Direct development in Atlantic Forest anurans: What can environmental and biotic influences explain about its evolution and occurrence?

Different environmental and biological factors can originate and support different alternative life histories in different taxonomic groups. Likewise, these factors are important for the processes that assemble and structure communities. Amphibians, besides being highly susceptible to environmental conditions, have various reproductive strategies, such as the direct development of individuals. Several hypotheses have been raised about possible selective pressures related to the emergence of direct development in anurans, as well as the relationship between environmental characteristics and the occurrence of these species. Such investigations, however, have mainly focused on specific clades and/or regions. Here, we use structural equation modelling to investigate the relationships between different abiotic (temperature, precipitation, humidity, and terrain slope) and biotic (phylogenetic composition and functional diversity) factors and the proportion of species with direct development in 766 anuran communities of the Atlantic Forest, a biome with a vast diversity of anuran species and high environmental complexity. Anuran communities with higher proportions of direct developing species were found to be mainly influenced by low potential evapotranspiration, low temperature seasonality, and high functional diversity. Phylogenetic composition and terrain slope were also found to be important in determining the occurrence of these species in Atlantic Forest communities. These results show the importance of these factors in the structuring of these communities and provide important contributions to the knowledge of direct development in anurans.

Anthropogenic influences on the distribution of a threatened apex-predator around sustainable-use reserves following hydropower dam installation.

Although previous studies demonstrate declines in many large bodied species following hydropower dam installation, others suggest that some species, including the giant otter (Pteronura brasiliensis) may return to newly created reservoir habitats. Yet, there is a lack of evidence to support such theories. Here, we analyzed the effects of a hydropower dam on giant otters using a before-after control-impact study design in the eastern Brazilian Amazon. We collected data 3 years before (2011-2012 and 2015) and after (2017-2019) dam construction, totaling 6,459 km of surveys along rivers with 43 direct sightings of giant otters. Contrary to expectations, our results revealed that giant otters did not remain nor did they return to the dam reservoir. Beyond the zone directly impacted by the dam giant otter occurrence and relative abundance declined next to sustainable-use reserves where the river was more intensely used by people. Our study showed that in the absence of active management sustainable-use reserves and low human density were not sufficient to maintain this apex-predator. Our findings suggest a need to proactively create and maintain areas with low levels of anthropogenic disturbance to enable sustainable coexistence between energy demands and biodiversity across Amazonia.

Is evolution faster at ecotones? A test using rates and tempo of diet transitions in Neotropical Sigmodontinae (Rodentia, Cricetidae).

We evaluated whether evolution is faster at ecotones as niche shifts may be needed to persist under unstable environment. We mapped diet evolution along the evolutionary history of 350 sigmodontine species. Mapping was used in three new tip-based metrics of trait evolution - Transition Rates, Stasis Time, and Last Transition Time - which were spatialized at the assemblage level (aTR, aST, aTL). Assemblages were obtained by superimposing range maps on points located at core and ecotone of the 93 South American ecoregions. Using Linear Mixed Models, we tested whether ecotones have species with more changes from the ancestral diet (higher aTR), have maintained the current diet for a shorter time (lower aST), and have more recent transitions to the current diet (lower aLT) than cores. We found lower aTR, and higher aST and aLT at ecotones than at cores. Although ecotones are more heterogeneous, both environmentally and in relation to selection pressures they exert on organisms, ecotone species change little from the ancestral diet as generalist habits are necessary toward feeding in ephemeral environments. The need to incorporate phylogenetic uncertainty in tip-based metrics was evident from large uncertainty detected. Our study integrates ecology and evolution by analyzing how fast trait evolution is across space.

Database of bird species composition in natural habitats and forest plantations.

In southeastern South America, the afforestation over grasslands imposes a severe threat to the grassy landscapes and associated biodiversity. To analyze the effect of forest plantations on grassland birds, we present a new database that considers the composition of bird communities in natural habitats, as well as in eucalyptus plantations from the southeastern South American grasslands. Data were previously used to investigate the effectiveness of legally protected grasslands in private lands to protect birds in "Bird-grassland associations in protected and non-protected areas in the southern Brazil" [1] and also the effects of afforestation of grasslands on different dimensions of bird diversity in "The effects of grassland ecosystem afforestation on avian phylogenetic diversity, taxonomic diversity and evolutionary distinctiveness" [2]. Data were collected during the breeding period of bird species (spring/austral summer), covering three breeding seasons during the years 2014-2016. Species presence and number of individuals were recorded, totaling 107 species and 1175 individuals. The dataset will be useful for researchers interested in conservation studies as it includes data from globally threatened bird species.

A global database on non-volant small mammal composition in natural and human-modified habitats.

Non-volant small mammals, which include small-bodied representatives from several mammal orders, have been used as a model group to test the effects of habitat conversion and edge creation on biodiversity. Small mammals occupy a large variety of habitat types and vegetation strata, and have varied lifestyles and diets. They include species with slow-to fast-life history (the Etruscan shrew Suncus etruscus and European Hare Lepus europaeus, respectively) and with very specialized to very generalist habits and diets (the Atlantic bamboo rat Kannabateomys amblyonyx and house mouse Mus musculus, respectively). There are no databases with global coverage focusing on small mammal composition in natural and human-modified habitats and that include neglected natural habitats (e.g. grasslands and savannas). Here, peer-reviewed articles were searched in the primary literature to synthesize almost half century (1973-2017) of research on small mammal composition in natural forests, grasslands and their natural edges, and in five types of human-modified habitats (human-induced forest edges, human-induced grassland edges, crop fields, clear-cuts and tree plantations). The complete database includes information from 199 peer-reviewed articles. Presence data were obtained for 534 species (including 30 unidentified) in 551 sites distributed in 45 countries, 92 ecoregions, 10 biomes and six realms. Measurements of sampling effort and number of species records (number of individuals, captures) per habitat were also obtained, from which researchers can calculate a measure of abundance standardized by the sampling effort. The database will be useful for researchers interested in local-to broad-scale patterns of alpha- and beta-diversity in natural and human-modified habitats.

Movement and longitudinal distribution of a migratory fish ( Salminus brasiliensis) in a small reservoir in southern Brazil

We investigated whether the movement and distribution of the migratory fish, Salminus brasiliensis, were affected by a small reservoir. We also examined how movement and distribution were related to water temperature, flow, and rainfall. In December 2011 and January 2012, 24 individuals were captured downstream from the dam, tagged with radio transmitters and released in the reservoir (5.46 km² total area). After being released in the reservoir, 18 of the 24 tagged fish travelled upstream, taking an average of 16.6 days to leave the reservoir, with daily movements varying from < 5 km/day to > 24 km/day. However, only seven tagged specimens (29.16%) returned to the lower reservoir section, while the rest remained in the intermediate and upper reservoir sections. Longitudinal distributions and movements were positively related to both upstream flow into the reservoir and water temperature. We found evidence that S. brasiliensis can recognize the longitudinal gradient and is able to continue its upstream migration. On the other hand, the reservoir negatively affected downstream movements, possibly because disorientation prevented movement to the lower reservoir section. Based on these results, we suggest that the impact of small reservoirs on migratory fish species should be objectively addressed in environmental impact assessments and management programs.(AU)

Neste estudo investigamos se o movimento e distribuição do peixe migrador, Salminus brasiliensis, são afetados por um pequeno reservatório. Também avaliamos como movimento e distribuição se relacionam com a temperatura da água, fluxo e pluviosidade. Em dezembro de 2011 e janeiro 2012, 24 indivíduos foram capturados a jusante da barragem, marcados com radiotransmissores e liberados no reservatório (5,46 km²). Depois de soltos, 18 dos 24 peixes marcados se deslocaram para montante, levando em média 16,6 dias para ultrapassar o reservatório com movimentos diários variando de < 5km/dia a > 24km/dia. Entretanto, apenas sete (29,16%) dos peixes marcados retornaram para seção inferior do reservatório, a maior parte mantendo-se nas seções intermediárias e superiores do reservatório. Distribuição longitudinal e movimento dos peixes foram relacionados positivamente com o fluxo de montante dentro do reservatório e com a temperatura da água. Assim, encontramos evidências que S. brasiliensis pode reconhecer o gradiente longitudinal e continuar sua migração ascendente. Por outro lado, nossos resultados também indicam que o movimento para jusante foi afetado, possivelmente, devido à desorientação, o que impede que os indivíduos alcancem as seções inferiores do reservatório. Com base nos resultados, sugerimos que impactos sobre peixes migratórios devem ser objetivamente abordados em avaliações ambientais e gestão ambiental de pequenos reservatórios.(AU)

Phylogenetic and morphological relationships between nonvolant small mammals reveal assembly processes at different spatial scales.

The relative roles of historical processes, environmental filtering, and ecological interactions in the organization of species assemblages vary depending on the spatial scale. We evaluated the phylogenetic and morphological relationships between species and individuals (i.e., inter- and intraspecific variability) of Neotropical nonvolant small mammals coexisting in grassland-forest ecotones, in landscapes and in regions, that is, three different scales. We used a phylogenetic tree to infer evolutionary relationships, and morphological traits as indicators of performance and niche similarities between species and individuals. Subsequently, we applied phylogenetic and morphologic indexes of diversity and distance between species to evaluate small mammal assemblage structures on the three scales. The results indicated a repulsion pattern near forest edges, showing that phylogenetically similar species coexisted less often than expected by chance. The strategies for niche differentiation might explain the phylogenetic repulsion observed at the edge. Phylogenetic and morphological clustering in the grassland and at the forest interior indicated the coexistence of closely related and ecologically similar species and individuals. Coexistence patterns were similar whether species-trait values or individual values were used. At the landscape and regional scales, assemblages showed a predominant pattern of phylogenetic and morphological clustering. Environmental filters influenced the coexistence patterns at three scales, showing the importance of phylogenetically conserved ecological tolerances in enabling taxa co-occurrence. Evidence of phylogenetic repulsion in one region indicated that other processes beyond environmental filtering are important for community assembly at broad scales. Finally, ecological interactions and environmental filtering seemed important at the local scale, while environmental filtering and historical colonization seemed important for community assembly at broader scales.

Checklist of climbing plants in an Araucaria forest of Rio Grande do Sul State, Brazil / Florística de trepadeiras em uma floresta de Araucária do Estado do Rio Grande do Sul, Brasil

Climbing plants are remarkable components of forests, highly contributing for the diversity and dynamics of communities. Studies focusing on climbing plants are scarce and for many vegetation types little is known about climbing species composition and their traits relevant for dispersal and establishment. The focus of this study is to provide the first floristic inventory of climbing plants in an Araucaria forest of Brazil, describing the dispersal syndromes and climbing mechanisms of species and comparing these traits and species composition patterns with other study sites in Southern Brazil. We found 104 taxa belonging to 33 families, with Asteraceae (22 spp.) and Apocynaceae (14 spp.) being the richest families. Among climbing mechanisms, stem twiner (50 spp.) is the most common, followed by tendril (20 spp.) and scrambler (12 spp.), while in relation to the dispersal syndromes, anemochoric species (65 spp.) are the most relevant followed by endozoochoric (28 spp.). Three new species registries were found for Rio Grande do Sul State expanding their occurrence range towards South Brazil. The comparison of climbers' survey sites showed two sharp groups in relation to species composition and traits proportion, Seasonal and Araucaria/Atlantic forest sites, but with no difference of traits frequency between sites. There is a predominance of stem twiners species in all sites, but the relative difference for tendril species increases in Araucaria and Atlantic forest sites. The Asteraceae and Apocynaceae families were the most relevant, contrasting to Seasonal forests of Southeast Brazil. Interesting patterns can be achieved with a more detailed classification of climbing mechanisms and the results found in this study contributes to enhance the knowledge on climbers' traits and diversity in South Brazil.

Trepadeiras são importantes componentes florestais, contribuindo na diversidade e dinâmica de comunidades vegetais. Estudos focados em trepadeiras são escassos e para muitos tipos vegetacionais pouco se sabe sobre a composição de espécies de trepadeiras e seus atributos relevantes para dispersão e estabelecimento. O foco deste estudo é fornecer o primeiro inventário florístico de plantas trepadeiras em uma floresta de Araucária no Brasil, descrevendo as síndromes de dispersão e mecanismos de escalada das espécies e comparando esses atributos e a composição de espécies com outros sítios no Sul do Brasil. Foram encontrados 104 taxa pertencentes a 33 famílias, sendo Asteraceae (22 spp.) e Apocynaceae (14 spp.) as famílias mais ricas. Dentre os mecanismos de escalada, o tipo volúvel (50 spp.) é o mais comum, seguido por gavinhas (20 spp.) e apoiantes (12 spp.), enquanto em relação ès síndromes de dispersão as espécies anemocóricas (65 spp.) são as mais relevantes seguidas por endozoocóricas (28 spp.). Três novos registros de espécies foram encontrados para o Estado do Rio Grande do Sul, expandindo suas extensões de ocorrência para o Sul do Brasil. A comparação entre sítios evidenciou dois grupos nítidos em relação è composição de espécies e proporção de atributos, sítios em florestas sazonais e nas florestas com Araucária e Atlântica, porém não há diferença na frequência dos atributos entre os sítios. Há uma predominância de espécies volúveis em todos os sítios, entretanto a diferença relativa para espécies com gavinhas aumenta nos sítios de floresta com Araucária e Atlântica. As famílias Asteraceae e Apocynaceae foram as mais relevantes, contrastando com florestas sazonais no Sudeste do Brasil. Padrões interessantes podem ser encontrados com uma classificação mais detalhada dos mecanismos de escalada e os resultados encontrados neste estudo contribuem para aumentar o conhecimento sobre os atributos e a diversidade de trepadeiras no Sul do Brasil.

Evaluation of trace metals (cadmium, chromium, copper and zinc) in tissues of a commercially important fish (Leporinus obtusidens) from Guaíba Lake, Southern Brazil

Concentrations of Cd, Cr, Cu and Zn were determined in liver and muscle of Leporinus obtusidens. During 2003, the fishes (N = 54) were sampled from three sites along Guaíba Lake (north, central and south zones). The hypotheses tested assumed that there were differences in the location and date as to levels of contamination, association between the trace metal content in the fishes and size, and that the sex influenced metal accumulation. Possible risks of contaminated fish consumption to human health were also evaluated. The level of mean concentration (µg/g) of metals in tissues was higher in liver than muscle: [Cd] = 2.32♂; [Cr] = 0.08♀; [Cu] = 30.82♀ and [Zn] = 97.77♀. The results showed differences between the local and date sampling for all metals except Cr. Metal content was higher in the warmer than colder seasons and in the central zone than at other points. Significant sexual differences were detected for Cd and Zn and there were positive associations between the size and metal concentrations for Cu and Zn. The concentration levels of metals in muscle tissue showed that the fish samples did not offer risks to human health.

As concentrações dos metais Cd, Cr, Cu e Zn foram determinadas para os tecidos muscular e hepático de Leporinus obtusidens no sul do Brasil. Durante o ano de 2003, 54 indivíduos foram capturados em três locais ao longo do Lago Guaíba (norte, centro e sul). Neste estudo verificamos se havia diferenças entre os locais de amostragem e as épocas do ano nas concentrações de metais nos tecidos analisados, bem como relação entre a concentração do metal e tamanho e sexo dos indivíduos. O risco para o consumo humano também foi avaliado. A concentração média (µg/g) dos metais foi maior no fígado do que no músculo para todos os metais: [Cd] = 2,32♂; [Cr] = 0,08♀; [Cu] = 30,82♀ e [Zn] = 97,77♀. Os resultados apresentaram diferenças significativas entre os locais (região central do lago com as maiores concentrações) e épocas do ano (meses de primavera e verão) para todos os metais, exceto Cr. Diferenças entre os sexos também foram detectadas, para Cd e Zn, e relações com o tamanho dos indivíduos para Cu e Zn. Os níveis encontrados no tecido muscular não oferecem riscos ao consumo da espécie.

Life-history of the South American darter, Characidium pterostictum (Crenuchidae): evidence for small scale spatial variation in a piedmont stream

The present study compares the reproduction, condition and size of the small characiform fish, Characidium pterostictum, sampled at close sites differing in severity of flash flood effects. Data were obtained from seasonal samples in two sites situated 8 km apart in the same stream. In the upstream site, habitat is more severely affected by flash floods than in the downstream site, and this difference was hypothesized to produce differences in life history and individual reproduction trade-off patterns, as predicted by life-history theory. The results provided evidence for small-scale spatial variation in life-history and trade-off patterns within the studied population. At the most severely disturbed site, C. pterostictum displayed a trade-off pattern that favored reproductive life-span (e.g., larger size, higher and seasonally stable condition, larger mean size of mature females) over instantaneous reproductive output (lower gonadosomatic index), while the opposite pattern was observed in the less disturbed site. Because of the differences in disturbance effects between each sampling site, these results suggest that within-stream variability in the severity of hydrological disturbance can influence life-history patterns at small spatial scales. An implication of the results is that fish occupying areas that are hydrologically more variable within a stream are not necessarily at an energetic or reproductive disadvantage, but may be simply under environmental conditions that favor distinct patterns of energy allocation (or trade-offs) and population persistence, as predicted by life-history theory. Therefore, plasticity in life-history is expected to be common in stream fish populations that are widespread in a stream system with spatially variable or patchy habitat characteristics.

Este estudo compara a estrutura populacional e a reprodução do pequeno caraciforme, Characidium pterostictum, amostrado em locais sujeitos a diferentes efeitos de perturbações hidrológicas naturais (enxurradas). Os dados foram obtidos a partir de amostragens sazonais em dois trechos distando 8 km entre si, no mesmo riacho. No trecho a montante, o habitat é mais severamente afetado pelas enxurradas do que no trecho a jusante e, devido a esta diferença, testou-se a hipótese de que haveria contrastes em padrões de alocação de energia entre reprodução e sobrevivência individual, como previsto pela teoria de história de vida. No trecho a montante, C. pterostictum apresentou características que favorecem a longevidade reprodutiva (como maior tamanho, condição mais elevada e sazonalmente pouco variável, maior tamanho de fêmeas maduras) em relação ao desempenho reprodutivo instantâneo (menor índice gonadossomático). O padrão oposto foi observado no trecho a jusante. Devido às diferenças em termos de efeito de perturbação (enxurradas) em cada trecho, esses resultados sugerem que a variabilidade espacial de perturbações hidrológicas pode influenciar padrões de história de vida dentro de uma população. Outra implicação dos resultados, é que os peixes que ocupam locais hidrologicamente mais variáveis em um riacho não estão necessariamente em desvantagem energética ou reprodutiva, mas podem estar simplesmente sob condições ambientais que favorecem padrões distintos de alocação de energia e persistência da população. Dessa forma, pode-se esperar que a plasticidade de história de vida seja comum em populações de peixes que sejam amplamente distribuídas em um sistema de riachos com características de hábitat espacialmente variáveis ou em mosaico.