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Bio2 Lecture 26

Bio2 Lecture 26 - Bio2 Lecture 26 Review...

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Bio2 Lecture 26 4/26/05 Review Density-independent mortality factors c. include rain storms, floods, and fire *An experimenter interested in testing r- and K- selection theory looked at populations of two species of related water beetles. Species A lived exclusively in temporary pools, while species B lived in permanent pools of water. She predicted a. species A would be r- selected , and have more offspring of a smaller size than species B Imagine that half of the oaks in a forest where the oak-dwelling tiger frog olived were cut down. One might expect the tiger frog population would then c. decline to a new, lower carrying capacity d. experience death rates that exceed birth rates e. c and d Density dependent factors operate by negative feedback Biotic environment Survivorship Curves – explains the distribution of deaths - 3 different types of growth curves o 1. Very little infant mortalities, then at the end, great deal of mortalities high survival early in life heavy mortality late in life has intense parental care, and community care as well, put enormous resources devoted to taking care of offspring near K Humans o 2. Fairly close to ones, pretty much even death rate through out entire line squirrels o 3. Produce lots of infants, infant mortalities are very high, then as you get high, not as much deaths, r strategists Produces thousands of individuals form one female No parental care Large r Oysters Things that change population density are: - Immigration – increase population - Natality – increase population - Mortality – decrease population - Emigration – decrease population
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o Locusts, reach a certain threshold, resources depleted, evolution caused them to have light bodies and big wings, so that they are able to emigrate, and they emigrate o
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