Flashcards in Sex and mating Deck (22)
What is reproduction?
The production of offspring
What is sex?
Fusion of genetic material from two different parents
What is different about asexual reproduction?
Doesn't require sex, as all genes come from one parent, to make genetically identical offspring
What are the benefits of asexual reproduction?
Quick, easy, cheap and relatively effort free and straightforward
What are the types of asexual reproduction?
fragmentation, binary fission, budding, parthenogenesis
What is fragmentation?
The breaking of the body into pieces followed by the regeneration of body parts missing - net effect is reproduction
What is binary fission?
Single cells divide into the independent, identical daughter cells
What is budding?
Offspring grows out of the body of the parent, specialised masses of cells are released form the parent that develop onto a new individual e.g. in hydra
What is parthenogenesis?
virgin birth, occurs in several fish/insects, unfertilised eggs develop into offspring but are not haploid - not in mammals due to haploid printing
When in a cycle of asexual/sexual reproduction would you expect each type to occur?
Low stress = asexual
high stress = sexual
depends on environmental factors
When did sexual reproduction evolve?
1.5 - 2 billion years ago
What are the three fundamental processes involved in sexual reproduction?
Gametogenesis (formation of gametes), mating (transferring of gametes), fertilisation (fusion of gametes)
What are the requirements of external fertilisation?
Requires water, gametes are shed into the water
What are the problems encountered with external fertilisation?
Can't control delivery, requires a huge number of gametes and there is heavy predation of eggs
What is indirect internal fertilisation?
Male deposits sperm 'packet' (spermatophore) and the female picks it up
What is direct fertilisation?
Copulation, sperm is transferred directly into the female, often by intermittent organs
What is a hectocotylus?
a modified arm used by male octopuses and some other cephalopods to transfer sperm to the female in direct fertilisation
What is a hermaphrodite?
Individual has both male and female parts, generally not self fertilising. Partners exchange sperm and use it to fertilise their own eggs
What happens during the copulation of bean weevils?
Female is wounded internally as penis has spines, leading to early death in the female. Female kicks to dislodge the male
What is traumatic insemination?
Female lacks genital opening, males pierce membranes and place sperm into the females haemocoel e.g. in bed bugs
What is sexual cannibalism and why might it be advantageous?
Female kills mate during or after copulation, may be partly for nutrition, could be beneficial for males to maximise paternity, or for females to prevent paternal monopoly