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The growth rings of Pinus occidentalis Swartz trees in La Celestina, Dominican Republic, show between-tree uniformity. With difficulty, two mean time series were made from ring widths of 1) all visible, including intra-annual, rings and 2) groups of rings that were hypothesized to be annual. Both were compared with a 63-year range of rainfall data. An annual periodicity in wood formation is present, but obscured by many intra-annual rings. The annual periodicity of the trees may be a remnant of their possible origin from higher altitudes, where frosts may occur during the cold season. The youngest of the 7 investigated trees was about 39 years old; the oldest about 46 years. These seven trees contain between approximately 2 and 6 growth rings per year, with an average of about 3.5-4.

Explosive or ballistic seed dispersal has been found in many plant species, genera and families (Ridley 1930); in both 'annuals and perennials, herbs and trees, and in open and shaded, wet and dry habitats' (Stamp & Lucas 1983). In the Leguminosae, explosive dehiscence 'is found most frequently in herbs (. . .), but also occurs in high forest trees, from which large seeds lacking dispersal devices are thrown many metres away' (van der Pijl 1982: 155). Little information is available about explosive dispersal by trees, although this dispersal method occurs frequently in specific forest types. For example, 'leguminous trees with explosively dehiscent pods dominate most primary and secondary dry forest and woodland types in the Zambesian Regional Centre of Endemism' (Bingham 1994). Unpublished observations by scientists of the Department of Plant Taxonomy in Wageningen have shown that explosive dispersal is a common feature of caesalpinioid trees in the African rainforests. In this paper, some observations and experiments on the explosive dispersal of the large rainforest tree Tetraberlinia moreliana Aubreville are described. The research was carried out in Rabi, Gabon, at 10 55' S and 90 51' E, and at c. 40 m altitude. Rabi has an average annual rainfall of 2166 mm (1987-1993), and a dry season from June to September. The prevailing wind direction is SSW. The distribution of T. moreliana is confined to west Gabon and a small area in south-west Cameroon (Rietkerk et al. 1995). T. moreliana can attain a height of 51 m. The crown has the shape of a hemisphere, and can emerge above the surrounding canopy. The pods are woody, and only grow on the crown surface, beyond the outermost leaves. The longitudinal axis of a pod usually has a horizontal orientation, like a pennant, but can point in any horizontal direction

The present paper is a monographic revision of the genus Alafia. The study is based mainly on herbarium material, but, in addition, the author has seen living plants in the wild belonging to 7 of the 23 species maintained here (15 in continental Africa and 8 in Madagascar). Two keys are provided -the first for species indigenous to mainland Africa and the second for those found in Madagascar. It has been possible to trace almost all the type specimens of the names and synonyms discussed here.

The domestication of lettuce, Lactuca sativa L. is described on the basis of literature study. The centre of origin is discussed. A historical survey is made of the distribution of the groups of Lactuca cultivars over the world.

Population structures were drawn for selected West African rain forest canopy tree species to evaluate whether regeneration was present. Regional variability was studied for five sites near the border between Liberia and Cote d'Ivoire. Population structures were highly variable. Three major types of population structures are recognised: a decrease in number of individuals with size, the typically inverse J-shaped curve indicating sufficient regeneration; an increase in number of individuals with size, indicating an absent or sparse regeneration; variable, consisting of strongly fluctuating patterns, in most cases many small individuals, no intermediate and many large ones. At a regional scale, most species show variable population structures. Population structures are static representations of a population composition at a certain moment in time. More long term information on population dynamics is needed to be able to interpret population structures correctly. To sustain the yield from tropical forest a minimum of juvenile trees of commercial species is required to compensate for logging of mature trees. The level of this minimum is hard to indicate without data on population dynamics. Regional variation in population structures warrants the use of local information as a basis for selection criteria of individual trees.

SUMMARY The closest relatives of the cultivated potato comprise a group of morphologically very similar species, which have been designated as the brevicaule-complex. The interrelationships among these species and their relationships to the cultivated species are unclear. The influences of the domestication process on these weedy plants may have determined their pattern of variation, making it difficult to assess the nature and delimitations of the entities to be recognized within this group. Multivariate methods were applied to analyse the taxonomic situation and the status of several of the involved species was evaluated.

SUMMARY Recent increase in commercial breeding in the genus Aster of cultivars particularly suitable for the cut-flower industry calls for a reassessment of the systematics of cultivated asters. A system of three cultivar-groups is proposed here to encompass most of the diversity of cultivars based on typical user criteria: the Dumosus Group, the Universum Group and the Novi-belgii Group. The applicability of numerical character analysis for cultonomic classification is outlined. The flexibility of open (‘cultonomic’) classifications for culta is demonstrated. It is shown that this system of cultivar-groups serves stability much better in the application of names to Aster cultivars than the continued use of Latin binomials. The use of the culton concept and its consequences for classifying Aster cultivars is outlined.

Important episodes in the history of the classification of cultivated plants are highlighted and commented upon in the light of recent developments in the systematics of cultivated plants. It is shown that throughout history, a division between classifying cultivated plants and plants as found in nature has existed in the minds of most taxonomists, but the slow development of systematic thought in cultivated plant taxonomy has slowed down progress in this field and left ample opportunity for too strong an influence of the taxon concept. As a result, the nomenclature of cultivated plants has always leaned heavily on the International Code of Botanical Nomenclature.

Phylogeographic relationships were inferred from nuclear rDNA internal transcribed spacer (ITS) sequences among ten biogeographic isolates of the cosmopolitan green alga Cladophora vagabunda from the Atlantic and Pacific Oceans as well as the Red Sea and SW Australia. Representatives of the closely related C. albida/sericea clade were used as outgroup and root, based on previous studies using 18S rDNA. High bootstrap values and negative g1-statistics revealed a strong phylogenetic signal regardless of assumption sets that included or excluded alignment-gaps in the analyses. The two main lineage found within the C. vagabunda complex are hypothesised to have shared a common Pacific ancestor, based on the basal position of Indo-West Pacific isolates relative to the outgroup. It is concluded that C. vagabunda represents the predicted intermediate case between ancient tropical species that exhibit strong vicariance imprints and recent, cold-temperate to boreal lineages that do not.

Background and aims – Floristic inventories are the primary means by which the plant diversity of an area can be understood and are important in underpinning management plans for conservation. One of the priorities set out for Loango National Park (LNP) in an IUCN assessment of Gabon's protected areas was to produce a vascular plant checklist. Therefore, the primary goal of this research was to significantly increase the number of specimens for the park and make a concentrated effort to increase knowledge of plant diversity in the area. The secondary goal of this study was to analyse the flora of LNP in terms of phytogeography and endemism. Methods – A specimen-based botanical inventory was carried out in LNP (1005 herbarium specimens collected for this study were added to 752 existing records) and vegetation observations were made. Phytogeographical analyses were also performed using two different methods and datasets for comparison. Key results – A preliminary checklist of 686 species of vascular plants of LNP is presented, making a significant contribution to our knowledge of the flora of Gabon with more than twenty new country records. Conclusions –There is a surprisingly high proportion (15%) of the overall Gabonese flora recorded from within the park in this preliminary checklist. Further inventory within the park will undoubtedly produce a much higher percentage of the flora of the whole country. This high proportion is explained in part by the combination of restricted coastal endemics, diversity of habitats, and dynamic biological and physical processes. Phytogeographical analyses reveal different floristic relationships between the forest and savanna components of the flora suggesting different origins of these two biomes in coastal Gabon. The forest species are typically Guineo-Congolian in distribution and the savanna species are Sudano- Zambezian or widespread in distribution. Together, the faunal elements and the high diversity of the flora of Loango National Park make it a globally important site for conservation

We conducted joint Bolivia/The Netherlands/United States wild potato (Solanum sect. Petota Dumort.) germplasm collecting expeditions in Bolivia from February 1-April 15, 1993, and January 1-February 26, 1994. The goals of the expeditions were to collect germplasm and gather data for continuing taxonomic studies of the approximately 43 taxa of Bolivian wild potatoes accepted by current taxonomists. We made 223 collections, 135 as true seed collections, 54 as tubers, 19 only as herbarium collections. Two recent taxonomic treatments of Bolivian wild and cultivated potatoes have clarified the taxonomy and distribution of these plants, but there are continuing disagreements between treatments regarding species boundaries and interrelationships. These disagreements, and the variability we observed in natural populations, present problems for identifications. We summarize the state of germplasm collections for Bolivia, provide our field data regarding the taxonomy of Bolivian wild potatoes, provide recommendations for future collecting, and provide new chromosome counts for S. hoopesii, S. ugentii, and S. yungasense.

Evolutionary relationships among species traditionally ascribed to the Siphonocladales/Cladophorales have remained unclear due to a lack of phylogenetically informative characters and extensive morphological plasticity resulting in morphological convergence. This study explores some of the diversity within the generic complex Cladophora and its siphonocladalaen allies. Twelve species of Cladophora representing 6 of the 11 morphological sections recognized by van den Hoek were analyzed along with 8 siphonocladalaen species using 18S rRNA gene sequences. The final alignment consisted of 1460 positions containing 92 phylogenetically informative substitutions. Weighting schemes (EOR weighting, combinatorial weighting) were applied in maximum parsimony analysis to correct for substitution bias. Stem characters were weighted 0.66 relative to single-stranded characters to correct for secondary structural constraints. Both weighting approaches resulted in greater phylogenetic resolution. Results confirm that there is no basis for the independent recognition of the Cladophorales and Siphonocladales. The Siphonocladales is polyphyletic, and Cladophora is paraphyletic. All analyses support two principal lineages, of which one contains predominantly tropical members including almost all siphonocladalean taxa, while the other lineage consists of mostly warm- to cold-temperate species of Cladophora.

This thesis aims to fill the gap of information on the potato landrace diversity present in farmer fields of Ecuador. Passport data from previous collections (1970’s and 1980’s) were used to identify Carchi, Chimborazo and Loja as representative areas of potato diversity. The status of on-farm conservation in these three selected areas is covered in Chapter 2. Microsatellites (SSRs) helped us to describe the genetic relationships among the landraces found in these areas (Chapter 3). The characterization of potato landraces with respect to late blight resistance (Chapter 4) and quality traits (Chapter 5) complement the description. Previous reports suggested loss of potato diversity (genetic erosion) in Ecuadorian farmer fields, but our collection of a total of 174 landraces showed that these areas still hold a substantial amount of potato landrace diversity (Chapter 2). More potato landraces were found in Chimborazo and Loja than previously sampled in the 70’s and 80’s. A comparison between the two collections, in each of the three areas, indicated only a small overlap in landrace names suggesting that the sampling of local landraces was far from exhaustive, both during the 70’s and 80’s and during the present collection trips. This is further supported by the fact that the diversity fair, which was organized after our collection trips in Chimborazo, resulted in many new landraces. Surveys and farmer meetings in the study areas were used to describe the landrace-holders and the characteristics of the farming system they use. Mostly elderly people and small-scale farmers are currently maintaining potato landraces. These farmers look for income alternatives besides agriculture, resulting in migration. The vulnerability of the potato conservation varies among our study areas. In Carchi younger farmers demonstrate a lack of interest in cropping potato landraces. In Loja farming is not seen as the only sustainable source of income and there is a perceived lack of support from the government for the activities necessary to maintain local landraces. In Chimborazo farmers are culturally more attached to their land and see agriculture as a family activity, rendering the potato landrace conservation less vulnerable. Externally driven on-farm conservation interventions, such as diversity fairs or re-introduction of landraces, were highly appreciated by the farmers and could help to conserve the potatoes. Diploid, triploid and tetraploid potato landraces are found in farmers fields. The material sampled at the three areas shows a high allelic diversity. At the tetraploid level (the most abundant) this was comparable to the variation present in an European collection of more than 800 varieties. More alleles are expected to be found when more material from other areas will be screened. There was no clear grouping of material collected according to study region, suggesting extensive movement of seed potatoes all over Ecuador. A comparison of the application of variety names with the genetic relationships among potato landraces can result in either under- or over-estimation of the variability present in farmer fields (Chapter 3). In a number of cases landraces with identical common names proved to be genetically different or individual collection samples were actually a mixture of two landraces, pointing at under-estimation of diversity present. On the other hand, cases that might lead to over-estimation were also evident, e.g. genetically identical material was present under different names. Our sampling of genetically different landraces for late blight (LB) resistance characterization (Chapter 4) confirmed that there was some variation for this trait among the landraces. Most of the landraces were susceptible to moderately resistant, but also some landraces with field resistance were identified. The observed field resistance was comparable to that in the widespread improved variety Fripapa. Possible strategies to improve late blight resistance in potato in Ecuador could include the identification of accessions with resistance among the local landraces, although only a few accessions may be expected to present field resistance. The introduction of new sources of resistance from other origins is a more viable alternative. One could attempt to introduce novel R-genes in material that already contains some level of quantitative resistance. We found varying levels of dry matter, total polyphenol and total carotenoid contents among Ecuadorian potato landraces, some were comparable to the improved varieties. Based on the dry matter content most of the Ecuadorian landraces evaluated were suitable for processing as French fries or chips. The total polyphenol content of these potatoes were quite similar to those reported by the International Potato Center (Peru) for a set of accessions representing more than 60% of the variability in their potato collection. The total carotenoid content values of the Ecuadorian potatoes included in our study were similar or lower compared to previous studies on improved or Andean potatoes. The identified outstanding potato materials could be used to develop new potato varieties through plant breeding. In Chimborazo and Loja farmers select landraces mainly based on their nutritional characteristics. However, in Carchi farmers prefer commercial improved varieties. Farmers´ preferences include empirical valuation of potato-quality rather than specific knowledge on nutritional characteristics of these potatoes. This thesis provides important knowledge about the potato landraces in Ecuador. Our results can serve as the basis for further description and use of Ecuadorian native potatoes by breeders and local communities.

Systematics of the blackfly subgenus Trichodagmia ENDERLEIN (Diptera: Simuliidae:Simulium) in the New WorldThe systematics of the New World subgenus Trichodagmia has been reassessed by employing anintegrated taxonomic approach based upon revisionary taxonomy, phylogenetic (cladistics) analysis, andDNA barcoding. This subgenus included several species of great medical importance, which are allmorphologically very similar. The history of the taxonomy and classification of the subgenusTrichodagmia has been put into context with other subgenera within New World Simuliidae, whiledescriptions and keys to the identification of species in this subgenus are also given.The subgenus Obuchovia is here considered a new junior synonym of Trichodagmia, and all itsconstituents’ species are now placed in the ALBELLUM species group to represent a Palaearcticelement within this subgenus. Three new junior synonymies are here proposed: Simulium chiriquienseFIELD is a synonym of S. ethelae DALMAT n. syn.; S. biuxinisa COSCARÓN & IBÁÑEZ-BERNAL is asynonym of S. paynei VARGAS n. syn.; and S. keenani FIELD is a synonym of S. earlei VARGAS, MARTÍNEZPALÁCIOS &DÍAZ NÁJERA n. syn. A neotype is designated for S. lahillei (PATERSON & SHANNON) and alectotype for S. pulverulentum KNAB.1 Simulium falculatum ENDERLEIN is transferred from theTARSATUM species group of to the CANADENSE species group based on the morphology of thefemale genitalia. Two species, S. rivasi RAMÍREZ PÉREZ and S. oviedoi RAMÍREZ PÉREZ, are transferredfrom the TARSATUM species group to the subgenus Psilopelmia based on the morphology of the malegonostyle and the ventral plate. Keys to separate all species groups and species based on the adults,pupae and larvae are also provided.The phylogeny and classification of the subgenus Trichodagmia is delineated using a cladisticanalysis of 63 taxa based on males, females, pupae and larvae, including two species belonging to thesubgenus Aspathia and two species of the subgenus Simulium s.str. that served as outgroups. Analysis ofthe original full data set [67 taxa and 67 characters] with multistate characters treated as unorderedunder equal weights led to poorly resolved trees, with many polytomies within TARSATUM [= oldsubgenus Hemicnetha] and CANADENSE [= old subgenus Hearlea]. Nonetheless, the ALBELLUM [=old subgenus Obuchovia] and PICTIPES [= old subgenus Shewellomyia] species groups, and some cladeswithin the CANADENSE species group were well supported. In the most parsimonious cladograms,the position of S. falculatum was problematic as it was placed basal to Trichodagmia. The position of S.jeteri, albeit within the ORBITALE [= old subgenera Trichodagmia + Thyrsopelma of MIRANDA-ESQUIVEL& COSCARÓN, 2001] clade, was also poorly resolved. This was certainly due to the numerous missingdata in these two taxa. Therefore, they were removed from the data set together with other taxa inwhich three life stages (> 70% of characters) were missing (e.g. S. paracarolinae and S. tarsale). A secondanalysis was then performed with 63 taxa and 67 characters. In this analysis, the Strict Consensus Treewas better resolved and certain clades within the expanded concept of Trichodagmia (sensu SHELLEY et al.,2010) were recovered as monophyletic with high support values. The ALBELLUM species group ismonophyletic in a sister-group relationship with the other species groups in Trichodagmia (sensu SHELLEYet al., 2010). The ORBITALE species group clade was recovered as monophyletic by a uniquecombination of seven characters with 89% bootstrap support. In this clade, all species close to S.guianense s.l. were better diagnosed by a combination of four characters, one of which (male ventral platewith a globular median process) was unique to this group. The position of S. hirtipupa is better resolvedin the latter clade by the presence of black spiniform setae in the frontoclypeus and thorax of the pupa.In contrast, the TARSATUM and CANADENSE species groups were diagnosed by only fourand five characters, respectively. Within the CANADENSE species group only species with larvaehaving sclerotized plates in the posterior region of the abdomen were well resolved. Species in theTARSATUM group were homoplastic. The PICTIPES group is only diagnosed by homoplasies, but thecombination of these characters is unique to this clade (polythetic taxon). In general, this study supportssome of the taxonomic changes proposed in SHELLEY et al. (2010), in which the subgeneric-namesHearlea, Hemicnetha, Shewellomyia, Trichodagmia + Thyrsopelma (sensu MIRANDA-ESQUIVEL & COSCARÓN,5022001) are treated as species groups within the subgenus Trichodagmia. Moreover, this study also supportsthe proposal of Obuchovia as a junior synonym within the clade Trichodagmia to represent theALBELLUM species group.The utility of the COI DNA barcoding methodology for identification of species in the subgenusTrichodagmia and related taxa has been tested. In total, 24 morphospecies within the current expandedmorphological concept of Trichodagmia were analyzed. In addition, three species of the subgenusAspathia and 10 species of the subgenus Simulium s.str. were also included in the analysis because of theirputative phylogenetic relationship with Trichodagmia. Within the barcoding neighbour-joining tree, mostof the specimens were grouped together according to morpho-taxon (species groups and species).Mean genetic distance amongst groups (morphospecies) averaged 11.2% (ranged 2.8-19.5%), whereasintraspecific genetic divergence within morphologically distinct species averaged 0.5% (range 0-1.3%).In known species complexes, maximum values of genetic divergence (3.28-3.79%) indicate the probablepresence of cryptic diversity. DNA barcoding achieved nearly 100% success in identifying all specimensof the subgenus Trichodagmia and related taxa.The existence of well defined groups within S. piperi, S. duodenicornium, S. canadense and S. rostratumhighlighted the possible presence of species complexes in these taxa. In addition, the suspectedpresence of a sibling species in S. paynei and S. tarsatum among populations of Belize, Costa Rica, andthe USA is confirmed. The use of shorter barcodes (midi and minibarcodes) from specimens held incollections was problematic with regards to the DNA quality and PCR success. However, in the casesthat a readable sequence was obtained, they were sufficient for reliable species identification. Withregards to the different extraction and preservation techniques tested, larvae preserved in dilutedCarnoy’s (10% acetic acid) provided full DNA barcodes. Furthermore, legs added directly to the PCRmix from freshly collected individuals provided full length barcodes sequences. However, specimens ofmore than 10 years old did not yield good PCR products. In short, I conclude that DNA barcoding incombination with a morphological benchwork platform is an effective approach for identification anddelineation of species in the subgenus Trichodagmia, and the discovery of hidden diversity in this taxon.&nbsp

Systematics of the blackfly subgenus Trichodagmia ENDERLEIN (Diptera: Simuliidae:Simulium) in the New WorldThe systematics of the New World subgenus Trichodagmia has been reassessed by employing anintegrated taxonomic approach based upon revisionary taxonomy, phylogenetic (cladistics) analysis, andDNA barcoding. This subgenus included several species of great medical importance, which are allmorphologically very similar. The history of the taxonomy and classification of the subgenusTrichodagmia has been put into context with other subgenera within New World Simuliidae, whiledescriptions and keys to the identification of species in this subgenus are also given.The subgenus Obuchovia is here considered a new junior synonym of Trichodagmia, and all itsconstituents’ species are now placed in the ALBELLUM species group to represent a Palaearcticelement within this subgenus. Three new junior synonymies are here proposed: Simulium chiriquienseFIELD is a synonym of S. ethelae DALMAT n. syn.; S. biuxinisa COSCARÓN & IBÁÑEZ-BERNAL is asynonym of S. paynei VARGAS n. syn.; and S. keenani FIELD is a synonym of S. earlei VARGAS, MARTÍNEZPALÁCIOS &DÍAZ NÁJERA n. syn. A neotype is designated for S. lahillei (PATERSON & SHANNON) and alectotype for S. pulverulentum KNAB.1 Simulium falculatum ENDERLEIN is transferred from theTARSATUM species group of to the CANADENSE species group based on the morphology of thefemale genitalia. Two species, S. rivasi RAMÍREZ PÉREZ and S. oviedoi RAMÍREZ PÉREZ, are transferredfrom the TARSATUM species group to the subgenus Psilopelmia based on the morphology of the malegonostyle and the ventral plate. Keys to separate all species groups and species based on the adults,pupae and larvae are also provided.The phylogeny and classification of the subgenus Trichodagmia is delineated using a cladisticanalysis of 63 taxa based on males, females, pupae and larvae, including two species belonging to thesubgenus Aspathia and two species of the subgenus Simulium s.str. that served as outgroups. Analysis ofthe original full data set [67 taxa and 67 characters] with multistate characters treated as unorderedunder equal weights led to poorly resolved trees, with many polytomies within TARSATUM [= oldsubgenus Hemicnetha] and CANADENSE [= old subgenus Hearlea]. Nonetheless, the ALBELLUM [=old subgenus Obuchovia] and PICTIPES [= old subgenus Shewellomyia] species groups, and some cladeswithin the CANADENSE species group were well supported. In the most parsimonious cladograms,the position of S. falculatum was problematic as it was placed basal to Trichodagmia. The position of S.jeteri, albeit within the ORBITALE [= old subgenera Trichodagmia + Thyrsopelma of MIRANDA-ESQUIVEL& COSCARÓN, 2001] clade, was also poorly resolved. This was certainly due to the numerous missingdata in these two taxa. Therefore, they were removed from the data set together with other taxa inwhich three life stages (> 70% of characters) were missing (e.g. S. paracarolinae and S. tarsale). A secondanalysis was then performed with 63 taxa and 67 characters. In this analysis, the Strict Consensus Treewas better resolved and certain clades within the expanded concept of Trichodagmia (sensu SHELLEY et al.,2010) were recovered as monophyletic with high support values. The ALBELLUM species group ismonophyletic in a sister-group relationship with the other species groups in Trichodagmia (sensu SHELLEYet al., 2010). The ORBITALE species group clade was recovered as monophyletic by a uniquecombination of seven characters with 89% bootstrap support. In this clade, all species close to S.guianense s.l. were better diagnosed by a combination of four characters, one of which (male ventral platewith a globular median process) was unique to this group. The position of S. hirtipupa is better resolvedin the latter clade by the presence of black spiniform setae in the frontoclypeus and thorax of the pupa.In contrast, the TARSATUM and CANADENSE species groups were diagnosed by only fourand five characters, respectively. Within the CANADENSE species group only species with larvaehaving sclerotized plates in the posterior region of the abdomen were well resolved. Species in theTARSATUM group were homoplastic. The PICTIPES group is only diagnosed by homoplasies, but thecombination of these characters is unique to this clade (polythetic taxon). In general, this study supportssome of the taxonomic changes proposed in SHELLEY et al. (2010), in which the subgeneric-namesHearlea, Hemicnetha, Shewellomyia, Trichodagmia + Thyrsopelma (sensu MIRANDA-ESQUIVEL & COSCARÓN,5022001) are treated as species groups within the subgenus Trichodagmia. Moreover, this study also supportsthe proposal of Obuchovia as a junior synonym within the clade Trichodagmia to represent theALBELLUM species group.The utility of the COI DNA barcoding methodology for identification of species in the subgenusTrichodagmia and related taxa has been tested. In total, 24 morphospecies within the current expandedmorphological concept of Trichodagmia were analyzed. In addition, three species of the subgenusAspathia and 10 species of the subgenus Simulium s.str. were also included in the analysis because of theirputative phylogenetic relationship with Trichodagmia. Within the barcoding neighbour-joining tree, mostof the specimens were grouped together according to morpho-taxon (species groups and species).Mean genetic distance amongst groups (morphospecies) averaged 11.2% (ranged 2.8-19.5%), whereasintraspecific genetic divergence within morphologically distinct species averaged 0.5% (range 0-1.3%).In known species complexes, maximum values of genetic divergence (3.28-3.79%) indicate the probablepresence of cryptic diversity. DNA barcoding achieved nearly 100% success in identifying all specimensof the subgenus Trichodagmia and related taxa.The existence of well defined groups within S. piperi, S. duodenicornium, S. canadense and S. rostratumhighlighted the possible presence of species complexes in these taxa. In addition, the suspectedpresence of a sibling species in S. paynei and S. tarsatum among populations of Belize, Costa Rica, andthe USA is confirmed. The use of shorter barcodes (midi and minibarcodes) from specimens held incollections was problematic with regards to the DNA quality and PCR success. However, in the casesthat a readable sequence was obtained, they were sufficient for reliable species identification. Withregards to the different extraction and preservation techniques tested, larvae preserved in dilutedCarnoy’s (10% acetic acid) provided full DNA barcodes. Furthermore, legs added directly to the PCRmix from freshly collected individuals provided full length barcodes sequences. However, specimens ofmore than 10 years old did not yield good PCR products. In short, I conclude that DNA barcoding incombination with a morphological benchwork platform is an effective approach for identification anddelineation of species in the subgenus Trichodagmia, and the discovery of hidden diversity in this taxon.&nbsp

This thesis aims to fill the gap of information on the potato landrace diversity present in farmer fields of Ecuador. Passport data from previous collections (1970’s and 1980’s) were used to identify Carchi, Chimborazo and Loja as representative areas of potato diversity. The status of on-farm conservation in these three selected areas is covered in Chapter 2. Microsatellites (SSRs) helped us to describe the genetic relationships among the landraces found in these areas (Chapter 3). The characterization of potato landraces with respect to late blight resistance (Chapter 4) and quality traits (Chapter 5) complement the description. Previous reports suggested loss of potato diversity (genetic erosion) in Ecuadorian farmer fields, but our collection of a total of 174 landraces showed that these areas still hold a substantial amount of potato landrace diversity (Chapter 2). More potato landraces were found in Chimborazo and Loja than previously sampled in the 70’s and 80’s. A comparison between the two collections, in each of the three areas, indicated only a small overlap in landrace names suggesting that the sampling of local landraces was far from exhaustive, both during the 70’s and 80’s and during the present collection trips. This is further supported by the fact that the diversity fair, which was organized after our collection trips in Chimborazo, resulted in many new landraces. Surveys and farmer meetings in the study areas were used to describe the landrace-holders and the characteristics of the farming system they use. Mostly elderly people and small-scale farmers are currently maintaining potato landraces. These farmers look for income alternatives besides agriculture, resulting in migration. The vulnerability of the potato conservation varies among our study areas. In Carchi younger farmers demonstrate a lack of interest in cropping potato landraces. In Loja farming is not seen as the only sustainable source of income and there is a perceived lack of support from the government for the activities necessary to maintain local landraces. In Chimborazo farmers are culturally more attached to their land and see agriculture as a family activity, rendering the potato landrace conservation less vulnerable. Externally driven on-farm conservation interventions, such as diversity fairs or re-introduction of landraces, were highly appreciated by the farmers and could help to conserve the potatoes. Diploid, triploid and tetraploid potato landraces are found in farmers fields. The material sampled at the three areas shows a high allelic diversity. At the tetraploid level (the most abundant) this was comparable to the variation present in an European collection of more than 800 varieties. More alleles are expected to be found when more material from other areas will be screened. There was no clear grouping of material collected according to study region, suggesting extensive movement of seed potatoes all over Ecuador. A comparison of the application of variety names with the genetic relationships among potato landraces can result in either under- or over-estimation of the variability present in farmer fields (Chapter 3). In a number of cases landraces with identical common names proved to be genetically different or individual collection samples were actually a mixture of two landraces, pointing at under-estimation of diversity present. On the other hand, cases that might lead to over-estimation were also evident, e.g. genetically identical material was present under different names. Our sampling of genetically different landraces for late blight (LB) resistance characterization (Chapter 4) confirmed that there was some variation for this trait among the landraces. Most of the landraces were susceptible to moderately resistant, but also some landraces with field resistance were identified. The observed field resistance was comparable to that in the widespread improved variety Fripapa. Possible strategies to improve late blight resistance in potato in Ecuador could include the identification of accessions with resistance among the local landraces, although only a few accessions may be expected to present field resistance. The introduction of new sources of resistance from other origins is a more viable alternative. One could attempt to introduce novel R-genes in material that already contains some level of quantitative resistance. We found varying levels of dry matter, total polyphenol and total carotenoid contents among Ecuadorian potato landraces, some were comparable to the improved varieties. Based on the dry matter content most of the Ecuadorian landraces evaluated were suitable for processing as French fries or chips. The total polyphenol content of these potatoes were quite similar to those reported by the International Potato Center (Peru) for a set of accessions representing more than 60% of the variability in their potato collection. The total carotenoid content values of the Ecuadorian potatoes included in our study were similar or lower compared to previous studies on improved or Andean potatoes. The identified outstanding potato materials could be used to develop new potato varieties through plant breeding. In Chimborazo and Loja farmers select landraces mainly based on their nutritional characteristics. However, in Carchi farmers prefer commercial improved varieties. Farmers´ preferences include empirical valuation of potato-quality rather than specific knowledge on nutritional characteristics of these potatoes. This thesis provides important knowledge about the potato landraces in Ecuador. Our results can serve as the basis for further description and use of Ecuadorian native potatoes by breeders and local communities.

In this paper the variation pattern of the Sicilian Beta germplasm collection is analysed. Accessions from Sicily were grown under controlled conditions and were evaluated morphometrically. Geographical distribution patterns of morphological characters are identified and the putative classification of the collection into coastal and inland populations is reassessed. Between adjacent populations significant variation was found for Petiole length, Leaf length, Leaf width and Biomass, however no one variable unambiguously reflected a geographical pattern. Overall differences between coastal and inland populations were small. Petiole length and rate of generative development were found to be important for distinguishing between these groups. Interferences are drawn on how the collection from Sicily could be rationalized to avoid excessive duplication.