Many rickettsia are PATHOGENS.
Pathogens are micro organism that cause diseases and rickettsia are majorly disease causing organisms. They are rod shaped bacteria and most species are gram negative. They are natural parasite of some arthropods and they cause diseases in both humans and animals.
Having two copies of the mutated genes cause sickle cell anemia, but having just one copy does not, and can actually protect against malaria - an example of how mutations are sometimes beneficial.
The majority of mutations have neither negative nor positive effects on the organism in which they occur. These mutations are called neutral mutations. Examples include silent point mutations. They are neutral because they do not change the amino acids in the proteins they encode.
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Population bottlenecks. but their genes still carry the marks of this bottleneck: they have much less genetic variation than a population of southern elephant seals that was not so intensely hunted.
Most organisms are Diploid, and as a result, they will have received 2 copies of the chromosomes, or sets of chromosomes, from both their parents. This they will have 2 sets of Genes that will perform almost exact same process, except with different phenotypes.
These chromosomes need to be homologous, in order for new alleles and other genetic combinations to be made.
What is this animal and i can answer it