Iteroparous

Humans can reproduce, then reproduce again. But that’s not the case in every species. 

Pacific salmon, for example, swim in the ocean for years before returning to the river of their birth, spawning, and dying.

There are two types of organisms that produce offspring to maintain their populations. 

Humans are iteroparous. Pacific salmon are semelparous. 

What is the difference between semelparous and iteroparous?

Iteroparity describes a reproductive strategy characterized by multiple reproductive cycles over the course of a lifetime. Iteroparous organisms produce a few large offspring. They have a fitness belt that determines their opportunity to have more offspring over time.

On the other hand, semelparous organisms produce many small offspring, using all of their resources to the point that they die after the reproductive episode. 

Which animal species are iteroparous?

Iteroparous vertebrates include birds, reptiles, fishes, and mammals. Most invertebrates, including most Mollusca and insects, are iteroparous as well. 

There are two types of iteroparity, continuous iteroparity (such as with humans and chimpanzees) and seasonal iteroparity, which describes when species have a specific breeding season (such as with birds and dogs). 

Which plant species are iteroparous?

Examples of iteroparous plants include the mango plant, daylily, orchids, hibiscus, and grapevine. Iteroparous plants, also called ‘polycarpic’ plants, flower more than once over their lifetimes. Most iteroparous plants are ”perennial” plants that live for more than one season, whereas semelparous plants that complete their life cycle in a single season with only one reproductive event tend to be “annuals.”

Short-lived annual and biennial plants, including grain crops and many herbaceous vegetables, tend to be semelparous.

Iteroparous plants experience reproductive delays. Also, production for iteroparous plants may translate to costs in terms of growth and survival. Unlike semelparous plants that have one and only reproductive event, iteroparous plants accrue lifetime fitness over multiple reproductive bouts. 

In iteroparous plant species, aging effects, including a decline in reproduction and root storage as well as late flowering, became particularly pronounced in the year before death.