Research

Current interests

Autopolyploidy in Physcomitrium

NSF funded grant (DEB-1753673)Diversity of Physcomitrium pyriforme in North America and Europe: significance of autopolyploidy within a phylogenomic and experimental framework. A collaborative project with Dr. Bernard Goffinet (UConn) and Dr. Matt Johnson (Texas Tech. University)

Plants are weird. Many of the mechanisms that result in the birth and diversification of new plant species differ from those that have been discovered using animal models, which are the majority. One of the favorite tricks of plant evolution involves the duplication of the genome (autopolyploidy: cells gain a complete extra set of chromosomes). In fact, we know that numerous plant evolutionary bursts were correlated with autopolyploidy events, including many that gave rise to current species of economic interest. However, the evolutionary significance of autopolyploidy is still not completely understood despite its relevance. Whole genome duplications are often difficult to detect, and at best we see their outcomes long after they occurred, since they are not always easy to observe under lab conditions. In this project we will address the role and consequences of polyploidy in plant evolution using as model organism the goblet moss (Physcomitrium pyriforme).

Normal life cycle of the goblet moss (A) and process to produce artificial autopolyploids in the lab (B)

This moss is ideally suited for this purpose: it harbors a morphologically-diverse complex of seven karyotypes, it is easily grown in the laboratory, and its genome content can be doubled with precision in vitro to create autopolyploid offspring. The goals of this collaborative project are to produce a phylogeny of the Physcomitrium pyriforme species-complex based on genome sequence data, to estimate past changes of genomic load over evolutionary time, and to compare reproductive barriers among naturally-occurring and artificially-induced autopolyploids.

In our lab we will be generating artificial autopolyploids, testing their fertility and their reproductive compatibility with their wild counterparts, and performing morphometric analyses to detect changes in the phenotype produced by the whole genome duplications. If you are a student in Augie and want to be a part of this, contact me! (Read more)

Phylogenomics of the Funariaceae

PipettingI conducted my research on the family Funariaceae using a phylogenomic approach when I was in the Goffinet lab. The ultimate objective of this project was to understand how the rapid radiation that characterizes this family occurred, resulting in the diversity of sporophytic architectures that we see today.

After culturing species from all over the world, collected by our collaborators and ourselves, I extracted the DNA and obtained genomic data combining High-Throughput Sequencing with targeted gene enrichment. We collected sequences from a selection of more than 90 Funariaceae (and outgroups), including all the coding organellar genes (83 from the chloroplast and 40 from the mitochondrial genome) and a selection of 600 nuclear single-copy genes.

IMG_0415Unlike our previous approaches using a limited number of genes, the analyses of the genomic data show resolved phylogenies for the organellar datasets, evidence of intergeneric hybridizations and re-gain of complex traits.

Publications: Medina et al. 2018. Molecular Phylogenetics and Evolution 120: 240-247 https://doi.org/10.1016/j.ympev.2017.12.002; Johnson et al. 2016. Applications in Plant Science 4: 1600016 https://doi.org/10.3732/apps.1600016; Medina et al. 2015 The Bryologist 118(1) https://doi.org/10.1639/0007-2745-118.1.022

Bryophytes of the Driftless Area (BRYDA)

The Driftless Area is a region of the upper Mississippi basin without geological evidence of glaciation during the Pleistocene. It is well known in biogeography due to its status of paleorefugium, demonstrated for many different relictual species and populations of plants and animals. The DA comprises unique ecosystems such as the algific talus slopes that host some of the oldest plant communities in the region. These habitats host a distinct combination of boreal and lowland bryophytes that remains vastly under-explored.  This project will assess the bryoflora of the DA with emphasis on the algific talus slopes and will test the relictual status of some of its most significant bryophytes using DNA fingerprinting. (Read more)

Bryophyte Flora of the Quad Cities area

LTID

Our lab is actively contributing to improve the knowledge of the local bryophyte flora (Scott county in Iowa and Rock Island county in Illinois), an area whose mosses and liverworts have never been systematically surveyed. Loud Thunder, a forest preserve by the Mississippi, was the first site we decided to explore. It combines several native ecosystems such as hickory-oak deciduous forest, silver maple floodplain forest and restored tallgrass prairies. Eric Shershen and Carissa Gilliland completed a catalog that included 19 new records for the county. Some of our new sites include Black Hawk Forest and Credit Island.

Publication: Shershen et al. 2018. Evansia 35

 

Other projects

Collaborations

  • I am part of the project funded by the Spanish Ministry of Science “Aproximación a los patrones de diversificación en un grupo fundamental de musgos epífitos mediante la resolución efectiva de su filogenia: Orthotrichoideae (Orthotrichaceae, Bryophyta)”, led by Dr. Isabel Draper
  • I took part in the sequencing and assembly of the mitochondrial genome of the moss Oxystegus tenuirostris, the project of Marta Alonso during her visit to our lab in 2015. Publication: Alonso et al. 2015. Mitochondrial DNA DOI: 10.3109 / 19401736.2015.1082087
  • I have collaborated with Dr. Yang Liu in his research on the evolution of the mitochondrial genome across the green plants. The assemblage of 12 newly sequenced bryophyte mitochondrial genomes demonstrated a structural stasis within mosses that has persisted since the Carboniferous. Publication: Liu et al. 2014 Molecular Biology and Evolution 31: 2586–2591

Taxonomy and phylogenetics of Orthotrichum

comosum2My Ph.D. dissertation topic focused on the species delimitation of some particular complexes within Orthotrichum, a diverse moss genus widely distributed in temperate epiphytic habitats and well known for its tricky taxonomy. Two taxa in particular, Orthotrichum tenellum Bruch ex Brid. and Orthotrichum consimile Mitt., previously considered disjunct species present in the Western Palearctics and Western North America, became the center of the project due to their morphological variability. Our integrative approach was based on the reciprocal illumination between a deep taxonomical revision and a phylogenetic reconstruction based on six loci from the chloroplast and the nuclear genomes.

The results of the study included the description of seven species new to science, the resurrection of two synonymized taxa and a more precise knowledge of the biogeography and evolution of this bryophyte lineage.

DSC00879PhD dissertation (pdf version) (Advisors: Drs Mazimpaka, Lara and Garilleti)

Main PhD publications: Medina et al. 2013 Taxon 62(6): 1133-1152; Medina et al. 2012 Taxon 61(6): 1180-1198; Medina et al. 2011 The Bryologist 114(2): 316-624; Medina et al. 2009 Journal of Bryology 31:86-92; Medina et al. 2008 The Bryologist 111(4): 670-675.

My participation in other side projects related to Orthotrichum has resulted in the delimitation of the genus Lewinskya (Lara et al. 2016. Cryptogamie, Bryologie), the study on the evolutionary history of the Canarian endemic Orthotrichum handiense (Patiño et al. 2013 Journal of Biogeography 40(5): 857-868), assistance in the elaboration of a new European key (Lara et al. 2009 Cryptogamie, Bryologie 30(1): 129-142) and several chorological records (Medina et al. 2012 Journal of Bryology 34(1): 52-55; Lara et al. 2010 Nova Hedwigia 138: 163-178; Garilleti et al. 2009 Journal of Bryology 31: 46-47; etc)

Epiphytic bryophytes of juniper forests

sabinarThe objectives of the project for my Diploma de Estudios Avanzados (≈ M.Sc.) were the characterization and classification of the epiphytic bryophyte communities of the forests of incense juniper (Juniperus thurifera). Incense junipers are endemic conifers of the Western Mediterranean region adapted to survive in harsh conditions of low precipitation and wide temperature intervals and also a hostile habitat for most epiphytic bryophytes. I planned and conducted most of the field work that included a representative  sampling of the main distribution cores of this juniper: mountains and high plateaus of the Iberian Peninsula, Morocco and the French Alps. The epiphytic communities were identified in the lab and their composition analyzed and compared with other forests’.

The study showed that these ecosystems host a very singular and rather constant combination of xerophytic bryophytes including rare species such as Orthotrichum vittii and O. tortidontium, enhancing even more the interest of such a particular type of forest.

Publication: Medina et al. 2010. Journal of Bryology 32: 23-31

Bryophyte collections, forays and small floristic works

Scuspidatum-rubellumI have collected more than 1,400 bryological collections from China, Ethiopia, France, Greece, Morocco, South Africa, Spain, Turkey and the United States of America (CA, CT, GA, SC, IA, KS, IL, LA, MA, ME, NH, NV, OK, WI), most of these specimens are kept at AUGIE, CONN and MAUAM.

I have contributed to different floristic notes published by the participants of the meetings of the Spanish Bryological Society (González Mancebo et al. 2007 Boletín de la Sociedad Española de Briología. 30/31: 43-51; Elías et al., 2006 Boletín de la Sociedad Española de Briología. 28: 25-31, etc); local floristic works (Villaverde et al. 2008 Boletín de la Sociedad Española de Briología. 32/33: 21-29; Medina, N.G. et al. 2008 Boletín de la Sociedad Española de Briología. 32/33: 1-7, etc) and mentored two unpublished B.Sc. theses focusing on the bryophyte flora of singular communities of the Spanish Central Range.