consumption Flashcards
(22 cards)
Herbivory (type of consumption)
takes place when herbivores consume plant tissues.
parasitism (type of consumption)
occurs when a parasite consumes relatively small amounts of tissue or nutrients from another individual called the host. Often occurs over a long period. Not necessarily fatal and parasites are usually small relative to their host.
predation (type of consumption)
occurs when a predator kills and consumes all or most of another individual. The consumed individual is called the prey. Predation can refer to carnivores and to the consumption of plants, especially seeds.
Natural selection strongly favors traits that allow individuals to
avoid being eaten.
standing or constitutive defenses
they are present even in the absence of predators. includes things such as armor or weapons.
cryptic coloration (constitutive)
helps prey escape detection.
escape behavior (constitutive)
prey may have adaptations to detect predators and run, fly, jump, or swim away.
Toxins and other defense chemicals (constitutive)
prey may lace their tissues with toxic compounds. Many advertise their toxicity with warning coloration.
schooling/flocking (constitutive)
predators can become confused by groups of prey.
defense armor and weapons (constitutive)
prey may have protective shells, sharp spines, or other defense structures.
mimicry
pattern of one species resembling another.
Batesian mimicry
natural selection favors mimic species that resemble the unpalatable species.
Müllerian mimicry
the existence of similar-looking unpalatable prey in the same habitat increases the likelihood that predators will learn to avoid them. Thus, co-mimicry boosts the fitness of both species.
Take-home message from studies of mimicry is that the +/- consumption interactions between two species can cause
unexpected consequences to other species in the community.
Natural selection in the form of predator-prey interactions can result in
mutualism, commensalism, and other types of interactions among prey species.
Although constitutive defenses can be extremely effective, they can also be
expensive due to the energy and resources that must be devoted to producing and maintaining them.
Inducible defenses
physical, chemical, or behavioral defensive traits that are induced in the prey in response to the presence of a predator. Decline in prey species if the predators leave the habitat. Efficient energetically, but they are slow – it takes time to produce them.
Prey are typically
smaller than predators, have larger litter or clutch sizes, and tend to begin reproducing at a younger age. As a result, they have a much larger intrinsic growth rate. this quantity, symbolized rmax, is the maximum growth rate that a population can achieve under ideal conditions.
Data indicate that in many instances, predators are efficient enough to
reduce prey populations below carrying capacity.
Meta-analysis
study of studies, meaning an analysis of a large number of data sets on a particular question.
Top-down control hypothesis
herbivore populations are limited by predation and disease. Predators and parasites remove herbivores that eat plants. As a result, a great deal of plant material remains uneaten.
Bottom-up limitation hypothesis
plant tissues offer poor nutrition and are well defended. Herbivore numbers are limited because plant tissues offer poor nutrition, or that plant tissues aren’t eaten because they are toxic.
