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Which came first?
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Bruce Brandhorst, 604.291.4627; bruce_brandhorst@sfu.ca
Diane Luckow, Media & PR 604.291.3219
Bruce Brandhorst, 604.291.4627; bruce_brandhorst@sfu.ca
Diane Luckow, Media & PR 604.291.3219
November 3, 2003
Which came first, the butterfly or the caterpillar, the tadpole or the frog? The mystery of metamorphosis – the amazing transformation of a larva into a very different adult animal form – has long perplexed humankind.
Now, SFU researchers have an interesting new theory on the subject that was published in a recent edition of the scholarly journal Evolution and Development. The big quandary scientists have always pondered is how the larval stage came to be so different from the adult and whether, in their early evolutionary phase, adults used to look like the much simpler present day larvae or whether the larval stage was somehow inserted into the life cycle.
Bruce Brandhorst, professor of molecular biology and biochemistry and post-doctoral fellow Cory Bishop have discovered that a simple gas called nitric oxide controls when metamorphosis occurs in some animals. "From that, we speculated that since nitric oxide also controls the timing of life cycle changes in the stages of other simple organisms, it may have a long evolutionary history of controlling life cycle transitions," explains Brandhorst, "allowing organisms to regulate when they become sexually mature, which in many animals involves going through metamorphosis from the larval stage to a juvenile or adult stage."
Based on their findings that nitric oxide allows larvae to delay metamorphosis, Brandhorst and Bishop propose that larval forms were an evolutionary insertion that arose because animals could delay their adult formation. Forming swimming larvae allowed them to more easily escape predation or to grow bigger and therefore produce more or bigger eggs, providing a selective advantage in the struggle for survival of the species.
The duo’s theory may hold a key to unlocking the mystery surrounding the evolution of complex life cycles.
-30-
electronic photo available
Now, SFU researchers have an interesting new theory on the subject that was published in a recent edition of the scholarly journal Evolution and Development. The big quandary scientists have always pondered is how the larval stage came to be so different from the adult and whether, in their early evolutionary phase, adults used to look like the much simpler present day larvae or whether the larval stage was somehow inserted into the life cycle.
Bruce Brandhorst, professor of molecular biology and biochemistry and post-doctoral fellow Cory Bishop have discovered that a simple gas called nitric oxide controls when metamorphosis occurs in some animals. "From that, we speculated that since nitric oxide also controls the timing of life cycle changes in the stages of other simple organisms, it may have a long evolutionary history of controlling life cycle transitions," explains Brandhorst, "allowing organisms to regulate when they become sexually mature, which in many animals involves going through metamorphosis from the larval stage to a juvenile or adult stage."
Based on their findings that nitric oxide allows larvae to delay metamorphosis, Brandhorst and Bishop propose that larval forms were an evolutionary insertion that arose because animals could delay their adult formation. Forming swimming larvae allowed them to more easily escape predation or to grow bigger and therefore produce more or bigger eggs, providing a selective advantage in the struggle for survival of the species.
The duo’s theory may hold a key to unlocking the mystery surrounding the evolution of complex life cycles.
-30-
electronic photo available