Lecture 8 - Asexual reproduction Flashcards
(25 cards)
What is reporduction?
The act or process of producing offspring
Two modes of Animal reproduction
Asexual reproduction
Sexual reproduction
Asexual reproduction
New individual whose genes all come from the one parent (clone)
no fusion of eggs and sperm (agametic)
Sexual reproduction
Offspring from fusion of haploid gametes to form a zygote
Agametic
No gametes
Fission
Budding Fragmentation
Pathenogenetic
Development of unfertilised eggs
Offspring from a single cell
Apomixis
Automixis
Apomixis
Eggs from mitosis
Automixis
Eggs from meiosis
Why be Asexual?
Removes the requirement to locate a mate
Facilitates rapid reproduction
Perpetuates successful genotypes
What animals are asexual?
Protozoa
Metazoans
Some invertebrates
Some vertebrates
Fission (Agametic reproduction)
Separation of a parent into two or more individuals
Budding (Agametic reproduction)
New individuals arise from outgrowths in existing ones
Fragmentation (Agametic reproduction)
Parent’s body broken into several irregular pieces, with some or all regenerating into complete adults
Parthenogenesis
<1% of animals
Development of an embryo from an unfertilized egg cell
Apomixis (parthenogenesis)
clonal offspring produced from unfertilized eggs, eggs made by mitosis e.g., aphids
Automixis (Parthenogenesis)
Development of unfertilized single egg, eggs made by meiosis e.g., lizards
Gynogenesis
sperm only used for egg activation and the egg develops without the sperms nucleus (female clone) e.g., some flatworms, bivalve molluscs, moths, fish
Hybridogenesis
Hybrids contain a genomic mix of parental species, but only pass on one of the parent’s genomes
Paternal DNA discarded at oogenesis
Haplodiploidy (parthenogenesis)
Unfertilized haploid eggs develop into males
Fertilised diploid eggs develop into females
e.g.., bees
Spontaneous mutation
a random change in the DNA arising from errors in replication that occur randomly
interspecific hybridization
sexual reproduction between members of different species
Asexual hybrids can have high fitness and heterozygosity
Contagious parthenogenesis
Pass asexuality genes into sexual populations
Produce new parthenogenetic populations
Induction by Bacteria
Bacteria makes a species asexual
Geographical and Ecological characteristics of Asexual
High latitude Habitat: simple, recent, disturbed Climate: Temperate Water: fresh Resources: unpredictable
