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Published byOscar Campbell Modified over 6 years ago
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Population Dynamics Populations are studied by looking at changes in:
1) size 2) density 3) dispersion (clumping*,uniform,random) 4) age distribution ? How is population growth measured? (Births + Immigration) – (Deaths + Emigration) = growth
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? What Affects Population Growth?
- Carrying Capacity determines the # of individuals a habitat can support - carrying capacity is determined by: a) Biotic Potential - how quickly a species can reproduce b) Environmental Resistance - limits to a species growth ex.- space, food, mates, etc.
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? What Ways Do Populations Grow?
2 Types of Growth 1) Exponential Growth - observed in quick reproducing species - can happen with unlimited resources
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- typical growth pattern for most species
2) Logistic Growth - typical growth pattern for most species - environmental resistance causes growth to level off and fluctuate at carrying capacity
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? What Affects the Density of Populations?
2 Types of Factors 1) Density-dependent - limits on growth that only affect very dense populations Examples- competition, disease, predation 2) Density-independent - affects a population regardless of size Examples- natural disasters, human disturbance
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Reproductive Methods - organisms can reproduce sexually/asexually
- asexual reproduction- - requires less energy - allows everyone to reproduce - doesn’t allow for diversity - sexual reproduction- - requires more energy - only females can reproduce - allows for increased diversity - males can provide protection
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Reproductive Strategies 1) Opportunists (r-selected species)
- put most of its energy into reproduction - reproduce at a young age - produce many offspring - no parental care - high growth rate 2) Competitors (K-selected species) - put most of its energy into survival - reproduce later - produce few offspring - provide parental care - low growth rate
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Life Expectancies for “r” & “K” species
“r-selected” species show: - early loss survivorship curves - reproductive strategy leads to many deaths “K-selected” species show: - late loss survivorship curves - reproductive strategy leads to fewer deaths Species with intermediate strategies show: - constant loss survivorship curves - reproductive strategy leads to a constant rate of death
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Survivorship Curves
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? How do we preserve species?
Conservation Biology measures: 1) size of populations 2) possible changes in size 3) whether sizes are sustainable Conservation Biology believes: 1) biodiversity is important for survival 2) humans should not alter ecosystems 3) we should protect whole ecosystems
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? How do we live more sustainably?
We should understand that: 1) Our lives are dependent on the Earth & sun. 2) Everything on Earth is connected. 3) We should minimize damage & work with nature.
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