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SS3: BIOLOGY - 2ND TERM

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  1. Reproductive Behaviours | Week 1
    1 Topic
    |
    1 Quiz
  2. Life Cycles of Insects, Toads | Week 2
    6 Topics
    |
    1 Quiz
  3. Social Insects | Week 3
    2 Topics
    |
    1 Quiz
  4. Biology of Heredity (Genetics) I | Week 4
    4 Topics
  5. Biology of Heredity (Genetics) II | Week 5
    6 Topics
    |
    1 Quiz
  6. Biology of Heredity (Genetics) III | Week 6
    7 Topics
    |
    1 Quiz
  7. Variation | Week 7
    1 Topic
    |
    1 Quiz
  8. Evolution | Week 8
    3 Topics
    |
    1 Quiz
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Topic Content:

  • Meaning of Courtship Behaviour
  • Types of Courtship Behaviour Pairing
    • Display
    • Territoriality
    • Seasonal migration
    • Pairing

Courtship behaviours are specialized patterns of behaviour that precede mating and reproduction in animals. 

The behaviour is carried out in sequence and each action is alternately performed by male and female animals, each step acts as a stimulus. 

In courtship the main process developed is communication. Communication can be developed by dancing, shaking, smell, and visual or auditory signals in different organisms. 

Types of Courtship Behaviour Pairing:

  • Display
  • Territoriality
  • Seasonal migration
  • Pairing

Pairing:

This is a type of reproductive behaviour in which a mature female and male leave their home and establish a new home elsewhere. This occurs when organisms leave their habitat in groups of two, one male and one female for the purpose of mating. The pairing may be very brief, in that it ends immediately after mating or may last for a lifetime. Pairing occurs in toads, winged termites, fishes e.g. Tilapia, Clarias etc.

toad
The male Toad clutches the female, with the help of nuptial pads, from behind in a tight embrace.

Display:

It is an elaborate process involving a series of fixed patterns of movements between mating partners. In other words, it is a reproductive behaviour an animal exhibits to attract the opposite sex into mating.

In animal breeding, it indicates when the animals are in heat.

The display can be in the form of sound, display of beautiful colours, dance, song, the release of chemicals, etc.

Examples 

a) Domestic fowls, and pigeons, dance, and stagger in a unique way. Hens scratch the ground and the lower part of their wings.

b) Peacock: Fan-like shape display of beautiful feathers which attracts females

Peacock
Peacock attracting a mate.

c) Male Agama Lizards: In the morning as they bask in the sun their vibrant colours return. Male lizards use a variety of methods to attract a female’s attention. They bob their head vigorously or display their brightest colours. The Male with the brightest head colour is the dominant.

agama lizard

Females tend to be less colourful than the males of the species. The female makes soliciting postures by arching her back and lifting her tail upright. The male displays its colour and lowers its gular fold.

d) Toad: During courtship, the male makes a croaking sound which attracts the female which is usually swollen with eggs.

Release of Chemicals:

Pheromones are chemical substances which are secreted to the outside by an animal and received by another animal of the same species.

Pheromones are chemical signals that some animals use to communicate with each other.

Sex pheromones are types of pheromones or chemical signals released by an organism (usually female) to attract an individual (a male), encourage it to mate with it, or perform some other function closely related to sexual reproduction.

For example, when lionesses are in heat, they will spread their sex pheromones from the Anal Glands upon Trees & Bushes. This scent will attract Male lions who then interpret the signal as a willingness to mate and produce offspring. A Grimace will be formed on The Lion’s Face which is called “Flehmen” response!

flehmen
Male Lion – “Flehmen” response!

Pheromones have been found in almost every kind of animal, including deer, squid, fish, salamanders, and mice, to name just a few.

Territoriality:

It is a behaviour whereby a mature animal establishes a territory from which it maps out a fixed area in a habitat, and claims ownership of the area while other rivals of the same species are driven away. Courtship displays are carried out within this territory.

In agama lizards, the territory contains an adult male, many young males, and females and adult females. Any male adult intruder is met with strict objection by fighting and threatening the intruder. Such fighting involves a lot of bobbing and weaving in an attempt to scare the opponent. If it comes to blows, they lash out with their tails and threaten each other with open jaws. Older males commonly have damaged tails from previous fights.

In tilapia fish, the male establishes a colony at the bottom of the pond. It defends its territory by showing threat displays, keeping median fins erect, pushing down the floor of the mouth and flicking off its tail. 

In lions, males establish territories twice as large as females and overlap the ranges of several females. Both sexes mark their ranges with urine.

Territorial behaviour is commonly observed in many different bird species. Large birds like Owls, hawks, and eagles are highly territorial when it comes to breeding, and feeding grounds, and require a large territory. Both males and females will use vocalizations and physically aggressive displays for all rivals to see and hear to make their claim to the ownership of a territory. Males are known to be more aggressive

Territory size often varies in the same species from habitat to habitat.

Territorial behaviour ensures an adequate supply of food, and nesting materials for the young thereby resulting in better growth. 

The young and the female are protected from attack from other males and rivals.

Seasonal Migration:

Migration is the movement of animals from one place or habitat to another, where conditions are favourable for breeding, and they may return to their original location when the weather warms or food becomes available.

For Example:

a. Migration in Fish:

i. Salmon fish breed in North America and Europe:

Newly young hatched Salmon fish migrate to the Atlantic Ocean, feeding and growing for several years, after a certain period they return to North America or Europe (where they were born) to breed and spawn. 

ii. Herring:

Herring migrate annually between their feeding grounds in Kattegat and Skagerrak of the North Sea, along Denmark, Norway, and Sweden and their coastal spawning grounds.

Spawning is breeding and conception outside the animal body, most commonly found in species living in aquatic environments.

iii. Eels – Common eels feed and grow in Eastern and Northern America but travel 5000 km to the Sargasso Sea in the Caribbean to breed and spawn. The young eels that hatch then travel back to feed and grow.

Salmon Migration
Salmon Migration.

b. Migration in birds: 

Birds such as cattle egrets migrate from the northern part of Nigeria to the southern states during the dry season to escape drought, and lack of food, and also to breed.

cattle egret
Cattle Egret.

c. Sea Turtle Migration:

Both males and females will migrate to nesting areas to breed, generally in the area where they were born.

Sea Turltes
Migrating Sea Turtle.
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