different reproductive strtegies evolved in animals under particular set of selection pressure

Dear student,
Reproductive strategies are the adaptation in the organism to improve the possibility of fertilisation and producing fertile offspring. Asexual reproduction is energy consuming process because it involves single sex but in sexual reproduction more amount of energy is invested as both sexes are involved.
Following are the reproductive strategies evolved in animals:-
1) Courtship behaviour is evolved in animals to attract opposite sex for mating by producing different stimuli like chemical visual and auditory. These are involved in simple strategy and in complex strategy females are allowed to choose healthier, larger showing greater energy in courtship behaviour.
2) External vs internal fertilizations : Aquatic animals mostly show external fertilizations which is a wasteful process as most of the eggs are wasted which evolved to internal fertilisation which occurs in terrestrial animals by inserting directly male gamete into female body.
3) a) ovipary : Eggs are released outside the body  which can be fertilised internally of externally.
b) ovovivipary: Ovipary evolved to ovovivipary  Fertilisation of egg occurs internally and are kept inside until they hatch and give birth to the child.
c) vivipary : Vivipary is the most evolved where egg is fertilised inside the female body but they do not have shell. After fertilisation eggs develop into embryo and finally offspring which comes out of mother's womb. Fertilisation is internal.
3) Precocial and altricial development : Precocial species are born after complete development but altricial species are born when they are not completely developed.
4) Amniotic egg : Eggs are surrounded by amnion which prevents the egg from dehydration. This is the most evolved structure.
5) Parental care : Parents invest their energy to improve the reproductive success of the child and child's survival.


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