Jurassic Park from a Swiss lake?

March 12, 2009
Daphnia Galeata

Ecological changes caused by humans affect natural biodiversity. For example, the eutrophication of Greifensee and Lake Constance in the 1970s and 1980s led to genetic changes in a species of water flea which was ultimately displaced. Despite the fact that water quality has since been significantly improved, this species has not been re-established. This was demonstrated by researchers from Eawag and from two German universities (Frankfurt and Konstanz), who analysed genetic material from Daphnia eggs up to 100 years old.

Evolutionary biologist Nora Brede explains, animatedly: “In the laboratory, we were able to revive over 40 years old isolated from Greifensee sediment.” For Eawag, this Jurassic Park-style method has a serious purpose: it makes it possible to determine retrospectively which Daphnia was dominant in the lake around 1960, and whether the species that prevailed in the 1970s and 1980s became more tolerant of pollutants. Daphnia, which are crustaceans, can produce diapausing (resting) eggs - e.g. when food supplies are inadequate - which develop into a when environmental conditions subsequently become more favourable. As these eggs are deposited in datable layers of , their DNA can be analysed even after the passage of 100 years or more.

What makes this biological archive particularly interesting is the fact that conditions in the lake have undergone dramatic changes since 1960. In the 1970s and 1980s, inputs of phosphate detergents and fertilizer runoff led to eutrophication, with the development of , including toxic cyanobacteria (blue-green ). Fish died as a result of . As reported in the latest edition of the , the results of the genetic analysis of Daphnia eggs indicate that genetic diversity was also affected by the excessive nutrient levels. At the beginning of the 20th century, only one species of (Daphnia hyalina) occurred abundantly in the two lakes studied. As eutrophication developed, this was displaced by another species (Daphnia galeata). In the transitional periods before and after peak nutrient inputs, hybrids also developed. However, although the lakes are now once again much cleaner (thanks to major efforts in the urban wastewater management sector), the original species has yet to recover.

According to Nora Brede, “This demonstrates that anthropogenic changes, such as eutrophication, can have major and not fully reversible effects on animal species.” In addition, the research project also showed how rapidly evolutionary processes can unfold in the animal kingdom. Brede comments: “In a mere 50 years, there have been measurable changes in the genome structure of a species, which is amazing, given that this is an extremely short period on the timescale of the Earth’s history.”

Biological archives such as the resting eggs of Daphnia in lake sediments are a valuable tool for investigating how organisms respond to changes in the ecosystem. Together with its partners, Eawag is therefore making the most of these opportunities to study and gain a better understanding of evolutionary processes. Research is focusing in particular on the question of how quickly plants and animals adapt genetically to the alterations in temperature associated with global climate change.

More information: Brede, N., C. Sandrock, D. Straile, P. Spaak, T. Jankowski, B. Streit & K. Schwenk. 2009. The impact of human-made on the genetic architecture of Daphnia species. Proceedings of the National Academy of Sciences of the USA. Link: PNAS

Provided by Swiss Federal Institute of Aquatic Science and Technology

Explore further: Male water fleas observed for first time

Related Stories

Choosy females make colourful males

May 9, 2006

Female fish prefer brightly coloured males because they are easier to see and are in better shape concludes Dutch researcher Martine Maan following her study of fish speciation in the East African Lakes. Environmental variation ...

Recommended for you

Study finds 'rudimentary' empathy in macaques

December 1, 2015

(Phys.org)—A pair of researchers with Centre National de la Recherche Scientifique and Université Lyon, in France has conducted a study that has shown that macaques have at least some degree of empathy towards their fellow ...

Scientists overcome key CRISPR-Cas9 genome editing hurdle

December 1, 2015

Researchers at the Broad Institute of MIT and Harvard and the McGovern Institute for Brain Research at MIT have engineered changes to the revolutionary CRISPR-Cas9 genome editing system that significantly cut down on "off-target" ...

Which came first—the sponge or the comb jelly?

December 1, 2015

Bristol study reaffirms classical view of early animal evolution. Whether sponges or comb jellies (also known as sea gooseberries) represent the oldest extant animal phylum is of crucial importance to our understanding of ...

Trap-jaw ants exhibit previously unseen jumping behavior

December 1, 2015

A species of trap-jaw ant has been found to exhibit a previously unseen jumping behavior, using its legs rather than its powerful jaws. The discovery makes this species, Odontomachus rixosus, the only species of ant that ...

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

not rated yet Mar 13, 2009
Phosphate containing detergents were banned in Europe in the 70's.

%u201CIn a mere 50 years, there have been measurable changes in the genome structure of a species, which is amazing, given that this is an extremely short period on the timescale of the Earth%u2019s history.%u201D

How many generations of daphnia in the 50 yrs???

Amazed as Brede is (and this is good, solid research as far as it went, i.e. She should look for genetic drift over 50 yrs in a lake that is unchanged over that time, too), she's ignorant of history and the rapidity that a species with a short reproduction time can evolve, e.g. the English moth that changed from black to gray in the few years after the burning of coal was banned in the 50's. THAT was a major change in a genome too and in one 10th the time of her example.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.