2.3 Variation And Sexual Reproduction Flashcards
Asexual Reproduction Costs
- lack of genetic variation
- harmful alleles last longer in gene pool
- not able to adapt easily to environmental conditions
Asexual Reproduction Benefits
- lower metabolic costs
- rapid offspring production
- every member can reproduce
- whole genome passed on
Sexual reproduction Costs
- higher metabolic costs (production of gamete’s)
- only half population can reproduce
- slow offspring production
- only half genome passed on
Benefits of Sexual Reproduction
- increased genetic variation
- continual adaptation possible
Why is sexual reproduction more common than asexual
Because benefits of sexual reproduction must outweigh the benefits. Meaning genetic variation allows adaptation which increases chances of survival.
What relation does genetic variation have to red queen hypothesis
Red queen would stop as no species would adapt and pressure other species
what type of reproduction has an advantage against parasitism?
sexual reproduction
what is the relation between parasitism and the fitness of the host
The fitter the host the better they are able to resist parasitism
why is sexual reproduction at an advantage with parasitism
If hosts reproduce sexually, the genetic variability in their offspring reduces the chances
that all will be susceptible to infection by parasites
When is passing on the whole genome advantageous
in very narrow, stable
niches or when re-colonising disturbed habitats
Examples of asexual reproduction in eukaryotes are
parthenogenesis and vegetative cloning in plants
What is parthenogenesis
the asexual production of offspring without males or fertilisation. Occurs due to female gamete alone
What conditions is parthenogenesis most common in
cooler climates and lower parasite density
What way, other than random mutations, can asexual reproduction experience genetic variation
Horizontal gene transfer
What is the result of horizontal gene transfer compared to vertical gene transfer
horizontal gene transfer results in faster evolutionary
change than in organisms that only use
vertical transfer.
What is a homologus chromosome
Homologous chromosomes are
chromosomes of the same size, same
centromere position and with the same
sequence of genes at the same loci.
Meiosis process on flashcard
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Define hermaphrodites
Species that have functioning male and female reproductive organs in each individual
Meaning on individual can produce both male and female gametes
What is the benefit of hermaphroditism
If the chances of encountering a partner/mate is uncommon, there is no requirement of the partner to be of the opposite gender
Describe environmental sex determination in crocodiles
Sex determination is controlled by temperature at which eggs are incubated
Sex ratio of offspring can be adjusts by
Population density and the resulting strain on resource availability
Sex can change in some species as a result of
- Size
- Parasitic infection
- Competition
In most mammals which gene determines the development of male characteristics
SRY Gene on the Y chromosome
What do homogametic males lack on the shorter chromosome? and what is the result of that?
Most of the corresponding homologus alelles
This can result in sex-linked patterns of inheritance
What is X chromosome inactivation
a process by which most of one X chromosome is inactivated.
What happens in homogametic females at a young age
In homogametic females (XX) one of the two X chromosomes present in each cell is randomly inactivated at an early stage of development
What does X Chromosome inactivation prevent? and how dos this affect carriers of sex linked diseases
A double does of gene products, which could be harmful to cells
Carriers are less likely to be affected by any deleterious mutations on these X chromosomes
Why is it significant that a random x chromosome is inactivated in females?
Half of the cells in any tissue will have a working copy of the gene in question
