What is meant by Volvocine line of evolution?
The Volvocine line of evolution is the first type of evolutionary trend in green algae (Chlorophyta). It is called volvocine trend as the unicellular Chlamydomonas develops into colonial (coenobia), motile type algae (volvocine) at the end of this line.
What is the importance of the Volvocine series in the study of development of Multicellularity?
A combination of molecular genetic and phylogenetic comparative approaches has resulted in a detailed picture of the transition from single cells to differentiated, multicellular organisms in this group. To be useful as a model system, the volvocine algae should provide information that is relevant to other groups.
How do Volvocine algae move?
The volvocine algae include both unicellular and multicellular organisms that are closely related and exist today (Kirk 1998). Chlamydomonas are single-celled organisms with two apical flagella, which they use for sensory transduction and for moving around in a wet environment (Figure 2F).
How are Chlamydomonas and Volvox different?
Chlamydomonas is unicellular and reflects the ancestral state of the group, while Volvox is multicellular and has evolved numerous innovations including germ-soma differentiation, sexual dimorphism, and complex morphogenetic patterning.
How do algae evolve?
Other scientists suggest that the red algae evolved from the Cryptophyceae, with the loss of flagella, or from fungi by obtaining a chloroplast. In support of this view are similarities in mitosis and in cell wall plugs, special structures inserted into holes in the cell walls that interconnect cells.
Is algae unicellular or multicellular?
Algae are morphologically simple, chlorophyll-containing organisms that range from microscopic and unicellular (single-celled) to very large and multicellular. The algal body is relatively undifferentiated and there are no true roots or leaves.
Are Choanoflagellates multicellular?
And in fact, some choanoflagellates do form multicellular colonies at stages of their life cycle. They suggested that the ancient common ancestor of choanoflagellates and animals was capable of forming simple colonies and that this property may well have been a first step on the road to animal evolution.
What does Volvox mean in science?
Volvox is a polyphyletic genus of chlorophyte green algae in the family Volvocaceae. It forms spherical colonies of up to 50,000 cells. They live in a variety of freshwater habitats, and were first reported by Antonie van Leeuwenhoek in 1700.
Why is Volvox important?
Volvox can be found in ponds, puddles, and bodies of still fresh water throughout the world. As autotrophs, they contribute to the production of oxygen and serve as food for a number of aquatic organisms, especially the microscopic invertebrates called rotifers.
Why is the volvocine algae a unique organism?
The volvocine algae represent a unique op- portunity to study this transition because they diverged relatively recently from unicellular relatives and because extant species display a range of intermediate grades between unicellular and multicellular, with functional specialization of cells.
When did Volvox diverge from its unicellular ancestors?
Volvox diverged from unicellular ancestors approximately 200 million years ago. Volvox colony: 1) Chlamydomonas -like cell, 2) Daughter colony, 3) Cytoplasmic bridges, 4) Intercellular gel, 5) Reproductive cell, 6) Somatic cell. Volvox is a polyphyletic genus in the volvocine green algae clade.
Is the Volvox a monoecious or dioecious species?
Volvox species can be monoecious or dioecious. Male colonies release numerous sperm packets, while in female colonies single cells enlarge to become oogametes, or eggs. Kirk and Kirk showed that sex-inducing pheromone production can be triggered in somatic cells by a short heat shock given to asexually growing organisms.
What can the green alga Volvox tell us?
Thus, the volvocine green algae and particularly V. carteri provide a unique opportunity to study multicellularity and cellular differentiation at the molecular level and to discover universal rules that characterize the transition to differentiated multicellularity.
