sex and life histories Flashcards
asexual reproduction
new offspring produced by a single parent
what is isogamous sex
two gametes are same
what is anisogomous reproduction
eggs and sperm - gametes different sizes
what is a simultaneous hermaphrodite
have both male and female reproductive organs - They can produce both sperm and eggs at the same time
what is a sequential hermaphrodite
produces eggs (female gametes) and sperm (male gametes) at different stages in life
define dioecious
male and female reproductive organs in different organisms
features of human reproduction
sexual
anisogamous
dioecious
genetic sex determinism
why may sexual reproduction be unfavourable/costly
Asexual females will transmit genomes at twice the rate of sexual females
Sexual production requires more units of energy for females than it does for males
why is sexual reproduction more favourable than asexual
Recombination and sexual reproduction allows for more variation - more resistant to environmental pressures when not clones
what is the red queen effect
Offspring end up with different gene combinations compared to parents - this means pathogens must then adapt to these new combinations
features of males (generally) in nature
larger
more ornamented
more aggressive
what is sexual dimorphism
two sexes have variations in phenotypical aspects
what is Bateman’s principle
Male reproductive success increases with each additional partner mated to a greater extent than is true in females
Females have limited resources - only one egg at a time
Males have constant sperm production
why do females pay attention to male ornaments
Signalling quality
Bias characteristics - want offspring to inherit traits - offspring will then continue generations as more likely to reproduce
what is sex role reversal
males carry eggs
number of mates increases for females and decreases for males
example of reverse sex roles
pipefish
what is a juvenile
15 years or more, growing and learning
reproductive stage
25years reproducing, parenting
post reproductive stage
30years or more, grandparenting
why do we age
the accumulation of unrepaired damage to the body over time
Organisms do not repair themselves completely
what is extrinsic mortality
the number of individuals alive declines with age
what is the disposable soma hypothesis
Evolution maximises representation in the population in the distant future
Natural selection favours allocation to reproduction at the expense of perfect self-maintenance
how is fertility related to mortality
Those with higher mortality rates are more likely to be fertile at earlier ages
what is the trivers willard hypothesis
Male reproductive success is determined by phenotypic condition
-not a conscious process
