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- Bodare, Sofia, 1984-
(författare)
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Conservation Genetics and Speciation in Asian Forest Trees
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Tropical forests are important because they are the home of millions of species at the same time as they perform ecosystem services and provide food, cash income and raw materials for the people living there. The present thesis elucidates questions relevant to the conservation of selected forest trees as it adds to the knowledge in the phylogeny, population structure, genetic diversity and adaptation in these species.We investigated the genetic diversity and speciation of four spruce species around the Qinghai-Tibetan Plateau (QTP), Western China, and one from Taiwan. Nucleotide diversity was low in P. schrenkiana and the Taiwanese P. morrisonicola but higher in P. likiangensis, P. purpurea and P. wilsonii. This can be explained by the population bottlenecks that were detected in the two former species by coalescent-based analysis. The phylogenetic relationships between the five species were difficult to interpret, possibly because other Asian spruce species might have been involved. However, all species are distinct except P. purpurea, which likely has a hybrid origin. The rate of bud set and expression of the FTL2 gene in response to photoperiod in the southernmost growing spruce species, P. morrisonicola, was studied. We found that in this species, although growing near the equator, bud set appears to be induced mainly by a shortening of photoperiod, similarly to its more northerly growing spruce relatives. In addition, seedlings originating from mother trees growing at higher elevations showed a trend towards earlier bud set than seedlings originating from mother trees at lower altitudes.We also studied the population structure and genetic diversity in the endemic white cedar (Dysoxylum malabaricum) in the Western Ghats, India. Overall, no increase in inbreeding that could be related to human activities could be detected. Populations appear to have maintained genetic diversity and gene flow in spite of forest fragmentation over the distribution range. However, there is a severe lack of juveniles and young adults in several populations that needs to be further addressed. Finally, we recommend conservation units based on population structure.
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| 2. |
- Bodare, Sofia, 1984-, et al.
(författare)
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Genetic structure and demographic history of the endangered tree species, Dysoxylum malabaricum (Meliaceae) in Western Ghats, India : Implications for conservation in a biodiversity hotspot
- 2013
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Ingår i: Ecology and Evolution. - : Wiley. - 2045-7758. ; 3:10, s. 3233-3248
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The impact of fragmentation by human activities on genetic diversity of forest trees is an important concern in forest conservation, especially in tropical forests. Dysoxylummalabaricum (white cedar) is an economically important tree species, endemic to theWestern Ghats, India, one of the world's eight most important biodiversity hotspots. As D.malabaricum is under pressure of disturbance and fragmentation together with overharvesting, conservation efforts are required in this species. In this study, range-widegenetic structure of twelve D.malabaricum populations was evaluated to assess the impact ofhuman activities on genetic diversity and infer the species' evolutionary history, using both nuclear and chloroplast (cp) DNA simple sequence repeats (SSR). As genetic diversity and population structure did not differ among seedling, juvenile and adult age classes, reproductive success among the old-growth trees and long distance seed dispersal by hornbills were suggested to contribute to maintain genetic diversity. The fixation index (F-IS) was significantly correlated with latitude, with a higher level of inbreeding in the northern populations, possibly reflecting a more severe ecosystem disturbance in those populations. Both nuclear and cpSSRs revealed northern and southern genetic groups with some discordance of their distributions; however, they did not correlate with any of the two geographic gaps known as genetic barriers to animals. Approximate Bayesian computation-based inference from nuclear SSRs suggested that population divergence occurred beforethe last glacial maximum. Finally we discussed the implications of these results, in particularthe presence of a clear pattern of historical genetic subdivision, on conservation policies.
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| 4. |
- Bodare, Sofia, 1984-, et al.
(författare)
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Origin and demographic history of the endemic Taiwan spruce (Picea morrisonicola)
- 2013
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Ingår i: Ecology and Evolution. - : Wiley. - 2045-7758. ; 3:10, s. 3320-3333
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Tidskriftsartikel (refereegranskat)abstract
- Taiwan spruce (Picea morrisonicola) is a vulnerable conifer species endemic to the island of Taiwan. A warming climate and competition from subtropical tree species has limited the range of Taiwan spruce to the higher altitudes of the island. Using seeds sampled from an area in the central mountain range of Taiwan, 15 nuclear loci were sequenced in order to measure genetic variation and to assess the long-term genetic stability of the species. Genetic diversity is low and comparable to other spruce species with limited ranges such as Picea breweriana, Picea chihuahuana, and Picea schrenkiana. Importantly, analysis using approximate Bayesian computation (ABC) provides evidence for a drastic decline in the effective population size approximately 0.3–0.5 million years ago (mya). We used simulations to show that this is unlikely to be a false-positive result due to the limited sample used here. To investigate the phylogenetic origin of Taiwan spruce, additional sequencing was performed in the Chinese spruce Picea wilsonii and combined with previously published data for three other mainland China species, Picea purpurea, Picea likiangensis, and P. schrenkiana. Analysis of population structure revealed that P. morrisonicola clusters most closely with P. wilsonii, and coalescent analyses using the program MIMAR dated the split to 4–8 mya, coincidental to the formation of Taiwan. Considering the population decrease that occurred after the split, however, led to a much more recent origin.
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