Sex Flashcards
whats the point of males?
usually cost females 80% of reproductive output
asexual females leave more offspring and more copies of their genes
no need to produce sons w/ all competition and showyness
cost of sex 50% but grows each generation
what is sex?
the mixing of genetic material from different individuals
what are gynogenetic species?
asexual species that still rely on sex
whats special about Poecilia formosa?
an all female species - mates with males of different species to instigate parthenogenic egg production
whats special about scale insects?
they show paternal genome elimination - mate but none of the male qualities are in the gametes
whats special about saga pedo?
parthenogenic but occasionally find a male suggesting it was once a sexual species
what does a lack of genetic variation lead to?
exposure of deleterious recessives
slow rate of evo
can’t track changing environment
vunerable to pathogens
what is lack of genetic variation represented by?
the red queen hypothesis
why bother having males?
example in snail P.antipudarum
predicts a positive relationship between male frequency, the level of infection and snail density
in New Zealand - both pops hermaphroditic - males produced as optional extra
when at high infection levels - more males produced - gives offspring higher chance of survival by diversifying genetic variation among offspring
what happens to obligate species with increased levels of infection?
recombination rate increases - females increase genetic diversity by increasing recombination as it maximizes survival value of offspring
advantages of sex?
can accumulate good mutations
can get rid of bad mutations
how can asexual species get beneficial mutations?
if one crops up in a lineage - but have to wait for them one after the other
how is fitness effected?
its more rapid in high population sizes with sex as they can adapt more quickly
what is Mullers Ratchet?
the accumulation of deleterious mutations – can be removed by sex/reproduction
what is Kondrashovs ‘mutational theory’?
an analogy of Mullers Ratchet
a theory that implies sex can eliminate deleterious mutations as long as genomic mutation rate to deleterious genes is actually quite high - humans and vertebrates have high U
