IB biology: option C (V)

what is natality?

increases to population through reproduction (births)

what is immigration?

increases to population from external populations

what is mortality?

decreases to population as a result of death

what is emigration?

decreases to population as a result of loss to external populations

how do we calculate population size?

population size = (natality + immigration) - (mortality + emigration)

what is a population?

all the individuals of a given species living in the same area at the same time

how are motile species sampled in a population?

capture-mark-release-recapture method

how are non-motile species sampled in a population?

quadrat

describe the capture-recapture method

1. area is selected and marked off, individuals in area captures, counted marked and released (n1)

2. after sufficient time has passed, second capture is made (n2)

3. both marked (n1) and marked (n2) are counted, (n3)

4. estimated population = n1xn2 / n3

what assumptions are made in capture-recapture?

1. all individuals in given area have an equal chance of being captured

2. marking of individuals will not affect mortality or natality of population

3. marked individuals will be randomly distributed after release

what are the two types of population growth patterns?

exponential growth (J curve) and logistic growth pattern (S curve)

what is logistic growth/S curve?

- occur when population begins to approach a finite carrying capacity

- environmental resistance occurs, slowing growth rate to plateau

what is carrying capacity in logistic growth/S curve?

the maximum number of a species that can be sustainably supported by the environment

what is exponential growth/J curve?

- occurs in an ideal, unlimited environment

- initial growth slow as reproducing individuals that may be widely dispersed

- as population increases rate of growth increases, biotic potential reached (maximal growth rate)

what is biotic potential in exponential growth/J curves?

the maximal growth rate for a given population

what are limiting factors?

environmental conditions that control the rate at which a process can occur

what factors can population growth be determined by?

density-dependent factors or density-independent factors

what are density-dependent factors for population growth?

factors that are influenced by the relative size of a population - PANDA

Predator numbers,

Availability of food,

Nutrient supply,

Disease,

Accumulation of waste

what are density-independent factors for population growth?

factors that are not influenced by the relative size of a population - PAW

Phenomena (natural disasters),

Abiotic factors (temp, CO2 levels),

Weather conditions

what are the 3 phases on a logistic/S curve graph?

exponential growth phase (same as J curve),

transition phase (resources become limited, natality starts to fall and mortality starts to rise)

plateau phase (mortality equals natality and population becomes static, reaches carrying capacity (k) and oscillate around k)

what is top down control?

pressures are applied to higher tropic levels to control the population dynamics of the ecosystem (example of wolves of Yellowstone)

- top predator suppresses abundance of its prey or alters behaviour to limit population growth

what is bottom up control?

pressures that limit the availability of resources to lower tropic levels (e.g producers),

lack of resources at lower trophic levels suppresses the abundance of organisms at higher trophic levels,

what is sustainability?

the capacity for a biological system to remain diverse and productive indefinitely

what is a sustainable yield?

the amount of a natural resource that can be taken from an ecosystem without reducing the base stock

what should the MAXIMUM sustainable yield typically be?

half the carrying capacity of the species, the stage when population growth will be highest

how can we estimate commercial stock?

capture-recapture,

echo sounders,

analysing fish catch data

what are some considerations in sustainable fishing practices?

population size (maximum sustainable yield = half carrying capacity),

age (mesh size restrictions means younger fish evade capture),

reproductive status (specific exclusion zones for breeding areas)