Population Ecology: Key Concepts and Population Growth - Prof. Monica M. Togna, Study notes of Biotechnology

Download Population Ecology: Key Concepts and Population Growth - Prof. Monica M. Togna and more Study notes Biotechnology in PDF only on Docsity! Population Ecology Chapter 56  Population: group of interbreeding individuals occupying the same habitat at the same time, a genetic unit with a specific gene pool o Water lilies in a particular lake o Humans in NYC  Population Ecology: the study of what factors affect population size and how these factors change over space and time  Population Range: most species have limited geographical range o Devils hole pupfish lives in single spring in southern Nevada  Demography: the study of how births and deaths change population over time o Tools of demography: birth rates, death rates, age distributions and size of populations o Demography Dynamics: changes thru time resulting from birth, death and movement of individuals o Demography Structure: density proportion of individuals in various age classes, spacing of individual relative to each other  Density: number of organisms in a given unit area  Rare vs common, recovery after serious threat  Population growth: affects population density  Reproductive strategies  Knowledge can help us make decisions about management of species o Classifications, hunting/fishing seasons, protected areas  Population density can be done by  Simple visual count  Sampling methods to extrapolate captured organism number to size of population  Mark recapture method o Captured animals may learn to avoid traps or seek out food bated traps  Dispersion pattern: o Clumped:  MOST COMMON b.c resources tend to be clustered in nature also asexual reproduction  Social behavior may promote this pattern o Uniform: competition may cause this pattern  Also may result from social interactions  Uniform distribution of shrubs in desert due to competition for water o Random: resources are rarely randomly space  May occur when resources are common and abundant  MOST RARE o Small populations are susceptible to extinction  Reproductive Strategies o Seemelparity: produce all offspring in single event – individuals reproduce once and then die o Have cohorts (groups of young all at the same age)  Neried worm- programmed death  Rare in animals  Sockeye salmon o Iteroparity: individuals reproduce in successive years or breeding seasons—induced or spontaneous ovulation—have young of different ages  Seasonal: distinct breeding seasons  Continuous: reproduce repreatedly anytime of year  Age classes o Reproductive strategy has strong effect on subsequent age classes of a population  Semelparous organisms with groups of same aged young called COHORTS  Iteroparous organisms have youn of different ages o Expect a pop increasing in size to have many young and if it decreasing in size to have few young  Life tables o Data on the number of individuals alive in a particular age class  Males usually not included  Survivorship curve: plots numbers of surviving individuals at each age  Use log scale to make it easier to examine wide range of pop sizes  3 patterns of suvivorship:  Type I: rate of loss of juveniles is low and most individuals lost later in life  Type II – fairly unifor death rate through the ages  beaver  Type III- rate of loss of juveniles is high then low for survivors  Like when an animal lays lots of eggs at once and hopes some will survive  To predict growth of populations they look at o Age specific fertility rate Mx  Proportion of female offspring born to females of reproductive age  100 females produce 75 female offspring Mx= .75 o Age specific survivorship rate Ix