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Biology 150: 2/22-2/24 Notes

by: Shea Flannery

Biology 150: 2/22-2/24 Notes Biology 150

Shea Flannery
GPA 3.23

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About this Document

These notes cover Population Ecology from 2/22 and Community Ecology from 2/24.
Organismal and Ecological Biology
Dr. Brian O'Meara
Class Notes
25 ?




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This 3 page Class Notes was uploaded by Shea Flannery on Monday March 7, 2016. The Class Notes belongs to Biology 150 at University of Tennessee - Knoxville taught by Dr. Brian O'Meara in Spring 2016. Since its upload, it has received 16 views. For similar materials see Organismal and Ecological Biology in Biology at University of Tennessee - Knoxville.


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Date Created: 03/07/16
2/22 – Population Ecology  Population ecology – the study of how and why the number of individuals in a population changes over time.  Per capita rate of increase (r) – the difference between the birthrate and death rate per individual. o r = b – d o If the birthrate is higher than the death rate, the population is growing. o If the birthrate is lower than the death rate, the population is decreasing. o r varies through time.  If r does not change over time, exponential population growth is occurring. o Density independent o 2 ways exponential growth happens:  Some individuals of a population find a new habitat.  A catastrophe happens, destroying most of the population and leaving the survivors to recover the population. o Cannot continue forever.  When the population density becomes very high, the birthrate of the population decrease and the death rate decreases causing the population to decrease (Density dependent).  The carrying capacity (K) can change depending on certain conditions such as: o Food o Space o Water o Soil quality o Resting/nesting sites  Hypothetically, density dependent growth has 3 stages: o 1. Exponential growth (r is constant) o 2. Growth rate starts to decrease (N increases) o 3. Population reaches carrying capacity (N vs t is flat)  Population sizes change due to: o Density-independent factors – abiotic; does not matter how dense the population is; weather patterns o Density-dependent factors – biotic; does matter how dense the population is; predation  K varies between species, populations, and time.  Population dynamics – the changes in populations through time.  Population cycles – regular fluctuations in size. o Normally caused by density-dependent factors. 2/24 – Community Ecology  Community – interacting species within a defined area.  Species are very closely connected to the other species in the habitat because they are constantly interacting.  Biologist analyze the interactions by fitness of the individuals.  Relationships that benefit both species have a + interaction.  Relationships that hurts one of the species have a – interaction.  Relationships that have no effect on either of the species have a 0 interaction.  4 types of interactions in communities: o Commensalism (+/0) o Competition (-/-)  Intraspecific competition – between organisms in the same species.  Interspecific competition – between organisms in different species.  Focuses on the niche.  Occurs when the niches of two species overlap  Competitive exclusion principle (G. F. Gause) – species in the same niche cannot coexist.  Asymmetric competition – one species suffers more of a fitness decline than the other.  Symmetric competition – both species suffer about the same amount of fitness decline.  Fundamental niche – a species’ niche in the absence of predators.  Realized niche – a species’ niche when competition occurs.  If a species is very good at competing, they’re probably not good at another aspect of survival (fitness trade-off). o Consumption (+/-)  3 types of consumption:  Herbivory  Parasitism  Predation  Natural selection strongly favors traits that protect individuals from being eaten.  Constitutive (Standing) Defenses – always present; use a lot of energy and resources.  Avoidance  Poison  Schooling/flocking  Fighting back  Mimicry o Müllerian mimicry – a harmful species that mimics another harmful species. o Batesian mimicry – a species which is not harmful mimics a species which is harmful.  Inducible defenses – only present when a predator is detected; energy efficient, but slow to produce. o Mutualism (+/+)  The individuals involved are not purposely helping each other; their own selfish acts just so happen to benefit the other individual. Word to Know Asymmetric Exponential Mutualism Competition Population Growth Parasitism Batesian Mimicry Fertility Per Capita Rate of Carrying Capacity Fitness Increase Coevolution Fitness Trade-Off Population Cycles Commensalism Fundamental Niche Population Dynamics Community Herbivory Population Ecology Competition Inducible Defenses Predation Competitive Interspecific Realized Niche Exclusion Principle Competition Replacement Rate Constitutive Defense Intraspecific Symmetric Competition Consumption Competition Mimicry Density Dependent Zero Population Müllerian Mimicry Growth Density Independent


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