Efeito da temperatura no comportamento e na distribuição de duas subespécies de Canthon rutilans Castelnau, 1840 (Coleoptera: Scarabaeinae)

Tese (doutorado) - Universidade Federal de Santa Catarina, Centro de Ciências Biológicas, Programa de Pós-Graduação em Ecologia, Florianópolis, 2018.Este trabalho teve como objetivo geral estudar o efeito da temperatura em duas subespécies de Canthon rutilans (Coleoptera: Scarabaeidae: Scarabaeinae) com a finalidade de observar diferenças na distribuição e no comportamento que justifiquem serem consideradas ecologicamente como duas espécies. Assim, esta tese foi dividida em três capítulos, sendo o primeiro sobre a distribuição geográfica das duas subespécies em um gradiente de elevação no estado de Santa Catarina, o segundo sobre o comportamento dos adultos e desenvolvimento larval em diferentes condições de temperatura e o terceiro sobre a distribuição real e provável em escala local e regional. O primeiro capítulo examinou o grau de segregação espacial e temporal das duas subespécies, ao longo de um gradiente de elevação com dados de um ano e verificou diferenças nos seus nichos térmicos. Os resultados mostraram que C. rutilans cyanescens e C. rutilans rutilans não se sobrepõem espacial nem temporalmente. Os limites de temperatura média dos dias de coleta para C. rutilans cyanescens foram de 15.3 e 24.0°C e no caso de C. rutilans rutilans foram de 14.4 e 18.6°C, com uma sobreposição do nicho térmico limitada a 5.6%. Esses resultados sugerem que ambas subespécies poderiam ser consideradas espécies distintas com diferentes requisitos fisiológicos e ecológicos. No segundo capítulo, comparamos em laboratório a influência da temperatura no comportamento e no desenvolvimento larval das subespécies para confirmar adaptações às diferentes condições térmicas das áreas de distribuição. Em cinco condições de temperatura (15, 20, 25, 30 e 35°C), o comportamento alimentar não diferiu entre as duas subespécies nem nas temperaturas, mas sim houve diferença no comportamento reprodutivo, sendo o tamanho das bolas-ninho dependente da temperatura e da subespécie, uma vez que as bolas-ninho de C. rutilans rutilans são maiores e mais pesadas a baixas temperaturas. O número de descendentes e o tempo de emergência dos adultos também foram dependentes da temperatura e o tempo de vida dos adultos de C. rutilans rutilans diminui quando a temperatura aumenta. Estes resultados confirmam que C. rutilans rutilans tem comportamento reprodutivo com adaptações para viver em regiões frias, sendo mais dependente da temperatura, em comparação com C. rutilans cyanescens que habita lugares mais quentes, reforçando que ambas as subespécies são ecologicamente diferentes. No terceiro capítulo criamos mapas da distribuição real e provável das duas subespécies baseados em dados provenientes de sete coleções entomológicas no Brasil, somando 46 localidades para C. rutilans rutilans e 120 localidades para C. rutilans cyanescens. As análises das médias de 23 variáveis ambientais mostraram diferenças evidentes entre as duas subespécies, principalmente nas variáveis relacionadas à temperatura e elevação. A área de sobreposição foi de 70% em âmbito regional, mas na escala local elas não ocorrem juntas. Dependendo da escala espacial, as duas subespécies poder ser simpátricas (escala regional) ou alopátricas (escala local) uma vez que C. rutilans rutilans e C. rutilans cyanescens têm requerimentos ambientais diferentes, com adaptações locais específicas

Differences in the reproductive behaviour and larval development of two Canthon rutilans subspecies reinforce their thermal regional segregation

Two dung beetle subspecies of Canthon rutilans Castelnau (Coleoptera: Scarabaeidae, Scarabaeinae), C. rutilans rutilans and C. rutilans cyanescens, inhabit different environmental temperature conditions in southern Brazil. We developed a laboratory breeding experiment with 60 pairs of individualsof the two subspecies at five temperature conditions (from 15 to 35°C) to compare the influence oftemperature on the behaviour of adults and the development of larvae. The behavioural patterns ofthe adults in both subspecies differ according to temperature. The size of food balls was smaller andlighter inC. rutilans cyanescens. Although temperature did not influence the feeding behaviour (mea-sured as the number of food balls made), reproductive behaviour (measured as the number of broodballs made by pair) was significantly lower at 15°C for both subspecies. Besides that, brood balls fromC. rutilans rutilanswere bigger and heavier at lower temperatures. The number of offspring and thetime of emergence depend on temperature too. However, the weight of the offspring and the longev-ity of adults depend on the subspecies and temperature treatment. These results demonstrate that thesubspecies have different thermal adaptations:C. rutilans rutilanshas reproductive behaviouradapted to living under colder and broader conditions thanC. rutilans cyanescens.We thank for the scholarship awarded to MCH (finance code 001) and CNPq for a Productivity Grant awarded to MIMH (process 307437/2017-5). This project had financial support provided by CAPES: ’Efeito comparado do clima e dasmudancas no uso do solo na distribuicao espacial de um grupo de insetos indicadores (Coleoptera: Scarabaeinae) na Mata Atlantica’ (process 88881.068089/2014-01)

Distribution of canthon rutilans rutilans and canthon rutilans cyanescens along spatio-temporal and temperature gradients

Subspecies is a debated taxonomic rank that, in some cases, could indicate that a speciation process is taking place. Studying the degree of co-occurrence among subspecies along environmental gradients may help to determine its taxonomic status. In this study, we explore the distribution of two subspecies of Canthon rutilans along spatio-temporal and temperature gradients in the Atlantic Forest of southern Brazil in order to reinforce their current subspecies status or to support their consideration as two different species. A yearly survey conducted along an elevational transect (from 250 m to 1630 m) shows that there is no spatio-temporal overlap between the two taxa. We collected 899 individuals of Canthon rutilans cyanescens and 29 individuals of Canthon rutilans rutilans. C. rutilans cyanescens can be found at 250 m (all year except in June), 430 m (August to April), and 840 m (September to April) in elevation, and when the air temperature oscillates from 15.3 °C to 24.0 °C. C. rutilans rutilans can be found at 1360 m (October to February), 1630 m (January) in elevation, and when the air temperature oscillates from 14.4 °C to 18.6 °C. Furthermore, local temperature data taken during the survey indicates that both subspecies also have a limited overlap in their thermal response curves. All these results suggest that these two taxa could be considered as two different species with dissimilar physiological and ecological requirements probably as a consequence of temperature-mediated divergent adaptation. Further molecular data can confirm or reject this supposition in the near future.This research was funded by Ciências Sem Fronteiras program of the Ministério da Educação via Coordenação de Aperfeiçoamento de Pessoal de Nível Superior–CAPES (88881.068089/2014-01).Peer reviewe

Exploring the predictive performance of several temperature measurements on Neotropical dung beetle assemblages: Methodological implications

Basic characteristics of species assemblages are frequently related to temperature variables recorded at a coarse-grained scale. In this study, 15 min instant-measurements of environmental and soil temperatures were recorded during 1 year in six Atlantic Forest sites of southern Brazil, ranging from 250 to 1,630 m a.s.l. These measurements were used to examine the comparative explanatory capacity of several temperature variables in predicting species richness and total or specific variations of dung beetle abundance. The results suggest that temperature measurements obtained during the survey period have the highest explanatory capacity. Furthermore, average temperature values seem to have a relatively higher explanatory capacity than absolute minimum or maximum values reflecting extreme conditions. In general, there is no rule in selecting a temperature variable when the objective involves explaining the variation in species abundances. Both soil and air variables can have similar explanatory capacities. The present results should be considered when designing future ecological studies in Neotropical conditions.We also thank the financial support provided by Ciências Sem Fronteiras program of the Ministério da Educação via Coordenação de Aperfeiçoamento de Pessoal de Nível Superior – CAPES (Process 88881.068089/2014-01).PGdS and VA thank CAPES for a Post -doctoral grant (Process 88881.068089/2014-01) and MIMH thanks the Conselho Nacional de Pesquisa (CNPq) for the Productivity grant (Process 309030/2013-7)

Variation in dung removal by dung beetles in subtropical Atlantic Rainforests

Dung consumption and removal is a fundamental ecological process carried out by dung beetles that drive soil nutrient cycling and associated ecosystem services. In this study, the removal rate of small droppings by dung beetles was estimated in natural subtropical rainforests of southern Brazil located along an elevational gradient, in order to understand the factors influencing variation in dung removal. To do that, the comparative explanatory capacity of three main types of variables was quantified: assemblage characteristics, local climatic and habitat conditions, and seasonal variation. The complete disappearance of dung within 48 h after deposition occurs in 73% of occasions. The highest explanatory capacity correspond to the combined effects of the three types of variables; however, average air temperature during the sampling period, total volume of dung beetles collected in the traps in which dung removal was measured, and the seasonal transition from summer to winter were the most important and representative predictors of dung removal. Thus, the dung nutrient incorporation into the soil will most likely be greater during spring‐summer conditions, when the air temperature at the time of dung deposition is high and the biomass of the dung beetle assemblage is bigger.Furthermore, we would like to thank Ciências Sem Fronteiras program of the Ministério da Educação via Coordenação de Aperfeiçoamento de Pessoal de Nível Superior – CAPES and CNPq (process 88881.068089/2014‐01) for their financial support. PGdS and VA thank CAPES for a post‐doctoral grant (process 88887.094506/2015‐00 and 88887.100542/2015‐00) and MIMH thanks the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) for the Productivity grant (process 309030/2013‐7)

Turnover and nestedness in subtropical dung beetle assemblages along an elevational gradient

[Aim]: We investigated changes in dung beetle β-diversity components along a subtropical elevational gradient, to test whether turnover or nestedness-related processes drive the dissimilarity of assemblages at spatial and temporal scales. [Location]: An elevational gradient (200–1,600 m a.s.l.) of the Atlantic Forest in southern Brazil. [Methods]: We investigated the extent to which β-diversity varied along the elevational gradient (six elevations) at both spatial (among sites at different elevations) and temporal (different months at the same site) scales. We compared both the turnover and nestedness-related dissimilarity of species and genera using multiple-site or multiple-month measures and tested whether these measurements were different from random expectations. [Results]: A mid-elevation peak in species richness along the elevational gradient was observed, and the lowest richness occurred at the highest elevations. We found two different groups of species, lowland and highland species, with a mixing of groups at intermediate elevations. The turnover component of β-diversity was significantly higher for both spatial (i.e. elevational) and temporal changes in species composition. However, when the data for genera by site were considered, the elevational turnover value decreased in relative importance. Nestedness-related processes are more important for temporal dissimilarity patterns at higher elevation sites. [Main conclusions]: Spatial and temporal turnover of dung beetle species is the most important component of β-diversity along the elevational gradient. High-elevation assemblages are not subsets of assemblages that inhabit lower elevations, but this relationship ceases when β-diversity is measured at the generic level. Environmental changes across elevations may be the cause of the differential establishment of distinctive species, but these species typically belong to the same higher taxonomic rank. Conservation strategies should consider elevational gradients in case-specific scenarios as they may contain distinct species assemblages in lowlands vs. highlands.We also want to thank the financial support provided by the Ciências Sem Fronteiras program of Ministério da Educação via Coordenação de Aperfeiçoamento de Pessoal de Nível Superior—CAPES (Process 88881.068089/2014‐01). PGdS thank CAPES for the post‐doctoral grant (Process 88881.068089/2014‐01) and MIMH thank Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) for the productivity grant (Process 309030/2013‐7)