Example:

A classic example is the clownfish. Clownfish live in social groups with one dominant female.

If the female dies, the dominant male changes sex and becomes the new female.

Examples: Pacific salmon, Atlantic eel, Broad-footed marsupial mouse.

This method allows animals to coincide the birth of their young with better environmental conditions so they are born having the best chance at survival as it is not worth the adults energy to spend energy growing young for them to not be able to thrive because they cannot find food.

Examples: Bears (Pause pregnancy until winter which allows them to condition themselves to give birth in spring), Marsupials, Roe deer (Implantation occurs in January but they mate in August).

Iteroparity allows animals to reproduce multiple times throughout their lives, leading to more flexible population dynamics and enhancing the survival rate of their offspring.

This strategy is common in stable environments where adult survival rates are high.

Almost all mammals are iteroparous, as well as birds and most reptiles.

A specific example is African Elephants, were females start reproducing around age 10 and have a calf every 4 years.

Measured as the number of individual offspring per reproductive event.

E.g. mola mola can release up to 300 million eggs in a single spawning event.

In domestic ferrets (Mustela putorius furo) an unmated jill will remain in a prolonged estrus, which can lead to dangerously high estrogen levels.

Unlike induced ovulators, they do not require mating to trigger ovulation. This process is common in humans, primates, rodents, and most domestic farm animals, allowing for pregnancy to occur at specific times.

Heat

Food availability

Water availability

Environmental triggers

Seasons

Rainfall

Humidity

Reproductive strategies

Synchronised reproductive - some species have reproductive cycles that coincide with availability of food and water. Camels demonstrate this strategy

Rapid reproduction - species will have short cycles of reproduction. Kangaroo mice demonstrate this strategy

Water availability - droughts limit seedling establishment & can cause high mortality of seeds & young plants.

Light limitation - high density of plants can lead to severe competition for light, which restricts the growth & reproductive capacity of smaller, less competitive plants.

Synchronising mating with lunar or seasonal cues

Some hermaphroditism and sex change to cope with low population density

Some mammals use internal fertilization and long-term parental investment

Migratory breeding for optimal environments

increased risks of offspring failing to develop, at risk to the abiotic factors

e.g. penguins

Krill make for an easy target for large prey such as baleen whales, which take in an enormous amount of water and filter the krill through its baleen plates. With such high fecundity, Krill numbers can remain stable, even when predation risk is high.

Common in corals, many fish, sea urchins, molluscs

Males and females release eggs and sperm directly into the water column

Fertilisation occurs externally

Often synchronised by moon cycles,

temperature, or chemical cues

Advantages

       Produces huge numbers of gametes

Increases genetic mixing

No need to find a mate physically

Limiting factors

       Very low survival rate

Gametes can be diluted or eaten

Offspring receive no parental care

Furthermore, increased temperatures caused by climate change can make it difficult for female polar bears to create stable dens, leaving the cubs exposed to severe weather and predators.

increases chances of offspring development

disadvantages

consumes large amounts of the mothers resources during development

can limit feeding and behaviour of the mother

Animals - seasonal breeding, opportunistic breeding, precocial & large young, burrowing & hiding offspring, & mobility/migration.

allows animals multiple opportunities to rear young, if animals fail to raise offspring one year they can try again the following

allows animals to gain experience