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Lecture

Lecture 21.docx

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Department
Biology
Course
Biology 1001A
Professor
Tom Haffie
Semester
Fall

Description
Chapter 45.3-45.5 (Lecture 21) 45.3- Demography • Age specific Mortality- The proportion of individuals that died during a given time • Age specific Survivorship- The number of individuals that survived during a given time • AGE SPECIFIC MORTALITY AND SURVIVORSHIP MUST SUM TO ONE • Age specific fecundity- the average number of offspring produced by surviving females during each age interval Population Ecology • Age structure and population growth • Life tables and survivorship curves • Life history strategies • Models of population growth Characteristics of Populations can affect population growth rates • Age structure pyramids o Female side drives the population growth To represent information: 1. Life Table Analysis • Summarize survival and reproduction for a cohort of individuals 2. Survivorship Curves • Graphic display of the rate of survival of individuals over a species’ life span Characteristic of Humans Characteristic of small body Fish, plants (Older individual less animals (Dying not due to likely to die than younger age) individual) Life History Characteristics • Life history-balancing energy or resources given competing demands o Growth o Reproduction o Self-Maintenance (repair) • Different environments favour different life histories 45.4-The Evolution of Life Histories • Maintenance, growth, and reproduction are the three main energy-consuming processes • Passive care occurs as nutrients cross the placenta from the mother to the developing baby • Active care involves nursing and other care provided after birth • Salmon have a short life span and devote a great deal of energy to reproduction. Deciduous trees may reproduce more than once and use only some energy in any reproductive event, balancing reproduction and growth • Early reproduction is favoured if adult survival rates are low or if, when animals age, they do not increase in size. In this case, fecundity does not increase with size Quantity vs. Quality (r and k) • r-selected species o Adapted to rapidly changing environments o Success of life history depends on flooding the environment with a large quantity of young o Small Body size o Invest highly in reproduction o Reproduce at younger age • k-selected species o Survive the early stages of life o Populations grow slowly o Success of life history is linked to the production of a relatively small number of high quality offspring Modeling Population Growth • ΔN= #births (and immigrations) - #deaths (and emigrations) • B, D, I, E = Total number of births, deaths, immigrations, and emigrations per unit time ∆ N =(B+I)−(D+E),perunittime ∆T • Per capita birth and death rates: B D b= N d= N Intrinsic Growth Rate= r • r= b – d • Example: A small town in Ke
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