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In order to understand the impacts of forest fragmentation on Araucaria angustifolia populations, we evaluated the genetic diversity and mating system using SSR markers and open-pollinated seeds from four populations of varying sizes and spatial isolation, in and around one of the best-conserved Araucaria Forest remnants in Southern Brazil. The four population types of A. angustifolia include: (1) a continuous forest; (2) a physically isolated cluster located 2 km from the continuous forest; (3) an open population in a field located between the cluster and continuous forest; and (4) a fragment on a private property located 5 km from the cluster. Approximately 28 seeds were collected from ten reproductive trees in each population. We found higher amounts of alleles (113) and exclusive alleles (25) in the continuous forest than in the other populations. The multilocus paternity correlation was significantly higher and effective number of pollen donors was significantly lower in the private population, decreasing the diversity and consequently the variance effective size of families sampled from that population. However, despite its isolation from the other studied fragments, the private population had the second highest number of alleles as well as unique alleles from the other populations. Therefore, strategies for A. angustifolia conservation should focus not only on larger populations, such as those found in protected areas, but also include smaller and isolated fragments on private properties as these populations are able to maintain high levels of genetic diversity and functional connectivity between isolated stands across a landscape.

In order to use molecular markers in population genetics studies, it is important to confirm that the molecular markers used present a Mendelian segregation. The aim of this paper was to investigate the genetic segregation of eight microsatellite loci of Araucaria angustifolia (Bert.) O. Kuntze (Araucariaceae). The study was carried out comparing genetic segregation in hand- and open-pollinated progenies of maternal dioecious and monoecious trees. The Mendelian segregation was confirmed for all eight loci studied (Ag20, Ag23, Ag45, Aang01, Aang14, Aang28, As90 and CRCAc1), as no deviation from the expected segregation hypothesis was detected in the studied progenies. Therefore, these eight loci can be used for further population genetics studies of A. angustifolia.

Understanding the mating system of a tree species is important in genetic conservation and tree breeding strategies because it affects the inbreeding and genetic diversity of the descendant populations. Araucaria angustifolia (Bert.) O. Kuntze is a mainly dioecious species that reproduces through outcrossing. However, some monoecious trees have been identified and they may reproduce through self-fertilization. The objective of this study was to confirm the expected relatedness of full-sibs in outcrossed hand-pollinated progenies of female seed trees, self-sibs of hand self-pollinated monoecious seed trees, and to investigate the mating system of open-pollinated progenies of female and monoecious A. angustifolia trees. To do this, eight microsatellite loci were used to genotype hand- and open-pollinated progenies. Our results show that the relatedness of outcrossed hand-pollinated progenies are true full-sibs and progenies from a selfed monoecious seed tree are self-sibs, which confirms the hand-pollination method used. Open-pollinated female seed trees reproduced only by outcrossing, generating progenies with a mixture of full- and half-sibs. Monoecious seed trees reproduced mainly by xenogamy, generating progenies with mixtures of self-sibs, full-sibs, half-sibs and self-half-sibs. We also found that an increase in the effective number of pollen donors ( $$ N_{\text{ep}} $$ ) would lead to an increase in the total number of alleles ( $$ K $$ ) within progenies. Our results also suggest that monecious trees have limited potential to modify the genetic structure through selfed seed production due to the very low estimated selfing rate in these trees and the rare occurrence of these trees in natural populations.

Araucaria angustifolia is an endangered tropical/subtropical coniferous of great interest for conservation due its economical, ecological, and social value. Only 3% of original Araucaria forests remain, which are generally confined to small forest fragments. Forest fragmentation can have serious consequences on genetic process in tree population, affecting long-term fitness and adaptability. To investigate the effects of forest fragmentation on genetic diversity and the structure of A. angustifolia populations, the genetic diversity of eight microsatellite loci was compared in four small fragmented populations (

As a matter of fact, Araucaria angustifolia populations occur predominately in small and isolated stands; only a minor number of continuous natural forests of this dioecious wind-pollinated coniferous tree species remain. To implement reasonable conservation, breeding and restorations program it is necessary to have the knowledge of pollen dispersal distance and fine-scale genetic structure. In this paper, levels and dispersion distance of pollen and spatial genetic structure of A. angustifolia were investigated in a 14 ha transect in a continuous forest in Parana State, Brazil. Analyses have been performed by the use of eight microsatellite loci, paternity and TwoGener approaches, and spatial autocorrelation analysis. In transect, 52 male and 56 female adult trees were mapped and genotyped, together with 190 seeds. In the present transect, A. angustifolia show spatial genetic structure at distances up to 75 m. Paternity analysis indicated that 54% of seeds were fertilized by pollen from trees outside the transect. The calculated average pollination distance within transect was 102 and 98 m based on the paternity analysis and TwoGener analysis, respectively. We found a significant pollen gene pool structure across seed-trees ( \(\widehat\Phi _{ft} = 0.078\), P 100 m) inside the continuous forest. However, the high proportion occurs in short-distance producing biparental and correlated mating as well as reducing the variance effective size.

In this study, genetic diversity, inbreeding, spatial genetic structure (SGS), and pollen dispersal are analyzed using ten microsatellite loci from two populations of the dioecious, wind-pollinated, coniferous tree Araucaria angustifolia in Southern Brazil. The study populations include an undisturbed 7 ha A. angustifolia cluster, where all adult trees were mapped and sampled, and an adjacent, long-abandoned, open agricultural area with an aggregated A. angustifolia population. Seeds were collected from 13 seed trees inside the forest cluster and from eight seed trees in the open forest. Our results showed that the adults present high levels of heterozygosity (H o = 0.91) and an absence of inbreeding. However, significant SGS was detected up to 90 m in the forest cluster suggesting that near-neighbor trees are related. The estimate of effective population size was lower than the total number of trees in the cluster (N e/N = 0.19), which can be explained by the presence of SGS in the stand. Substantial external pollen flow was detected in the forest cluster (26 %) and open forest (20 %), indicating that the reproductive population size is greater than the sampled populations, explaining the high genetic diversity in this population. Our results indicate that this site has potential for in and ex situ conservation due to high levels of genetic diversity and gene immigration resulting from pollen flow. Conservation strategies for A. angustifolia should focus not only on forest fragments but should also include the preservation of isolated trees throughout the landscape.

Paternity analysis based on eight microsatellite loci was used to investigate pollen and seed dispersal patterns of the dioecious wind-pollinated tree, Araucaria angustifolia. The study sites were a 5.4 ha isolated forest fragment and a small tree group situated 1.7 km away, located in Paranalpha State, Brazil. In the forest fragment, 121 males, 99 females, 66 seedlings and 92 juveniles were mapped and genotyped, together with 210 seeds. In the tree group, nine male and two female adults were mapped and genotyped, together with 20 seeds. Paternity analysis within the forest fragment indicated that at least 4% of the seeds, 3% of the seedlings and 7% of the juveniles were fertilized by pollen from trees in the adjacent group, and 6% of the seeds were fertilized by pollen from trees outside these stands. The average pollination distance within the forest fragment was 83 m; when the tree group was included the pollination distance was 2006 m. The average number of effective pollen donors was estimated as 12.6. Mother-trees within the fragment could be assigned to all seedlings and juveniles, suggesting an absence of seed immigration. The distance of seedlings and juveniles from their assigned mother-trees ranged from 0.35 to 291 m (with an average of 83 m). Significant spatial genetic structure among adult trees, seedlings, and juveniles was detected up to 50 m, indicating seed dispersal over a short distance. The effective pollination neighborhood ranged from 0.4 to 3.3 ha. The results suggest that seed dispersal is restricted but that there is long-distance pollen dispersal between the forest fragment and the tree group; thus, the two stands of trees are not isolated.

Background Araucaria angustifolia (Bert.) O. Kuntze is a mainly dioecious species that reproduces through outcrossing. However, some monoecious trees have been identified and they may reproduce through self-fertilization. The objective of this study was to confirm the expected relatedness of self-sibs of hand self-pollinated monoecious seed trees, and to investigate the mating system of open-pollinated progenies of monoecious A. angustifolia trees.

Maytenus ilicifolia é um arbusto de ocorrência natural da Floresta Ombrófila Mista (Floresta com Araucária). Esta espécie tem uso popular em comunidades tradicionais e povos indígenas no Brasil. A fragmentação da Floresta com Araucária, nas últimas décadas, juntamente com a comprovação terapêutica em males gástricos e o uso em larga escala, causaram grande devastação de populações naturais de Maytenus ilicifolia, resultando na perda do complexo genético deste recurso medicinal. Há necessidade urgente de estudos para elaborar estratégias de conservação genética e domesticação deste germoplasma. O objetivo deste estudo foi determinar a variabilidade genética em populações naturais Maytenus ilicifolia por meio da análise do polimorfismo de DNA utilizando marcadores RAPD. Três populações foram estudadas, uma no município da Lapa e duas na região de Guarapuava. Estas áreas são distintas, tanto geologicamente quanto em relação a paisagem. Selecionou-se sete primers RAPD, os quais produziram 52 bandas em Maytenis ilicifolia, sendo 44 polimórficas. A análise da distância genética foi realizada pelo agrupamento das amostras segundo os princípios da taxonomia numérica, utilizando-se o coeficiente de similaridade de Jaccard. A partir das distâncias genéticas, montou-se um dendrograma, o qual separou o material estudado em quatro grupos distintos, dois para a região da Lapa e dois para Guarapuava. Os grupamentos formados estão arranjados de acordo com as características geológicas e classes de solos em que os indivíduos se encontram. A variabilidade genética das populações de Guarapuava, quando comparada a da Lapa, apresentou uma maior similaridade entre os grupos formados. Estratégias para conservação genética em Maytenus ilicifolia devem ser estruturadas de acordo com os parâmetros ecogeográficos locais, realizando a coleta em cada um dos compartimentos ambientais em que os indivíduos se encontram.

Habitat fragmentation and a decrease in population size may lead to a loss in population genetic diversity. For the first time, the reduction in genetic diversity in the northernmost limit of natural occurence (southeastern Brazil) of Araucaria angustifolia in comparison with populations in the main area of the species continuous natural distribution (southern Brazil), was tested. The 673 AFLPs markers revealed a high level of genetic diversity for the species (Ht = 0.27), despite anthropogenic influence throughout the last century, and a decrease of H in isolated populations of southeastern Brazil (H = 0.16), thereby indicating the tendency for higher genetic diversity in remnant populations of continuous forests in southern Brazil, when compared to natural isolated populations in the southeastern region. A strong differentiation among southern and southeastern populations was detected (AMOVA variance ranged from 10%-15%). From Bayesian analysis, it is suggested that the nine populations tested form five “genetic clusters” (K = 5). Five of these populations, located in the northernmost limit of distribution of the species, represent three “genetic clusters”. These results are in agreement with the pattern of geographic distribution of the studied populations.