Grade 12 Environmental Studies - Part 5 Social organisation Flashcards
Define social organisation:
Structure of relationships within a group
What features need to be divided among the group for social organisation?
- Resources = food, territories, nests etc.
- Activities = protection and other skills
What is the **value **of social organisation?
It improves the** survival and reproductive success** of an individual.
Makes it easier to:
1. avoid attacks by predators
1. find food by hunting collectively
1. divide labour
1. find mates
1. protect resources
1. regulate population size
List groups that have developed social organisation to a high degree:
- Insection e.g. termites, bees
- Mammals e.g. wild dogs, naked mole rats
Discuss herds or flocks as a PREDATOR AVOIDANCE strategy:
Advantage = safety of the group increased by avoiding and defending against predators
Why are less prey captured?
- Group more watchful, particularly individuals on the edge
- Can mob a predator = surround and overpower
- Dilution effect = the greater number of individuals, the greater survival chances
- Confusion and distraction = herd scatters, confusing predator
- **Protection of vulnerable **e.g. penguins protecting the moulting and vulnerable
- Migration = protection for inexperienced
Explain how zebras use herds and flocks avoidance strategies:
- Group more watchful, particularly individuals on the edge
- Can mob a predator = surround and overpower
- Dilution effect = the greater number of individuals, the greater survival chances
- Confusion and distraction = herd scatters, confusing predator
- **Protection of vulnerable **e.g. penguins protecting the moulting and vulnerable
- Migration = protection for inexperienced
ZEBRA also use stripes to cause individual zebras in herd to blend together when viewed form distance.
See Learning activity 16
Explain ho “the pack” is used as a successful hunting strategy? Use and example the African Wild Dog as an example.
African Wild Dogs = highly sociable
* Complex methods of communication
* Slim, long-legged animals about the size of Alsation dog
* Mottled coats = combination of tan, black and white - each with individual pattern.
* Differ from true dogs and wolves - has only four toes on each foot
* Large rounded ears = very sharp sense of hearing
In SA found in Nature Reserves, free roaming in parts of Namibia
How do they catch their prey?
One of highest success rates as predator in Africa
Hunt in close-knit packs - up to 15 adults
Prey includes antelope, zebra, warthog
**How do they catch their prey? **
1. After detecting prey by sight and sound they chase it at a fast run - about 45 km/h. Even for more than hour.
1. Tire out the prey - then they immobolise it. One grabs tail, other lip - rest kill the prey.
1. Whole pack shares in the kill AND young feeds first (unusual!).
1. WIld dogs left behind in den, e.g. very young, dominant female and pups = fed by regurgitated meat
Explain the social grouping of animals with a dominant breeding pair such as African Wild Dog:
E.g. wild dogs (dominant male and female)
Strict ranking system - led by **dominant alpha male and female **(stay mates for life) and prevent other females from breeding.
What happens to the offspring?
Females reach sexual maturity at 18 months to 2 years - they leave to join a new pack.
Males remain with their pack for rest of their lives - e.g. 11 years.
What are the benefits of a dominant breeding pair as a form of social organisation?
- Keeps the pack under control - operates as highly succesful unit
- raising pups of dominant breeding pair and caring for suck and old = group task
- Subordinate members of group benefit too - they have access to mates and other resources shared by group. They may later become dominant as well.
Why are wild dogs the second most endangered carnivore (after Ethiopian wolf) in Africa?
- Hunting
- Loss of habitat
- Vulnerable to the spread of disease
Explain how **division of tasks among castes **as a social organisation functions:
**DIVISION OF TASKS OR LABOUR **- for most animals that live in social groups e.g. bees, wasps, naked mole rats etc.
Each individual has role to play - NB for group success
EUSOCIAL ANIMALS - MOST ADVANCED form of social organisation - live in colonies in which:
1. Dominant breeding pair or single female (queen)
1. Non-breeding animals have different tasks to perform - strict caste system: collecting food, caring for young, building, maintaining and protecting nest.
Such individuals would not survive on own, due to environmental pressures THUS MAJOR EVOLUTIONARY INNOVATION
Define eusocial:
Species that exhibit the **highest level **of social organisation.
Discuss TERMITES as an example of eusocial organisation - refer to role of REPRODUCTIVES, WORKERS AND SOLDIERS
Cellulose - eating insects, living in colony which is **highly organised and integrated. **
African and Australian termites create **large mounds **of soil which are cemented with faeces and salive - termetaria.
The CASTE system includes:
REPRODUCTIVES:
1. Alates = Two winged termites, the founders of the colony. Appear in rainy season and mate. Each pair found a new colony.
1. **Queen and King = After loosing their wings, pair burrow underground. Female becomes the Queen and male the King. The (thousands of) eggs that queen lays weekly, hatches into **NYMPHS - young terminates that will grow into different roles. King also plays NB part - mating with queen regularly.
1. Young reproductives = Young termites that will become either new ALATES or SUPPLEMENTARY REPRODUCTIVES (that can replace K and Q if they die)
WORKERS:
* Most of the colony termites are workers - male or female.
* Tunnels, build mounds, forage for food, look after eggs and nymphs, feed them
* They can digest cellulose in leaves and wood by using bacteria and protozoa - passing on partially digested food to king and queen.
SOLDIERS:
* Make up around 5% of colony = develop HUGE BITING AND SQUIRTING MOUTHPARTS
* This helps with defense of colony, especially from ants
(See image page 27 textbook)
How is the ratio of CASTES regulated?
KIng, Queen and a set ratio of soldiers to workers to nymphs.
All nyhms are genetically identical at hatching, but could develop into 3 major castes:
* If individuals of any caste are lost, additional members of that caste develop - to restore balance
* If there is overproduction of a caste, selective canabalism restores balance.
Both reproductives and soldier castes secrete PHEROMONE (chemical message) that is transmitted through food sharing and grooming to other members which inhibits the development of reproductives or soldiers.
If the balance of the colony is upset, some undifferentiated nymphs do not receive the pheremone message, and develop into soldiers or reproductives.
Complete Learning Activity 17
