Sex and Behaviour Flashcards
Why are eggs are much larger and fewer in number?
Due to the presence of an energy store
Why do females make a greater sexual investment?
due to the production of a lower number of larger gametes.
A far greater investment is made by females due to the production of a lower number of larger gametes. What effect does this have on their chance of reproductive success and the chance of passing on genes?
their chance of reproductive success is lower and the chance of passing on genes is reduced.
In mammals, it is typically the female who have a relatively larger parental investment in producing each offspring. Why is this the case?
Placental Nourishment
Lactation – feeding the young
Post-natal care and protection
What are sessile organisms?
Sessile organisms are those that are fixed to a surface and therefore cannot move.
How do slow moving and sessile organisms reproduce?
Slow moving and sessile organisms are often hermaphroditic or employ parasitism as a reproductive strategy. Barnacles, for example, are hermaphroditic. They use extremely long sex organs to reach another for the transfer of sperm.
What can parental investment be? What benefit can it bring?
Parental investment is costly but increases the chance that young will survive.
Give the characteristics of a r-selected species. (9)
Unstable environment Short maturation time Short life span Usually high death rate Many offspring produced per reproductive episode Usually one reproduction in lifetime Early in life - Timing of first reproduction Small size of offspring or eggs No parental care
Give the characteristics of a k-selected species. (9)
Stable environment Long maturation time Long life span Usually low death rate Few offspring produced per reproductive episode Often several reproductions in lifetime Later in life - Timing of first reproduction Large size of offspring or eggs Often extensive parental care
What is a survivorship curve?
A survivorship curve is a graphic representation of the number of individuals in a population that can be expected to survive to any specific age.
What is monogamy?
one male mating with one female
What are the two types of polygamy? What do they mean?
Polygamy:
- Polyandry - One female and multiple males
- Polygyny – One male and multiple females
What is courtship?
Courtship is a specialised behaviour in animals that attracts a member of the opposite sex and leads to mating.
What is sexual dimorphism?
Sexual Dimorphism is defined as any physical differences between males and females.
What are the three main physical differences between males and females?
Size – Males are often larger than females.
Colouration – Females are inconspicuous, and males are very conspicuous using colour to display during courtship and territorial behaviour.
Secondary Structures – Males tend to have adornments such as antlers, ornate plumage or a mane.
What is reverse sexual dimorphism?
Reverse sexual dimorphism is when the normally inconspicuous female is larger or more ornate than the male.
Describe male-male rivalry.
Males demonstrate different strategies to gain access to females to ensure successful mating:
Acquiring and defending territories and harems – engaging in direct conflict with other males – superior size and weaponry ensuring success – the alpha male approach.
Adopting the role of a ‘sneaker’ or a ‘satellite’ male – not engaged in direct conflict – seeking alternative opportunities to mate.
What does sneaking behaviour refer to?
Sneaking behaviour refers to a strategy that allows smaller, less threatening males to more stealthily access to a female partner, often avoiding alterations with dominant males.
Who retains primary control over reproduction?
females
What does male courtship and appearance provide females with?
Male courtship and appearance provides, females with honest signals of male fitness.
What does an impressive courtship display or good appearance indicate?
An impressive courtship display or good appearance indicates a healthy male with a low parasite burden and the presence of advantageous genes – both indicators of ‘fitness’.
What do females use honesty signals for?
Females use honesty signals to choose healthier males in order to increase their own fitness and reproductive success.
What is lekking?
During the breeding season males cluster at a communal display area or lek – displaying and possibly fighting to attract females.
What does lekking allow?
This allows female choice. Females observe the display enabling them to select the fittest male who they will then mate with.
