EEBio Lect 3
EEBio Lect 3 Ecology and Evolutionary Biology 100
Popular in Introduction to Ecology and Behavior
Popular in Behavioral Sciences
This 5 page One Day of Notes was uploaded by Marissa Mayeda on Thursday February 5, 2015. The One Day of Notes belongs to Ecology and Evolutionary Biology 100 at University of California - Los Angeles taught by Dr. Johns in Winter2015. Since its upload, it has received 128 views. For similar materials see Introduction to Ecology and Behavior in Behavioral Sciences at University of California - Los Angeles.
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Date Created: 02/05/15
Lecture 3 Notes Ecology and Behavior EEB 100 Philip Johns philipjohnslucaedu Population Growth On discussion readings 0 Posted discussion readings on CCLE 0 Only 1 per week 0 Will try to use MasteringBiology Office hours Philip Johns philipjohnslucaedu Tue HH 316 11001200 Wed HH 328 11001200 Fri HH 316 11001200 From last time refer to graph in slides 0 Per capita birth rate b 0 Per capita death rate d 0 When b amp d are constant density independent growth When b or d change with density density dependent growth Activity organisms have a birth rate b organisms have a death rate d per capita population growth rate r bd Eg at t0 N 1000 at t1 N1100 r 1 1001 0001 00 000 rN r01 Population growth 0 Population next generation population this generation change Nt1 Nt rNt r 1Nt or Let quotnet reproductive rate R0 r 1 Nt1 RONt From last time refer to graph 0 Per capita birth rate b 0 Per capita death rate d 0 When b amp d are constant density independent growth Unconstrained population growth 2 parents amp population doubles every generation R0 2 t 0 Nt 2 Nt1 Nth0 2x2 4 1 4 Nt2 Nt1xR0 Nth0xR0 NtROAZ 2 8 3 16 4 32 5 64 13 gt10000 19 gt1000000 Population Nt x R0quotn Ntn ROAnNt Exponential or Geometric Growth Numbers refer to graph for Unconstrained population growth 0 Locusts grasshoppers L 0 Populations grow exponentially with ample food 0 When food runs out take on migratory phase R when food run out bump into each other at the very few last plants and take on migratory form swarm caught of air current and go places with no food and make mats of dead locusts floating in the Caribbean example of boom bust populations crill sardines locusts refer to graph huge growth of populations followed by huge decrease 0 httpwwwsciencedirectcomsciencearticlepii 50169534714000706gr1b1 Unconstrained population growth Human Population Growth refer to graph graph shows humans are experiencing seemingly exponential growth Constrained population growth 0 Limits to growth food space predators competition Nt1 Nt rNt 0 New population old population change 0 dNdt rNt Density dependent reproduction 0 Density dependence can affect birth or death birth rate decreasing with pop densities refer to three graphs on Goby fish rate of clutch production number of eggs per clutch and rate of egg production decrease with density Not just Allee effect Bridled goby reef fish reproduction Forrester amp Harmon 2011 Pop Ecol 53 155 163 httpwwwpopulationecologyorg RecentArticlePageaspxDO101007 510144 010 0225 6 Population Biology Demographics refer to graph Population size increase when bgtd Most populations do not increase exponentially forever 0 Where bd population at equilibrium two points on graph one at K other is when rates of both birth and death are low 0 Carrying capacity K 0 Is this a stable equilibrium Yes unlike allee effect Activity we have all the ingredients we need to make a simple growth model our goal is to modify dNdt rNt to incorporate K dNdt r per capita growth rate K carrying capacity Nt and Nsubt1 where new pop old pop Chan e Define dNdt by a function sensitive to pop size h when KgtgtNsubt population grows exponentially dNdt rNt when NtgtK pop decreases dNdtlt0 When Nt pop is stable dNdt0 Population biology logistic growth Logistic equation How population approaches K depends on r refer to graph Population Biology Demographics MacCauley amp Murdoch 1987 Daphnia and algae in lakes daphnia is a water flea refer to various graphs for following patterns Pattern 1 Both daphnia and algae populations are stable over time Notice the when each peaks Pattern 2 Both cycle over time Period frequency correlated Pattern 2 Both cycle over time Population Biology Demographics Pattern 3 Daphnia cycle algae stable Pattern 3 Daphnia cycle algae stable Patterns driven in part by demographics of Daphnia which in turn determines how much reproduction there is Population biology demographics 0 How often are species populations near K 1 Rarely r selected 1 Possibly many insects like flies sometimes Population crash before reaching K 0 seasonality small scale catastrophes eg Birth and death rates are density independent Selection favors rapid reproduction and quantity at the expense of quality Aphids as r selected refer to graph 2 Often K selected Large carnivores Birth and death rates are density dependent Selection favors slower reproduction and quality at the expense of quantity 0 Truth there is an r to K continuum and all species can be either r or K selected depending on environmental conditions Population Biology Demographics 0 Some flies invest tons per offspring these insects break down stereotype that insects don t care for young example of the tiki fly k selected Population Biology 0 What determines the size and persistence of populations in given habitats Abiotic factors Ecophysiology 0 Water 0 Temperature 0 Climate 0 Nutrients Biotic factors Ecological modeling 0 Prey or food species 0 Competitors 0 Predators Species interactions Competition include predation herbivory parasitismdisease Species interactions 1 Competition Exploitative vs Interference 0 Exploitative scramble individuals may not directly interact at all 0 Interference individuals directly deny access to resources eg territories Interspecific vs Intraspecific 0 ntra gt Inter often 0 Why Intraspecific competition occurs when members of same species compete thus they have the same needs 0 Inter can lead to species extinction Species interactions 1 Competition Paramecium caudatum vs P aurelia Gause et al 1934 Competitive exclusion principle Two species cannot coexist in same ecological niche P caudatumquotGrows faster more efficient at using resources P AureliaBetter at surviving dealing with stressful environment Lots of food little waste Paramecium caudatum do better Food declining toxic medium P Aurelia do better
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