Trophic, functional and isotopic ecology of terrestrial mammals of the Atlantic Forest

Author(s)

Marcelo Magioli

• Document type: Doctoral Thesis
• Press: Piracicaba.
• Institution: Universidade de São Paulo (USP). Escola Superior de Agricultura Luiz de Queiroz
• Defense date: 20 jun. 2018

Examining board members

Katia Maria Paschoaletto Micchi de Barros Ferraz; Adriano Garcia Chiarello; Ronaldo Gonçalves Morato; Adriano Pereira Paglia; Mauro Galetti Rodrigues

• Advisor: Katia Maria Paschoaletto Micchi de Barros Ferraz; Marcelo Zacharias Moreira

Abstract

The knowledge about species ecology in ever changing ecosystems is necessary to understand how they persist, how they used the new habitats molded by human activities, and if they are still performing ecological functions; this kind of information is essential to subsidize the conservation of ecosystem. The objectives of this thesis are: 1) to determine if the puma (Puma concolor) can occupy the niche of the jaguar (Panthera once) where it is functionally absent, by assessing the puma\' feeding habits and comparing it to the jaguar; 2) analyze changes in resource and habitat use, and trophic structure of mammal assemblages in preserved and modified landscapes of the Atlantic Forest, Brazil, by using the analysis of carbon and nitrogen stable isotopes; 3) identify changes in the functional effectiveness of mammal assemblages in response to changes in landscape structure within the Atlantic Forest. To determine the diet of the puma, we collected fecal samples in two areas of the largest Atlantic Forest continuum and identified 15 prey taxa. We observed that pumas consumed preferentially large prey, a proportion superior to other areas in the biome. Compared to the jaguar\' diet, the proportion of large prey was also higher. Thus, the puma may at as a functional equivalent where the jaguar is functionally absent, and there is availability of large prey. In the study with isotopic ecology, we used mammal\' hair for analysis, which were collected in preserved and modified landscapes. To compare these areas, we classified mammals in trophic guilds and corrected isotopic values using species-specific fractionation factors. We observed a huge difference in mammals\' resource use, with predominant use of C3 resource in preserved landscapes, and a higher incorporation of C4 carbon in the modified ones. The trophic structure was clear in preserved landscapes, with an orderly 15N enrichment, while unordered in modified landscapes, with floating enrichment. We highlight that the agricultural matrix plays an important role as source of food items and as habitat for resilient mammals, including threatened species, and its management is essential for species conservation. To study the functional effectiveness of mammal species, we created two databases, one with mammal assemblages, and other to assess the contribution of species in ecological functions. We selected 10 trophic functions for analysis, which were classified in vulnerable (performed by sensitive species) and persistent (performed by resilient species). For each assemblage we calculated the defaunation level and five landscape variables. We analyze the data using the Hierarchical Modelling of Species Communities and extrapolate the results for the entire Atlantic Forest. Species richness, body mass and vulnerable functions showed a positive relationship with increasing habitat amount, while negative for anthropogenic land uses, similar to the defaunation pattern; the inverse was observed for persistent functions. Vulnerable functions were restricted to the large forest block, which have high species diversity, highlighting its importance for ecological functions maintenance. Human-modified landscapes may still perform an important role for functions persistence, especially if connected to the largest forest blocks. (AU)

• FAPESP's process: 14/10192-7 - Trophic ecology of carnivorous mammals of the Atlantic Forest: use of stable isotope and functional diversity for conservation
• Grantee: Marcelo Magioli
• Support type: Scholarships in Brazil - Doctorate