Week 10: Interactions: Competition, Predation, Parasitism and Symbiosis Flashcards
Population dynamic and Intraspecific competition, Interspecific Interactions and Interspecific competition, Predator- prey and Host- parasite interactions and Symbiosis (28 cards)
Describe the methods we used to measure population abundance and differentiate between absolute and relative measures.
absolute population size (total number): surveys, mapping nests, drone, mark release recapture
relative population size (trends in number): standardized walks/ observations
population size model equation (closed and open)
Nt+1 = Nt + B – D (+ I - E)
Nt =population size at some specified time
Nt+1 = population size one time period later
B = number of births in the time period
D = number of deaths in the time period
() = inclusion of immigrants and emigrants makes it an open model
Outline the phases of population growth, and the concepts of intrinsic rate of increase (r) and carrying capacity (K)
Define the terms density dependent and density independent in relation to survival/reproduction, outline the causes of density dependent mortality, and for any particular factor, state if it is density dependent or independent.
- Density dependent effects (growth of pop size caused by density): increases in mortality, fecundity/fertility decreases, dispersal increases. Because lower food, increased disease and predation
- Density Independent effects (changes in pop size not to do with density): environmental factors such as hard winters and warm summers
Be able to identify the maximum sustainable yield for harvesting.
Point where pop growth is maximized
Have way up the sigmoidal curve
Distinguish between exploitation and interference competition and be able to calculate expected distributions under an Ideal Free model of exploitation competition.
E: no direct interaction, competition through shared resource.
I: prevent access of others to resource to gain exclusive use
Ideal free distribution:
Relate the consequences of different competition modes for population size stability.
- Exploitation (less stable): if over k no one gets enough so little breeding, reproduction and pop crash
- Interference: winners and losers, winning species takes control of whole resource and other becomes extinct
Account for the rarity of big fierce animals, and why small populations are at risk of extinction.
Carrying capacity (K) depends on:
size of food base (Kcal), size of species, ecological efficiency (calories lost on other things)
Rare because:
larger than prey so low ecological efficiency, endotherm means more E on R and active hunting
Contrast patterns of human population growth with the logistic model and relate different scenarios for human population size.
does not show classic exponential growth
-over 2 billion: predicted famine
-Cohen’s solutions: new tech, reduce pop and consumption, eliminate corruption/violence/ inequalities between rich and poor
Explain the importance and the role of interspecific interactions in different fields of science and industry.
ecology, conservation, agriculture, microbiology, medicine
Identify and describe with examples the main types of interspecific interactions
- Competition: interaction between organisms that require the same limited resource
- Predation: predator kills prey
- Parasitism: one benefits by feeding/living in host causing harm not death
-Mutualism: symbiosis where they live in close physical contact whilst both gaining adv
Commensalism: one benefits whilst other neither helped nor harmed
Amensalism: one is heavily harmed whilst other unaffected
-Saprotrophs, Decomposers and detritivores. Defining these terms, provide examples, and explain their significance in ecosystems.
-Saprotrophs (do not control supply): organisms that make use of dead organic matter
- Decomposers (e.g. bacteria + fungi): break down at molecular level , release nutrients back
- Detritovores (e.g. earthworms, millipedes) feed on dead plant/ animals and break down larger particles
Define interspecific competition and explain the conditions necessary for it to occur.
competition between different species for the same limited resources
Differentiate between the fundamental niche and the realized niche, explain how competition restricts species to their realized niche.
F: full range of environmental conditions and recourses a species COULD occupy
R: ACTUAL range of env conditions they live in taking into account abiotic factors like predation
Explain the competitive exclusion principle with examples. Identify factors that mediate coexistence.
Two species competing for the same limiting resource CANNOT coexist , one will outcompete and the other will locally extinct
Mediators: resource partitioning (diff niche), env variation, disturbance
Define character displacement, provide examples, explain its role in reducing niche overlap and competition between sympatric species. Explain the requirements for character displacement to occur. Describe the challenges in demonstrating character displacement.
The evolutionary divergence of traits in sympatric species due to competition. Reduces niche overlap as selection for each species to utilise separate niche.
Requirements:
- phenotypic differences between sympatric species are greater than allopatric
- p differences have genetic basis
- resource use related to trait
- competition for that resource exists
Challenges:
- historical factors can be difficult to rule out
- heritability of traits needs to be examined
Explain the purpose and utility of the Lotka-Volterra model, its key assumptions and predicted outcomes.
Mathematical model for understanding competition
- pop growth: each group grows separate but there is a limit to how many
- competition: when two species meet they compete for food which affects speed
of growth
- carrying capacity: the max number of animals the area can support
Predicted outcomes:
- competitive exclusion
- coexistence
- unstable dynamics
Define predation and describe its key characteristics.
Define and explain the key aspects of predator-prey coevolution concepts, such as Arms Race and Red Queen Hypothesis.
Red Queen: continuous adaptation works like an evolutionary treadmill maintaining coevolutionary dynamics pushing genetic diversity
Explain the main idea of the Lotka-Volterra predator-prey model, including its assumptions, population cycles, and limitations.
assumptions: cyclical relationships/ oscillations in both prey and predator, exponential growth of prey with absent predator, predator dependence on specific prey, continuous data of overlapping generations, unlimited food supply.
Limitations: doesn’t account for multiple predator species, migration, diseases, environmental changes
- Name factors affecting predator-prey dynamics and provide examples of predator-prey dynamics.
Trophic Cascades: powerful indirect interactions where the effects of a predator propagate through a food web, impacting other species
ecological interaction between P and p mean that their numbers depend on each other
e.g. deer hunting to manage pop of predators
Predator Responses:
I: No limit to amount of prey (filter feeders)
II: with increasing prey density there is a decline in prey consumption
III: Exponential increase in the rate of consumption with increasing density to max point
Identify prey defences against predation, including physical, chemical, crypsis, mimicry, and behavioural strategies.
P: shells, spines, armour
Ch: poisons either made or taken from plants
Cr (camo): alter skin colour and texture, fur changes seasonally, pattern matching
M: Batesian mimicry (harmless species imitates harmful) Mullerian mimicry (two or more species with effective defences share similar warnings for mutual protection)
B: alarm calling, schooling
- Classify types of predators (true predators, grazers, etc.) and describe their adaptations for capturing prey.
- Taxonomic: Carnivores, herbivores, omnivores
- Functional: Predators, grazers, parasites, parasitoids (insect whose larvae feed on other arthropods
- Foraging types (increasing in range): monophagous -> oligophagous -> polyphagous (strategies include hunting and sit + wait)
KEYSTONE predator: plays a critical role in maintaining the structure and diversity of an environment
Define symbiosis and relate the diversity of symbioses in terms of identity of partners, means of formation, and requirement of parties for each other.
a symbiont and host living together
-Varying location: Endosymbiont (inside body/intracellular), Gut symbiont (colon/lumen/villi/rumen), Ectosymbiont (outside)
- Varying formation: through environmental horizonal transmission OR vertical transmission through mum
- Varying Impact: obligate/Required, facultative mutualist/not required, parasitism/ exploitative
