Biotic factors with reference to mutualism, amensalism, commensalism and parasitism

types of relationships with suitable examples

1. Biotic factors with reference to Mutualism, Amensalism , Commensalism and Parasitism with suitable examples BY: MARIYAM NAZEER AGHA KUD NO: 15S14233 DEPT. OF STUDIES IN ZOOLOGY GOVT. ARTS AND SCIENCE COLLEGE, KARWAR

2. Contents Mutualism Amensalism Commensalism Parasitism (with examples)

3. Mutualism MUTUALISM is the way two organisms of different species exist in a relationship in which each individual benefits from the activity of the other. Mutualistic interactions are vital for terrestrial ecosystems  as more than 48% of land plants rely on  mycorrhizal  relationships with fungi to provide them with inorganic compounds and trace elements. Mycorrhizal association is an example for mutualism

4. Types of mutualistic relationships Types of relationships Service-resource relationships Pollination in which nectar or pollen (food resources) are traded for pollen dispersal (a service) or ant protection of aphids, where the aphids trade sugar-rich  honeydew in return for defense against predators such as ladybugs. Service-service relationships In the relationship between sea anemones and anemone fish, the anemones provide the fish with protection from  predators and the fish defend the anemones against  butterflyfish , which eat anemones. Humans Humans are involved in mutualism with other species. T heir  gut flora is essential for efficient  digestion. Some relationships between humans and domesticated animals and plants are to different degrees of mutualism. For example, agricultural varieties of maize provide food for humans and are unable to reproduce without human intervention because the leafy sheath does not fall open, and the seed head does not shatter to scatter the seeds naturally. Pollination (service – resource) Sea anemone and anemone fish (service – service)

5. AMENSALISM Amensalism is the type of relationship that exists where one species is inhibited or completely obliterated and one is unaffected by the other. There are two types of Amensalism ; competition and antibiosis. Competition is where a larger or stronger organism deprives a smaller or weaker one from a resource. Antibiosis occurs when one organism is damaged or killed by another through a chemical secretion. 

6. Contd. Competition: A sapling growing under the shadow of a mature tree: The mature tree can rob the sapling of necessary sunlight and, if the mature tree is very large, it can take up rainwater and deplete soil nutrients. Throughout the process, the mature tree is unaffected by the sapling. Indeed, if the sapling dies, the mature tree gains nutrients from the decaying sapling. Antibiosis: Juglans nigra  (black walnut), secretes juglone , a substance which destroys many herbaceous plants within its root zone. Competition between trees and saplings Antibiosis in Black walnut

7. Commensalism In commensalism, one organism benefits from the relationship while the other species involved neither benefits nor is harmed. The unharmed organism is unaware of what is happening, or chooses to ignore it. The organism benefitting is often gaining food or shelter. The benefits for one organism can be in a variety of forms, including food, shelter, transportation and seed dispersal.

8. Types of commensalism C ommensalisms vary in strength and duration from intimate, long - lived  symbioses to brief, weak interactions through intermediaries. Phoresy Phoresy  is one animal attached to another exclusively for transport, mainly arthropods, examples of which are mites on insects (such as beetles, flies or bees ), millipedes  on  birds, etc. Inquilinism Inquilinism is the use of a second organism for permanent housing. Examples are epiphytic plants (such as many orchids) that grow on trees ,  or birds that live in holes in trees. Metabiosis Metabiosis is a more indirect dependency, in which one organism creates or prepares a suitable environment for a second. Examples include maggots, which feast and develop on corpses; and hermit crabs, which use gastropod shells to protect their bodies. Phoretic mites on Sexton beetle Inquilinism in birds Hermit crab

9. PARASITISM Parasitism  is a non-mutual relationship between species, where one species, the  parasite , benefits at the expense of the other, the host.  P arasites typically do not kill their host, are generally much smaller than their host, and often live in or on their host for an extended period.

10. Contd. Parasites reduce hosts’  biological fitness by general or specialized pathology, from impairment of secondary sex characteristics, to the modification of host behavior . Parasites increase their own fitness by exploiting hosts for resources necessary for their survival, in particular transmission. Although parasitism often applies unambiguously, it is part of a continuum of types of interactions between species, grading via parasitoidy into  predation . E xamples include interactions between vertebrate hosts and tapeworms, flukes, the  Plasmodium  species, and fleas.  Tapeworm in mammalian gut Broodal parasitism