While asexual reproduction only involves one organism, sexual
reproduction requires both a male and a female. Some plants and
unicellular organisms reproduce asexually. Most mammals and fish use
sexual reproduction. Some organisms like corals and komodo dragons
can reproduce either sexually or asexually. But in the long term (over
several generations), lack of sexual reproduction compromises their ability
to adapt to the environment because they do not benefit from the genetic
variation introduced by sexual reproduction.
Moon Jellies has two main stages in its life cycle – polyp stage (asexual
reproduction) & medusa stage (sexual reproduction)
Types
There are several different types of asexual reproduction. These include
budding, where the offspring grows out of the body of the parent, and
gemmules, where the parent releases a specialized mass of cells that will
become a new individual.
There are two types of sexual reproduction. Syngamy is the permanent
fusion of two haploid gametes to create a zygote. In humans, this is called
fertilization. Conjugation, on the other hand, is temporary fusion using a
cytoplasmic bridge. This is particularly seen in bacteria, which pass DNA
across the bridge.
Process
Asexual reproduction is reproduction that occurs without any interaction
between two different members of a species. Cells divide using mitosis, in
which each chromosome is copied before the nucleus divides, with each
new cell receiving identical genetic information.
Cell division in asexual and sexual reproduction
Sexual reproduction is reproduction that requires a male and a female of
the same species to contribute genetic material. Special cells called
gametes are produced through meiosis, which halves the number of
chromosomes in each resulting cell. These cells are called haploid
gametes. Fertilization occurs when two gametes – one from a male and
one from a female – combine, producing a diploid zygote with its own
individual genetic makeup.
Examples
Asexual reproduction is used by many plants, e.g. spider plants, bacteria,
hydra, yeast, and jellyfish. It is also involved in the creation of identical
twins, when one zygote splits into two identical copies.
Sexual reproduction is used by most mammals, fish, reptiles, birds and
insects.
Advantages and Disadvantages
Asexual reproduction is well suited for organisms that remain in one place
and are unable to look for mates, in environments that are stable. It is
usually used by simple organisms such as bacteria. However, asexual
reproduction does not lead to variation between organisms, meaning that
entire groups can be wiped out by disease, or if the stable environment
changes.
Sexual reproduction allows for variation, the most fundamental element of
evolution. It therefore creates species that can adapt to new environments
and that cannot be wiped out by a single disease. However, sexual
reproduction requires significant energy on the part of the organism to
find a mate. It is not well suited to organisms that are isolated or stuck in
place.
References
The Two Methods of Reproduction - BioTopics
Types of Sexual Reproduction - Tutorvista.com
Related Comparisons
Eukaryotic Cell vs Prokaryotic Cell
Diploid vs Haploid
Gamete vs Zygote
Mitosis vs Meiosis
DNA vs RNA
Abiotic vs Biotic