Biology 3466B Lecture Notes - Inbreeding
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There is a type of lizard that only has a female sex. They don’t need sperm cells to
reproduce. Their offspring are clones of their mother.
The fish with black spots are parasitized and had asexual reproduction, and another
type of fish didn’t have any spots/not parasitized and had sexual reproduction when
they were all living in the same environment.
Asexual fish are an easy target for short lived, fast evolving parasites. While, sexual
fish are a moving target and each has a new combination from their parents’ genes.
For parasites, each one of them is unique and individual challenge and slows down
transmission of parasites through the population.
Sexual reproduction is the best defence from rapidly evolving enemies.
A draught occurred, and after the population returned. But parasites were affecting
the sexual population as well. Found out that sexual species, during the process of
re-colonization, had lost their genetic variation, making them inbred. They
resembled each other, and they outnumbered the true clones, so they were targeted
by the parasites.
So the researcher added fish from a lower pool, where fish had genetic variation.
Then parasite level dropped to previous years.
In nature, ornaments are usually only on males – to attract females.
Males – competition
Females – choice – they’re choosy because they put in so much effort.
Peacocks – fancier their feathers, more likely for females to choose them. Offspring
had a better chance to survive when fathered by a fancier peacock.
For some species, chances of offspring surviving increase if a female chooses a mate
that will stick around over the one with best gene.
Human babies are very dependent on parental care.
Cheating might provide better genes and better chance of surviving until they can
Sex role change might occur when there are a lot of predations on eggs or babies. So
males keep the eggs warm, and females go out and find more males to mate and
pass on her genes. Females would be larger and brighter than males.
Human t-shirt experiment – young males wore the same tshirt for a couple nights
and let girls smell them. Girls found the smell of a guy who had the most different
immune genes most attractive.
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