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Topic 8
BIOL 213 Topic 8
| Question | Answer |
|---|---|
| population | all of the individs of a given species that live and reproduce in a particular place |
| pop size | the number of individs alive at a particular time in a particular place |
| what influences population size | birth, death and migration |
| births, deaths, and migration influence | population size |
| population growth eqn | (Nt + 1) - Nt = B - D |
| N = | pop size |
| t = | time/generation |
| B = | number born |
| D = | number die |
| b = | per capita birth rate |
| per capita birth rate b = | B / Nt |
| d = | per capita death rate |
| per capita death rate d = | D / Nt |
| r = | per capita growth rate |
| what is used to predict pop size changes | per capita growth rate |
| what is per capita growth rate used to predict | pop size change |
| per capita growth rate eqn | r = b - d |
| r > 0 | pop is growing |
| r < 0 | pop is shrinking |
| r = 0 | at carrying cap (K) |
| eqn to calculate change in pop size | Nt + 1 = (1 + r) * Nt |
| exponential model of pop growth predicts | growth under ideal conditions |
| what model predicts pop growth under ideal conditions | exponential |
| what will the per capita growth rate be at that max for that pop | in exponential model |
| rmax = | max intrinsic rate of increase |
| max intrinsic rate of increase = | rmax |
| rmax is always | constant and positive |
| rmax varies by species | bacteria rmax ~10 humans rmax ~0.0001 |
| how does rmax scale with body size | hypometrically |
| generation time increases as | body size increases |
| as body size increases what also increases | generation time |
| eqn used to calculate the size of a pop growing exponentially | Nt = N0 (1 + r)^t |
| r is not | constant |
| factors that impact birth and death rates | food, sunlight, predators, disease, shelter, water, mating patterns, etc. |
| the rate of pop growth tends to decline as | abundance increases |
| how does the rate of population growth change | by changing b and d |
| carrying capacity (K) | abundance where birth and death rates are equal |
| r changes with K in what type of growth model | logistic growth |
| what model predicts pop growth based on changing growth rates as pop reach carrying cap (K) | logistic growth |
| what growth model assumes r decreases as pop increases | logistic |
| at k, b ___ d, r = ___ | b = d, r = 0 |
| when does r = 0 | at K |
| when b = d, r = | r = 0 |
| N > K, b ___ d, r = ___ | b > d, r > 0 |
| when is r < 0 | when N > K |
| N < K, b ___ d, r = ___ | b < d, r < 0 |
| when N > K, growth rate is | decreasing |
| when N < K, growth rate is | increasing |
| as pops grow, b and d ____ | decrease |
| as N increases, r _____ | decreases |
| rt eqn | rt = rmax (( K - Nt) / K) |
| eqn to determine pop size growing logistically | Nt + 1 = Nt (1 + rt) |
| rmax (( K - Nt) / K) = | rt |
| why is K variable overtime | environmental factors like seasons |
| environmental factors like seasons causes variation in ___ | carrying cap |
| density dependent factors affect | individuals, per-individual rates of b and d change as pop density changes |
| what type of factors are density dep | biotic |
| what type of factors are density indep | abiotic |
| types of dens depend factors | competition, predation, disease |
| crowding influences | reproduction, growth rate, adult size and survival |
| low dens = ____ reproduct | increased |
| high dens = ______ reproduct | decreased |
| reproductive success _____ at higher dens | decreases |
| reproductive success _____ at lower dens | increases |
| growth rate ____ at higher dens | decreases |
| growth rate _____ at low dens | increases |
| plant size decreases at ____ dens | high |
| plant size increases at ____ dens | low |
| survival rates _____ at low dens | increase |
| survival rates _____ at high dens | decrease |
| types of dens independ factors | temp, precipitation, ocean acidity, disturbances(fire, flood, hurricane, etc. |
| dens independ factors affect | all individuals equally |
| ex of factor that is both dens depend and independ | drought, independ is the drought, depend is the resulting competition |
| what type of factors affect per-individual | dens depend |
| what type of factors affect all individuals equally | dens independ |
| small body size = | shorter gen time |
| large body size = | longer gen time |
| what causes increased variability in pop dynamics | increased rmax |
| what causes decreased variability in pop dynamics | decreased rmax |
| high rmax = high potential to overshoot K -> | unstable dynamics |
| high birth rate in unfavourable conditions = | high mortality |
| nat select might fav diff phenotypic traits and life histories at | diff pop densities ( r vs k ) |
| dens near K may select for | k selection |
| fluctuating unpredictable dens and sensitivity to bad environment may select for | r selection |
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