Reproductive Behaviours And Mating Systems

Question 1

What are the different types of mating systems?

Answer 1

• monogamy
• polygamy (polygyny and polyandry)

Question 2

Monogamy

Answer 2

The mating of a pair of animals to the exclusion of all others

Question 3

Polygamy

Answer 3

When individuals of one sex have more than one mate. This tends to be one male mating with many females but not always. The term ‘promiscuity’ may also be used for this type of mating system.

Question 4

What is the difference between polygyny and polyandry?

Answer 4

• polygyny is when one male mates exclusively with a group of females
• polyandry is when one female mates with a number of males in the breeding season

Question 5

Why are female courtship displays much less common than male displays in nature?

Answer 5

Investing energy in both exaggerated traits and gamete production would be challenging

Question 6

Species specific sign stimuli examples

Answer 6

• sounds
• displays
• releasing certain chemicals

Question 7

Purpose of species-specific stimuli

Answer 7

These indicate to the other member of sex that they are fertile, and thus chances of successful reproduction are maximised.

Question 8

Why is it important that these signals are species-specific?

Answer 8

It avoids unnecessary attention from members of a different species. It makes no evolutionary sense to copulate with members of another species.

Question 9

Fixed action pattern

Answer 9

An innate sequence or series of actions that occur as an organism’s response to a specific stimulus called a sign stimulus.

Question 10

Sign stimulus

Answer 10

Any outside environmental interaction that elicits some response from an organism.

Question 11

Reversed sexual dimorphism

Answer 11

In some species, the female is larger or more conspicuous than the male. Some males have to travel long distances to find a female, so a smaller size may be advantageous in terms of speed and stealth.

Question 12

Common examples of sexual dimorphism

Answer 12

• insects
• spiders
• fish
• reptiles
• birds of prey
• spotted hyenas
• blue whales

Question 13

Female choice

Answer 13

Involved females assessing honest signals of the fitness of males.

Question 14

Lekking behaviour

Answer 14

In lekking species, males gather to display at a lek, where female choice occurs. Dominant males occupy the centre of the lek, with subordinates and juveniles at the fringes as ‘satellite’ males. During the display, female choice occurs.

Question 15

What are the three hypotheses for why species form less?

Answer 15

1. The preference model
2. The hotshot model
3. The hotspot model

Question 16

The preference model

Answer 16

They are more advantageous for males and/or females than mating at isolated sites, in ways such as decreasing the costs associated with searching for a mate or giving honest signals as to the strength and fitness of the males on lek.

Question 17

The hotshot model

Answer 17

Due to inherent variation in mating success, less successful males tend to cluster around successful males in order to intercept some of the females that are attracted to the “hotshots”.

Question 18

The hotspot model

Answer 18

Suggests that female movement patterns and behaviours are the cause of lek formation and males lek in areas of highest female density.

Question 19

How might males without such dominance gain access to females?

Answer 19

They may use sneaking behaviours. This allows less threatening mates to stealthily access a female partner without having an altercation with a bigger, more fearsome male.