Class Notes (836,153)
Canada (509,662)
Statistics (235)
STAT 2230 (44)
Dan Meegan (28)
Lecture 2

lecture 2.docx

2 Pages
Unlock Document

STAT 2230
Dan Meegan

BIRTH AND DEATH RATES  ecologists use estimates of pop’n densities to estimate the rate at which births, deaths and movements take place in a pop’n and study how rates are influences by environmental factors  the number of individuals in a pop’n at given time is equal to the # present at some time in past plus the # born between then and now, minus the # tht died, plus the # that immigrated into teh pop’n, minus the # that emigrated  life table-created by tracking a group of individuals born at the same time (cohort) and determining the # that are still alive at later dates (survivorship)  used to predict future trends in pop’n  study of the seed-eating cactus finch-210 birds that hatched in 1978, followed until 1991, only 3 alive; mortality rates high during first yr then dropped for several yrs, then increase later; survival of birds depends on seed production which is related to rainfall  graphs are helpful for highlighting important changes in pop’ns  survivorship curves fall into 3 patterns: o most individuals survive for most of their potential life span and die about the same age o probability of surviving to the next yr is abt the same over most of the life span once individuals are a few months old o produce a large # of offspring, each of which receives little investment of energy  high death rates of young individuals are followed by high survival rates 54.2 HOW DO ECOLOGICAL CONDITIONS AFFECT LIFE HISTORIES  life history: describes how organism allocates its time and energy among the variance activities that occupy its life  female rockfish continue to grow throughout their lives; larger females are much more productive than smaller females b/c the # of eggs a female produces is proportional to her size; older, larger females produce eggs with larger oil droplets-provide energy to newly hatched- grow faster and survive better  guppies living in predator-free areas upstream from those waterfalls have low mortality rates; those that live below the falls have high mortality rates; david reznick reared 240 guppies from high-predation and low predation sites; supplied some with plentiful food and others with limited; where no predators were present, guppies from high-predation sites matured earlier, reproduced more 54.3 WHAT FACTORS INFLUENCE POPULATION DENSITIES  as the # of individuals in a pop’
More Less

Related notes for STAT 2230

Log In


Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.