Showing papers by "José Gabriel Segarra-Moragues published in 2010"

Postfire response and genetic diversity in Erica coccinea: connecting population dynamics and diversification in a biodiversity hotspot.

Abstract: Understanding the processes of biological diversification is a central topic in evolutionary biology. The South African Cape fynbos, one of the major plant biodiversity hotspots out of the tropics, has prompted several hypotheses about the causes of generation and maintenance of biodiversity. Fire has been traditionally invoked as a key element to explain high levels of biodiversity in highly speciose fynbos taxa, such as the genus Erica. In this study, we have implemented a microevolutionary approach to elucidate how plant-response to fire may contribute to explain high levels of diversification in Erica. By using microsatellite markers, we investigated the genetic background of seeder (fire-sensitive) and resprouter (fire-resistant) populations of the fynbos species Erica coccinea. We found higher within-population genetic diversity and higher among-population differentiation in seeder populations and interpreted these higher levels of genetic diversification as a consequence of the comparatively shorter generation times and faster population turnover in the seeder form of this species. Considering that genetic divergence among populations may be seen as the initial step to speciation, the parallelism between these results and the pattern of biodiversity at the genus level offers stimulating insights into understanding causes of speciation of the genus Erica in the Cape fynbos.

Systematic Revision of the Epipetrum Group of Dioscorea (Dioscoreaceae) Endemic to Chile

Abstract: A systematic revision of the Epipetrum group of Dioscorea (Dioscoreaceae), which traditionally included three taxa endemic to Chile, is presented. We evaluated the taxonomic value of macro- and micromorphological traits to delimit generic boundaries with respect to other yams and to identify and separate its taxa. The comprehensive survey included 10 qualitative and 43 quantitative traits related to all plant organs and new microanatomical features of leaf, fruits, seeds, and pollen. Discriminant analyses were conducted with three accumula- tive morphological data sets to test seven taxonomic hypotheses of differentiation among taxa. Our results indicate that these taxa are charac- terized by the combination of prominent pistillodes in male flowers and a base chromosome number of x = 7, which separate it from all other Dioscoreaceae, plus different sets of morpho-anatomical traits that differentiate it from other putatively closely related yams with unwinged seeds in Dioscorea (the Borderea group, the Nanarepenta group, the Tamus group, etc.). Dioscorea biloba is the most distinctive species. Our analy- ses revealed significant morphological differences between northern and southern populations of this species resulting in the recognition of two subspecies, the northern D. biloba subsp. biloba , and the new southern D. biloba subsp. coquimbana . Dioscorea humilis and D. polyanthes are morphologically similar and only differ in qualitative leaf traits. This minor variation is better treated by reducing D. polyanthes to subspecific rank in D. humilis , and the combination D. humilis subsp. polyanthes is made herein.

The fewer and the better: prioritization of populations for conservation under limited resources, a genetic study with Borderea pyrenaica (Dioscoreaceae) in the Pyrenean National Park

Abstract: Taxa considered under low International Union for the Conservation of Nature categories of extinction risk often represent cases of concern to conservation biology Their high relative abundance precludes management of the entire range due to limited economical resources Therefore, they require a cost-effective management plan Borderea pyrenaica (Dioscoreaceae), an endemic plant of the Central Pyrenees and pre-Pyrenees, reaches the French side of the Central Pyrenees on its narrow northernmost boundary at Gavarnie (Parc National des Pyrenees, PNP, France), where it is protected as Vulnerable and considered a priority species We have used nuclear microsatellite population genetic data to design a management strategy for the 11 populations of B pyrenaica present in this area and to identify Relevant Genetic Units for its Conservation The 18 SSR loci analysed identified 56 alleles, 24 of which fulfilled the rarity criterion for this set of populations Genetic structuring of populations and representativity values derived from regression analyses of probabilities of loss of rare alleles together support differentiation of the B pyrenaica populations into different management units Estimates derived from G ST values indicate that five populations would adequately represent the 999% of the variation relative to most common alleles whereas calculations based on representativity values indicated that these five populations should equate the proportion 2:2:1 from the three different phylogeographical subdivisions of Gavarnie (Western, Eastern-1 and Eastern-2 ranges) This scheme would allow the preservation of 9821% of the total B pyrenaica alleles present in Gavarnie, according to the post glacial history of its populations This conservation genetic approach could be applied to other low-extinction risk categories of extremely rare and subalpine plants in need of regulatory plans in European National Parks and Natural Reserves

Pollen morphology of Iranian species of Typha L. (Typhaceae) and its taxonomic significance

Abstract: Pollen analyses of 12 Iranian species of Typha L. were conducted through light microscopy and scanning electron microscopy. Among the twelve studied species, we found that five species, T. caspica, T. latifolia, T. lugdunensis, T. minima and T. shuttleworthii, present pollen in tetrads, whereas the remaining seven species, T. angustifolia, T. azerbaijanensis, T. domingensis, T. grossheimii, T. kalatensis, T. laxmanii and T. tourcomanica, have pollen in monads. The exine of Typha species is mostly reticulate although a few species present perforate-microreticulate and rugulate exine. Our analyses revealed that using a combination of light microscopy and scanning eletron microscopy characters the identification of species is feasible. A diagnostic key based on palynological traits is presented for all studied taxa (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

New microsatellite loci in the dwarf yams Dioscorea group Epipetrum (Dioscoreaceae)

Abstract:  Premise of the study: Microsatellite loci were isolated and characterized from enriched genomic libraries of two taxa of the Chilean Epipetrum group of Dioscorea to assess their levels of genetic diversity and population differentiation.  Methods and Results: Eleven microsatellite loci were identifi ed. Six out of nine microsatellites from D. biloba amplifi ed in D. humilis , and the two microsatellites from D. humilis amplifi ed in both taxa. Two different sets of eight loci amplifi ed in each of the two tested taxa, D. biloba and D. humilis . The average number of alleles was 5.75 and 5 for D. biloba and D. humilis , respectively. Higher levels of mean genetic diversity were found in D. biloba ( H E = 0.639) than in D. humilis ( H E = 0.414).  Conclusions: These microsatellite primers will be useful in population genetic studies and to establish conservation strategies in the endangered taxa of the Epipetrum group of Dioscorea .