BIO 2129 Lecture 7: 7 - Abundance and Species Diversity
18 Oct 2016
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Population density - number of individuals per unit space (e. g. individuals/km^2) Can be difficult in nature so use "indirect counting" Section off small area and count, extrapolate to total area. To have more accurate estimate, use multiple quadrats. One "line" walk down and count individuals in column. Neutral interactions between individuals, individuals and environment e. g. dandelions, don"t care where they land, random. Antagonistic interactions between individuals or local depletion of resources. Staying away from each other, competition e. g. plants that secrete toxins. Clumped (individuals live in areas of high abundance with separated by low abundance. Stay better as a team e. g. elephants, easier to find food, protections. Attraction between individuals or attraction of individuals to a common resource. Brisson and reynolds found competitive interactions with neighboring shrubs appear to influence distribution of creosote roots. With competition, roots hardly overlapped --> regular distribution. Uniform has less variance, random more, clumped huge.
