L9 - Ecological drift Flashcards
Define ecological drift
Genes that survive into adulthood through random chamce and controllble factors
What happens when b (birth rate) and d (death rate) are equal
Population reaches an equillibrium with a minor flux of stochatisticity
What effect does stochasticity have if a population is small
Plays a bigger role, flux may be more extreme
What is the setuo if the barro colorado experiment
50 hct plot in panama tropical moist forest, data collection over 30 years
What are the main findings of the barro colorado experiment (4)
The plot is rich in species, density and biomass constant throughout, light gaps play an important role however future composition of gaps is difficult to predict
What is ecological neutral theory and who came up with it
Stephen P Hubbel, has the assumption that all individuals regardless of species identity have an equal probability of birth, death and dispersal
How do light gaps utilize ecological neutral theory
Helps determine what species will colonize newly formed light gaps, suggest model that chooses a species at random with a zero sum dynamic as no new individuals can be added until one has been removed
What role does extinciton play in neutral models and what counters extinction
It is irrevrisble, therefore through chance wewould expect to be a monodominance over time, which however does not happen as it is countered by immigration and speciatiton
What are some examples of how ecological neutral theory was used in models?
- Adjusting the island biogeography model to focus on individuals rather than species, using concepts like immigration, death, and dynamic equilibrium while still considering speciation and extinction.
- Spatially explicit neutral model where every individual occupies explicit space, and newborns are chosen based on dispersion kernels.
- Voter model illustrating how political preferences spread based on chance rather than ideology.
Examples include the adjustment of island biogeography and the voter model for political preferences.
What was found about species abundance distribution in the Barro Colorado experiment?
The experiment revealed that very abundant species are not very common, while many rare species exist. The neutral theory model predicted the relationship between the number of individuals per species and the number of species with those individual counts.
The relationship is represented as (x) number of individuals per species and (y) number of species having those numbers.
What is protracted speciation?
Protracted speciation is the concept of abandoning the assumption that a new species appears suddenly, instead suggesting that the likelihood of a new species forming increases steadily over time.
How did the neutral theory model apply to Pacific reef fish range sizes?
The model utilized the characteristics of pelagic and non-pelagic eggs and adult mobility to predict the range of fish guilds, achieving accurate predictions with the correct proxies.
Define ‘pelagic’.
Pelagic refers to fish eggs that can move with currents and are not fixed to one location, in contrast to non-pelagic eggs.
