Kate Chun - 3.2 K-selected & R-selected Species

K-selected species

Species that produce a few, often fairly large offspring but invest a great deal of time and energy to ensure that most of those offspring reach reproductive age.

ex: elephants, whales, humans

R-selected species

Species that reproduce early in their life span and produce large numbers of usually small and short-lived offspring in a short period and exert low parental care.

ex: frogs, jellyfish, dandelions

Why do r-selected species have many offspring?

R-selected species invest less energy for each offspring, leading to lower rates of survival. This means that they need to have the most offspring at once for higher chances of survival.

Why do K-selected species have few offspring per reproduction event?

K-selected species expend significant energy for each offspring and have high levels of parental care. As a result, their offspring tend to have longer lifespans and stronger rates of survival.

Which type matures faster?

R-selected species tend to mature earlier.

Which type may reproduce more than once?

K-selected species may reproduce more than once.

Which type has high competition for resources in their environment?

K-selected species tend to have high competition for resources in K-selected species' habitats because they are adapted to environments where resources are more stable, and they use more resources in order to survive.

K-selected species have populations that fluctuate near the ______________________.

carrying capacity

Biotic potential?

The maximum rate at which a population can grow under ideal conditions with unlimited resources.

Do r-selected species have high or low biotic potential?

R-selected species have high biotic potential because there is a large number of offspring produced under each breeding season (population can grow exponentially).

Which type is most likely to be an invasive species?

R-selected species are more likely to be an invasive species because they are suited to rapidly changing environmental conditions (adaptive).

Which type is most likely to be affected by invasive species?

K-selected species mature later, and therefore reproduce slower than invasive species which can take over the population.

Are all species strictly r-selected or K-selected?

Many species have reproductive strategies that do not adhere perfectly to either types. Or, they might change based upon the environmental conditions.

Why are humans K-selected?

Humans are K-selected because they have high parental care, longer lifespans, and can reproduce more than once.