BIOL 210 Lecture Notes - Vernal Pool, Zygosity, Daphnia Pulex

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yellowchinchilla381

23 Sep 2014

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Does sex facilitate adaption: goddard, godfray and burt (nature 2005) used yeast! knocked out two genes responsible for recombination, creating an asexual, diploid strain. See sex adapt faster than asex in new envrionment. Diversity & uncertainty: sex wins in the real world. Much theory has been based on infinite populations for two reasons: Models all intercomparable, extra parameters removed: the role of genetic drift ( sampling error" / chance) may have been under-appreciated. Sex is often related to stress and seasonality. They have now evolved ability to produce ephippia, which allows them to remain in sediment for long time! ephippia: sturdy resting eggs, can survive winter. Life cycle of daphnia pulex in round lake. Cp or op: obligate parthenogenic, or conditionally. 18 years of date or ratio of asexual and sexual. One of only ponds in world that only contain sexual daphnia. Almost all others have been invaded by asexuals. See that even in lab sexuals have slight edge.

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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
6_________________________________________________________________
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

1. What is the chromosome theory of inheritance?

2. Understand how independent assortment can cause gametes to have four combinations of alleles when an individual is heterozygous for two genes on two different chromosomes.

3. What are linked characters and linked genes? Understand why linked genes will not independently assort.

4. How can crossing over affect linked genes?

5. What are recombinant gametes?

6. Define recombinant frequency. Be able to use the recombinant frequency to determine how close two genes are on a chromosome.

7. What is a linkage map?

8. What is the function of the SRY gene on the Y chromosome? What happens if you don't have this gene?

9. Know how sex is determined in mammals, birds, bees and ants, and reptiles.

10. How many autosomes and sex chromosomes do normal human haploid and diploid cells have?

11. What does it mean for a gene to be X-linked or Y-linked?

12. Be able to answer word problems and fill out a Punnet square involving an X-linked recessive trait.

13. Which sex is more likely to have an X-linked recessive disorder? Understand why.

P.s The most simple answer would be preferable. I would be copping the notes over that you will provide to my noteb book and add my details to it.

greylocust179

Need help with evolution questions:

1.) A haplotype is best defined as the ________________.

	haploid genotypes of all the gametes produced by a diploid individual

ABO blood type conferred by an individual gamete

genotype of either the paternal or maternal chromosomal complement

multilocus genotype of a chromosome or gamete

2.) Which of the following statements regarding linkage disequilibrium is true?

Exists when D is less than zero, but not when it is greater than zero.

Is reduced by sexual reproduction.

Is increased by crossing-over during meiosis.

Is increased by any random sampling error that happens to create or destroy certain chromosome genotypes but not others.

Is reduced by selection that favors certain combinations of genotypes.

3.) Selection on multilocus genotypes in random-mating populations leads to linkage disequilibrium when _______________.

it reduces mutation rates

it eliminates all haplotypes from the population

it prevents crossing-over during meiosis

some allele combinations confer greater fitness than do others

4.) When two loci are in linkage equilibrium, the allele carried on a chromosome at one locus is independent of the allele carried on the chromosome at another locus. When this is the case, _________________.

allele frequencies will not change over time

the two loci (or, more specifically, their protein products) do not interact

the frequency of each haplotype can be calculated by multiplying the frequency of its two alleles

all possible haplotypes occur at equal frequency

5.) Which of the following accurately characterize(s) Muller's ratchet model for the selective advantage of sexual reproduction?

Drift establishes linkage disequilibrium because multilocus genotypes with few mutations are eliminated by chance events.

In populations without sexual reproduction, deleterious mutations accumulate, eventually imposing such a burden that the population goes extinct.

Sex is favored selectively because it recreates the zero-mutation genotypes lost due to drift.

All of the above correctly characterize Muller's ratchet model for the evolution of sexual reproduction.

6.) The genetic signature of recent positive selection on a locus is _______________.

high frequency and low linkage disequilibrium

low frequency and low linkage disequilibrium

low frequency and high linkage disequilibrium

high frequency and high linkage disequilibrium

7.) Sexual reproduction is advantageous both in changing environments and in constant environments, compared to asexual reproduction.

True

False

8.) Sexual reproduction causes genetic recombination via crossing-over, which combines genotypes from different parents.

True

False

9.) One reason sex may be maintained in natural populations is proposed by the "Red Queen Hypothesis", which states that.....

genotypes created by sex are created by natural selection over and over

recombination creating novel genotypes that can resist infection by parasites

mutation load is reduced by novel adaptive mutations

the ability of sex to fix multiple

BIOL 210 Lecture Notes - Vernal Pool, Zygosity, Daphnia Pulex

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