Key reasons for producing many eggs in semelparous species:
1. High Mortality Rates: Semelparous animals often live in environments with high levels of predation, disease, or other hazards that can lead to high mortality rates among offspring. By producing a large number of eggs, they increase the odds that some will survive despite these risks.
2. Limited Parental Care: Unlike animals that provide extensive parental care, such as providing food, protection, and teaching survival skills, semelparous species invest minimal energy in raising their young. Instead, they focus on reproducing as many times as possible before they die.
3. Short Lifespan: Many semelparous species have relatively short lifespans. They may only have one or a few reproductive cycles during their lifetime, so producing a large number of eggs during each cycle is crucial for ensuring their genes are passed on to the next generation.
4. Adaptability: Producing many eggs allows for a higher degree of genetic diversity among offspring. This diversity increases the chances that some individuals will possess traits that are better suited to changing environmental conditions, thus enhancing the species' chances of survival in the long run.
5. High Reproductive Success: Semelparous species' primary goal is to reproduce successfully before their lifespan ends. By producing many eggs, they maximize their chances of achieving reproductive success even with limited resources and a high risk of offspring mortality.
Examples of semelparous animals include Pacific salmon, mayflies, and some species of squid and octopus. These animals invest heavily in producing large numbers of eggs, often at the cost of their own lives, to ensure the continuation of their species.