Book ReviewAlejandra Manjarrez
Isa Schön, Koen Martens & Peter van Dijk:
Lost Sex: The Evolutionary Biology of Parthenogenesis.
Hardcover: 616 pages
Publisher: Springer; 2009 edition (December 4, 2009)
Price: 171.00 EUR
Aphids (also known as “plant lice” or “greenflies”) can reproduce parthenogenetically. Photo: Bugman50
Even though many animals and plants reproduce sexually, plenty of creatures don’t need males to procreate. Maybe they have chosen an even better way.
Since Darwin’s theory of evolution, scientists have tried to find an explanation for the existence of sex, which nowadays is recognised as a paradox: why look for a mate if you can reproduce without one? Why did sex evolve and why did most of the life that we see out there arise from it?
There may be no clear and unified answer explaining the ubiquity of sex in the complex lineages of eukaryotes. But what about looking at the ones that have given up sex? Plants and animals that reproduce through parthenogenesis can throw some light on one of the lesser understood paradoxes in biology.
The word “parthenogenesis” might remind some of the famous Parthenon temple on the Acropolis of Athens, and that is not surprising since both terms originate from the Greek parthenos meaning ‘virgin’ and genesis for ‘birth’, or ‘virgin birth’. Parthenogenesis is, therefore, a form of asexual reproduction where females, such as the Greek goddess Athena, to whom the Parthenon is dedicated, give birth to offspring without the involvement of males. Parthenogenetic animals and plants produce new individuals through unfertilised eggs. As its title implies, this is the major topic of Lost Sex: The Evolutionary Biology of Parthenogenesis, a publication arranged by the editors Isa Schön and Koen Martens, both of the Royal Belgian Institute of Natural Sciences, and Peter van Dijk, who currently works at Keygene, a molecular genetics R&D company in Wageningen, The Netherlands.
The first third of this extremely expensive book – it will cost you almost a euro every three pages – is mainly an introduction to the topic and to the theory that surrounds it. It includes a historical overview of how scientists have perceived sex and the absence of it in nature. Curiously, many of these chapters describe different confusions that have been raised around terminology in the field. This also reflects the complexity involved in both methods of reproduction, not yet completely unravelled.
The misunderstandings increase when botanists and zoologists get together, in part because terminology differs in both fields. For example, in plants, asexual reproduction through seeds is called ‘apomixis’ and parthenogenesis is an element of that process. In animals, however, apomixis is a form of parthenogenesis. Although in both cases it refers to the formation of eggs through the suppression of meiosis, the implications are different because the egg cell in plants is not a direct product of meiosis, as it is in animals. Since the book deals with both groups, the chapters explaining asexual reproduction in each of the two multicellular lineages, as well as a clarification of their differences and terminology, are greatly appreciated.
The rest of this section focuses on evolutionary theory related to asexuality. Although these chapters are appealing and well organised, one downside is that some of them offer overlapping, and therefore redundant, information.
Examples range from the ‘evolutionary scandal’ of classic bdelloid rotifers, ‘ancient asexuals’ that contradict the assumption that “multicellular eukaryotes that abandon sex are doomed to early extinction”, to reptiles (the only vertebrates where true parthenogenesis is found) via dandelions, a common flowering plant example. The approach to each case is very thorough and includes detailed descriptions. This encyclopaedic section, written by specialists, is possibly the most valuable part of the book, as there is currently no other up-to-date compendium of these organisms.
Lost Sex is a wonderful reference work. Its target audience includes biology students and researchers at any level. Given its specialist textbook structure, it can only be recommended to laypeople with a modicum of background reading. Its high price, however, is likely to deter even the most enthusiastic amateur.
Letzte Änderungen: 29.07.2013