I addressed how light availability influences sexual and clonal offspring production, demographic performance and contribution to population dynamics by studying the Neotropical understory herb Calathea marantifolia across a light gradient in Costa Rica. To understand how demographic performance was influenced by light availability I conducted a transplant experiment in the field. Both seedlings and clonal offspring grew best when planted in high light areas, but seedlings showed a faster and more dramatic response. Survival of seedlings was greatest in high light sites but clonal offspring survival was greatest where light availability was low. To examine the demographic consequences of physiological integration between parent plants and their clonal offspring I combined an isotope tracing study with a severing experiment in natural populations. Very little water was transported between parent and offspring. Severing the connections between parent and offspring did not influence the demographic performance of parent plants, but clonal offspring were negatively affected, especially prior to rooting. I investigated the demographic cost of sexual reproduction by manipulating the sexual reproductive effort of plants in the field. Increasing the sexual reproductive effort of plants did not reduce their future demographic performance. However, subsequently produced clonal offspring displayed a small reduction in size due to their parent's increased reproduction. To understand the contribution of both reproductive modes for population growth rate I used field data collected in plots with high and low light. Data from the first census interval were used to develop a new size-structured integral projection model that includes both sexual and clonal recruitment. Population growth rate was faster in high light than in low light and a life table response experiment revealed that this difference was primarily due to improved survival and growth at large sizes and increased clonal reproduction in high light. By removing reproductive modes from the model, I found that sexual reproduction contributes more to population growth than clonal reproduction. When only sexual reproduction is included in the model population growth rate is fastest in high light environments. By contrast, when only clonal reproduction is included in the model population growth rate is fastest low light.

Although capable of sexual reproduction, many plants also rely heavily on clonal reproduction. The formation of multiple, physiologically-independent units with the same genotype has important implications for spatial genetic structure and genetic diversity in these plants. The endangered scrub-dwelling perennial, Polygonella myriophylla is known to reproduce both sexually and clonally but no study to date has been able to investigate the spatial genetic patterns that occur in this species. I use microsatellite markers to investigate questions about clonal structure and genetic diversity in five populations of P. myriophylla and address some of the implications of my findings for conservation of this species: Overall, I find that 57% of sampled clusters of P. myriophylla are composed of a single genet (genetic individual) with multiple physiological units (ramets) while the remainder are made up of two or more genets. I found differences in both clonal reproduction and genetic diversity among populations. I also found evidence of limited gene flow even over small spatial scales (less than 10 km) and for at least 4 genetic clusters occurring within the species range. Despite high levels of genetic diversity overall, there is evidence of reduced genetic diversity in two populations My results suggest that high levels of clonality may be important in maintaining genetic diversity in P. myriophylla. I also provide evidence that dirt roadsides may not represent a refuge for this species.

Seagrass restoration of Halodule wrightii, has become crucial as seagrass coverage in the Indian River Lagoon (IRL) declined by 58% between 2011 and 2019. To understand the abundance of seagrass fragments available for natural recruitment and restoration, we tracked the abundance of viable fragments found in the wrack in Mosquito Lagoon. Wrack is plant material, including seagrass fragments, mangrove propagules, and detritus. Seagrass fragments were considered viable if the fragment had an apical meristem present. Replicate samples were collected from 5 locations every two weeks, starting in September 2022 and ending in September 2023, and the samples were processed in the laboratory. To date, H. wrightii is the most common species and is most abundant during the fall season. Among the total H. wrightii fragments collected, 54.1% had apical meristems, the growth tips needed to produce leaf-bearing shoots. Annually, on average, 7 fragments with apical meristems per square meter a month were recorded. Among only fragments with an apical meristem found during this study, 92.8% had less than five shoots. The average fragment that was washing ashore had only two shoots. This study will assist restoration practitioners in understanding the availability of viable H. wrightii fragments for natural and active restoration efforts.

Univerzita Karlova v Praze Přírodovědecká fakulta Studijní program: Molekulární biologie, genetika a virologie Bc. Jan Röslein Mutační a substituční tempo u sexuálních a klonáních forem: možný klíč k vysvětlení persistence sexu u modelové skupiny sekavců Mutation AND substitution rates in sexual and asexual forms: a clue to the persistence of sex in a model group of Cobitis? Typ závěrečné práce Diplomová Vedoucí závěrečné práce: Mgr. Karel Janko, Ph.D. Praha, 2015 Velký dík náleží mému školiteli Mgr. Karlu Jankovi, Ph.D. za velmi nápomocné, direktivní vedení práce. Též bych rád poděkoval panu Mgr. Janu Pačesovi, Ph.D. za více než vzdělávací rozměr v oblasti bioinformatické analýzy a Mgr. Ladislavu Pekárikovi, Ph.D., Mgr. Janu Kočímu za pomoc při analýze vybraných kapitol. Také bych rád poděkoval rodině za podporu. Všem participantům na této diplomové práci se hluboce omlouvám za způsobenou psychickou újmu. Prohlášení: Prohlašuji, že jsem závěrečnou práci zpracoval/a samostatně a že jsem uvedl/a všechny použité informační zdroje a literaturu. Tato práce ani její podstatná část nebyla předložena k získání jiného nebo stejného akademického titulu. V Praze dne 12. 8. 2015 Podpis: Abstrakt Klíčová slova: Abstract Key words: Obsah 1...

TITLE: Mutation and substitution rates in sexual and asexual forms: a clue to the persistence of sex in a model group of Cobitis? AUTOR: Jan Röslein DEPARTMENT: Ústav živočišné fyziologie a genetiky AVČR, v.v.i. SUPERVISOR: Mgr. Karel Janko, Ph.D. ABSTRACT: Subject of this thesis is to test several hypotheses about the evolution of asexual reproduction in model group of fish family Cobitis and its mutual competition among sexual and asexual forms, which touches one of the oldest unresolved issues of biology. Specifically, the work deals with the accumulation of non-synonymous mutations, which accelerated accumulation in the genome of clonal lineages theoretically leads to increased extinction compared with sexually reproducing populations (so-called. The theory of Muller's ratchet and Kondrashov's hatchet). This thesis is based on a normalized cDNA sequencing data from oocytes and liver tissue, which has served as a base matrix (generated based on non-normalized cDNA data) for transcriptome sequencing (RNAseq). Consequently, the RNAseq data have served as validation for acquired polymorphisms, detection of differential expression of allele- specific expression (ASE) hybrid biotypes. This diploma thesis balances among the edges of vast spectrum of hypotheses regarding the evolution of the genus hybrid...