Mating system parameters in a high density population of andirobas in the Amazon forest

The objective of this work was to estimate the mating system parameters of a andiroba (Carapa guianensis) population using microsatellite markers and the mixed and correlated mating models. Twelve open‑pollinated progeny arrays of 15 individuals were sampled in an area with C. guianensis estimated density of 25.7 trees per hectare. Overall, the species has a mixed reproductive system, with a predominance of outcrossing. The multilocus outcrossing rate (t m = 0.862) was significantly lower than the unity, indicating that self‑pollination occurred. The rate of biparental inbreeding was substantial (t m ‑ t s = 0.134) and significantly different from zero. The correlation of selfing within progenies was high (r s = 0.635), indicating variation in the individual outcrossing rate. Consistent with this result, the estimate of the individual outcrossing rate ranged from 0.598 to 0.978. The multilocus correlation of paternity was low (r p(m) = 0.081), but significantly different from zero, suggesting that the progenies contain full‑sibs. The coancestry within progenies (Θ = 0.185) was higher and the variance effective size (Ne(v) = 2.7) was lower than expected for true half‑sib progenies (Θ = 0.125; Ne(v) = 4). These results suggest that, in order to maintain a minimum effective size of 150 individuals for breeding, genetic conservation, and environmental reforestation programs, seeds from at least 56 trees must be collected.

Mating system in Myracrodruon urundeuva (Anarcadiaceae): implications for conservation genetics

The aims of this study were to investigate the mating system of a fragmented population of the dioecious tropical tree Myracrodruon urundeuva Allemão, using five microsatellite loci and the mixed mating and correlated mating models. The study was conducted in the Estação Ecológica de Paulo de Farias (436 ha), where the population occupies about 142 ha. The mating system was estimated using 514 open-pollinated offspring, collected from 30 seed-trees. Estimates of the multilocus outcrossing rate confirm that the species is dioecious (t m = 1.0). Low levels of mating among relatives were detected in the population (1 - t s = 0.020). The estimate of paternity correlation (r p(m)) indicated that offsprings were composed of mixtures of half-sibs and full-sibs, with the latter occurring at a low frequency (average of 0.148). The estimated coancestry coefficient within families (Θ = 0.147) was larger and the effective population size (Ne(v)) was lower (Ne(v) = 2.98) than expected in progenies from panmictic populations (Θ = 0.125, Ne(v) = 4, respectively). In terms of conservation, the results indicate that to retain an effective population size of 150, is necessary to collect seeds from at least 50 seed-trees.

Mating system in Myracrodruon urundeuva (Anarcadiaceae): implications for conservation genetics

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Contemporary pollen flow, mating patterns and effective population size inferred from paternity analysis in a small fragmented population of the Neotropical tree Copaifera langsdorffii Desf. (Leguminosae-Caesalpinioideae)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Correlated matings in dioecious tropical tree, Myracrodruon urundeuva fr. all.

The correlated matings in two populations (Selvíria - SEL and Paulo de Faria - PFA) of dioecious Myracrodruon urundeuva were studied in the Southwest of Brazil, by allozyme analysis of progeny arrays using the sibling-pair model. Open-pollinated seeds were collected from 25 to 30 trees within populations. Departure from random matings were evident from the differences in pollen and ovule allele frequencies. The high and significant correlation of paternity (SEL r̂p = 0.671 ± 0.074; PFA r̂p = 0.371 ± 0.062) and a low number of effective pollinating trees (ranging from 2 to 3) were detected in the populations, suggesting high proportion of full-sibs progenies. According to these results, the estimate of coancestry within families (θ = 0.209 - SEL; θ = 0.171 - PFA.) exceeded the expectation of the half-sib progenies (θ = 0.125). Result outcomes are discussed from a conservation and breeding point of view.

Mating system variation among populations, individuals and within and among fruits in Bertholletia excelsa.

The aim of this study was to investigate variation in mating system among three Brazilian Amazon populations of the tree Bertholletia excelsa with different levels of anthropogenic interventions. We collected open-pollinated seeds from one natural population, remnant trees dispersed in a pasture, and trees from a plantation. Outcrossing rate not varied among the populations and indicates that all seeds were originated from outcrossing (tm=1.0). Mating among relatives was significant higher in the plantation than forest and pasture populations, probably due the fact that many trees are related in the plantation. Correlated mating was significantly higher in pasture (rp=0.47) and plantation (rp=0.51) than in the natural population (rp=0.22), suggesting that trees in natural population are pollinated by a higher number of pollen donors. The paternity correlation was significantly higher within (rp(w)=0.41) than among fruits (rp(a)=0.18), showing a higher probability to find full-sibs within than among fruits. The fixation index was generally lower in seed trees than in their seedlings, suggesting selection for heterozygous individuals from seedling to adult stages. Progeny arrays collected from the natural population had a lower proportion of pairwise full-sibs than in pasture and plantation and higher variance effective size (2.75) than trees in pasture (2.15) and plantations (2.22). Results highlight that seed collections for conservation, breeding and reforestation programs preferentially should be carried out in natural populations due low proportion highest variance effective size within progeny.

Taxas de cruzamento em uma população natural de Cryptocarya Moschata Nees (Lauraceae)

O sistema de cruzamento da espécie arbórea de dossel da Mata Atlântica brasileira, Cryptocarya moschata, foi estudado a partir de material proveniente do Parque Estadual Carlos Botelho, São Miguel Arcanjo, São Paulo, Brasil. As taxas de cruzamento foram determinadas através de marcadores alozímicos obtidos de plântulas germinadas de coortes de sementes coletadas de 35 árvores. O valor médio da taxa de cruzamento de equilíbrio (estimador indireto) foi t^eq = 0.51. As estimativas das taxas de cruzamento uniloco e multilocos (estimadores diretos) foram t^s = 0.725± 0,041 e t^m = 0,884 ± 0,034, respectivamente, indicando um sistema de cruzamento predominantemente alogâmico. As taxas de cruzamento de árvores individuais variaram de 27 a 100 ( x¯ = 87,8) porcento, a partir de t^m calculado com as freqüências gênicas de pólen mantidas constantes ao nível populacional. A partir do modelo de par de irmãos (modelo de cruzamento correlacionado) de Ritland, a correlação entre duas progênies irmãs oriundas de autofecundação (r^s) e a correlação entre duas progênies irmãs oriundas de paternidade por exocruzamento (r^p) foram 35,7% e 99,0%, respectivamente. Esses resultados corroboram o fato de haver variação nas taxas de autocruzamento entre as diferentes árvores, podendo também indicar que quando há endogamia, a maior parte das sementes nas árvores são provavelmente irmãs-germanas.

Estimating coancestry within open-pollinated progenies of a dioecious species: the case study of Myracrodruon urundeuva

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Sistema de reprodução, parentesco e tamanho efetivo em sementes de polinização livre de populações fragmentadas de Copaifera langsdorffii Desf. por análise de locos microssatélites

Anthropogenic changes in the reproductive population density can affect the mating system and result in an increase in selfing and correlated matings. This study investigated the mating system in small fragmented populations of the insect pollinated tropical tree species Copaifera langsdorffii, using microsatellite loci and the mixed and correlated mating models. Open-pollinated seeds were collected from 15 seed-trees located in a small forest fragment (4.8 ha), denominated Bosque and from 14 other seed-trees located in other small forest fragments of the north-western region of São Paulo State. No significant differences were observed between the seed-trees from Bosque (tm=0.933±0.028) and other fragments (tm=0.971±0.032), although these estimates were significantly different from 1.0, suggesting that selfing was occurring. Differences between multilocus and unilocus outcrossing rate were significantly high in both seed-trees of Bosque (tm -ts=0.478±0.05) and other forest fragments (tm -ts=0.475±0.018), suggesting a spatial genetic structure in those stands. The results also showed high rates of correlated mating in the samples, indicating that a good part of the offspring were full-sibs. As a consequence of selfing, mating among relatives and correlated matings, the coancestry within families was equally high in the seed-trees of Bosque ((Θ=0.237) and in the seed-trees of the other forest fragments (Θ=0.241) and the effective population size was lower than expected in panmitic populations (Ne<4). The results were discussed, focusing on the sample size of seed-trees to collect seeds for genetic conservation and enviromental reforestation.

Distância e padrões de dispersão contemporânea de pólen e sistema de reprodução em pequeno fragmento isolado de Copaifera Langsdorfii Desf. (Leguminosae – Caesalpinoideae)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Sistema de reprodução em populações naturais de Peltophorum dubium

A Multi-locus mixed mating model and correlated mating model were used to analyze the mating system of four natural populations of Peltophorum dubium (Sprengel) Taubert from Western Sao Paulo State, Brazil. Open pollinated seeds were collected from 19 to 33 seed-trees per population and evaluated by allozyme electrophoresis analysis. Significant differences between pollen and ovule gene frequencies were detected in more than 50% of loci in each population, indicating deviations from random mating, probably due to correlated mating, self-fertilizations and mating among relatives. The comparison the fixation index estimated from seed trees ((F) over cap (m), ranged from 0.009 to 0.285) with their progenies ((F) over cap (p), ranged from 0.127 to 0.364) suggested selection against inbreeding between offspring of adult stages. The estimates of multi-locus outcrossing rate (t(m)) ranged from 0.557 to 0.924, indicating that the species has a mixed-mating system. Differences between multi-locus and single-locus outcrossing rate (t(m)-t(s))was positive and significantly different from zero for all populations, with values ranging from 0.092 to 0.111, suggesting mating among relatives within the populations, probably due to the presence of intra-population spatial genetic structure. The mean coefficient of co-ancestry (Theta) within progenies ranged from 0.147 to 0.251; confirming that the progenies are compounded by mixtures of different kinds of relatedness. The results are discussed from the view of genetic improvement and conservation of the species.

Estudo hierárquico do sistema de reprodução entre e dentro de frutos, fluxo de pólen e estrutura genética espacial em um fragmento e em árvores isoladas na pastagem de hymenaea stigonocarpa mart. ex hayne na região de cerrado

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Correlated evolution of mating strategy and inbreeding depression within and among populations of the hermaphroditic snail Physa acuta

Inbreeding depression is one of the main forces opposing the evolution of self-fertilization. Of central importance is the hypothesis that inbreeding depression and selfing coevolve antagonistically, generating either low selfing rate and high inbreeding depression or vice versa. However, there is limited evidence for this coevolution within species. We investigated this topic in the hermaphroditic snail Physa acuta. In this species, isolated individuals delay the onset of egg laying compared to individuals having access to mates. Longer delays (''waiting times'') indicate more intense selfing avoidance. We measured inbreeding depression and waiting time in a large quantitative-genetic experiment (281 outbred families derived from 26 natural populations). We observed large genetic variance for both traits and a strong positive genetic covariance between them, most of which resided within rather than among populations. It means that, within populations, individuals with higher mutation load avoided selfing more strongly on average. This genetic covariance may result from pleiotropy and/or linkage disequilibrium. Whatever its genetic architecture, the fact it emerges specifically when individuals are deprived of mates suggests it is not fortuitous and rather reflects the action of natural selection. We conclude that a diversity of mating strategies can arise within populations subjected to variation in inbreeding depression.

Understanding the genetic diversity, spatial genetic structure and mating system at the hierarchical levels of fruits and individuals of a continuous Theobroma cacao population from the Brazilian Amazon

Understanding the mating patterns of populations of tree species is a key component of ex situ genetic conservation. In this study, we analysed the genetic diversity, spatial genetic structure (SGS) and mating system at the hierarchical levels of fruits and individuals as well as pollen dispersal patterns in a continuous population of Theobroma cacao in Para State, Brazil. A total of 156 individuals in a 0.56 ha plot were mapped and genotyped for nine microsatellite loci. For the mating system analyses, 50 seeds were collected from nine seed trees by sampling five fruits per tree (10 seeds per fruit). Among the 156 individuals, 127 had unique multilocus genotypes, and the remaining were clones. The population was spatially aggregated; it demonstrated a significant SGS up to 15m that could be attributed primarily to the presence of clones. However, the short seed dispersal distance also contributed to this pattern. Population matings occurred mainly via outcrossing, but selfing was observed in some seed trees, which indicated the presence of individual variation for self-incompatibility. The matings were also correlated, especially within ((r) over cap (p(m)) = 0.607) rather than among the fruits ((r) over cap (p(m)) = 0.099), which suggested that a small number of pollen donors fertilised each fruit. The paternity analysis suggested a high proportion of pollen migration (61.3%), although within the plot, most of the pollen dispersal encompassed short distances (28m). The determination of these novel parameters provides the fundamental information required to establish long-term ex situ conservation strategies for this important tropical species. Heredity (2011) 106, 973-985; doi:10.1038/hdy.2010.145; published online 8 December 2010

Mating aggregations and mating success in the flower thrips, Frankliniella schultzei (Thysanoptera: Thripidae), and a possible role for pheromones

Aggregations of Frankliniella schultzei males were observed on the corollas of Hibiscus rosasinensis and Gossypium hirsutum flowers in southeast Queensland. Aggregations were seen only on the upper surfaces of corollas but may have occurred on other flower parts, which were hidden from view. Conspecific females entered aggregations and a small proportion of them mated [18% (n = 163), H. rosasinensis; 30% (n = 181), G. hirsutum]. Most females (87 and 72%, respectively) that did not mate in aggregations walked to other flower parts. Behavior was difficult to observe on these parts, but mating was sometimes observed there. The number of females that landed within aggregations on the upper surfaces of both H. rosasinensis and G. hirsutum corollas was highly correlated with the number of males (r = 0.88, r = 0.93, respectively; P < 0.001). Significantly more mating pairs were observed in high-density aggregations (mean +/- SE, 1.10 +/- 0.22 and 4.44 +/- 0.48, respectively) than in low-density aggregations (0.37 +/- 0.11 and 1.67 +/- 0.29, respectively) (P < 0.05) on flowers of both species. More F. schultzei females were attracted to sticky traps baited with live conspecific males set among flowering Ipomoea indica (mean +/- SE, 8.83 +/- 0.32) and G. hirsutum (10.90 +/- 0.79) plants than to control traps (0.10 +/- 0.05 and 0.70 +/- 0.25, respectively)( P < 0.05), presumably in response to male-produced pheromones. Significantly more females were attracted to traps with high male densities than to traps with low densities. We found no statistical evidence that aggregation size influenced mating success (proportion males that mated). Mating success, however, should be evaluated with respect to mating on all flower parts and not just the upper surfaces of corollas. The results of this study constitute the first behavioral evidence for an attractant sex pheromone in thrips.