the forest were actively recorded. The rate of return of the translocated individuals to their original forest patch as a function of the distance was evaluated with Cox survival analysis together with the ratio between the individuals which returned and the total amount per distance. Path tortuosity was measured through the Correlated Random Walk analysis together with the ratio between the effective distance and the sum of lengths for each path. An ANOVA was conducted to check for tortuosity differences between distances. To relate this index with the distance to the forest, generalized linear models were used. These models were compared through AICc. The angles orientation was analyzed through circular statistics with Rayleigh test, V-test and histograms. As distance increased the number of individuals returning to the forest decreased. The return rate dropped to 50% at 150m. Through Cox analysis it was noted that the distance together with tortuosity and release site influenced the return rate. The time of the day and the release site explained the tortuosity range. Angle analysis showed that as further than 150m the flights become random. Therefore, to ensure the conservation of the Heliconius genus in agricultural landscapes that include structurally distinct crops from forest fragments it is important to maintain a 100m mean inter-patch distance. (AU)

• FAPESP's process: 15/08211-6 - Analysis of the functional connectivity through the characterization of movement of the species Heliconius erato
• Grantee: Julia de Lima Pinheiro
• Support Opportunities: Scholarships in Brazil - Master