Population ecology
[2] The discipline is important in conservation biology, especially in the development of population viability analysis which makes it possible to predict the long-term probability of a species persisting in a given patch of habitat.
The term autecology (from Ancient Greek: αὐτο, aúto, "self"; οίκος, oíkos, "household"; and λόγος, lógos, "knowledge"), refers to roughly the same field of study as concepts such as life cycles and behaviour as adaptations to the environment by individual organisms.
[8] The beginning of population dynamics is widely regarded as the work of Malthus,[9] formulated as the Malthusian growth model.
According to Malthus, assuming that the conditions (the environment) remain constant (ceteris paribus), a population will grow (or decline) exponentially.
When the per capita rate of increase takes the same positive value regardless of population size, the graph shows exponential growth.
Originally from South America, Monk Parakeets were either released or escaped from people who owned them.
These birds experienced exponential growth from the years 1975-1994 and grew about 55 times their population size from 1975.
This growth is likely due to reproduction within their population, as opposed to the addition of more birds from South America (Van Bael & Prudet-Jones 1996).
Environmental and social variables, along with many others, impact the carrying capacity of a population, meaning that it has the ability to change (Schacht 1980).
Harvest above that level is termed "additive" mortality, because it adds to the number of deaths that would have occurred naturally.
For example, a fish & game agency might aim to reduce the size of a deer population through additive mortality.
[13] While the use of population dynamic models along with statistics and optimization to set harvest limits for fish and game is controversial among some scientists,[14] it has been shown to be more effective than the use of human judgment in computer experiments where both incorrect models and natural resource management students competed to maximize yield in two hypothetical fisheries.
[17][18] At its most elementary level, interspecific competition involves two species utilizing a similar resource.
Offspring of K-selected species generally have a higher probability of survival, due to heavy parental care and nurturing.
If there were no top carnivores in the ecosystem, then herbivore populations would rapidly increase, leading to all plants being eaten.
Survivorship curves play an important role in comparing generations, populations, or even different species.
[27] A Type I survivorship curve is characterized by the fact that death occurs in the later years of an organism's life (mostly mammals).
"[30]: 105 Metapopulation ecology is a simplified model of the landscape into patches of varying levels of quality.
Metapopulation models examine patch dynamics over time to answer questions about spatial and demographic ecology.
An important concept in metapopulation ecology is the rescue effect, where small patches of lower quality (i.e., sinks) are maintained by a seasonal influx of new immigrants.
Ecologists utilize a mixture of computer models and field studies to explain metapopulation structure.
Metapopulation data is extremely useful in understanding population dynamics as most species are not numerous and require specific resources from their habitats.
To elaborate, metapopulation ecology assumes that, before a habitat becomes uninhabitable, the species in it will emigrate out, or die off.
