Parecer da Comissão Científica

Projeto Externo - de Outra Unidade da USP

Dados do solicitante

Laurel Hiebert

Natureza do projeto

Projeto de docente ou pesquisador
Projeto de Pós-Doutorado

Pesquisadores ou docentes associados


Bolsa de Pós-Doutorado

Descrição do projeto

Origens da colonialidade: mecanismos de desenvolvimento e direcionalidade da coalescência colonial em ascídias [Origins of coloniality: Developmental mechanisms and directionality of colonial coalescence in ascidians]
Coloniality evolved numerous times within the metazoans, leading to many convergent ecological and developmental features that differ from those associated with a solitary lifestyle. Colonial animals - those having the capacity to asexually reproduce and remain connected - not only grow and occupy space differently from their solitary relatives, but they also show extensive regeneration abilities, have unique allorecognition systems and display systematized senescence. Many of these features are linked to the fact that colonial species posses tissues besides the germline that remain pluripotent. In order to determine the origins of coloniality and the traits associated with the colonial life style, I plan to examine the evolutionary origins and functions of these pluripotent cells. Along with collaborators, I will examine stem cells in the vascular system of ascidians (subphylum Tunicata), which are essential for asexual budding and regeneration in colonial species. We will focus on the family Styelidae since they exhibit broad variation in the degree of coalescence, i.e. some are solitary, some clone and remain only loosely connected, and others are highly integrated, sharing a tunic and vasculature. We will compare stem cell populations in styelids to test the hypothesis that more highly coalesced species have more abundant and more diverse stem cell types. We will reconstruct the phylogenetic origins of the stem cell types and degree of coalescence within the styelids. We will focus on transcriptome-based tree reconstruction. I will determine if abundances of particular stem cell types correlates to life history phases (i.e. sexually reproducing vs. asexually proliferating). Results from this study will be essential to our understanding of how blood stem cells function and how they originated and diversified. In addition, I plan to explore the environmental factors that favor the evolution of coloniality along the Southweste
Coloniality, ascidians, evolutionary transitions, stem cells
Our understanding of ecology, evolution, and development comes primarily from the study of solitary organisms. However, many plants, animals, and fungi are colonial - they are made up of connected asexually-derived modules. Within the animals, colonial forms such as corals, hydroids, bryozoans, and ascidians exhibit higher diversity than solitary forms and predominate the hard-substratum communities of shallow seas. Thus, animals with a colonial lifestyle make up a major component of Earth s biodiversity.
Unlike most solitary species, many colonial animals can pass on their genes in two ways: sexually and asexually. Sexual reproduction in colonial marine invertebrates typically involves release of sperm and eggs into the water, or just sperm, in which case the eggs are brooded. Time to larval settlement in clonal species is often rapid compared to aclonal species, leading to short dispersal distances for many clonal species. Asexual reproduction of clonal animals involves budding, fission, fragmentation, or other mechanisms, in which units typically remain organically attached to the colony. Clonal units are generally smaller than their solitary counterparts in ecologically-equivalent species. However, clonal animals can grow rapidly compared to solitary species and have the ability to utilize patchy resources and obtain large biomasses. Clonal species also have the ability to survive damage and quickly regenerate lost parts. In general, clonal animals do not exhibit senescence, thus they live far longer than aclonal animals.
The origins, significance, and underlying mechanisms of many features particular to colonial organisms are poorly understood. Regeneration, escape from senescence, and other traits of clonal animals are partially explained by the fact that, unlike in solitary animals, the germline is not
2015 Semester II: Ascidian collection for phylogenetics, RNA extraction and cDNA preparation, begin examining field sites for ecological study.
2016 Semester I: Ascidian collection, RNA extraction and cDNA preparation, observational study of ecological parameters affecting coloniality.
2016 Semester II: Transcriptome sequencing and assembly, Phylogenetic analysis, Stem cell identification, Set up study to examine role of ecological parameters that influence abundance of colonaial and solitary species.

2017 Semester I: Examination of abundances of distinct stem cell populations in various reproductive modes, Finish ecological study.


Table for lab work, seawater table
Dissecting microscope
Ascidians (family Styelidae)
Ilhabela, Praia Grande, Alrededores do CEBIMAR
Não aplicável
Por favor, selecione
Por favor, selecione