I am studying for ecology and am trying to come up with evolutionary mechonisms that lead to the development of iteroparous reproduction. Does anyone have any ideas or knowledge about this? Thanks for your help!
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iteroparous if it is characterized by multiple reproductive cycles over the course of its lifetime. Some species die following reproduction due to putting the max effort to accomplish this regardless of future life. Iteroparous may have started this way and evolved and now able to reproduce more than once before kicking the bucket. Peace Ninja.
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Iteroparity is probably the ancestral mode of reproduction. We can see this in binary fission among bacteria. Bacteria reproduce by splitting into 2 individuals, and the parent lives on, rather than dying. Therefore, rather than coming up with a mechanism on how iteroparity evolved from semelparity (reproducing once and then dying), we may have to come up with a mechanism on how and why semelparity evolved from iteroparity.
One famous semelparous organism is the salmon. It is born in a freshwater stream, and then it gradually migrates downstream towards the sea, spend the growing years in the sea, and returns to the stream to reproduce once and then dies. We can ask why and how semelparity evolved in salmon, and why salmon do not go back to the sea after egg laying and make the same journey again. One reason is that the journey is filled with danger. Many fish never made it to the spawning grounds because of predators. Those that made it are often in no shape to return to the sea. Therefore there is a simple choice to make: spend all that you have left and try to maximize reproduction once, or try to save some energy and return to the sea in order to have a slim chance of reproducing again.
The same choice is not available to some trout species which evolved from salmon when the streams they inhabit no longer empty into the sea because of geological processes. These salmon are trapped in streams and spend their whole life there. They re-evolved iteroparity, because semelparity is no longer the most attractive alternative.
One famous semelparous organism is the salmon. It is born in a freshwater stream, and then it gradually migrates downstream towards the sea, spend the growing years in the sea, and returns to the stream to reproduce once and then dies. We can ask why and how semelparity evolved in salmon, and why salmon do not go back to the sea after egg laying and make the same journey again. One reason is that the journey is filled with danger. Many fish never made it to the spawning grounds because of predators. Those that made it are often in no shape to return to the sea. Therefore there is a simple choice to make: spend all that you have left and try to maximize reproduction once, or try to save some energy and return to the sea in order to have a slim chance of reproducing again.
The same choice is not available to some trout species which evolved from salmon when the streams they inhabit no longer empty into the sea because of geological processes. These salmon are trapped in streams and spend their whole life there. They re-evolved iteroparity, because semelparity is no longer the most attractive alternative.