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Floral evolution of Philodendron subgenus Meconostigma (Araceae).

de Oliveira LL, Calazans LS, de Morais É, Mayo SJ, Schrago CG, Sakuragui CM - PLoS ONE (2014)

Bottom Line: Our phylogeny shows that Meconostigma is composed of two major clades, one comprising two Amazonian species and the other all the species from the Atlantic Forest and Cerrado biomes with one Amazonian species.The evolution of these characters seems to have occurred independently in some lineages.We propose that the morphological and anatomical diversity observed in the gynoecial structures of subgenus Meconostigma is the result of an ongoing process of fusion of floral structures leading to a reduction of energy wastage and increase in stigmatic surface.

View Article: PubMed Central - PubMed

Affiliation: Departamento de Genética, Instituto de Biologia, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil.

ABSTRACT
Elucidating the evolutionary patterns of flower and inflorescence structure is pivotal to understanding the phylogenetic relationships of Angiosperms as a whole. The inflorescence morphology and anatomy of Philodendron subgenus Meconostigma, belonging to the monocot family Araceae, has been widely studied but the evolutionary relationships of subgenus Meconostigma and the evolution of its flower characters have hitherto remained unclear. This study examines gynoecium evolution in subgenus Meconostigma in the context of an estimated molecular phylogeny for all extant species of subgenus Meconostigma and analysis of ancestral character reconstructions of some gynoecial structures. The phylogenetic reconstructions of all extant Meconostigma species were conducted under a maximum likelihood approach based on the sequences of two chloroplast (trnk and matK) and two nuclear (ETS and 18S) markers. This topology was used to reconstruct the ancestral states of seven floral characters and to elucidate their evolutionary pattern in the Meconostigma lineage. Our phylogeny shows that Meconostigma is composed of two major clades, one comprising two Amazonian species and the other all the species from the Atlantic Forest and Cerrado biomes with one Amazonian species. The common ancestor of the species of subgenus Meconostigma probably possessed short stylar lobes, long stylar canals, a stylar body, a vascular plexus in the gynoecium and druses in the stylar parenchyma but it is uncertain whether raphide inclusions were present in the parenchyma. The ancestral lineage also probably possessed up to 10 ovary locules. The evolution of these characters seems to have occurred independently in some lineages. We propose that the morphological and anatomical diversity observed in the gynoecial structures of subgenus Meconostigma is the result of an ongoing process of fusion of floral structures leading to a reduction of energy wastage and increase in stigmatic surface.

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Morphological characters of Philodendron subg. Meconostigma.a. P. bipinnatifidum inflorescence as an example of a typical Philodendron subg. Meconostigma inflorescence, b. Upper view of some of the P. bipinnatifidum female flowers showing stylar lobes, c. Longitudinal cut of P. bipinnatidifum female flowers, d. Transversal cut of a P. bipinnatifidum female flower, e. Longitudinal cut of a P. adamantinum female flower. Acronyms list: MZ = male zone; SZ = sterile male zone; FZ = female zone; SL = stylar lobes; SB = stylar body; SC = stylar canals; Ov = ovules; Lo = locules; Dr = druses; Ra = raphides.
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pone-0089701-g002: Morphological characters of Philodendron subg. Meconostigma.a. P. bipinnatifidum inflorescence as an example of a typical Philodendron subg. Meconostigma inflorescence, b. Upper view of some of the P. bipinnatifidum female flowers showing stylar lobes, c. Longitudinal cut of P. bipinnatidifum female flowers, d. Transversal cut of a P. bipinnatifidum female flower, e. Longitudinal cut of a P. adamantinum female flower. Acronyms list: MZ = male zone; SZ = sterile male zone; FZ = female zone; SL = stylar lobes; SB = stylar body; SC = stylar canals; Ov = ovules; Lo = locules; Dr = druses; Ra = raphides.

Mentions: To infer evolutionary changes in the gynoecium, we composed a reduced data set containing the 22 species that were characterized morphologically. It consisted of 19 species of subgenus Meconostigma (P. xanadu and P. leal-costae are absent in this analysis) with two other Philodendron species {subgenus Philodendron (1), subgenus Pteromischum (1)} and one Homalomena species as outgroup. The morphological character states of the gynoecium are listed in Table S4 in File S1, as well as the state codes used to construct our matrix. Figure 2 illustrates these characters. The terminology used to name the characters follows the definitions of Mayo [4].


Floral evolution of Philodendron subgenus Meconostigma (Araceae).

de Oliveira LL, Calazans LS, de Morais É, Mayo SJ, Schrago CG, Sakuragui CM - PLoS ONE (2014)

Morphological characters of Philodendron subg. Meconostigma.a. P. bipinnatifidum inflorescence as an example of a typical Philodendron subg. Meconostigma inflorescence, b. Upper view of some of the P. bipinnatifidum female flowers showing stylar lobes, c. Longitudinal cut of P. bipinnatidifum female flowers, d. Transversal cut of a P. bipinnatifidum female flower, e. Longitudinal cut of a P. adamantinum female flower. Acronyms list: MZ = male zone; SZ = sterile male zone; FZ = female zone; SL = stylar lobes; SB = stylar body; SC = stylar canals; Ov = ovules; Lo = locules; Dr = druses; Ra = raphides.
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC3935929&req=5

pone-0089701-g002: Morphological characters of Philodendron subg. Meconostigma.a. P. bipinnatifidum inflorescence as an example of a typical Philodendron subg. Meconostigma inflorescence, b. Upper view of some of the P. bipinnatifidum female flowers showing stylar lobes, c. Longitudinal cut of P. bipinnatidifum female flowers, d. Transversal cut of a P. bipinnatifidum female flower, e. Longitudinal cut of a P. adamantinum female flower. Acronyms list: MZ = male zone; SZ = sterile male zone; FZ = female zone; SL = stylar lobes; SB = stylar body; SC = stylar canals; Ov = ovules; Lo = locules; Dr = druses; Ra = raphides.
Mentions: To infer evolutionary changes in the gynoecium, we composed a reduced data set containing the 22 species that were characterized morphologically. It consisted of 19 species of subgenus Meconostigma (P. xanadu and P. leal-costae are absent in this analysis) with two other Philodendron species {subgenus Philodendron (1), subgenus Pteromischum (1)} and one Homalomena species as outgroup. The morphological character states of the gynoecium are listed in Table S4 in File S1, as well as the state codes used to construct our matrix. Figure 2 illustrates these characters. The terminology used to name the characters follows the definitions of Mayo [4].

Bottom Line: Our phylogeny shows that Meconostigma is composed of two major clades, one comprising two Amazonian species and the other all the species from the Atlantic Forest and Cerrado biomes with one Amazonian species.The evolution of these characters seems to have occurred independently in some lineages.We propose that the morphological and anatomical diversity observed in the gynoecial structures of subgenus Meconostigma is the result of an ongoing process of fusion of floral structures leading to a reduction of energy wastage and increase in stigmatic surface.

View Article: PubMed Central - PubMed

Affiliation: Departamento de Genética, Instituto de Biologia, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil.

ABSTRACT
Elucidating the evolutionary patterns of flower and inflorescence structure is pivotal to understanding the phylogenetic relationships of Angiosperms as a whole. The inflorescence morphology and anatomy of Philodendron subgenus Meconostigma, belonging to the monocot family Araceae, has been widely studied but the evolutionary relationships of subgenus Meconostigma and the evolution of its flower characters have hitherto remained unclear. This study examines gynoecium evolution in subgenus Meconostigma in the context of an estimated molecular phylogeny for all extant species of subgenus Meconostigma and analysis of ancestral character reconstructions of some gynoecial structures. The phylogenetic reconstructions of all extant Meconostigma species were conducted under a maximum likelihood approach based on the sequences of two chloroplast (trnk and matK) and two nuclear (ETS and 18S) markers. This topology was used to reconstruct the ancestral states of seven floral characters and to elucidate their evolutionary pattern in the Meconostigma lineage. Our phylogeny shows that Meconostigma is composed of two major clades, one comprising two Amazonian species and the other all the species from the Atlantic Forest and Cerrado biomes with one Amazonian species. The common ancestor of the species of subgenus Meconostigma probably possessed short stylar lobes, long stylar canals, a stylar body, a vascular plexus in the gynoecium and druses in the stylar parenchyma but it is uncertain whether raphide inclusions were present in the parenchyma. The ancestral lineage also probably possessed up to 10 ovary locules. The evolution of these characters seems to have occurred independently in some lineages. We propose that the morphological and anatomical diversity observed in the gynoecial structures of subgenus Meconostigma is the result of an ongoing process of fusion of floral structures leading to a reduction of energy wastage and increase in stigmatic surface.

Show MeSH
Related in: MedlinePlus