Community Ecology Flashcards
Most populous countries
China, India, US
Human Population Growth
growing rapidly
Human Population Projected Growth
low, medium, and high refers to different projections of fertility rates
Age structure/pyramid
-relative number of individuals of each age in a population
Community
- all of the species that interact with each other in a certain area
- direct or indirect
Direct interactions
- competition
- predation
- mutualism
Indirect interactions
-species interact through one or more intermediary species
Types of interactions
-categorized by effects of fitness
negative (-)
positive (+)
neutral (0)
Amensalism
neutral - negative
e. g. termites being stepped on by elephant
- negative on termite
- neutral on elephants
Commensalism
positive - neutral
e. g. barnacles on the whale fin
- neutral for whale
- positive for barnacle
- direct
Competition
- typically negative - negative
- intraspecific or interspecific
- general positive correlation between overlap and competition intensity
- between species with overlapping niches
Intraspecific
- same species
- population ecology
- often density dependent (logistic growth)
Interspecific
- different species
- community ecology
Competitive Exclusion
- one species outcompetes others (asymmetric competition)
- leading to the local extinction of weaker competition
Niche
range of resources used and conditions tolerated
Fundamental Niche
theoretical range of conditions that a species can tolerate
Realized Niche
- portion of the fundamental niche that is actually occupied (given limiting factors)
- what is actually in the real world
Reasons why the realized niche is not the full fundamental niche
- they just haven’t gotten there yet (e.g. a barrier)
- other species preventing them to
Niche Differentiation or Resource Partitioning
- change in resource use caused by competition over generations
- one or both species change their niche space to avoid competition
Character Displacement
- changes in traits that makes niche differentiation possible
- e.g. finches: g. fortis gets a deeper beak due to competition with g. fuliginosa
- sympatric or allopatric
Sympatric
occurring in the same geographical place
Allopatric
occurring in separate areas/different geographical places
Consumption
positive - negative
includes:
- herbivory
- predation
- parasitism
Constitutive Defenses
-defensive traits by plants or prey that are expressed even when there are no herbivores or predators
Includes (slides):
- cryptic coloration
- escape behavior
- toxins
- schooling or flocking
- armor or weapons
Aposematic Coloration
- distinct colors that contrast with the natural background
- makes it more conspicuous
- increases fitness
- helps these populations have a defense from the predators because they remember what tastes badly along with their bright colors
Predator Adaptations
- strength
- speed
- heightened senses
- chemicals
- stalking
- surprise
- cooperation
Coevolution
when two interacting species reciprocally influence each other’s adaptations over time
Co-evolutionary arms races
- with predator-prey or host-parasite
e. g. as snakes develop more tolerates of the newts toxins, the newts become more toxic
Why aren’t all nets highly toxic and all snakes highly resistant?
many traits have trade-offs on performance and may only increase fitness when the selection pressure is sufficiently high
Mimicry
- when one species resembles another
- 3 main types: Batesian, Müllerian, and Aggressive
Batesian Mimicry
- when a harmless/palatable species mimics a dangerous/unpalatable species
- named after Henry Walter Bates (Wallace’s Companion in Brazil)
e. g. Coral snake (toxic) and Kind (nontoxic)
Müllerian Mimicry
- two or more harmful species mimic each other
- named after Fritz Müller
Aggresive Mimicry
- when a predator mimics a harmless or desirable species
e. g. venus fly trap
Inducible Defense
- physical, chemical, or behavioral defensive traits that are expressed only in the response to a predator
- phenotypic plasticity
- economical
- trade-off
Phenotypic Plasticity
- the ability of one individual (genotype) to produce different phenotypes depending on the environment
- an example is inducible defenses
Inducible Defenses in Plants
-when exposed to herbivores, many plants produce proteins that inhibit herbivore damage
- e.g. radish produce glucosinalotes in increased densities when exposed to herbivores
- hair
- results in increased fitness
-indirect inducible defense are most common in plants
Indirect Inducible Defences
- Inducible defense that attracts predators to attack herbivores
- most common in plants
Parasitism
Host (-) and Parasite (+)
-a relationship between species, where one organism, the parasite, lives on or in another organism, the host, causing it some harm, and is adapted structurally to this way of life.
- parasites can control host behavior
- e.g. nematode parasite of ant causes ant’s color and behavior to change and increases the likelihood of predation by birds; needed for nematode to complete life cycle
Cordyceps Fungi
- genus of endoparasitic fungi
- invades host tissue and often affects behavior
- zombie ants
Obligate brood parasites
- reproduce only by laying eggs in the nests of other species
- no nest building, incubation, or parental care behavior
- about 1% of bird species (evolved independently 7 times)
- often leads to co-evolutionary arms races between hosts and parasites
- e.g. Eurasian Reed Warbler (Host) and Common Cuckoo (Parasite)
Obligate Brood Parasites Adaptations
- fast egg laying
- egg mimicry
- begging calls
- faster development
- chick aggression
- chick mimicry
Adaptations of the Hosts of the Obligate Brood Parasites
- nest defense
- nest desertion
- egg rejection
- chick rejection
Mutualisms
positive - positive
- resource-resource
e. g. fungi gettin carbs from plants and plants getting nitrogen - resource-service
e. g. flowers get pollinated (movement of gametes) and bees get food (nectar) - service-service
e. g. clownfish has a safe area and it protects the sea anemone from predators
Judith Bronstein
Said that “mutualism are best viewed as reciprocally exploitative interactions that provide net benefits”
Cheaters and Mutualisms
- some flowers do not produce nectar, but still attract pollinators
- nectar robbing: feeding on nectar without pollination
- cleaner mutualists may also feed on host tissue
- resource sharing between plants and fungi can be asymmetrical
Nectar Robbing
feeding on nectar without pollination
can be mutualist or a different species
Symmetric competition
said to occur and both species may persist in the area of overlap, even if in reduced numbers
Fitness trade-offs
inevitable compromises in adaptation
Endoparasites
- live inside their hosts and typically have adaptations for harvesting fluids from their hosts
- e.g. tapeworms
Ectoparasites
-e.g. ticks, aphids, and mistletoe live on the outside of their hosts and typically have adaptations for harvesting fluids from their hosts
Parasitoid
- free living as an adult but endoparasitic as larva
- usually fatal to the host
Integrated Pest Management
- strategies to maximize crop and forest productivity while using a minimum of insecticides or other types of potentially harmful compounds
- uses predators, herbivores, and parasites as biocontrol agents
Asymmetric Competition
-one species outcompetes another
