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BIOL/ BMSC 114: Asexual vs. sexual reproduction
Asexual and sexual reproduction
• Two modes of animal reproduction: asexual and sexual reproduction. – In most cases asexual reproduction relies on mitotic cell division. – Sexual reproduction is the creation of offspring by fusion of haploid gametes to form a zygote. • Gametes are formed by meiosis. • Sexual reproduction directly reduces your contribution to the next generation!
Phil Lester, KK413
• Asexual reproduction has many advantages: – All your wonderful genes are contributed to the next generation (no dilution!). – It enables animals living in isolation to reproduce. – It can create numerous offspring in a short amount of time. • Theoretically it is most advantageous in stable, favourable environments because it perpetuates successful genotypes precisely.
Types of asexual reproduction: Fission.
• Many invertebrates reproduce asexually by fission. – The separation of a parent into two or more individuals of roughly equal size.
Phylum Cnidaria– sacs with central digestive system.
Types of asexual reproduction: Budding.
• A new individual splitting off from an existing one. – For example certain species in the Phylum Cnidaria: new individuals grow out from the body of a parent. – May detach or remain joined to the parent.
Phylum Cnidaria– hydras can reproduce sexually when conditions are unfavourable.
Types of asexual reproduction: Fragmentation.
• The breaking of the body into several separate pieces. – Some or all of which may develop into new adults. – Always associated with regeneration e.g. crown-ofthorns starfish.
Types of asexual reproduction: Gemmules.
• Some invertebrates release specialized cells that can grow into new individuals. – For example the gemmules of Porifera that are formed when certain cells migrate together within the…...