Cannibalism of the young allows individual fish to specialize

May 23, 2007

Whitefish, Arctic char, threespine stickleback and some sunfishes display quite discrete groups living in the same lakes but utilizing different food resources in order to survive. The phenomenon is called "resource polymorphism." Why don't all species show this pattern? Early cannibalism is found in all species displaying resource polymorphism.

If you go fishing for Arctic char you may end up catching distinctly different-looking individuals although they were all caught in the same lake. Similarly, whitefish, threespine stickleback, and some sunfishes also display quite discrete groups living in the same lakes but utilizing different food resources in order to survive.

The phenomenon is called resource polymorphism and has been observed and documented as early as in the 18th century, but has continued to receive a lot of scientific interest since it gives us a chance to study ongoing evolution. However, not all species display resource polymorphism, and naturally, in order to gain deeper understanding of evolutionary facilitators, the question arises: Why do some species display resource polymorphism, whereas other don't?

In this study, a team of European researchers combines literature data and advanced ecological theory in order to look for species-specific life history patterns explaining the presence/absence of resource polymorphism in fish. Interestingly and not at all obvious, the study suggests that early cannibalism, which is found in all species displaying resource polymorphism, is a promoting factor. However, incorporating recently explored and presented population dynamic theory, based upon the population's size distribution and the effect of the individual's size on its relative competitiveness, a logic explanation is given.

The effect of early cannibalism is twofold. First, it stabilizes the variation in the number of individuals over time, which in turn increases the benefit of specializing on any resource since the risk of being dependent on a vanishing resource decreases. Second, an early disappearance of small newborn individuals increases the abundance of their prey due to decreased consumption from the small ones, hence increasing the benefit for larger individuals to specialize on this specific prey (typically zooplankton). The team now plans to do new modeling exercises and practical experiments in order to further explore the suggested hypothesis.

Source: University of Chicago

Explore further: Pollen on birds shows feeding grounds

add to favorites email to friend print save as pdf

Related Stories

How repeatable is evolutionary history?

Jun 23, 2014

Writing about the weird soft-bodied fossils found in the Burgess Shale in the Canadian Rockies, paleontologist Stephen Jay Gould noted that of 25 initial body plans exhibited by the fossils, all but four ...

Cotton breeding researchers take giant leap

Dec 02, 2013

Narrow germplasm base and limited technology have made it difficult for cotton researchers to identify specific DNA markers needed to locate genes that confer desirable traits. But that's no longer the case.

Decoding the genome of the camel

May 28, 2013

By sequencing the genome of a Bactrian camel, researchers at the Vetmeduni Vienna have made a significant contribution to population genetic research on camels. The study has laid the foundation for future ...

Recommended for you

Researchers look at small RNA pathways in maize tassels

4 hours ago

Researchers at the University of Delaware and other institutions across the country have been awarded a four-year, $6.5 million National Science Foundation grant to analyze developmental events in maize anthers ...

How plant cell compartments change with cell growth

4 hours ago

A research team led by Kiminori Toyooka from the RIKEN Center for Sustainable Resource Science has developed a sophisticated microscopy technique that for the first time captures the detailed movement of ...

Plants can 'switch off' virus DNA

4 hours ago

A team of virologists and plant geneticists at Wageningen UR has demonstrated that when tomato plants contain Ty-1 resistance to the important Tomato yellow leaf curl virus (TYLCV), parts of the virus DNA ...

A better understanding of cell to cell communication

5 hours ago

Researchers of the ISREC Institute at the School of Life Sciences, EPFL, have deciphered the mechanism whereby some microRNAs are retained in the cell while others are secreted and delivered to neighboring ...

User comments : 0