Higher biology Unit 3 P2

Symbiosis

An intimate relationship that has coevolved between members of two different species.

Parasitism

Relationship between a parasite and its host. Parasite benefits in terms of energy and nutrients and their host is harmed by a lack of those.

Common feature of a parasitic organism

They have a limited metabolism and cannot survive outside of contact with a host.

3 ways parasites can be transmitted to new hosts

1. Direct contact

2. Resistant stages

3. Vectors

Example of parasitic transmission by direct contact

Head lice passed from person to person.

Resistant stage

Some parasites have stages in their life cycle in which they can survive adverse environmental conditions until a new host comes in contact with them.

How can vectors be used to transmit parasites ?

Some parasites use other species to transfer them from one host to another. For example plasmodium parasite (malaria) is carried by mosquitoes from one human to another.

Primary host

Organism in which the parasite reproduces and reaches adulthood.

Secondary host

An organism that is involved in a stage of the life cycle of a parasite separate from the main host.

Mutualism

Moth mutualistic partner species benefit in an interdependent relationship. For example, cattle and cellulose digesting bacteria.

3 benefits to animals living in social groups

1. Individuals benefit from increased protection.

2. There are opportunities for cooperative hunting

3. It allows for the division of labour.

Social hierarchy

A rank order within a group of animals consisting of dominant and subordinate members.

How does social hierarchies benefit the entire group?

Reduce conflict, increase chances of the dominant animals favourable genes being passed onto offspring.

How can individuals increase their social status?

By forming alliances.

What displays does dominant and subordinate individuals carry out to maintain social hierarchy?

Dominant individuals carry out ritualistic display and subordinate animals carry out appeasement behaviours.

Cooperative hunting

Members of a social group working together to hunt prey. This occurs in populations of lions, wild dogs and wolves.

How does cooperative hunting benefit the group?

It allows larger prey to be caught, it increases chances of success.

What is a social defence strategy?

A method of working together which reduces the chance of attack by predators.

Altruism

A donor harming itself to benefit the recipient. Altruistic behaviour is common between related individuals.

Reciprocal altruism

When roles of donor and recipient are later reversed.

Kin selection

Altruistic behaviour that occurs between related members of the group.

How does kin selection indirectly benefit the donor?

Increased chance of survival of shared genes in the recipient’s offspring or future offspring.

Social insects

Insects that live in social colonies for example bees, wasps and ants.

Structure of a social insect society

Only queens and drones carry out reproduction

Sterile workers help raise close relatives, defends the hive, collects pollen and carries out waggle dances to show direction of food.

Examples of primates

Lemurs, monkeys, apes and humans.

Why do primates have a long period of parental care?

To allow learning of complex social behaviours.

What are complex social behaviours that primates need to learn?

Communication, cooperation and sharing. To support the social hierarchy and improve chances of survival. Reduction in conflict through ritualistic display and appeasement behaviour.

4 examples of complex social behaviours in primates.

1. Grooming

2. Facial expression

3. Body posture

4. Sexual presentation.

When are ritualistic behaviours used?

When competing over resources. These behaviours are used to make the individual look larger and fiercer.

When are appeasement behaviours used?

To reduce reduce unnecessary conflict between individuals within the social group.

Biodiversity

The variety of species found in an ecosystem

3 components of biodiversity

1. Genetic biodiversity

2. Species diversity

3. Ecosystem diversity

What is genetic diversity?

Number and frequency of all the alleles within a population.

How does loss of one population of one species affect ability of the entire species to survive?

The species would have lost some of its genetic diversity, this may limit its ability to adapt to changing conditions.

Species richness

Refers to the number of different species in an ecosystem.

Relative abundance

Proportion of each species in the ecosystem.

Species diversity

Comprises the species richness and relative abundance.

How does presence of a dominant species affect species diversity?

Lower species diversity.

Ecosystem diversity

Number of different ecosystems within a defined area.

Island biogeography

Island biogeography explains that the biodiversity and number off species inhabiting an island is impacted by the islands land size and degree of isolation.

Over exploitation

Using resources at a rate that they cannot be replaced.

Bottleneck effect

When populations become so small that they lose the genetic variation necessary to enable evolutionary responses to environmental change.

Why is genetic diversity particularly important for small populations to survive?

Inbreeding can result in poor reproductive rates.

Habit fragmentation

When a habitat is broken up into smaller fragments or sections.

2 issues of habitat fragmentation

1. Increased competition between species as the fragment becomes smaller, this decreases biodiversity.

2. Smaller more isolated fragments exhibit lower species diversity.

How can biodiversity be increased when habitat fragmentation has taken place?

Habitat corridors

Introduced species

Non native species that humans have moved either intentionally or accidentally to new geographic locations.

Naturalised species

Introduced species that become established within wild communities.

Invasive species

Naturalised species that spread rapidly and eliminate native species, they may prey on native spevies, outcompete them or hybridise with them. They reduce species diversity.

Why do invasive species often outcompete native species?

They may well be free of the predators, parasites, pathogens and competitors that limit their population in their native habitat.