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A Major Evolutionary Transition To More Than Two Sexes?, Joel D. Parker
A Major Evolutionary Transition To More Than Two Sexes?, Joel D. Parker
Joel D Parker
Two recently discovered cases of genetic caste determination in social insects might provide the first example of a major evolutionary transition from two to more than two sexes. I argue here that the system can be interpreted as comprising primarily individuals requiring gametes from three parental types and having four sexes from the perspective of demographic extinction. Additionally, I show how this mating system can be seen as a major evolutionary transition. For these populations, it is apparent that the mechanism for a three- or four-sex system does not lie within the myriad of possible arrangements of chromosomes within individuals, …
Molecular Phylogenetic Evidence For An Extracellular Cu Zn Superoxide Dismutase Gene In Insects, Joel D. Parker
Molecular Phylogenetic Evidence For An Extracellular Cu Zn Superoxide Dismutase Gene In Insects, Joel D. Parker
Joel D Parker
Representatives of three ancient gene families of the antioxidant enzyme superoxide dismutase (SOD) can be found in most metazoans. In mammals and Caenorhabditis elegans , there is at least one gene each of the cytoplasmic, mitochondrial and extracellular lineages of SOD genes. The cytoplasmic SOD was one of the first enzymes to be implicated in ageing due to its protection against damaging oxygen free radicals. In contrast to other metazoans, insects were thought to lack a gene for the extracellular SOD. We have cloned and sequenced an SOD mRNA in the ant Lasius niger that appears to belong to this …