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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
151

Genética de paisagens de espécies da planície costeira do Atlântico Sul

Arias, Gustavo Adolfo Silva January 2016 (has links)
O entendimento da contribuição diferencial de processos neutros e adaptativos envolvidos na diferenciação genética entre populações, assim como sua relação com varáveis físicas e ambientais da área de distribuição das espécies, é fundamental para melhorar o conhecimento da história evolutiva, mas também para fazer um manejo e conservação mais adequados da diversidade genética das espécies. O surgimento da Planície Costeira do Atlântico Sul foi um processo relativamente recente, que conduziu a processos de colonização e expansão dos organismos para um ambiente costeiro. Os padrões de estrutura genética gerados em processos de colonização e expansão podem ser difíceis de interpretar devido ao fato de que podem apresentar sinais sobrepostos de efeito fundador em série, isolamento por distância e isolamento por ambiente quando envolvem gradientes ecológicos na área de estudo. No presente trabalho foram conduzidas caracterizações da diversidade e estrutura genética de dois taxa predominantemente costeiros co-distribuídos, Calibrachoa heterophylla e Petunia integrifolia ssp. depauperata, em toda a amplitude da distribuição. Também foram inferidas as dinâmicas de fluxo gênico entre populações e sua relação com variáveis topográficas e climáticas reconstruídas pelo meio de um levantamento exaustivo e modelamento para a área de estudo. Processos de diferenciação genética promovidos pelo regime diferencial de chuvas nos extremos da distribuição foram inferidos para as duas espécies. Também foram identificadas populações das duas espécies apresentando alto nível de mistura de identidade genética nas localidades ao redor da Lagoa dos Patos. Isso foi associado a alta instabilidade na história geomorfológica recente desta região e dinâmicas atuais do vento que favorecem a dispersão secundária de sementes a maiores distâncias. Adicionalmente foram identificados processos espécie-específicos que se relacionaram principalmente a fatores históricos de cada táxon. Em P. depauperata o efeito fundador relacionado a um processo único de colonização do ambiente costeiro determinou o nível superior de estrutura genética, enquanto que em C. heterophylla foi a história filogeográfica da espécie na qual a diferenciação intraespecífica é anterior à colonização da região costeira atual o fator preponderante. As diferenças de duração do ciclo de vida entre as espécies também influenciaram as dinâmicas contrastantes de fluxo gênico dos dois taxa, sugerindo que a colonização e adaptação local de C. heterophylla nas bordas da distribuição poderia ser condizente com um processo de monopolização. Em vista dos resultados obtidos neste trabalho, propõem-se o desenvolvimento de experimentos de transplante recíproco para confirmar o processo de adaptação local nas duas espécies e abordagens genômicas para identificar regiões do genoma responsáveis pelos processos de adaptação ao ambiente costeiro e de adaptação local nas margens da distribuição. / The understanding of differential contribution of neutral and adaptive processes to the genetic differentiation among populations, as well as its relationship to physical and environmental variables of species’ distribution area, is essential to improve the knowledge of species evolutionary history, but also to direct appropriate management and conservation policies for the genetic diversity. The emergence of the South Atlantic Coastal Plain was a relatively recent event that led to colonization and expansion processes to the coastal environment. Genetic structure patterns generated in colonization and expansion processes can be difficult to interpret because the overlapping signals, which can present the founder effect in series, isolation by distance, and isolation by environment in the presence of ecological gradients in the study area. In this work characterization diversity and genetic structure were conducted to two co-distributed and predominantly coastal taxa, Calibrachoa heterophylla and Petunia integrifolia ssp. depauperata alongside their complete geographical range. Moreover, we also inferred dynamic of gene flow among populations and investigated the relation between topographical and climatic variables reconstructed by means of an exhaustive survey and modeling for the study area and the gene flow. Shared genetic differentiation processes promoted by differential rainfall conditions at the distribution edges were inferred. In addition, we identified populations from both species with high level of mixed genetic membership in locations around the Patos Lagoon. This was associated with a high instability in recent geomorphological history of coastal region and current wind dynamics that favor the secondary seed dispersal over longer distances. Additionally, specific species processes were identified mainly related to historical factors of each taxon. In P. depauperata founder effects associated with unique colonization process to coastal environment determined the upper level of genetic structure, while in C. heterophylla the upper level of genetic structure was related to the phylogeographical history wherein the intra-specific differentiation preceded colonization to the current coastal region. The differences of the life span length of the species were also related to contrasting gene flow dynamics indicating that the colonization and local adaptation of C. heterophylla at the edges of the distribution could lead to monopolization process. In view of the results we propose the development of reciprocal transplant experiments to confirm the local adaptation process in both species and genomic approaches to identify regions of the genome responsible for the processes of adaptation to the coastal environment and local adaptation in distribution margins.
152

Variabilidade genética em populações de Heliothis virescens (Lepidoptera: Noctuidae) no Brasil inferida por marcadores microssatélites / Heliothis virescens (Lepidoptera: Noctuidae) populational genetic variation in Brazil inferred by microsatellite markers

Felipe Antonio Domingues 16 June 2011 (has links)
Estudos de genética de populações de pragas agrícolas têm destacado a importância de se conhecer a estruturação genética e os padrões de fluxo gênico entre populações para o refinamento de estratégias de Manejo Integrado de Pragas (MIP). A lagarta-da-maçã do algodoeiro, Heliothis virescens (F.), é um inseto praga amplamente distribuído e importante economicamente por causar danos consideráveis à cultura do algodão no Brasil. O controle dessa praga tem sido feito principalmente pelo uso de inseticidas e de plantas geneticamente modificadas (GM) que expressam proteína(s) de Bacillus thuringiensis Berliner e o potencial de evolução da resistência é alto. O conhecimento de quanto as populações de H. virescens são capazes de trocar informação genética entre si é de fundamental importância para a implantação de estratégias de manejo dessa praga. No entanto, pouco se sabe sobre a estrutura genética e os padrões de fluxo gênico em H. virescens em escalas locais e regionais no Brasil. Assim, o objetivo desse trabalho foi avaliar a variabilidade genética em populações de H. virescens utilizando marcadores microssatélites. Foram amostrados indivíduos de H. virescens oriundos de populações coletadas nas safras de 2007/08, 2008/09 e 2009/10 nas principais regiões produtoras de algodão e soja no Brasil. Foram estudados nove locos polimórficos em 12 populações, em um total de 205 indivíduos. O número médio de alelos por loco foi de 14,11. Os valores de heterozigosidade média esperada (HE) e observada (HO) foram de 0,303 e 0,438, respectivamente. O coeficinete de endocruzamento da espécie f foi de 0,294 (IC 95% de 0,178 a 0,406). As estimativas de estruturação genética foram = 0,132 (IC 95% de 0,072 a 0,218) e RST = 0,252. Esses valores indicam uma estruturação genética moderada entre as populações. Estimativas do número de migrantes indicaram um pequeno fluxo gênico, principalmente no sentido Centro- Oeste Nordeste, embora a maioria dos indivíduos dentro das populações seja residente; adicionalmente, foi verificado que o estabelecimento das populações do algodão ocorre a partir de indivíduos migrantes da soja ou descendentes desses indivíduos. Análises de Componentes Principais e de atribuição usando inferência Bayesiana revelaram a formação de dois grupos, porém não foi possível identificar um padrão de agrupamento (por região, safra ou hospedeiro). Desta forma os resultados do presente trabalho sugerem uma estruturação genética incipiente para as populações de H. virescens no Brasil. Desse modo, é importante levar esses resultados em consideração para que o MIP em geral, e especificamente para que as abordagens para retardar a evolução da resistência sejam implementadas de forma efetiva para o manejo de H. virescens no Brasil. / Agricultural pests population genetics studies have emphasized the importance of genetic structure and patterns of gene flow knowledge for Integrated Pest Management (IPM) strategies. The tobacco budworm, Heliothis virescens (F.), is a widespread and economically important insect pest renowned for causing considerable damage in cotton fields in Brazil. This pest has been controlled by the use of insecticides and genetic modified plants (GM) expressing proteins from Bacillus thuringiensis Berliner, and it has already been shown to present a high potential to develop resistance to these control technologies. To a successful application of these strategies it is needed to know the capacity of the pest populations to exchange genetic information among them. However, for H. virescens a scarce amount of information about genetic structure and patterns of gene flow is available at local and regional scales in Brazil. In this way, the main objective of this study was to evaluate the genetic variability of H. virescens based on microsatellite markers. Specimens were sampled during 2007/08, 2008/09 and 2009/10 from the main cotton and soybean producers regions in Brazil. From this, nine polymorphic loci from 12 populations were studied in 205 specimens. The average number of alleles was 14.11. Expected (HE) and observed (HO) heterozygosity were 0.303 and 0.438, respectively. Inbreeding coefficient f was 0.294 (IC 95% 0.178 - 0.406). Genetic structure indices were: = 0.132 (IC 95% 0.072 0.218) and RST = 0.252. These values point to a moderate genetic structure among H. virescens populations. Migrants estimative indicate a low gene flow, mainly in the Center-Western Northern direction, although most individuals are residents within populations; additionally it was suggested that immigrants to cotton populations come from soybean fields. Genetic relationships inferred by Principal Component Analysis and Bayesian assignment tests identified two groups, although no group pattern was recognized, even by geographic region, year of sampling or host plant. These results suggest an incipient genetic structuring for H. virescens populations within Brazil. Thus, such results should be considered for IPM strategies aiming in an efficient control of H. virescens in Brazil.
153

Sistema reprodutivo e fluxo gênico via pólen em uma coleção de germoplasma de Eugenia dysenterica DC. / Mating system and pollen-mediated gene flow in a germplasm collection of Eugenia dysenterica DC.

Rodrigues, Eduardo Borges 03 September 2012 (has links)
Submitted by Luciana Ferreira (lucgeral@gmail.com) on 2017-05-26T13:04:27Z No. of bitstreams: 2 Dissertação - Eduardo Borges Rodrigues - 2012.pdf: 6019074 bytes, checksum: f7a43bf329af77b351ce74ec756dc615 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2017-05-26T13:04:48Z (GMT) No. of bitstreams: 2 Dissertação - Eduardo Borges Rodrigues - 2012.pdf: 6019074 bytes, checksum: f7a43bf329af77b351ce74ec756dc615 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2017-05-26T13:04:48Z (GMT). No. of bitstreams: 2 Dissertação - Eduardo Borges Rodrigues - 2012.pdf: 6019074 bytes, checksum: f7a43bf329af77b351ce74ec756dc615 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2012-09-03 / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / The success of any breeding program or genetic resources conservation depends on the knowledge about gene flow, reproductive system and genetic variability in the studied populations. For perennial plants, germplasm collection maintained ‘in vivo’ and ‘ex situ’ can be an efficient method for conserving the genetic variability of a species is maintained outside its original habitat. This study aimed to evaluate the reproductive system and pollen-mediated gene flow in one generation of Eugenia dysenterica DC. from the germoplasma collection of the Escola de Agronomia e Engenharia de Alimentos from Universidade Federal de Goiás. We collected leaves from 404 adult plants and seeds from 23 mother-trees in the germplasm collection. Genotypes were obtained using eight microsatellite loci, four of them developed for E. dysenterica, and four transferred from Eucalyptus spp. The total number of alleles was 88, ranging from 4 to 20 for the eight loci analyzed (mean of 11 alleles per locus). The mean expected (He) and observed (Ho) heterozygosity were equal to 0.646 and 0.423, respectively. Additionally, the high combined paternity exclusion probability (QC= 0.99579), and the low combined probability of identity (IC = 7.9 x10-5) indicate that markers can be reliable for this kind of analysis. Multilocus outcrossing rates (t ̂_m= 0.957) and single locus outcrossing rates (t ̂_s= 0.848) were high. Biparental inbreeding (t_m-t_s =0,109) ) combined for all families analyzed was also high and significant, sugesting the occurrence of 10.9% of cross-fertilization between related individuals. Paternity correlation was also low (r ̂_p=0,119), with 11.9% of the progeny sired by cross-fertilization with the same pollen donor. On average 10.79% of the progeny analyzed were derived by biparental cross, whereas 84.70% were formed by multi-parental crosses, being related to the degree of half-sibs. Only 4.6% of the seeds were formed by selfing. Paternity was successfully assigned with 95% of confidence to 32% (171) of the seeds analyzed, most likely due to non-sampled candidate pollen donors or because the loci battery could not demonstrated the optimal values for the combined exclusion. The maximum pollen dispersal distance (224 m) corresponded to the length of the orchard. The “big-bang” flowering pattern and the aggregated spatial distribution of adults may have favored short distance pollen dispersal at the germplasm collection of E. dysenterica. Our results show that the E. dysenterica germplasm collection preserves the genetic diversity present in natural populations of southeastern Goiás and can be a reliable approach for maintenance of genetic diversity of the species for the future. / A definição de qualquer programa de melhoramento ou de conservação de recursos genéticos depende, inicialmente, do conhecimento do fluxo gênico, do sistema reprodutivo e da variabilidade genética existente nas populações. Nesse sentido, as coleções de germoplasma podem funcionar como um método de conservação in vivo e ex situ, em que amostras da variabilidade genética de determinada espécie é conservada fora do habitat da espécie. O objetivo geral desse estudo foi avaliar o fluxo via pólen de uma geração, o sistema reprodutivo e caracterizar molecularmente os indivíduos que compõem a coleção de germoplasma in vivo e ex situ de Eugenia dysenterica DC., mantida pela Escola de Agronomia e Engenharia de Alimentos da Universidade Federal de Goiás. Para tanto, foram coletadas folhas das 404 árvores e frutos de 23 árvores (matrizes) que compõem a coleção de germoplasma. Para a obtenção dos genótipos das árvores e das progênies foram utilizados oito locos microssatélites, quatro desenvolvidos para espécie e os outros quatro desenvolvidos para Eucalyptus ssp. e transferidos para E. dysenterica. Com base nos genótipos foram realizadas as análises descritivas de variabilidade genética, testes de paternidade, distância de dispersão de pólen e taxa de fecundação cruzada para todas as progênies. Para os oito locos analisados, o número de alelos foi igual a 88, variando entre 4 e 20 com uma média igual a 11 alelos por loco. Os valores médios de heterosigozidade esperada (He) e observada (Ho) foram iguais a 0,646 e 0,423. Avaliada a variabilidade genética nas duas gerações foi possível concluir que a coleção de germoplasma de E. dysenterica está preservando bem a diversidade genética oriunda das populações naturais da região sudeste do Estado de Goiás. Adicionalmente, a probabilidade de exclusão combinada (QC) foi igual a 0,99579 e a probabilidade de identidade combinada (IC) foi igual a 7,9x10-5. As taxas de cruzamento multiloco (t ̂_m) e uniloco (t ̂_s) foram altas e iguais a 0,957 e 0,848, respectivamente. A diferença da taxa de cruzamento multiloco e uniloco (t_m-t_s ) combinada para todas as famílias analisadas também foi positiva e significativa, indicando a ocorrência de 10,9% (t_m-t_s=0,109) de fecundação cruzada entre indivíduos aparentados. A correlação de paternidade foi baixa (r ̂_p=0,119) sugerindo que 11,9% dos indivíduos das progênies são filhos do mesmo doador de pólen. Em média 10,79% das progênies analisadas foram originadas por cruzamentos biparentais, sendo aparentados no grau de irmãos germanos, 84,70% foi formada por cruzamentos, sendo aparentados no grau de meios-irmãos e somente 4,6% das sementes foram formadas por autofecundação. Na análise de paternidade, apenas 32% (171) das sementes tiveram seus doadores de pólen atribuídos para um nível de confiança de 95%, o que pode ser explicado por três fatores: a presença de indivíduos juvenis não amostrados; a presença de outros indivíduos de E. dysenterica em outras estações experimentais próximas a coleção de germoplasma; ou pela bateria de locos, que não apresentou os valores considerados ótimos para a probabilidade de exclusão combinada. O efeito da floração “big-bang” e a distribuiçao agregada dos indivíduos adultos torna predominante os eventos de fecundação cruzada em curtas distâncias na coleção de germoplasma de E. dysenterica. O alcance máximo de dispersão de pólen foi de 224 m, esse valor abrange quase toda a área experimental da coleção de germoplasma.
154

Análise da estrutura populacional e do desequilíbrio de ligação de um painel de acessos de sorgo: uma abordagem usando teoria da coalescência / Analysis of population structure and linkage disequilibrium of a sorghum accession panel: an approach using coalescent theory

João Ricardo Bachega Feijó Rosa 12 April 2016 (has links)
A estrutura populacional e o desequilíbrio de ligação são dois processos fundamentais para estudos evolutivos e de mapeamento associativo. Tradicionalmente, ambos têm sido investigados por meio de métodos clássicos comumente utilizados. Tais métodos certamente forneceram grandes avanços no entendimento dos processos evolutivos das espécies. No entanto, em geral, nenhum deles utiliza uma visão genealógica de forma a considerar eventos genéticos ocorridos no passado, dificultando a compreensão dos padrões de variação observados no presente. Uma abordagem que possibilita a investigação retrospectiva com base no atual polimorfismo observado é a teoria da coalescência. Assim, o objetivo deste trabalho foi analisar, com base na teoria da coalescência, a estrutura populacional e o desequilíbrio de ligação de um painel mundial de acessos de sorgo (Sorghum bicolor). Para tanto, análises de mutação, migração com fluxo gênico e recombinação foram realizadas para cinco regiões genômicas relacionadas à altura de plantas e maturidade (Dw1, Dw2, Dw4, Ma1 e Ma3) e sete populações previamente selecionadas. Em geral, elevado fluxo gênico médio (Μ = m/μ = 41,78 − 52,07) foi observado entre as populações considerando cada região genômica e todas elas simultaneamente. Os padrões sugeriram intenso intercâmbio de acessos e história evolutiva específica para cada região genômica, mostrando a importância da análise individual dos locos. A quantidade média de migrantes por geração (Μ) não foi simétrica entre pares recíprocos de populações, de acordo com a análise individual e simultânea das regiões. Isso sugere que a forma pela qual as populações se relacionaram e continuam interagindo evolutivamente não é igual, mostrando que os métodos clássicos utilizados para investigar estrutura populacional podem ser insatisfatórios. Baixas taxas médias de recombinação (ρL = 2Ner = 0,030 − 0,246) foram observadas utilizando o modelo de recombinação constante ao longo da região. Baixas e altas taxas médias de recombinação (ρr = 2Ner = 0,060 − 3,395) foram estimadas utilizando o modelo de recombinação variável ao longo da região. Os métodos tradicional (r2) e via coalescência (E[r2 rhomap]) utilizados para a estimação do desequilíbrio de ligação mostraram resultados próximos para algumas regiões genômicas e populações. No entanto, o r2 sugeriu padrões descontínuos de desequilíbrio em várias ocasiões, dificultando o entendimento e a caracterização de possíveis blocos de associação. O método via coalescência (E[r2 rhomap]) forneceu resultados que pareceram ter sido mais consistentes, podendo ser uma estratégia eventualmente importante para um refinamento dos padrões não-aleatórios de associação. Os resultados aqui encontrados sugerem que o mapeamento genético a partir de um único pool gênico pode ser insuficiente para detectar associações causais importantes para características quantitativas em sorgo. / Population structure and linkage disequilibrium are two fundamental processes for evolution and association mapping studies. Traditionally, both have been investigated using classical methods that are commonly used. These methods certainly provided important advances for the understanding of the evolution processes of the species. However, in general, none of them uses a genealogical view to consider genetic events occurred in the past, making difficult the understanding of the variation patterns observed in the present. An approach that enables the retrospective investigation based on the actual observed polymorphism is the coalescent theory. Here, we used the coalescent theory to analyze the population structure and linkage disequilibrium of a worldwide sorghum (Sorghum bicolor) accession panel. To reach this purpose, analyses of mutation, migration with gene flow and recombination were performed to five genomic regions related to plant height and maturity (Dw1, Dw2, Dw4, Ma1 e Ma3) and seven previously selected populations. In general, high average gene flow (Μ = m/μ = 41,78 − 52,07) was observed between populations considering each genomic region and all the regions simultaneously. The patterns suggested a high exchance of accessions between populations and a specific evolutionary history for each genomic region, showing that the individual analysis of each locus was important. The average number of migrants per generation (Μ) was not symmetric between reciprocal pairs of populations, according to the specific and simultaneous analyses of the regions. This result suggests that the historical and recent evolutionary relations between populations are not equal, showing that the classical methods to investigate population structure may be unsatisfactory. Low average recombination rates (ρL = 2Ner = 0,030 − 0,246) were observed using a constant recombination model along the region. Low and high average recombination rates (ρr = 2Ner = 0,060 − 3,395) were estimated using a variable recombination model along the region. Both traditional (r2) and coalescent (E[r2 rhomap]) methods for the estimation of linkage disequilibrium showed similar results for some genomic regions and populations. However, r2 suggested discontinuous patterns of linkage disequilibrium in several cases, making difficult the understanding and definition of the association blocks. The coalescent method (E[r2 rhomap]) provided results that seemed to be more consistent and could be an eventually important strategy to refine the non-random association patterns. The results detected here suggest that the genetic mapping from a unique gene pool may be insufficient to detect important causal associations for quantitative traits in sorghum.
155

Past and present genetic diversity and structure of the Finnish wolf population

Jansson, E. (Eeva) 14 May 2013 (has links)
Abstract Many species and populations have perished as a consequence of human actions. During the last ~200 years, large carnivores have been almost completely extirpated from Western Europe. Large-scale wolf hunting started in Finland around the 1850s, and the population size quickly collapsed. The population was very small until the mid-1990s, when wolves started to regularly reproduce in Finland again. The wolf is an endangered species in Finland, and the biggest threat to the species’ survival is excessive hunting. In this doctoral thesis study, I inspected the genetic structure and diversity of the Finnish wolf population using neutral genetic markers. Almost 300 wolves from the contemporary Finnish population and over 50 wolves from the north-western Russia were analyzed with genetic methods. Additionally, the genetic history of the population was examined with the help of over 100 museum samples. The modern Finnish wolf population proved to be genetically as diverse as the non-endangered Eastern European and North American wolf populations. However, the genetic diversity decreased significantly during the study period (1995–2009), and was at its lowest level in the final phase of the examination. In tandem, the inbreeding coefficient rose to a relatively high level. Genetic sub-structures were observed due to social structures within wolf packs. The mean dispersal distances of wolves were approximately only 100 km. The Finnish wolf population is divided into neighbourhoods of related individuals, and their size substantially decreased during the study period. This pattern, together with the growth of the inbreeding coefficient, suggests that lost alpha individuals in wolf packs are replaced by their offspring. This study demonstrated that Russian and Finnish wolf populations are nowadays genetically differentiated. Gene flow between the populations is low, despite the geographic interconnection. Only a few possible immigrants from Russia into Finland were detected in the study. The effective size of the Finnish wolf population proved to be small, and was mainly below the often-considered critical size of 50. Historical analysis revealed that the Finnish wolf population was formerly genetically more diverse, more continuous with the Russian wolf population, and had a more than 90% larger effective size. On the basis of this study, the genetic status of the Finnish wolf population is worrying and needs to be monitored. The population should be substantially larger than today and/or the amount of gene flow higher, so that the population viability could be considered secured even in the short term. / Tiivistelmä Ihmisen toiminnan seurauksena lukuisat eliölajit ja –populaatiot ovat hävinneet. Viimeisten noin 200 vuoden aikana suurpedot hävitettiin lähes koko Länsi-Euroopasta. Laajamittainen sudenmetsästys alkoi Suomessa 1850-luvun paikkeilla ja kanta romahti nopeasti. Populaatio oli hyvin pieni lähes koko 1900-luvun, ja sudet ovat jälleen lisääntyneet yhtäjaksoisesti Suomessa vasta 1990-luvun puolivälistä. Susi on erittäin uhanalainen Suomessa ja merkittävin uhka lajin säilymiselle on liiallinen metsästys. Tarkastelen tässä väitöskirjatyössäni Suomen susipopulaation geneettistä rakennetta ja monimuotoisuutta neutraaleja geenimerkkejä käyttäen. Tutkimuksessa analysoitiin geneettisin menetelmin lähes 300 sutta nyky-Suomesta sekä yli 50 sutta Luoteis-Venäjältä. Lisäksi populaation geneettistä historiaa selvitettiin yli 100 museonäytteen avulla. Nykyinen Suomen susipopulaatio osoittautui tutkimuksessa geneettisesti yhtä monimuotoiseksi kuin ei-uhanalaiset susipopulaatiot Itä-Euroopassa ja Pohjois-Amerikassa. Geneettisen muuntelun määrä kuitenkin laski tutkimusajanjaksolla (1995–2009) merkitsevästi ollen matalin tarkastelujakson lopussa. Samanaikaisesti populaation sukusiitoskerroin nousi verrattain korkeaksi. Susipopulaatiossa havaittiin sosiaalisista rakenteista johtuvia geneettisiä alarakenteita. Susien dispersaalimatkat olivat keskimäärin vain noin 100 km. Suomen susipopulaatio on jakautunut toisilleen sukua olevien yksilöiden naapurustoiksi, joiden koko pieneni huomattavasti tutkimusajanjaksolla. Tämä yhdessä sukusiitoskertoimen kasvun kanssa viittaa susilaumojen menetettyjen alfayksilöiden korvautumiseen jälkeläisillään. Tutkimus osoitti, että Venäjän ja Suomen susipopulaatiot ovat nykyisin geneettisesti erilaistuneet. Geenivirta populaatioiden välillä on maantieteellisestä yhteydestä huolimatta vähäistä. Tutkimuksessa havaittiin vain muutamia todennäköisiä immigrantteja Venäjältä Suomeen. Suomen susipopulaation efektiivinen koko osoittautui pieneksi ollen pääosin alle kriittisenä rajana pidetyn 50:en. Historiallinen tarkastelu osoitti Suomen susipopulaation olleen aiemmin geneettisesti monimuotoisempi, yhtenäisempi Venäjän susipopulaation kanssa ja efektiiviseltä kooltaan yli 90 % nykyistä suurempi. Tutkimuksen perusteella Suomen susipopulaation geneettinen tila on huolestuttava ja tarvitsee seurantaa. Populaation tulisi olla nykyistä huomattavasti suurempi ja/tai geenivirran määrän korkeampi, jotta populaation elinvoimaisuuden voitaisiin katsoa olevan turvattu edes lyhyellä aikavälillä.
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The annual ragweeds (Ambrosia artemisiifolia L. - Ambrosia trifida L.) : adaptive response to chemical weeding and population genetics in agricultural environments / Les ambroisies annuelles (Ambrosia artemisiifolia et Ambrosia trifida) : réponse adaptative au désherbage chimique et connectivité des populations dans les paysages agricole

Meyer, Lucie 23 January 2018 (has links)
Ce travail a eu pour but premier d’étudier le risque d’évolution de la résistance aux herbicides inhibiteurs de l’acétolactate synthase (ALS) chez l’ambroisie à feuilles d’armoise (Ambrosia artemisiifolia L.) à travers quatre points : (i) la pression de sélection (étude de l’efficacité d’une gamme d'herbicides inhibiteurs de l’ALS), (ii) la capacité de réponse adaptative de l’adventice (détermination de la variation de la sensibilité aux inhibiteurs de l’ALS entre plantes et mise en place d’un programme de sélection récurrente), (iii) une étude de terrain (recherche de résistance aux inhibiteurs de l’ALS au champ en France), (iv) l’étude des mécanismes de résistance (liée à la cible – RLC – et non liée à la cible – RNLC – par une approche de transcriptomique). Le second objectif fut d’étudier la connectivité des populations d’A. artemisiifolia dans des paysages agricoles à l’aide de marqueurs microsatellites développés lors de ce travail afin de déterminer les facteurs qui pourraient faciliter la dispersion de cette espèce et de la résistance à l’échelle du paysage agricole.En ce qui concerne la résistance aux herbicides :-La réponse de d’A. artemisiifolia aux herbicides inhibiteurs de l’ALS est très variable entre substances.-Des plantes ayant survécu à la dose maximale autorisée et à des doses supérieures de metsulfuron ont été sélectionnées pour débuter un programme de sélection récurrente. Après deux cycles de sélection, on observe une intensification de la résistance au metsulfuron et une émergence de la résistance à l’imazamox et au tribénuron.-Trois cas de résistance à l’imazamox ont été identifiés au champ dont deux cas de pure RNLC et un cas de coexistence RLC – RNLC.-Un transcriptome d’A. artemisiifolia a été généré grâce à la technique de séquençage PacBio pour rechercher des gènes impliqués dans les mécanismes de RNLC (approche RNAseq). 62 gènes candidats ont été identifiés dont des transporteurs ABC, des cytochromes P450 ainsi que des glutathione-S-transférases connus pour être impliqués dans la dégradation des herbicides.Pour l’étude de la connectivité des populations agricoles :-26 marqueurs microsatellites ont été développés et ont révélé une forte variabilité génétique. La structuration génétique a été étudiée à grande échelle pour des populations d’A. artemisiifolia d’Europe (aire d’invasion) et d’Amérique du Nord (aire d’origine).-À une échelle plus fine (paysage agricole), la structure génétique des populations reste influencée par les événements de colonisation. Les événements de migration qui ont été identifiés entre zones de présence de l’ambroisie suggèrent des flux de gènes (pollen/semences) et une connectivité modérés à l’échelle d’un territoire agricole. Dans les environnements agricoles, la dispersion des allèles de résistance aux herbicides pourrait se faire facilement de proche en proche via les flux de pollen, et également à plus longue distance via des dispersions de graines. Les activités anthropiques jouent un rôle majeur dans la dispersion des semences (machineries agricoles, lots de semences contaminés…).-L’analyse du système de reproduction a confirmé que cette espèce est allogame ce qui entraîne des flux de gènes intra- et inter-populations importants.Les connaissances acquises au cours de ce travail pourront aider à développer des stratégies de contrôle mieux adaptées, pour lutter efficacement contre A. artemisiifolia afin de limiter son expansion, telles que :-Des stratégies de désherbage diversifiées : combinaison de lutte mécanique (dont faux semis) et chimique (diversification des modes d’action herbicides).-Un allongement et une diversification des rotations de cultures en favorisant des cultures d’hiver et/ou des cultures couvrantes et compétitrices.Ces connaissances pourront aussi être utilisées dans la lutte contre une autre espèce adventice du genre Ambrosia, Ambrosia trifida.Mots-clés (6) : Ambrosia artemisiifolia L., ambroisies, résistance aux herbicides, / The first aim of this work was to investigate the risk for the evolution of resistance to acetolactate synthase inhibitor (ALS) herbicides in the common ragweed (Ambrosia artemisiifolia L.) through four points: (i) the selection pressure (effectiveness of a range of ALS inhibitor herbicides), (ii) the adaptive response of Ambrosia artemisiifolia (recurrent selection experiment), (iii) a resistance monitoring in fields in France, and (iv) the investigation of the mechanisms underlying herbicide resistance (target-site (TSR) and non-target-site resistance (NTSR) using transcriptomic analyses). The second aim was to study the connectivity of A. artemisiifolia populations in agricultural landscapes using microsatellite markers developed during this work, to determine factors that could facilitate the spread of this invasive weed species and the spread of herbicide resistance.In regards to herbicide resistance:-The sensitivity of A. artemisiifolia to ALS-inhibiting herbicides is variable between active ingredients.-Plants that survived the French maximum authorized field rate and higher rates of metsulfuron were selected to implement a recurrent breeding program. After two selection cycles, the resistance level to metsulfuron increased and resistance to imazamox and tribenuron emerged.-Three cases of imazamox resistance were identified in the field, including two cases of pure NTSR and one case of TSR - NTSR coexistence.-A transcriptome for A. artemisiifolia, AMBELbase, was generated using the PacBio sequencing technology to search for genes involved in NTSR mechanisms (RNAseq approach). 62 candidate contigs were identified including ABC transporters, cytochromes P450 and glutathione S-transferases known to be involved in the degradation of herbicides.In regards to population connectivity:-26 microsatellite markers were developed and revealed high genetic variability. Genetic structuring has been studied on a large scale for populations of A. artemisiifolia from Europe (invasion range) and North America (native range).-On a finer scale (agricultural landscape), the genetic structure of populations was influenced by colonization events. Migration events detected among the areas colonized by A. artemisiifolia suggested moderate pollen/seed flows and connectivity at the farmland scale. In agricultural environments, herbicide resistant alleles could be easily spread among neighbouring populations via pollen flow, and also at longer distances via seed dispersal. Human-related activities play a major role in the dispersal of seeds (agricultural machinery, contaminated seed lots, etc.).-The mating system analysis confirmed that A. artemisiifolia is an obligate outcrossing species which leads to important intra- and inter-population gene flow.The knowledge acquired during this work may help to foster the development of better management strategies to effectively control A. artemisiifolia to limit its spread, such as:-Diversified weed control strategies: combination of mechanical (including false-seed) and chemical weeding (diversification of herbicide modes of action).-Longer diversified crop rotations including more winter crops and/or cover and competitive crops to break the life cycle of A. artemisiifolia.These knowledge may also be used to better control of another weed species of the genus Ambrosia, Ambrosia trifida L.
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Caracterização molecular de chrysodeixis includens em soja no Brasil / Molecular characterization of Chrysodeixis includens in soybean in Brazil

Palma, Janine 27 February 2015 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Soybeans are one of the crops with the highest expression in Brazil, both in area planted as in sales volume. The culture has as main pests defoliating caterpillars. Among these, stands out Chrysodeixis includens, pest that went from of secondary status in the 90s to a major defoliating caterpillar soybeans. Studies on genetic variation among populations and genetic structure of this species have not yet been carried out, and can help to indicate management practices. Molecular markers are tools indicated to genetically characterize insect populations. In order to use molecular tools, first, it is necessary a method for DNA extraction in quantity and quality that enables the practice in the laboratory. The goals of the study were to compare three DNA extraction methods for soybean caterpillars to applicate in PCR techniques, and analyze the molecular variability and the genetic structure of populations of C. includens in soybeans. Caterpillars of C. includens and S. eridania were collected from different sites in center soybean regions of Brazil, in 2011/12. The confirmation of the species was based on morphological characteristics of caterpillars according to identification keys. Samples of C. includes and S. eridania coming from Goiás were used for DNA extraction comparison test. The methods used were based on cell lysis by Sarcosyl, CTAB and SDS. Each method was compared for quantity, quality, economy and performance in PCR. The best DNA extraction method was chosen for extraction of all the caterpillars samples for molecular characterization work. Thirty populations of C. includens from nine Brazilian states were subjected to analysis of molecular variability and genetic structure with ISSR markers. The observed DNA extraction method with the best performance in the variables o was the DNA extraction method by Sarcosyl. ISSR generated 247 loci in 262 specimens analyzed. The estimated genetic diversity (HE) in populations ranged between 0.072 and 0.120, while the average was 0.094. The analysis of molecular variance indicates that 94% of the variability between individuals was expressed in 6% of the population and among populations (FST = 0.056, p = 0.001). The high level of gene flow and low genetic structure are indicatives of genetic information exchange between different sampling locations. The analysis of the genetic structure suggests the presence of two major groups which are not correlated to their sampling locations in Brazil. These results may indicate the recent colonization of C. includens in Brazil or the pattern of migration of moths following the cropping system in Brazil. Furthermore, the presence of two groups of C. includens suggest that the studies of development of resistance need to be further assessed for them both. / A soja é uma das culturas de maior expressão no Brasil, tanto em área plantada como em volume comercializado, e tem como principais pragas desfolhadoras as lagartas. Dentre essas, se destaca Chrysodeixis includens, praga que passou de secundária na década de 90 para uma das principais lagartas desfolhadoras da soja. Estudos sobre variações genéticas entre populações e estruturação genética dessa espécie ainda não foram realizados, e podem auxiliar na indicação práticas de manejo. Marcadores moleculares são ferramentas indicadas para caracterizar geneticamente populações de insetos. Mas para utilizar ferramentas moleculares, primeiramente, se faz necessário a extração de DNA em quantidade e qualidade que possibilita a prática no laboratório. Dessa forma, os objetivos do trabalho foram comparar três métodos de extração de DNA para lagartas da soja visando a aplicação com técnicas que utilizem a PCR. E analisar a variabilidade molecular e a estruturação genética de populações de C. includens na cultura da soja. Espécimes de lagartas de C. includens e Spodoptera eridania foram coletados de diferentes sítios de coleta nas principais áreas produtoras de soja do Brasil, safra de 2011/12. A confirmação da espécie foi baseada em características morfológicas das lagartas de acordo com chaves de identificação. As amostras de C. includens e S. eridania procedentes de Goiás foram utilizadas para o teste de comparação de extração de DNA. Os métodos utilizados eram cada um baseados na lise celular por Sarcosyl, CTAB e SDS. Cada método foi comparado quanto à quantidade, qualidade, economia e desempenho na PCR. O melhor método de extração de DNA foi utilizado para a extração de todas as amostras de lagartas para o trabalho de caracterização molecular. Trinta populações de C. includens de nove estados brasileiros foram submetidas a análise da variabilidade molecular e estrutura genética com marcadores ISSR. O método de extração de DNA que apresentou melhor desempenho nas variáveis observadas foi o método de extração de DNA por Sarcosyl. Os marcadores ISSR geraram 247 locos em 262 espécimes analisados. A diversidade genética estimada (HE) nas populações variaram entre 0,072 e 0,120, enquanto a média foi 0,094. A análise da variância molecular indica que 94% da variabilidade foi expressa entre indivíduos dentro das populações e 6% entre populações (FST = 0,056, p = 0,001). O alto nível de fluxo gênico e baixa estrutura genética são indicativos de troca de informação genética entre as diferentes locais de amostra. A análise da estrutura genética sugere a presença de dois grupos maiores que não se correlacionam com seus locais de amostragem no Brasil. Esses resultados podem indicar a recente colonização de C. includens no Brasil ou o padrão de migração das mariposas seguindo o sistema de cultivo no Brasil. Além disso, a presença de dois grupos de C. includens sugere que estudos sobre o desenvolvimento de resistência precisa ser avaliado sob outros ângulos para ambos os grupos.
158

Genetic structure of the brown bears (<em>Ursus arctos</em>) in Northern Europe

Kopatz, A. (Alexander) 15 April 2014 (has links)
Abstract Wild populations of large carnivores in Europe were almost wiped out during the last centuries. Nowadays, the number of brown bears in North and Eastern Europe has increased, and the current situation suggests that these populations have recovered or are in the process of recovery. Knowledge of the population genetic consequences of demographic recovery in large carnivores, especially across national borders and on broader geographical scales, is still limited. In this study, we collected 3,757 fecal and hair samples as well as 881 tissue samples from brown bears across Northern Europe, with a focus on the Finnish population and neighboring areas, to investigate the population structure, connectivity, and genetic diversity on a spatial as well as a temporal scale. Bayesian clustering analysis of the population structure suggested the division of brown bears in Northern Europe into several genetic clusters, and the subdivision of the Finnish population into a northern and southern subpopulation. The estimation of gene flow pointed to better connectivity of the bears between Southern Finland and Western Russia, while migration between Scandinavia and Northern Finland as well as between Scandinavia and Southern Finland/Western Russia appeared to be restricted. Genetic clusters identified in Finland, Russia and Northern Norway displayed high genetic diversity, which was among the highest reported in wild brown bears. Recovery of the Finnish population has been accompanied by a detected range expansion towards the north, while genetic differentiation between clusters has decreased and genetic diversity has increased in the southern population, suggesting expansion from the south. Our results demonstrated that the immigration of bears from Russia still plays a major role in the Finnish bear population; however, connectivity between the Finnish-Russian population and Scandinavian bears appears to be restricted and should be improved, as well as regularly monitored. / Tiivistelmä Suurpetojen luonnonpopulaatiot hävisivät Euroopasta melkein kokonaan viimeisten vuosisatojen aikana. Ruskeakarhujen määrä on viime aikoina kasvanut Pohjois- ja Itä-Euroopassa, ja karhupopulaatiot ovat toipuneet tai toipumassa. Tieto demografisen toipumisen geneettisistä seurauksista populaatioissa on varsin rajoittunutta etenkin laajemmassa maantieteellisessä mittakaavassa, yli valtiorajojen. Keräsimme tätä tutkimusta varten 3757 uloste- ja karvanäytettä ja 881 kudosnäytettä Suomesta ja sen lähialueilta. Tarkoituksenamme oli kartoittaa Pohjois-Euroopan karhupopulaatioiden geneettistä rakennetta ja monimuotoisuutta, sekä populaatioiden välisiä yhteyksiä huomioiden ajallinen ja maantieteellinen ulottuvuus. Bayesiläisen ryhmittelyanalyysin perusteella Pohjois-Euroopan karhut jakaantuvat useaan geneettiseen ryhmään. Suomen populaatiossa erottuivat eteläinen ja pohjoinen alapopulaatio. Analyysit geenivirran määrästä osoittivat, että Etelä-Suomen ja Länsi-Venäjän karhupopulaatiot ovat yhteneväisemmät, kun taas migraatio Skandinavian ja Pohjois-Suomen sekä Etelä-Suomen ja Länsi-Venäjän välillä vaikuttaisi olevan rajoittunutta. Suomesta, Venäjältä ja Pohjois-Norjasta tunnistetut alaryhmät olivat geneettisesti hyvin monimuotoisia, ja muuntelu oli korkeampaa kuin koskaan aiemmin karhuilla havaittu. Suomen karhupopulaation toipuessa ja levitessä pohjoiseen, geneettinen erilaistuminen maan sisällä on vähentynyt ja eteläisen alapopulaation monimuotoisuus kasvanut. Tämä viittaa populaation laajentumiseen etelästä käsin. Tulosten perusteella karhujen tulomuutto Venäjältä on yhä tärkeää Suomen populaatiolle. Suomen ja Venäjän karhupopulaatioiden yhteyttä Skandinavian karhupopulaatioihin tulisi seurata ja parantaa.
159

Demographic history and climatic adaptation in ecological divergence between two closely related parapatric pine species

Zhou, Y. (Yongfeng) 25 November 2014 (has links)
Abstract Both demographic histories and natural selection complicate the speciation process. There is a need to jointly study the effects of natural selection on so called magic traits that can cause reproductive isolation such as climatic adaptation, and its interaction with neutral demographic histories. Closely related incipient coniferous species offer us a great system for this effort. I used genetic variation at one set of climate-related candidate genes and another set of reference loci and cytoplasmic genomic fragments of two closely related parapatric pine species: Pinus massoniana Lamb. and Pinus hwangshanensis Hisa. Population genetic analyses were used to measure genetic variation and detect signals of ancient and recent selection. Speciation parameters including migration rates and divergence times at candidate genes and reference loci were compared under the Isolation with migration model. Hierarchical Approximate Bayesian Computation (ABC) was used to define demographic and speciation models. Intra- and interspecific genetic variation at cytoplasmic and nuclear intronic sequences were compared between parapatric populations and allopatric populations to distinguish the effects of introgression and incomplete lineage sorting in generating shared genetic variation between the species. The results showed that ancient selection were shared by the lineages leading to the species while recent selection has been species-specific. Candidate genes had significant lower migration rates compared to reference loci. Recent differential climatic selection might counteract against gene flow at underlying genes, which therefore favors divergence between the two pines through ecological speciation. Shared mitotypes were randomly distributed across species’ ranges, which therefore supported the incomplete lineage sorting hypothesis, but the shared nuclear intronic variation distributed more frequently in parapatric populations than in allopatric populations, supported the introgression hypothesis. ABC and species’ distribution modeling also supported the secondary gene flow model. The three genomes had different rates of mutation and gene flow might mirror different phases of the speciation continuum. The results in this thesis are valuable for understanding evolution in general and for other applied purposes such as tree breeding and climate change adaptation. / Tiivistelmä Luonnonvalinta ja populaatioiden historian demografia tekevät lajiutumisesta monimutkaisen tapahtumaketjun. Luonnonvalinnan ja demografisten tekijöiden vuorovaikutusta on paras tutkia samanaikaisesti, kun tarkastellaan lajiutumiseen vaikuttavia ominaisuuksia. Tällaisia ovat esimerkiksi ilmastoon sopeutumiseen liittyvät ominaisuudet. Lähisukuiset havupuulajit tarjoavat erinomaiset mahdollisuudet tähän työhön. Tutkin geneettistä muuntelua yhtäältä ilmastosopeutumiseen liittyvissä ns. ehdokasgeeneissä ja toisaalta neutraaleiksi oletetuissa verrokkigeeneissä sekä sytoplasman genomeissa kahdessa lähisukuisessa mäntylajissa Pinus massoniana Lamb. ja Pinus hwangshanensis Hisa, joiden populaatiot esiintyvät joskus erillään toisistaan (allopatrisesti), toisinaan vierekkäin (parapatrisesti). Mittasin muuntelun määrää ja etsin merkkejä valinnan vaikutuksesta. Vertasin erilaisia lajiutumismallien parametrejä verrokki- ja ehdokasgeeneissä. Käytin simulaatioita etsiäkseni parhaat demografiset ja lajiutumiseen liittyvät mallit. Vertasin kloroplastien ja mitokondrioiden genomien sekvenssien lajinsisäistä ja lajien välistä muuntelua allopatrisissa ja parapatrisissa populaatioissa tutkiakseni onko lajien yhteinen muuntelu seurausta siitä että lajien eriytymisestä on kulunut vain vähän aikaa vai siitä että sen jälkeen on tapahtunut geenivirtaa. Kauan sitten tapahtunut valinta on vaikuttanut samalla tavalla kumpaankin lajiin, osin koska tutkimus kohdistui myös niiden yhteiseen edeltäjälinjaan. Äskettäinen valinta taas oli suuremmassa määrin kummallekin lajille ominaista. Viime aikojen ilmastoon liittyvä valinta on voinut vähentää geenivirtaa ehdokasgeeneissä, mikä voisi edistää ekologista lajiutumista. Tuman DNA:n muuntelu jakautuminen tuki sitä mahdollisuutta että lajien yhteinen geneettinen muuntelu johtuu äskettäisestä geenivirrasta, ei vain siitä että lajiutuminen on niin varhaisessa vaiheessa. Mitokondrioiden geeneissä lajeilla yhtä paljon yhteistä muuntelua sekä allopatrisissa että parapatrisissa populaatioissa, mikä tukee sen sijaan eriytymisen jälkeistä epätäydellistä muuntelun erilaistumista. Eri genomit heijastavat lajiutumisprosessin eri vaiheita. Väitöskirjan tulokset ovat osaltaan tuottaneet uutta tietoa lajiutumisesta ja valinnasta. Lisäksi niillä on merkitystä ilmastomuutoksen vaikutusten ymmärtämisessä ja metsänjalostuksessa.
160

Population divergence at small spatial scales : – theoretical and empirical investigations in perch

Bergek, Sara January 2009 (has links)
Genetically structured populations arise when gene flow between groups of individuals is hindered by geographical, behavioural or temporal barriers. The identification of such groups is important for understanding evolution and has large implications for conservation concern. The field of population subdivision has received a lot of interest throughout the years and gained empirical support from a number of species. However, very little is known about population structure at small spatial scales, especially in a highly mobile species such as fish. The main object for my thesis was to further investigate population differentiation, explicitly at small spatial scales in the Eurasian perch. My results show that in this species, genetic differentiation occurs, even at very small spatial scales, both within lakes and in the Baltic Sea. Additionally, the differentiation can be stable over years and thus have a large impact in the evolution of adaptation to different environments. I also found barriers to gene flow that overlapped with the largest change in spring temperature, suggesting a temporal difference in spawning. Morphological differences were found at these small scales as well which indicates that a difference in food resources might be an underlying cause of change. My thesis work shows that the aquatic environment might not be as homogenous as widely thought and that there could be barriers or adaptations to different environments that hinder the fish from genetic panmixia. Slight patterns of isolation by distance (IBD) were found in the Baltic Sea, implying that the distance (i.e. currents) effect the level of differentiation via drifting of larvae and/or small fish. However, I have also theoretically investigated the IBD model of and seen that it is no longer correct when differences in population sizes are introduced. The pattern of IBD can mean high levels of gene flow or no gene flow at all, solely dependent on population size differences and fluctuations. My thesis has resulted in new and important findings regarding the existence and cause of genetic differentiation at very small spatial scales and thus added new knowledge into the field of evolution and speciation. In addition, my results also give insights into the contemporary state of the Eurasian perch and future evolutionary potential.

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