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Chlamydomonas reinhardtii is a unicellular green alga whose lineage diverged from land plants over 1 billion years ago. It is a model system for studying chloroplast-based photosynthesis, as well as the structure, assembly, and function of eukaryotic flagella (cilia), which were inherited from the common ancestor of plants and animals, but lost in land(More)
The multicellular green alga Volvox carteri and its morphologically diverse close relatives (the volvocine algae) are well suited for the investigation of the evolution of multicellularity and development. We sequenced the 138-mega-base pair genome of V. carteri and compared its approximately 14,500 predicted proteins to those of its unicellular relative(More)
The fitness of an evolutionary individual can be understood in terms of its two basic components: survival and reproduction. As embodied in current theory, trade-offs between these fitness components drive the evolution of life-history traits in extant multicellular organisms. Here, we argue that the evolution of germ-soma specialization and the emergence(More)
Explaining the adaptive value of sex is one of the great outstanding problems in biology. The challenge comes from the difficulty in identifying the benefits provided by sex, which must outweigh the substantial costs of sex. Here, we consider the adaptive value of sex in viruses, bacteria and fungi, and particularly the information available on the adaptive(More)
Reproductive altruism is an extreme form of altruism best typified by sterile castes in social insects and somatic cells in multicellular organisms. Although reproductive altruism is central to the evolution of multicellularity and eusociality, the mechanistic basis for the evolution of this behaviour is yet to be deciphered. Here, we report that the gene(More)
The continued well being of evolutionary individuals (units of selection and evolution) depends upon their evolvability, that is their capacity to generate and evolve adaptations at their level of organization, as well as their longer term capacity for diversifying into more complex evolutionary forms. During a transition from a lower- to higher-level(More)
Programmed cell death (PCD) represents a significant component of normal growth and development in multicellular organisms. Recently, PCD-like processes have been reported in single-celled eukaryotes, implying that some components of the PCD machinery existed early in eukaryotic evolution. This study provides a comparative analysis of PCD-related sequences(More)
Although the conditions favoring altruism are being increasingly understood, the evolutionary origins of the genetic basis for this behavior remain elusive. Here, we show that reproductive altruism (i.e., a sterile soma) in the multicellular green alga, Volvox carteri, evolved via the co-option of a life-history gene whose expression in the unicellular(More)
Contrary to conventional views that assume all cells in a neoplasm can propagate the tumor, the cancer stem cell hypothesis posits that only a fraction of the cells (the cancer stem cells) can act as tumor-propagating cells, while most of the tumor is composed of cells with limited replication potential. Here, we offer an evolutionary approach to this(More)