Evolutionary biologist at Bielefeld University compiles international special
issue on sperm competition
Why do male animals need millions of sperms every day in order to reproduce?
And why are there two sexes anyway? These and related questions are the
topic of the latest issue of the research journal Molecular Human Reproduction
(published 16 October 2014). The evolutionary biologist Steven Ramm from
Bielefeld University Bielefeld has compiled this special issue on sperm
competition.
In nature, it is not unusual for a female to copulate with several males in quick succession – chimpanzees are one good example. ‘The sperm of the different males then compete within the female to fertilize the eggs,’ says Ramm. ‘Generally speaking, the best sperm wins. This may involve its speed or also be due to the amount of sperm transferred. It can also be useful for the seminal fluid to be viscous, meaning it sticks inside the female reproductive tract to try to keep other sperm at bay.’
When the sperm of one male compete with those of another, the sperm cells
they produce need to be well adapted to this ‘fight over the egg’.
‘Producing the optimum sperm type occurs in the testis, during spermatogenesis,’
explains Ramm. This is the topic of his own article, written together
with three colleagues from the Universities of Basel (Switzerland) and
Münster. Sperm are considered to be the most diverse type of cell
in the entire animal kingdom. The researchers describe how different sperm
cells are formed in for example flies, roundworms, and vertebrates. They
also show that it is not just the amount of sperm that is important, but
also its form. ‘Even just the size of the individual sperm cell
may provide a competitive advantage,’ says Ramm. Alongside human
sperm that are tiny and swim with their tails, there are, for example,
spherical and crawling sperm or even giant sperm that are larger than
the male that produces them.
Evolutionary biologists study how living creatures have developed over
millions of years. They focus on asking how they are adapted to their
environment. ‘The main concern in our special issue is to try to
understand why reproduction in animals happens in the way that it does,’
says Ramm. ‘In the long term, this knowledge could, for example,
help reproductive biologists to modify sperm genetically to increase the
chance of fertilization. One possible application of such methods could
be to help conserve endangered species.’
Dr. Steven Ramm has been engaged in research at Bielefeld University’s
Faculty of Biology since 2012. One of his research topics in the Department
of Evolutionary Biology is to identify what characteristics of male animals
enable them to successfully reproduce. In 2006, Ramm graduated with his
doctorate from the University of Liverpool (England) where he carried
on doing research until 2009. This was followed by research at the University
of Innsbruck (Austria) and the University of Basel (Switzerland). Ramm
is leading the project ‘Functional and evolutionary genetics of
seminal fluid’, funded by the German Research Foundation (DFG).
He is also responsible for the EU research project ‘SpermEvolution’.
Steven A. Ramm, Sperm competition and the evolution of reproductive systems (Editorial). Molecular Human Reproduction, http://dx.doi.org/10.1093/molehr/gau076 , published on 16 October 2014
Steven A. Ramm, Lukas Schärer, Jens Ehmcke, Joachim Wistuba, Sperm competition and the evolution of spermatogenesis. Molecular Human Reproduction, http://dx.doi.org/10.1093/molehr/gau070 , published on 16 October 2014
Contact:
Dr. Steven Ramm, Bielefeld University
Faculty of Biology
Telephone: +49 521 106-2719
Email: steven.ramm@uni-bielefeld.de