ecology exam4 studyguide

Interference

Direct and aggressive interaction between individuals.

Intraspecific

Competition with members of the same species.

Gause's Competitive Exclusion Principle

Two species with identical niches cannot coexist indefinitely.

Fundamental Niche

The full range of environmental conditions and resources a species can potentially occupy.

Realized Niche

The actual space a species occupies due to competition and other ecological interactions.

Exploitation Competition

Indirect inhibitory effects due to reduced resource availability.

Interference Competition

Direct inhibitory effects due to reduced resource use.

Mutualism

Interactions beneficial to both species involved.

Symbiosis

A specialized form of mutualism where species become physiologically integrated.

Mycorrhizae

A fungus/plant root association benefiting both parties.

Describe intraspecific competition among herbaceous plants.

In low-density populations, plant growth rates and weights increase. However, at higher population densities, competition for resources intensifies, leading to 'self-thinning' or mortality among competing plants.

Define interspecific competition.

It refers to competition between individuals of more than two species

How does Gause's principle of competitive exclusion explain coexistence?

two species with identical niches cannot coexist indefinitely. In a given set of conditions, one species will be a better competitor, leading to higher fitness and eventually excluding the other.

Describe the multi-dimensional nature of niches.

two species may have complete overlap in one or more dimensions, but they cannot have complete overlap in all dimensions. Complete overlap in all dimensions would make them the same species.

What did Connell study regarding interspecific competition in barnacles?

Balanus plays a role in determining the lower limit of Chthamalus within the intertidal zone, showing that niche restrictions are well understood but do not account for all actual patterns.

How did the presence of Balanus affect Chthamalus in different zones of the intertidal area?

In the upper intertidal zone, removal of Balanus had little effect on Chthamalus, suggesting little competition. In the middle intertidal zone, the removal of Balanus had a major effect on Chthamalus, indicating significant competition.

Describe the impact of interspecific competition on Tribolium spp. infesting stored grain products.

Tribolium confusum and T. castaneum demonstrated interspecific competition under varied environmental conditions, restricting the realized niches of both species to fewer environmental conditions when grown together.

What is the significance of individual beak depths in ground finches according to Grants' findings?

Beak depth in ground finches correlates with the size of seeds eaten, with individuals having the deepest beaks feeding on the hardest seeds.

How does competition occur in niches with regard to limited resources?

Competition occurs where niches overlap concerning limited resources, leading to direct or aggressive interactions between individuals.

Describe exploitative interactions in ecology.

involve predators, parasites, and pathogens influencing the distribution, abundance, and structure of prey and host populations.

What are some examples of exploitative interactions in ecology?

predation, herbivory, pathogens inducing disease, and parasitism.

Define interference competition in ecology.

Interference competition involves direct inhibitory effects arising from reduced use of resources or interference with resource acquisition.

How do parasites alter host behavior in exploitative interactions?

Parasites may alter host behavior to increase the likelihood of being consumed by a predator, ultimately benefiting the parasite.

Describe the predator-prey paradox in ecology.

The predator directly influences the growth and survival of the prey, while prey density influences the growth and survival of the predator, leading to reciprocal selection pressures.

What is the role of parasitoids in exploitative interactions?

Parasitoids consume and kill the host, unlike typical parasites that aim to consume without killing the host.

Explain the concept of exploitation competition in ecology.

Exploitation competition involves indirect inhibitory effects due to reduced availability of resources, where a competitor becomes a more effective exploiter/user.

What is the significance of territoriality and allelopathy in exploitative interactions?

Territoriality and allelopathy can lead to reduced success for individuals involved in interactions, affecting the fitness of exploited individuals.

Describe the complex interactions involving spiny-headed worms and amphipods.

Spiny-headed worms alter the behavior of amphipods to increase the likelihood of being eaten by a vertebrate host, showcasing a complex exploitative interaction.

How do blister beetle larvae interact with burrowing bees in exploitative interactions?

Blister beetle larvae mimic female pheromones to swarm into male bees during mating attempts, then move to females during later mating efforts, consuming pollen, nectar stores, eggs, and larvae before returning to the burrow.

Describe the impact of exploitation on, abundance, and structure.

Exploitation can affect the distribution, abundance, and community structure by altering the biomass of benthic animals and reducing the abundance of their own food supply.

What were the effects of mangemites (Sarcoptes scabiei) on foxes in Sweden according to Lindstrom et al. (1994)?

Mangemites caused hair loss, deterioration, and death in foxes, leading to a 70% decline in fox populations and an increase in mountain hares.

Define abundance cycles in the context of snowshoe hares and their predators.

Abundance cycles refer to the fluctuating population levels of snowshoe hares and their predators, influenced by factors like habitat, food availability, and predation.

How did Elton propose abundance cycles were driven?

Elton proposed that abundance cycles were driven by variations in solar radiation.

Describe Keith's 'overpopulation theories' regarding predator-prey dynamics.

Keith suggested that predator-prey dynamics could be influenced by decimation due to disease and parasitism, physiological stress at high density, and starvation from reduced food.

What is the role of predation in snowshoe hare populations during peak densities?

Predation can account for 60-98% of mortality during peak densities, as hare populations increase while their food supply decreases, leading to starvation and increased predation.

Define mutualisms and differentiate between facultative and obligate mutualisms.

Mutualisms are interactions beneficial to both species. Facultative mutualisms are where species can survive without the interaction, while obligate mutualisms require the interaction for survival.

How is symbiosis defined in the context of mutualism?

where the species involved become physiologically interconnected for mutual benefit.

Describe the role of Arbuscular Mycorrhizal Fungi (AMF) in plant-fungus symbiosis.

provide plants with phosphorus and enhance root absorption. They form arbuscules for material exchange, have hyphae for growth, and vesicles for storage.

Define Ectomycorrhizae and its function in plant roots.

form a mantle around roots, increasing access to immobile nutrients.

How does resource availability influence plant allocation in the context of mycorrhizal fungi relationships?

with fertilization leading to less root allocation and potentially selecting for better mycorrhizal fungi competitors.

Describe the concept of species abundance and diversity in ecological communities.

influenced by richness, evenness, and environmental complexity, with disturbance levels impacting diversity.

What are the four ways in which communities can be structured?

physiognomic (physical structure), species composition, trophic interactions, and temporal activity.

Explain the concept of Lognormal Distribution of Abundance in ecological communities.

follows bell-shaped curves, with significant effort required to capture rare species due to the effect of sample size.

List factors that can affect species diversity in ecological communities.

climatic stability, resource division. Predation and disturbance

Describe the Intermediate Disturbance Hypothesis.

suggests that both high and low levels of disturbance reduce diversity, while intermediate levels promote higher diversity.

What are the characteristics used to describe disturbances?

Size, frequency, turnover, intensity, and severity.

Explain Hutchinson's view on phytoplankton communities.

appear paradoxical as they compete for the same nutrients in relatively simple environments, but environmental heterogeneity contributes significantly to their diversity.

How did Jordan describe the diversity in tropical forests?

organized in two ways: a large number of species within communities and a large number of plant communities with distinct species compositions in a given area.

What happens in ecosystems with no or rare disturbances according to the content?

only good competitors succeed.

Define competitive exclusion in the context of species colonization.

It refers to the process where one species outcompetes another leading to the exclusion of the less competitive species.

Explain the impact of severe or frequent disturbances on species in an ecosystem.

lead to only tolerant species succeeding, with competitive exclusion likely prohibited and r-selected species favored.

What role does environmental heterogeneity play in promoting diversity in phytoplankton communities according to Hutchinson?

account for a significant portion of the diversity in phytoplankton communities despite their competition for the same nutrients in relatively simple environments.