Without a doubt, the emergenceof eukaryotic fossils is not only extremely interesting, but is also asignificant event for the diversity of life on planet Earth. Regardless of the way theyoriginated, eukaryotes have had a significant impact on diversity and life onearth. Eukaryotes resulted in the diversity of microbial predators 750 millionyears ago. As ecological theory predicts that diversity at one level of thefood web will cause diversity at lower levels, this abundance of microbialpredators may have fueled diversification as a whole.
Additionally, theemergence of eukaryotic organisms would have led to the emergence of sexualreproduction, in turn allowing for greater genetic variation and evolution. (Porter,2004) We are also unsure of howexactly eukaryotes came to be, as they are similar to archaea and Bacteria, butalso possess some specific characteristics. This being said, some theories regardingthe development of eukaryotes include the fusion of several prokaryotic cells,or evolution from a proto-eukaryotic last common ancestor. (Javeaux, 2007) Due to the fossil record beinginconsistent, we are unable to provide exact historical dates as to when eukaryotesemerged.
However, the best estimates we have indicate that eukaryotic crowngroups would have originated 1200 million years ago, although perhaps as earlyas 1700 million years. (Porter, 2004) Before looking at theappearance of eukaryotic fossils, we must first define what a eukaryote is. Eukaryotesare one of the 3 major domains of life, the others being archaea and bacteria,which are prokaryotes. What separates eukaryotes from their counterparts is theexistence of a membrane bound nucleus, a complex endomembrane system, andorganelles such as mitochondria and plastids.
Eukaryotes are perhaps best knownfor including in their domain multicellular organisms, including plants, aswell as animals. Looking back at the fossil record, we are able to learn aboutthe earliest eukaryotes, and consider questions such as how they came about,how long ago, and the impact the development of eukaryotes had on life onEarth. (Porter, 2004)