Unit 2 - section 4 Flashcards
Compare sperm and eggs
Sperm smaller and more numerous
Eggs have larger food store and are a greater energy investment
Which gamete requires the most parental investment?
Eggs
What is the problem faced by sessile organisms in terms of sex?
Not able to move together to mate
Examples of how sessile organisms over come not being able to move to mate
Barnacles - hermaphroditic, long penis extends to next barnacle abc swaps sperm
Coral - eggs and sperm released simultaneously into water
Flowering plants - pollination, insects gametes from one flowering plant to another
What are the costs and benefits of external fertilisation?
Costs
Energy used to produce lots of gametes
High mortality rate of gametes
Timing difficult although use day length and chemical signals
Benefits
Little energy investment in parental care
Good survival numbers due to large number of gametes produced
What are the costs and benefits of internal fertilisation?
Costs
More energy invested per egg produced
Lot of energy invested in parental care
Protection must be given to developing embryos
Benefits
Fewer egg cells are produced
High rate of reproductive success
Low mortality rate of offspring
What is parental care?
The energy parents invest into the survival of their offspring
Why do animals invest energy in parental care?
It increases the probability of production and survival of young
Describe R-selected parental care
Develop rapidly Smaller in size as an adult Many small offspring Have a short generation time Example fish
Describe K-selected parental care
Develop slowly Larger in size as an adult Few large offspring Have long generation time Example elephants
What are the restrictions with the terms K-selected and R-selected?
Many organisms are difficult to place into distinct groups
Trees live for a long time but produce massive numbers of offspring mammalian males R-type whereas females tend to be K-type
How have reproductive strategies evolved and what is the premise optimal reproduction is based on?
Have evolved to maximise reproductive success
Optimal reproduction is based on the premise of a trade off in terms of the number and quality of current offspring versus potential future offspring
What is polygamy?
Promiscuous short-lived interactions for the purpose of reproducing
What is monogamy?
Having long term reactions with one partner
What is sexual dimorphism?
When males and females look distinctly different
What is the cause of sexual dimorphism?
Sexual selection
What are the two ways males can gain access to females?
Male-male rivalry: use their strength, size or other characteristics to beat other males and impress females
Sneaking: sneak past dominant male to mate with female
Compare the markings, structure and behaviours of males to females
Females are usually more inconspicuous than males
Males will display behaviour to try and attract a mate eg have a tidy nest
What is female choice?
The female assesses honest signals of the fitness of males
What are two ways fitness can be assessed on males?
Parasite abundance
Good genes
Describe how leaking species uses alternative strategies for successful reproduction
It is common in species where male only provide sperm
Males display at a lek and the females choose from the displaying males
Satellite males may try and sneak a chance at reproducing rather than face aggression
What is reversed sexual dimorphism?
When the female is larger and more conspicuous than the male
Occurs when males have large distances to travel so it makes sense for the to be smaller in terms of energy expenses
What is species specific sign stimuli?
Animals often use signals that only other members of the same species understand to signal they are ready to mate. It ensures animals are most fertile when they mate improving reproductive success
What is the role of fixed action pattern responses?
They attract females and can entice aggression in other males. They increase fitness by increasing the chance of successful mating
