Variabilidade genética em Caryocar brasiliense Camb. (Caryocaraceae) : estrutura genética, sistema de cruzamento, filogeografia e subsídios para a conservação

Tese (doutorado)—Universidade de Brasília, Instituto de Ciências Biológicas, Programa de Pós-Graduação em Ecologia, 2000.Este trabalho teve como objetivo estudar a estrutura genética de populações e o sistema de acasalamento de Caryocar brasiliense (Camb., Caryocaraceae), gerando subsídios para a conservação e manejo desta espécie, além de estudar a filogeografía da espécie no Cerrado. Foram desenvolvidos dez locos microsatélites para C. brasiliense altamente informativos, com probabilidade de identidade genética da ordem de IO' 1 e exclusão de paternidade combinada de 0,99999995. Os genótipos multilocos são únicos permitindo discriminar os indivíduos de C. brasiliense em estudos detalhados de vínculo genético em populações naturais. Os resultados da estrutura genética de populações indicaram que existe diferenciação genética significativa entre populações conforme o modelo de “isolamento por distância”, com correlação positiva entre distância geográfica e FSr entre pares de populações. As estimativas sugerem que a diferenciação deve ser ocasionada principalmente pelo cruzamento entre indivíduos aparentados. O estudo do sistema de acasalamento indicou que C. brasiliense é preferencialmente alógamo. Entretanto, a taxa de endogamia biparental indicou uma alta freqüência de acasalamento entre parentes. Nossos resultados indicaram que C. brasiliense apresenta uma estrutura em demes, com alta freqüência de acasalamentos entre parentes. Assim, a fragmentação pode limitar o fluxo gênico, isolando os dispersores de sementes e os polinizadores, aumentando a taxa de cruzamento entre parentes. Dessa forma, a conservação de populações não isoladas em grandes áreas pode ser necessária para garantir eventos de polinização cruzada entre indivíduos não aparentados e, assim, manter a viabilidade desta espécie no Cerrado. Os dados obtidos com cpDNA também indicam uma alta diferenciação das populações devido à restrição ao fluxo de semente. Para o genoma nuclear as populações tenderam a ser agrupadas de acordo com a distância geográfica, mas não para o genoma de cloroplasto. O padrão de quebra filogenética não coincide, entretanto. com padrões geográficos. O padrão filogeográfico encontrado pode ser explicado por restrições ao fluxo de semente e por eventos de colonização posterior à ultima glaciação e efeito de fundador.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) e World Wildlife Fund (WWF)

Pollination ecology of the tropical weed Triumfetta semitriloba Jacq. ( tiliaceae), in the south- eastern Brazil

This work aimed to study the pollination ecology of the tropical weed Triumfetta semitriloba Jacq. (Tiliaceae), in Viçosa, South-eastern Brazil, during the flowering season of 1993 and 1994. Two patches located in pasture (P1 and P2) and one patch in a forest trail (P3) were chosen and ten plants on each patch were sorted. The number of opened flowers were counted during one day, in each flowering month and patch. All observed flower visitors were identified and their behavior while visiting flowers was recorded. Frequency of visits to flowered branches was obtained and some pollinator individuals were captured for analysis of pollen load. Flowers are conspicuously yellow and actinomorphic, with five nectaries around the ovary base, and opened sequentially in the afternoon. Flower phenology followed a modified steady-state Gentry's pattern. The number of opened flowers was higher in P2, but differences between months were not homogeneous between patches. Considering behaviour when collecting pollen or nectar, which permitted impregnation of stigma with pollen, visiting frequency and percent of T. semitriloba pollen on pollen load (100% for all of them, except for Augochlorella michaelis which was 81%) the following species were the mainly pollinators: Augochloropsis cupreola, Augochlorella michaelis, Cressomiella aff. sussurans, Cressomiella sussurans, Cressomiella sp., Pseudocentron paulistana, Ceratinula sp1, Ceratinula sp2 and Ceratinula sp3, Melissodes sexcincta, Apis mellifera, Plebeia cf. nigriceps, Plebeia droryana. Frequency of pollinators visitation was not different between patches and not uniform during anthesis. There was a higher pollinator activity between 15:00 and 17:00 hr.Este trabalho tem por objetivo estudar a ecologia da polinização da planta invasora Triumfetta semitriloba Jacq. (Tiliaceae), em Viçosa, MG, Brasil, durante a estação de floração de 1993 e 1994. Foram escolhidas duas manchas de plantas localizadas em pastos abandonados (P1 e P2) e uma mancha em clareira de mata (P3). Dez plantas, em cada mancha, foram sorteadas. Durante um dia de cada mês de floração foi contado o número de flores abertas por planta. Todos os visitantes florais foram identificados e registrado o comportamento. Foi obtida a freqüência de visitas aos ramos floridos e alguns polinizadores foram coletados para análise da carga de pólen. As flores de T. semitriloba são actinomórficas com cinco nectários em torno da base do ovário, e abrem, seqüencialmente, no período da tarde. A fenologia floral seguiu o padrão "steady-state" modificado de Gentry. O número de flores abertas foi maior em P2, mas as diferenças entre meses não foram homogêneas entre as manchas. Considerando o comportamento enquanto coletavam pólen ou néctar, a freqüência de visita e a porcentagem de pólen de T. semitriloba na carga polínica (100% para todas as espécies de abelhas, exceto para Augochlorella michaelis que foi igual a 81%) as seguintes abelhas foram consideradas como principais polinizadoras: Augochloropsis cupreola, Augochlorella michaelis, Cressomiella aff. sussurans, Cressomiella sussurans, Cressomiella sp., Pseudocentron paulistana, Ceratinula sp1, Ceratinula sp2 e Ceratinula sp3, Melissodes sexcincta, Apis mellifera, Plebeia cf. nigriceps, Plebeia droryana. A distribuição de freqüência de visitas dos polinizadores não foi diferente entre manchas e não foi uniforme durante a antese. Houve uma maior atividade dos visitantes entre 15 e 17 horas

The role of demography and climatic events in shaping the phylogeography of Amazona aestiva (Psittaciformes, Aves) and definition of management units for conservation

Aim: The blue‐fronted amazon (Amazona aestiva) is a widely distributed Neotropical parrot with two recognized sub‐species, which are mainly characterized by the colour of the shoulder. We explored mitochondrial DNA variability to determine how demographic processes and historical climatic fluctuations may have contributed to phylogeographical pattern and morphological variation of A. aestiva, and how this information could be useful to understand the evolutionary relationship of this species and the Amazona ochrocephala complex and to determine management units for conservation purposes. Location: Brazil and north‐eastern Argentina. Methods: We analysed a fragment of COI gene of 78 A. aestiva and 27 A. ochrocephala. We computed a median‐joining network, and the population structure of A. aestiva populations was assessed using a hierarchical analysis of nucleotide diversity. The mismatch distribution, Fu's Fs‐test of neutrality and R2 test were used to detect past population expansion. Results: All A. aestiva haplotypes and A. ochrocephala subspecies from north‐eastern and southern South America were recovered within the South American clade. Hierarchical analysis of nucleotide diversity of A. aestiva populations detected two geographical groups as obtained by median‐joining network. These two A. aestiva groups showed evidence of a recent population expansion. The time of populations splitting estimated corresponding to the Middle Pleistocene. Main conclusions: The two A. aestiva genetic groups identified in our analyses agree with the morphological variation, corresponding to named subspecies. These two A. aestiva groups have undergone a recent population expansion, with low gene flow between them. The expansion of savannah areas may have contributed to the population expansion of these two groups. We concluded that introgression after isolated diversification may better explain haplotype sharing between A. aestiva and A. ochrocephala subspecies. We suggest that management and conservation strategies should consider these two A. aestiva groups (or subspecies) as different management units and should maintain viable populations of these two management units.Fil: Caparroz, Renato. Universidade Católica de Brasília; BrasilFil: Seixas, Gláucia Helena Fernandes. Fundação Neotrópica do Brazil; BrasilFil: Berkunsky, Igor. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; ArgentinaFil: Collevatti, Rosane Garcia. Universidade Católica de Brasília; Brasi

Contrasting patterns of genetic structure in Caryocar (Caryocaraceae) congeners from flooded and upland Amazonian forests

In the present study, we compare the genetic structure of a flooded forest tree Caryocar microcarpum and a terra firme forest tree Caryocar villosum in the lower Rio Negro region and test the hypothesis that the Rio Negro, the largest tributary on the left bank of the Amazon River, has been acting as a geographical barrier to gene flow between populations from the left and right banks. Seventeen adult individuals on the left bank and 27 on the right bank of Rio Negro were sampled for C. microcarpum, whereas 27 on the left and 20 on the right bank were sampled for C. villosum. Two chloroplast DNA regions were sequenced: the intron of trnL gene and the intergenic region between psbA and trnH genes; and all individuals were genotyped using ten microsatellite loci. The trnL intron and psbA-trnH intergenic spacer generated fragments of 459 bp and 424 bp, respectively. For C. microcarpum, six haplotypes were identified for trnL and seven for psbA-trnH. By contrast, only one haplotype was found for C. villosum for both sequences. The results obtained showed that the Rio Negro has not been a barrier to gene flow by pollen and seeds for either species. No genetic differentiation and a high migration rate between populations from the left and right banks of the Rio Negro were detected for the chloroplast sequences and nuclear microsatellites, for both C. villosum and C. microcarpum. Although the two analysed sequences showed a sharp topology difference, both indicated that multiple lineages may have contributed to the origin of C. microcarpum populations in the Rio Negro basin. Nevertheless, for C. villosum, from terra firme, the results obtained may provide evidence of a recent expansion of one maternal lineage from an ancient relic population surviving in one of the few moist forest refuges of the Guiana Shield during extended droughts of the glacial periods. We hypothesize that the contrasting environments colonized by this congener pair may have played an important role in shaping the genetic structure of both species. © 2009 The Linnean Society of London

Adjacency and Area Explain Species Bioregional Shifts in Neotropical Palms

Environmental and geographical variables are known drivers of community assembly, however their influence on phylogenetic structure and phylogenetic beta diversity of lineages within different bioregions is not well-understood. Using Neotropical palms as a model, we investigate how environmental and geographical variables affect the assembly of lineages into bioregions across an evolutionary time scale. We also determine lineage shifts between tropical (TRF) and non-tropical (non-TRF) forests. Our results identify that distance and area explain phylogenetic dissimilarity among bioregions. Lineages in smaller bioregions are a subset of larger bioregions and contribute significantly to the nestedness component of phylogenetic dissimilarity, here interpreted as evidence for a bioregional shift. We found a significant tendency of habitat shifts occurring preferentially between TRF and non-TRF bioregions (31 shifts) than from non-TRF to TRF (24) or from TRF to TRF (11) and non-TRF to non-TRF (9). Our results also present cases where low dissimilarity is found between TRF and non-TRF bioregions. Most bioregions showed phylogenetic clustering and larger bioregions tended to be more clustered than smaller ones, with a higher species turnover component of phylogenetic dissimilarity. However, phylogenetic structure did not differ between TRF and non-TRF bioregions and diversification rates were higher in only two lineages, Attaleinae and Bactridinae, which are widespread and overabundant in both TRF and non-TRF bioregions. Area and distance significantly affected Neotropical palm community assembly and contributed more than environmental variables. Despite palms being emblematic humid forest elements, we found multiple shifts from humid to dry bioregions, showing that palms are also important components of these environments

Disentangling landscape effects on population genetic structure of a Neotropical savanna tree

ABSTRACTGeographical patterns of genetic variation and population structure and their relationship with habitat loss and fragmentation have been investigated at distinct scales and extents using spatially explicit statistics. Here, we analyzed population genetic structure of Dipteryx alata (Fabaceae; the “baru” tree), an economically important tree widely distributed in Central Brazil that is endemic to the “Cerrado” (savanna) biome, relating population genetic divergence with broad-scale landscape patterns. Genetic divergence among 25 populations, estimated based on eight microsatellite loci for a total of 644 individuals, was correlated with landscape features using several forms of Mantel tests (standard Mantel correlations, Mantel correlograms, partial correlations, and multiple regression). Patterns of genetic divergence are significantly correlated with human-driven landscape features of habitat loss and fragmentation, after taking into account isolation-by-distance and historical effects of range expansion after the last glacial maximum. Our findings present important implications for the conservation of this species, because interruption of gene flow by habitat loss and fragmentation jeopardize the persistence of population in the medium- and long term due to disruption of demographic patterns, increased endogamy, and recruitment problems.© 2014 Associação Brasileira de Ciência Ecológica e Conservação. Published by Elsevier Editora Ltd