SPECIES INTERACTION

SPECIES INTERACTION

Which interaction shows cost to both actor and recipient?

In social-evolution terminology, spite describes an action that imposes a fitness cost on both the actor and the recipient. Its direct payoff is therefore (−, −), unlike altruism, which costs the actor but benefits the recipient, or mutualism, which benefits both. Spite can evolve only under restricted conditions because an allele that simply harms its bearer should be eliminated. Indirect fitness can make such behavior favorable when harm is directed preferentially toward individuals less related than the population average and thereby benefits the actor’s relatives through reduced competitio

Ref: Ecology: From Individuals to Ecosystems, Begon et al., 5th Ed., Ch. 8-13

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SPECIES INTERACTION

Which syndrome matches a flower that is red, tubular, with no odor?

Red, tubular, unscented flowers are associated with ornithophily, the bird-pollination syndrome. Many flower-visiting birds have strong color vision, including sensitivity to red, but rely less on odor than nocturnal moths or many insects. A tubular corolla can match a bird’s bill and position pollen on the head or body as nectar is reached. Such flowers often provide abundant, dilute nectar and are robust enough to withstand bird contact. Pollination syndromes are probabilistic trait combinations, not rigid rules: bees can visit red flowers, birds can visit nonred flowers, and actual pollinat

Ref: Ecology: From Individuals to Ecosystems, Begon et al., 5th Ed., Ch. 8-13

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SPECIES INTERACTION

Which of the following is an example of metabolic commensalism?

A hermit crab occupying a dead snail shell exemplifies metabiosis, a form of commensalism in which one organism uses a structure or environmental modification left by another after the producer has died or departed. The crab gains protection for its soft abdomen, while the former snail cannot be affected; there is no continuing reciprocal exchange. Tapeworms are parasites, ants and aphids are mutualists, and epiphytes on living trees illustrate support-based commensalism or inquilinism. The keyed example is therefore biologically appropriate for metabiosis. However, “metabolic commensalism” is

Ref: Ecology: From Individuals to Ecosystems, Begon et al., 5th Ed., Ch. 8-13

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SPECIES INTERACTION

Remora fish attaching to sharks for food and transport shows:

A remora gains transportation and access to food by attaching to a shark with a modified dorsal-fin suction disc. It may consume scraps from the shark’s meals and exploit feeding opportunities encountered during travel. In the traditional interpretation, the remora benefits while the shark experiences little measurable effect, giving the (+, 0) sign pattern of commensalism. The remora does not normally extract host tissue like a parasite, and reciprocal benefit is not required as in mutualism. Some remoras remove ectoparasites or clean wounds, which could benefit the shark and shift particular

Ref: Ecology: From Individuals to Ecosystems, Begon et al., 5th Ed., Ch. 8-13

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SPECIES INTERACTION

Plants avoiding herbivory by association with unpalatable neighbors is:

Associational resistance occurs when a plant suffers less herbivory because of the identity, abundance, or arrangement of neighboring plants. An unpalatable or chemically defended neighbor may mask host odors, visually conceal the focal plant, repel herbivores, reduce landing probability, or support predators and parasitoids that attack herbivores. The protected plant need not possess the neighbor’s defensive compound; reduced damage emerges from community context. This differs from chemical defense produced by the focal plant itself and from camouflage based solely on matching an abiotic back

Ref: Ecology: From Individuals to Ecosystems, Begon et al., 5th Ed., Ch. 8-13

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SPECIES INTERACTION

Which of the following is NOT a service provided by mutualistic interactions?

Mutualists commonly provide three broad kinds of services: resources, protection, and transport. Resource exchange includes plant carbon traded for fungal phosphorus or fixed nitrogen supplied by microbes. Protection includes ants defending plants and cleaning symbioses that remove parasites. Transport includes pollination and seed dispersal. “Energy conversion” is not usually listed as a separate service category in this simplified functional scheme, so it is the intended exclusion; biochemical conversion is normally treated under resource provision. The wording is scientifically problematic,

Ref: Ecology: From Individuals to Ecosystems, Begon et al., 5th Ed., Ch. 8-13

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SPECIES INTERACTION

Penicillin secreted by fungi harming bacteria is an example of:

Penicillin production illustrates antibiosis and is commonly classified as amensalism when susceptible bacteria are harmed while the fungus is assumed to be unaffected. Penicillin binds penicillin-binding proteins and inhibits transpeptidation of peptidoglycan, weakening the bacterial cell wall. Actively growing cells then become vulnerable to osmotic lysis. In ecological sign notation, this simplified interaction is (0, −), unlike parasitism (+, −), mutualism (+, +), or competition (−, −). However, assigning zero effect to the fungus is an assumption. If bacterial suppression releases nutrien

Ref: Ecology: From Individuals to Ecosystems, Begon et al., 5th Ed., Ch. 8-13

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SPECIES INTERACTION

What is the type of interaction in which ants protect aphids in exchange for honeydew?

Ants tending aphids illustrate defensive mutualism. Aphids ingest phloem sap and excrete excess carbohydrate as honeydew, which provides ants with an energy-rich food. Ant workers patrol the colony and attack ladybirds, lacewings, and parasitoid wasps, thereby lowering aphid mortality. Some ants also move aphids to suitable shoots or shelter them during unfavorable conditions. The aphid’s principal service is a resource, whereas the ant’s principal service is defense, so the association is classified by the protective function emphasized. It is not commensalism because both partners can benefi

Ref: Ecology: From Individuals to Ecosystems, Begon et al., 5th Ed., Ch. 8-13

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SPECIES INTERACTION

Which type of commensalism describes birds nesting in trees?

Inquilinism is a form of commensalism in which one species uses another organism, its body, or its constructed space as shelter or a place to live without significantly harming it. A bird nesting in a tree gains support and a protected site for eggs and young, while the tree is ordinarily treated as unaffected. Phoresy would require the tree to transport the bird, and metabiosis usually involves using a structure or environmental modification after its producer has finished with it, such as a hermit crab occupying an abandoned snail shell. Parasitism would require a net cost to the tree caused

Ref: Ecology: From Individuals to Ecosystems, Begon et al., 5th Ed., Ch. 8-13

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SPECIES INTERACTION

Which term defines competition where one organism excludes another without direct interaction?

Allelopathy is chemical interference in which one organism releases secondary metabolites that inhibit another organism’s germination, growth, survival, or reproduction. Plants may emit compounds from roots, leach them from leaves, volatilize them, or release them during litter decomposition. The target is excluded without physical confrontation, so allelopathy can contribute to interference competition at a distance. Black walnut juglone and compounds from some invasive plants are commonly discussed examples, although rigorous experiments must separate direct chemical effects from shade, nutr

Ref: Ecology: From Individuals to Ecosystems, Begon et al., 5th Ed., Ch. 8-13

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SPECIES INTERACTION

The algae and coral reef relationship is best described as:

Reef-building corals live in an intimate nutritional mutualism with intracellular dinoflagellates of the family Symbiodiniaceae, commonly called zooxanthellae. The algae photosynthesize and transfer a substantial fraction of fixed carbon to the coral host, supporting respiration, growth, and rapid calcium-carbonate deposition in nutrient-poor tropical water. Corals supply carbon dioxide, nitrogenous wastes, phosphorus, and a protected, well-lit cellular habitat. This reciprocal metabolic exchange explains the high productivity of reefs despite low surrounding nutrient concentrations. Many reef

Ref: Ecology: From Individuals to Ecosystems, Begon et al., 5th Ed., Ch. 8-13

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SPECIES INTERACTION

Cattle stirring insects for cattle egrets is:

Cattle egrets often forage near grazing cattle because the mammals’ movement through grass flushes insects and other small animals into view. The bird gains a higher capture rate or reduced search effort, while the cattle are generally assumed to experience neither benefit nor harm. This asymmetrical (+, 0) effect is commensalism. The egret is not consuming tissue from the cattle, so the relationship is not parasitism; its predation is directed at the disturbed insects. Mutualism would require evidence that cattle benefit, perhaps through removal of ectoparasites, but the classic example speci

Ref: Ecology: From Individuals to Ecosystems, Begon et al., 5th Ed., Ch. 8-13

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