BIO152H5 Lecture Notes - Lecture 19: Genetic Recombination, Androstenone, Zygosity

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17 Oct 2021

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UTM

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Biology

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BIO152H5

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Energy isn"t wasted on finding/securing a mate. Don"t have to move (sessile animals) slow rate of evolution. More efficient: all individuals are producing offspring. Exposure to predation when searching offspring (genetic recombination, random segregation, random sterilization) favourable when environment is not stable lower extinction rate for a mate conflict with the need to find food/shelter/caring for existing offspring. Breaks up good allele combinations arms race. Goal: pass on genes to the next generation. Asexual reproduction (1 parent - all genetic content) A single individual gives rise to offspring without fusion of gametes (that is, without genetic input from another individual) sexual reproduction (2 parents - share genetic content) Male and female parents produce offspring through the union of egg and sperm generated by meiosis recombination the key genetic event of prophase i. Asexual reproduction involving mitosis occurs by three basic mechanisms: fission (eg. platyhelminthes) Parthenogenesis (parthenos = virgin; genesis = birth/creation) Growth and development of an unfertilized egg.

Related Questions

Asexual reproduction: the first step to extinction
When species become asexual they could be taking the first stepto
extinction, say researchers who have been studying the geneticstructure
of Penicillium marneffei, an asexual fungus only found in parts ofsouthÂ
east Asia. Their research found that although P. marneffei sporeswere
able to spread over large distances on currents of air, they werenot able
to âinvadeâ the new environments in which they landed.
âWe believe the failure of P. marneffei to adapt to newenvironments is
because the fungus has largely dispensed with sexualreproduction.
Without sex, you will not have the mixing of genes it causes,something
all organisms need in order to be able to adapt to newenvironmentsâ, said
a member of the research team. Evolutionary theory predicts thatwhile
asexual organisms can initially prosper and out-compete theirsexual
cousins, they pay a price for being unable to adapt throughthe
recombination of genes caused by sexual reproduction.
DNA typing was used to show that different clones of the fungusare
found in different environments, and the researchers believe thatthe
adaptation of the fungus to these environments is limiting theirability to
adapt to other areas. They believe this is why P. marneffei isonly
endemic to a relatively small area of south-east Asia. Even thoughthe
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fungus makes spores which can spread over very large distances,the
researchers found that all the samples from any given locationwere
genetically very similar. This led them to the conclusion that thefungus
becomes highly adapted to its local environment, making ithighly
successful there, but stopping it spreading to other areas.
âBy being asexual, P. marneffei is not only limiting its ability toadapt, it
may be at risk of becoming extinct. If it is unable to adapt tonew
environments, it will be unable to adapt to changes in itscurrent
environment. While becoming asexual may provide short term
advantages to a species, in the long term, they are likely to endup in
evolutionâs ultimate dustbin â extinctionâ, concluded a member ofthe
research team

You should introduce your article by very briefly explaining thepurpose of
biological reproduction and touching upon the strategies used toachieve it, then
write your account using the following list as a guide to thepoints you should
discuss in your answer:
? How does asexual reproduction differ from sexual reproduction interms of
the biological processes involved and the genetic diversity andvariation of
the DNA produced?
What are the advantages and disadvantages of asexual andsexual
reproduction?
In terms of survival and adaptation, which reproduction strategy ismore
likely to allow a species to evolve rapidly (or to become extinct)?In your
answer briefly describe the two main mechanisms used to creategenetic
variation. Also, explain the factors and pressures that are likelyto drive the
process of adaptation.

sapphireantelope107

Explain how meiosis and sexual reproduction generate biodiversity. Discuss the advantage(s) and disadvantage(s) of sexual reproduction in the light of evolution.

Differentiate between asexual and sexual reproduction, and explain the advantages and disadvantages of each.

Differentiate between dominant and recessive alleles, and describe how they are expressed in homozygous, heterozygous, and recessive states.

Distinguish between phenotype and genotype. Which of them interacts directly with the environment? When would a mutation in only one allele affect the phenotype of a diploid organism? When would a mutation in only one allele affect adaptation to a changing environment?

Distinguish between a gamete and a zygote.

bluebear718

BIO152H5 Lecture Notes - Lecture 19: Genetic Recombination, Androstenone, Zygosity

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