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: Invasion of non-native species exposed by environmental DNA

Related Stories

Invasion of non-native species exposed by environmental DNA

September 7, 2015

A research group, headed by Dr. MINAMOTO Toshifumi (Project Assistant Professor, Graduate School of Human Development and Environment, Kobe University), Dr. UCHII Kimiko (Assistant Professor, Faculty of Pharmacy, Osaka Ohtani ...

How repeatable is evolutionary history?

June 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 were quickly eliminated. ...

Simplifying SNP discovery in the cotton genome

April 1, 2015

The term "single-nucleotide polymorphism" (SNP) refers to a single base change in DNA sequence between two individuals. SNPs are the most common type of genetic variation in plant and animal genomes and are, thus, an important ...

'TRAP' preserves genetic properties of popular geranium

November 5, 2007

Reseachers at The Ohio State University have demonstrated that Target Region Amplification Polymorphism, or TRAP, is an effective method for preserving the important genetic diversity of ornamental flower collections.

Recommended for you

CERN collides heavy nuclei at new record high energy

November 25, 2015

The world's most powerful accelerator, the 27 km long Large Hadron Collider (LHC) operating at CERN in Geneva established collisions between lead nuclei, this morning, at the highest energies ever. The LHC has been colliding ...


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.