K-Selected & r-Selected Species (College Board AP® Environmental Science): Flashcards
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Define K-selected species.
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Define K-selected species.
K-selected species tend to be large, produce few offspring per reproduction event, invest significant energy in each offspring, and have long life spans.
What type of environment do r-selected species typically live in?
r-selected species typically live in unstable or unpredictable environments with low competition for resources.
True or False?
K-selected species usually reproduce only once in their lifetime.
False.
K-selected species reproduce multiple times in their lifetime; it is r-selected species that may reproduce only once.
Define biotic potential.
Biotic potential is the maximum reproductive rate of a population under ideal environmental conditions.
Define r-selected species.
r-selected species tend to be small, produce many offspring per reproduction event, invest minimal energy in each offspring, and have short life spans.
K-selected species mature after many years with extended youth and care.
K-selected species mature after many years with extended youth and parental care.
Which factors influence the biotic potential of a species?
Biotic potential is influenced by reproductive rate, number of offspring per reproduction event, age at reproductive maturity, frequency of reproduction, and lifespan of reproductive individuals.
True or False?
Elephants have a high biotic potential.
False.
Elephants have a low biotic potential because they produce few offspring, so their populations grow slowly even under ideal conditions.
Which type of species dominates the early stages of succession?
r-selected species dominate the early stages of succession because they quickly colonize new or disturbed areas.
Why is biotic potential rarely achieved in natural ecosystems?
Biotic potential is rarely achieved because of environmental resistance, such as predation, competition, disease, and carrying capacity.
True or False?
All species fit neatly into either the r-selected or the K-selected category.
False.
Many species show traits of both strategies, depending on environmental conditions.
How do sea turtles show a mixed reproductive strategy?
Sea turtles lay many eggs (an r-selected trait) but invest significant energy in choosing nesting sites (a K-selected trait).
True or False?
Plants cannot be K-selected species.
False.
Oak trees are K-selected: they produce fewer acorns, but these have a better chance of growing into mature trees in the stable environment of a mature forest.
Environmental factors, such as resource availability and , drive variation in reproductive strategies.
Environmental factors, such as resource availability and competition, drive variation in reproductive strategies.
How might frogs change their reproductive strategy in drier conditions?
In drier conditions, frogs may select only safer water sources to increase offspring survival, which is a K-selected trait.
Why do K-selected species dominate the later stages of succession?
K-selected species dominate later stages because they thrive in stable, mature ecosystems and outcompete r-selected species in resource-rich environments.
True or False?
Invasive predators mainly threaten species with fast reproductive rates.
False.
Invasive predators mainly threaten K-selected species with slow reproductive rates, such as native birds on Guam after the brown tree snake was introduced.
Are K-selected or r-selected species more negatively affected by invasive species?
K-selected species are more negatively affected by invasive species, while r-selected species are often minimally affected.
Why are most invasive species r-selected?
Most invasive species are r-selected because of their rapid reproduction, short generation times, high dispersal ability, and adaptability.
How does the invasive zebra mussel outcompete native freshwater mussels in North America?
The zebra mussel rapidly colonizes hard surfaces, which hinders native mussel attachment and filter feeding.
How can an invasive species disrupt habitats to disadvantage K-selected species?
It can alter habitats to favor r-selected traits; for example, kudzu smothers native vegetation in the southeastern U.S., reducing habitat complexity.
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