John Du Vall Hay

Population genetic structure of the endangered tropical tree species Caryocar brasiliense, based on variability at microsatellite loci

We report the population genetic structure of the endangered tropical tree species Caryocar brasiliense, based on variability at 10 microsatellite loci. Additionally, we compare heterozygosity and inbreeding estimates for continuous and fragmented populations and discuss the consequences for conservation. For a total of 314 individuals over 10 populations, the number of alleles per locus ranged from 20 to 27 and expected and observed heterozygosity varied from 0.129 to 0.924 and 0.067 to 1.000, respectively. Significant values of θ and RST showed important genetic differentiation among populations. θ was much lower than RST, suggesting that identity by state and identity by descent have diverged in these populations. Although a significant amount of inbreeding was found under the identity by descent model (f = 0.11), an estimate of inbreeding for microsatellite markers based on a more adequate stepwise mutation model showed no evidence of nonrandom mating (RIS = 0.04). Differentiation (pairwise FST) was positively correlated with geographical distance, as expected under the isolation by distance model. No effect of fragmentation on heterozygosity or inbreeding could be detected. This is most likely due to the fact that Cerrado fragmentation is a relatively recent event (~60 years) compared to the species life cycle. Also, the populations surveyed from both fragmented and disturbed areas were composed mainly of adult individuals, already present prior to ecosystem fragmentation. Adequate hypothesis testing of the effect of habitat fragmentation will require the recurrent analysis of juveniles across generations in both fragmented and nonfragmented areas.

Reproductive biology of the palm Acrocomia aculeata in Central Brazil

Phenology, floral biology, the reproductive system, and pollination of the macauba palm, Acrocomia aculeata were studied in Central Brazil. The species is arborescent, single-stemmed, and reaches heights of up to 16 m. Flowering occurs between August and December, peaking between October and November. Fruit fall (harvest) is between June and March, with a peak in November. Inflorescences are androgynous with marked protogyny. The basic pollination syndrome is by beetles, with wind playing a secondary role. The principal pollinators are Andranthobius sp. (Curculionidae), Mystrops cf mexicana (Nitidulidae) and Cyclocephala forsteri (Scarabaeidae). Cross-pollination between different individuals (xenogamy) accounts for most of the reproductive system. However, the species is self-compatible, with geitonogamy accounting for a significant percentage of fruit set. The combination of two pollination strategies (wind and insects) with a flexible reproductive system (crossand self-pollination) suggests that A. aculeata can be highly successful in the colonization of new areas, as is evidenced by the ample distribution of species in the Neotropics.

Evidences for multiple maternal lineages of Caryocar brasiliense populations in the Brazilian Cerrado based on the analysis of chloroplast DNA sequences and microsatellite haplotype variation

In this work we report on the phylogeography of the endangered tree species Caryocar brasiliense based on variability in two classes of maternally inherited chloroplast DNA sequences with different rates of molecular evolution. Eleven sequence haplotypes of a noncoding region between the genes trnT and trnF and 21 distinct 10‐locus microsatellite haplotypes could be identified in a total of 160 individuals, collected in 10 widespread populations of C. brasiliense. An amova indicated that most of the variation can be attributed to differences among populations, both for DNA sequence (87.51%) and microsatellites (84.38%). Phylogeography based on a median‐joining network analysis of the noncoding region showed a sharp difference from the analysis of microsatellite haplotypes. Nevertheless, both analyses indicated that multiple lineages may have contributed to the origin of C. brasiliense populations in Brazilian Cerrado. Incongruences in the microsatellite haplotypes network suggest that homoplasy, which emerged from recurrent and independent mutations, greatly influenced the evolution of the C. brasiliense chloroplast genome. We hypothesize that our results may show the outcome of the restriction of ancient relic populations to moist refugias during extended droughts coinciding with glaciation in the northern hemisphere. The subsequent spread to favourable areas throughout Central Brazil may have caused contact between different lineages during the interglacial periods. The extinction of megafauna dispersers in the last glaciation may have caused a restriction in seed movement and currently, gene flow has been occurring mainly by pollen movement.

High resolution microsatellite based analysis of the mating system allows the detection of significant biparental inbreeding in Caryocar brasiliense, an endangered tropical tree species

In this work we investigate the mating system of four populations of the endangered tropical tree species Caryocar brasiliense, using genetic data from 10 microsatellite loci. Eight to 10 open-pollinated progeny arrays of 16 individuals, together with their mother tree, were sampled per population. Mating system parameters were estimated under the mixed mating model, implemented by the software MLTR. The single-locus outcrossing rate (ts) varied among loci and populations, but multilocus outcrossing rates (tm) were equal to one for all four populations. Nevertheless, biparental inbreeding (tm − ts) was different from zero for all populations, indicating that outcrossing events may occur between relatives. Our results also indicate that the high polymorphism of microsatellite markers provide an extraordinary resolution to discriminate precisely selfing events from outcrossing events between close relatives. Our results indicate that, although highly outcrossed, C. brasiliense shows high levels of biparental inbreeding, most likely due to the limited flight range of pollinators and restriction in seed dispersal. Furthermore, these results suggest that Cerrado fragmentation could limit gene flow by isolating seed dispersers and territorial small sized bat pollinators inside fragments, increasing the rate of mating between close relatives. The conservation of nonisolated populations in large preserved areas may be necessary to foster outcrossing events between unrelated individuals and thus maintain species viability.

Pollination ecology of Caryocar brasiliense (Caryocaraceae) in Central Brazil cerrado vegetation

The floral biology, breeding system and pollination of Caoyocar brasiliense were studied in the cerrado vegetation of Central Brazil. The large, yellowish-cream, brush-like flowers are pollinated mainly by glossophagine bats (Glossophaga soricina and Anoura geoffroyi). Three non-glos- sophagine bats (Plyllostomus discolor, Vampyrops lineatus and Carollia perspicillata) and two short pro- bosisced hawk moths (Eriibyis ello and Pseudosphinx tetrio) may also act as occasional pollinators. Caryocar brasiliense is self-compatible although it sets significantly more fruits when crossed than when selfed. The natural fruit set (fruit/flower ratio) and seed set (seed/ovule ratio) are 3. 1% and 1.0% respectively. Most of the fruits and seeds are formed through the action of the flower visitors, despite the fact that about 20% of the non-visited flowers receive self pollen on at least one stigma.

Perfil florístico e estrutura da comunidade arbórea de uma floresta de vale no Parque Nacional da Chapada dos Guimarães, Mato Grosso, Brasil

The purpose of the present study was to describe the floristic composition and the structure of the arboreal community of a valley-forest in Veu de Noiva waterfalls, Chapada dos Guimaraes National Park, Mato Grosso, Brazil. The floristic and phytosociological analyses aimed at assessing, respectively: (a) the influence of the main Brazilian phytogeographic provinces on the floristic composition of the valley-forest studied, and (b) the role of the most important tree species in terms of abundance, ecological group, and stature at maturity. Every tree with stalk circumference at breast height (CBH) ³ 15 cm found within 36 quadrats of 30 x 10 m was sampled. 172 species of trees belonging to 133 genera and 61 families were registered. The floristic profile showed strong links with both the Amazonian and Atlantic (sensu lato) forests, reinforcing the transitional nature of that community. The most important tree species, in terms of value of importance, were also important in other surveys carried out in the region.

Flowering and fruiting phenologies of the palm Acrocomia aculeata: patterns and consequences

Fruit set, fruit production, and fruit fall of the arborescent palm Acrocomia aculeata were documented for the Distrito Federal in central Brazil in 1984-1986. Flowering began in August and extended to mid-December with the highest concentration of open inflorescences (>50% of the total) occurring from mid-October until mid-November. There was a significant correlation (Spearman rank correlation coefficient; r = 0.69; N = 8; P = 0.05) between flowering time and fruit set over the course of the reproductive season. The inflorescences that opened in October were those that produced highest fruit set, with fruit set mean of 25.4 percent (SD = 20.9) in the first half and 28.9 percent (SD = 24.4) in the second half of October. Overall, fruit set was less than 10.0 percent, although it ranged from 0 to 85.0 percent. Each infructescence produced about 60 fruits, but it ranged from 0 to 271 fruits. Fruit fall occurred for 6 to 10 months, generally concentrated from October to January.

Comparação do padrão da distribuição espacial em escalas diferentes de espécies nativas do cerrado, em Brasília, DF

Comparison of scale in the spatial distribution of native species of the cerrado, em Brasilia, DF). The scale of spatial distribution of three native tree species, Caryocar brasiliense, Pterodon pubescens and Sclerolobium paniculatum, and two native palm species, Syagrus comosa and S. flexuosa, in the cerrado was determined using three quadrat variance methods. The data were collected in an area of cerrado, sensu stricto, on the Fazenda Agua Limpa of the University of Brasilia in 128 contiguous quadrats of 5x8m each. In each quadrat, all individuals of each species were located and their height measured. The scale of spatial distribution of each species was evaluated with the following methods: blocked quadrat variance (BQV); two-term local quadrat variance (TTLQV) and paired quadrat variance (PQV), for both all individuals and all woody individuals over 130 cm in height. The total number of individuals was 138 for C. brasiliense ,3 4 forP. pubescens ,8 2 forS. paniculatum ,e ight forS. comosa and 36 forS. flexuosa. All species showed a group in at least one of the methods. The time spent in collection of data was comparable to that for other studies of spatial distribuition and three of the five species had similar results in all methods. The pattern for C. brasiliense was similar to that found in another study using the same methodology, with a distance of approximately 350 m between groups. RESUMO - (Comparacao do padrao da distribuicao espacial em escalas diferentes de especies nativas do cerrado, em Brasilia, DF). O padrao de agrupamento espacial de tres especies arboreas, Caryocar brasiliense, Pterodon pubescens e Sclerolobium paniculatum, e duas especies de palmeiras, Syagrus comosa e S. flexuosa, nativas do cerrado, foi investigado usando tres metodos de variância entre parcelas. Os dados foram coletados em uma area de cerrado sensu strictu da Fazenda Agua Limpa da Universidade de Brasilia, em Brasilia, DF, em 128 parcelas contiguas de 5x8mc ada. Em cada parcela, foram procurados todos os individuos das especies, anotando o numero encontrado e suas alturas. Os dados foram tabelados e analisados usando as tecnicas de variância entre blocos de parcelas (BQV), variância movel entre blocos de parcelas (TTLQV) e variância entre parcelas pareadas (PQV), tanto para todos os individuos encontrados quanto para somente os individuos lenhosos maiores do que 130 cm em altura. O numero total de individuos encontrado foi 138 para C. brasiliense ,3 4 paraP. pubescens ,8 2para S. paniculatum, oito para S. comosa e3 6 paraS. flexuosa. Todas as especies apresentaram um padrao agrupado de distribuicao espacial em pelo menos uma das metodologias e tres das cinco especies tiveram resultados semelhantes em todos os metodos. O padrao para C. brasiliense foi semelhante ao encontrado para esta mesma especie em outra regiao do cerrado, utilizando a mesma metodologia, com uma distância de aproximadamente 350 m entre grupos.

Temporal Dynamics and Resource Availability for Drosophilid Fruit Flies (Insecta, Diptera) in a Gallery Forest in the Brazilian Savanna

Seasonality can cause severe bottlenecks in natural populations, even leading to local extinction. Large variation in resource availability may explain the bottlenecks, but the role of these variations is still poorly understood. The goal of this study was to analyze if temporal variations in the guild of drosophilids breeding in fruits of Mauritia flexuosa (Arecaceae) can be explained by the shortage of this resource during the dry season. Fruits of M. flexuosa were collected over one year in a gallery forest located in the Central Brazilian Savanna. The drosophilid assemblage varied over time, with a lower density of species and of individuals in the dry season, when the percentage of colonized fruits was also smaller. These findings suggest that although the fruits were available during the dry season, they were underused. This way, the resource availability does not seem to regulate the community in the dry season.

Impacto da invasão e do manejo do capim-gordura (Melinis minutiflora) sobre a riqueza e biomassa da flora nativa do Cerrado sentido restrito

No Brasil, varias especies de gramineas sao citadas como invasoras em Unidades de Conservacao. Contudo, ainda se conhece muito pouco sobre o impacto do estabelecimento e da colonizacao dessas especies nas areas protegidas. Entre as gramineas exoticas introduzidas no bioma Cerrado merece destaque a especie africana Melinis minutiflora P. Beauv., o capim-gordura. O presente estudo objetivou avaliar o impacto desta invasora na biomassa e na riqueza da comunidade nativa em uma area de Cerrado Ralo invadido, como tambem estudar a dinâmica da vegetacao do estrato rasteiro submetida a aplicacao de diferentes tecnicas de manejo para o controle do capim-gordura. Os resultados mostraram que, na area experimental, onde o capim-gordura representa cerca 62% da biomassa total do estrato rasteiro, o numero de especies nativas encontradas foi alto. Nas areas onde o capim-gordura apresentou alto indice de colonizacao (> 98%), sua biomassa alcancou cerca de duas vezes a biomassa do estrato rasteiro registrada para o Cerrado. A realizacao de uma queimada nao foi suficiente para controlar o capim-gordura, porque apos tres anos a sua biomassa se aproximou aos valores encontrados inicialmente. Por outro lado, no tratamento manejo integrado (maio ou setembro) a reducao de mais de 99,9% na sua presenca favoreceu a expansao da vegetacao nativa, configurando-se, assim, uma estrategia promissora para a recuperacao ambiental das areas invadidas pelo capim-gordura no Cerrado.