Animal Behaviour-Mating Systems

Question 1

How often do Semelparous and Iteparous animals breed?

Answer 1

Semelparous=single time/once e.g Salmon

Iteparous=multiple events e.g rats

Question 2

Another way to define mating systems is when the animal can breed. What are Gryllus campestris an example of? What are Gryllus bimaculatus an example of? What are so special about breeding periods in Pandas?

Answer 2

Gryllus campestris= one mating season annually driven by climate/food availability
Gryllus bimaculatus= year round breeding
Pandas=254-72 hour window in a year

Question 3

Another way to define mating systems is how many partners an animal has in a breeding season. What are the following:
Monogamy
polygyny
polyandry
promiscuous/polygamous

Answer 3

Monogamy- e.g Oyster catchers have one partner in a breeding season (can however divorce)
polygyny- Males have many females
polyandry- Females have many males
promiscuous/polygamous- Both have many partners

Question 4

What different types of gamete release/fusion are there?

Answer 4

Broadcast spawning- when gametes are just released into their surroundings e.g Coral
Spermatophores- when a packet of sperm is produced and deposited on the ground. The female then has to walk over it to pick it up e.g Newts
Intromittent organs- An external organ that delivers sperm e.g Duck

Question 5

What is the difference between viviparous species and oviparous species?

Answer 5

Viviparous- when the offspring develop inside the mother e.g puppies
Oviparous- Offspring develops outside e.g turtles

Question 6

What is Anisogamy?

Answer 6

Anisogamy (noun) (also called heterogamy) refers to a form of sexual reproduction involving the union or fusion of two dissimilar gametes (differing in size and/or form)- usually big egg and smaller sperm

Question 7

Females are often the choosy sex. This means there is usually a lot of variation in the males. Some males may mate a lot and have many offspring and some may not.
What direct benefits may choosy females get? Give an example of a species.

Answer 7

Direct benefits such as food and territory

E.g North American bullfrogs- males compete to hold the best territory and these are preferred by females

Question 8

Females are often the choosy sex. What sort of genetic benefits may the female get? Give 3 reasons/examples.

Answer 8

1) ‘Sexy sons’ (more productive sons) aka Fisher’s runaway hypothesis. (Covariation between female choice and male traits must be present)
e.g Stalk eyed flies, males with wider apart eyes are found with more females
2) Good genes may signal better health/condition.
E.g Stickleback females prefer redder males which is linked to better body condition and parasite infection/ immunity (this was tested by putting the fish under white light where they could see the male colours and this choosiness was shown. When put in orange light, they couldn’t distinguish colours and so did not show this)
3) Attraction may signal better survival of offspring.
E.g Peacocks with larger eye spots on feathers had better survival of offspring and so females choosing these males will help their offspring

Question 9

What are leks?

What group of animals is this mostly seen in?

Are the females or males the choosy sex?

Answer 9

A lek is an aggregation of males that gather to engage in competitive displays that may entice visiting females who are surveying prospective partners for copulation. This is usually seen in avian species (e.g Greater sage-grouse) and in areas where females are the choosy sex

Question 10

There is a lot of competition for males that lek, so why may they do it?

Answer 10

Resource “hotspots” i.e. where females are abundant e.g. sage grouse on route between female wintering and nesting ranges (so coincidental lekking)

Reduce predation e.g. frog chorus size and bat predation

Increase female attraction e.g. tephritid flies bigger lek = more females (make display bigger-more females will be attracted)

Aggregate around “hotshot” males

Female preference for aggregations to enable choice

Question 11

Why is it beneficial in species, such as hanging flies, that give gifts to give a big one?

Answer 11

This increases the time that the female mates with it

Question 12

How can males cheat with giving gifts to females?

Answer 12

Spiders wrap their gifts before they mate with the female so sometimes they cheat and wrap worthless gifts to enable them to mate

Question 13

Crickets can rub their wings together and produce a song to attract females. Unfortunately, parasitoid wasps are also attracted and lay their eggs in the cricket. Newer flat-winged males cannot produce a song. How do they ensure they mate?

Answer 13

They get close to singing males and steal the females

Question 14

Male territory is often where the females are. The more female and male territories overlap, the more successful the male will be. What drives the distribution of females?

Answer 14

Female distribution and territory size is linked to food availability. In addition, territory size also alters the number of males the female chooses to mate with.

Question 15

What was the result of a test in red singed blackbirds – experimentally manipulate to give newly arriving females a choice of an improved territory with a resident female or a poor territory without another female?

Answer 15

The females almost all chose the better quality environment with a resident female. Even though they have chosen this territory, they often mix or travel to others and mate with males there

Question 16

Diversity is found with different species and how long they choose to defend a territory for. Give examples of this variation.

Answer 16

dik dik – monogamous as female range too large for a male to defend more than 1
impala – males defend herds of females only during oestrus
Ugandan kob – males defend a small territory on a lek
buffalo – several males associate with a large group of females

Question 17

Is it always the males defending territories/competing for females? Is there an example of when it is the other way round?

Answer 17

Topi antelope are in oestrus for a day and so compete for the best male. This results in much more conflict

Question 18

Timing is important in mating systems. Snakes emerge from their overwintering sites and often form ‘mating balls’ in which many males are competing for a single female. How do garter snakes use alternative strategies based on their size/condition?

Answer 18

Males that are in better condition and so are likely to be able to win in the mating ball fights stay in the ball and spend more time in courtship behaviour than periscoping (lifting head and surveying around). The males in less good condition leave the den to find areas of less competition and spend more time periscoping, seeing where females are than in courtship behaviour

Question 19

Timing is important in mating systems. Male redstarts have overwintering sites in central America but breed in North America. What is the difference between their success if they arrive back early compared to later arrivals? Which ones tend to arrive back earlier?

Answer 19

If they arrive back early, almost half breed multiple times/ are polygynous, if they arrive later, most will be monogamous
Those who have good overwintering habitats are in better condition and therefore arrive back earlier

Question 20

Climate change affects the match-mismatch theory. How? Give an example.

Answer 20

Arctic caribou plan their reproduction with food availability. Climate change means that there is a change of plant emergence but the Arctic caribou is not changing its reproductive patterns. This means there is a mismatch

Question 21

Is resource defence always by males? Use the dung beetles to explain how the roles can be reversed.

Answer 21

Females need carcass to lay eggs. Males may go off to mate with others or just attract females to the carcass. This creates competition between females. Females can enforce monogamy on males to prevent this (prevent him displaying)