New User Special Price Expires in

Let's log you in.

Sign in with Facebook


Don't have a StudySoup account? Create one here!


Create a StudySoup account

Be part of our community, it's free to join!

Sign up with Facebook


Create your account
By creating an account you agree to StudySoup's terms and conditions and privacy policy

Already have a StudySoup account? Login here

BSC 116 Notes Week 13- Lectures 37-39

by: Alexia Acebo

BSC 116 Notes Week 13- Lectures 37-39 BSC 116

Marketplace > University of Alabama - Tuscaloosa > Biology > BSC 116 > BSC 116 Notes Week 13 Lectures 37 39
Alexia Acebo
GPA 3.7

Preview These Notes for FREE

Get a free preview of these Notes, just enter your email below.

Unlock Preview
Unlock Preview

Preview these materials now for free

Why put in your email? Get access to more of this material and other relevant free materials for your school

View Preview

About this Document

A collection of the twelth week of notes from BSC 116 covering material from lectures 37-39!
Principles Biology II
Jennifer G. Howeth
Class Notes
25 ?




Popular in Principles Biology II

Popular in Biology

This 9 page Class Notes was uploaded by Alexia Acebo on Friday November 20, 2015. The Class Notes belongs to BSC 116 at University of Alabama - Tuscaloosa taught by Jennifer G. Howeth in Summer 2015. Since its upload, it has received 30 views. For similar materials see Principles Biology II in Biology at University of Alabama - Tuscaloosa.


Reviews for BSC 116 Notes Week 13- Lectures 37-39


Report this Material


What is Karma?


Karma is the currency of StudySoup.

You can buy or earn more Karma at anytime and redeem it for class notes, study guides, flashcards, and more!

Date Created: 11/20/15
Lecture  37     Ecology=  study  of  how  organisms  interact  with  each  other  and  their  environment     •organisms  interact  with  other  organisms  and  their  environments  on  various  scales   –individual   –populations:  groups  of  the  individuals  of  the  same  species   –communities:  groups  of  populations   –ecosystems:  groups  of  communities   –landscapes:  groups  of  ecosystems   –global:  the  Earth:  biosphere   •ecology  and  evolutionary  biology   –evolutionary  time:  populations  change  to  adapt  to  their  environments   –ecological  time:  response  of  organisms,  populations,  etc.  to  their   environments   •ecology  and  environmentalism   –not  the  same  thing:  science  vs.  advocacy   –but,  people  that  understand  how  the  natural  world  works  tend  to  be   advocates   **NO  species  occurs  everywhere     –multiple  factors  determine  distributions   •dispersal   •behavior   •biotic:  other  living  things;  e.g.,  predators,  prey,  pathogens,  competitors,  etc.   •abiotic:  physical  factors;  e.g.,  temperature,  light,  water,  etc.     -­‐Organisms  do  not  occur  places  even  though  they  could  survive  there.   –dispersal:  movement  of  individuals  to  new  areas   –barriers  to  dispersal  can  explain  species  distributions   •ranges  always  changing:  species  might  not  be  there  yet   •may  choose  to  avoid  a  livable  habitat:  psychological  barrier,  habitat  selection       *Species’  distributions  are  often  limited  by  other  species.     -­‐other  species=  biotic   •species  absent  because  other  species  is  missing   –food,  host,  pollinator,  etc.   •species  absent  because  other  species  is  present   –predator,  parasite,  competitor,  etc.     *Species’  distributions  are  limited  by  their  physiological  tolerances.     •physical/chemical  properties  =  abiotic  factors   –temperature:  too  hot,  too  cold   •species  adapted  to  one  extreme,  not  well  suited  to  another   –water:  too  wet,  too  dry   •salinity:  osmotic  issues   –sunlight:  esp.  for  photosynthetic  organisms   •UV  from  sun  can  do  damage  to  animals  too   –geology:  the  inorganic  parts  of  the  habitat   •minerals,  pH,  physical  structure  of  land  (e.g.,  rocks)     •Earth  is  not  homogeneous  for  abiotic  factors     **Are  local  variations  in  Climate   •proximity  to  water:  moderates  temperatures  and  humidity   •mountains  have  several  effects   –shadow  to  sunlight   •e.g.,  northern  hemisphere,  south  facing  slopes  warmer,  drier   –altitude  &  temperature:  every  1000  m  equiv.  to  880  km  in  latitude  (6°  C)   •e.g.,  northern  species  can  extend  south  at  high  altitude   –“rain  shadow”:  warm  air  passing  mountains  cools  and  drops  moisture   •e.g.,  deserts  on  the  leeward  side  of  mountains   •tilt  of  the  earth  results  in  predictable  seasonality:  leads  to  variation  in  day  length,   sunlight,  temperature       *Is  a  long-­‐term  variation  in  global  climate   •some  periods  are  warmer/cooler,  wetter/drier  than  others   •until  15-­‐20,000  ya:  northern  latitudes  covered  by  glaciers   •species  continue  to  move  north  (i.e.,  away  from  equator)  as  global  climate   continues  to  warm     **Biotic  &  abiotic  factors  combine  to  create  characteristic  biomes.     •biomes:  major  habitat  types,  determined  by  both  biotic  and  abiotic  factors     •latitudinal  variation  in  temperature,  moisture,  etc.  leads  to  latitudinal  variation  in   animals  &  plants   –characterized  by  plant  types  especially   –species  composition  variations  across,   among  biomes   –ecotones:  areas  of  transition  between  biomes   •disturbance  leads  to  community  variation,  patchiness       **Aquatic  biomes  are  characterized  by  salinity  and  depth.     •ca.  75%  of  Earth’s  surface  aquatic:  several  aquatic  biomes   –freshwater  (<0.1%)  vs.  marine  (3%)   –pelagic  (open  water)  vs.  benthic  (bottom)   •most  photosynthesis  occurs  near  the  surface   –light  filtered  out  quickly:  photic  vs.  aphotic       Lecture  38   •population:  conspecific  individuals  occurring  in  a  particular  area   –live  in  same  environment   –use  same  resources   –interact/breed  with  each  other   •populations  are  dynamic:  changing   –gain  individuals  from  births     –gain  individuals  from  immigration  (arriving)   –lose  individuals  from  deaths   –lose  individuals  from  emigration  (leaving)   •use  3  characteristics  to  describe  populations   –density:  number  of  individuals  per  unit  area  (or  volume)   •boundaries  difficult  to  define  (e.g.,  migration)   •various  methods  to  estimate  size/density:  e.g.,  mark-­recapture   method     -­‐dispersion:  pattern  of  spacing  among  individuals   •clumped:  aggregated  in  patches;  attracted  to  resources   •uniform:  evenly  spaced;  repulsed  by  each  other,  as  with  territories   •random:  independent  of  other  individuals   –demographics:  age-­‐  and  sex-­‐structure  of  the  the  population     **Life  tables  are  a  useful  way  to  summarize  population  demography.         •survivorship  curve:  number  alive  plotted  vs.  each  age   –y-­‐axis  plotted  on  a  log  scale   –e.g.,  Belding’s  ground  squirrel   •males  tend  not  to  live  as  long   •both  have  relatively  constant  death  rates  thru  life   •species  have  characteristic  survivorship  curves,  depending  on  life  history:  pattern   of  reproduction  and  survival   –e.g.,  humans:  low,  constant  death  rate  until  late  in  life   •type  I,  put  energy  into  caring  for  a  few  offspring   –e.g.,  oysters:  high  death  rates  early  on,  low  for  survivors   •type  III,  put  energy  into  producing  many  offspring  w/o  parental  care   –e.g.,  Belding’s  ground  squirrel:  type  II   •survivorship  is  one  factor  that  determines  population  size     **Reproduction  rates  as  important  as  death  rates   •reproductive  table  =  fertility  schedule   –generally  pay  attention  only  to  females  in  population   –follow  reproductive  output  of  cohort   –calculate  average  number  female  offspring   •varies  with  age   •e.g.,  peaks  with  maturity,  then  declines   •HUGE  variation  in  life  histories:  results  from  trade-­‐offs;  costs-­‐benefits  of   reproduction,  etc   –cost  of  reproduction:  energy  spent  on  offspring  not  spent  on  parent   –iteroparity  =  repeated  reproduction:  multiple  reproductive  periods   •e.g.,  Belding’s  ground  squirrel   •favored  in  more  predictable  environments   –semelparity  =  “big-­‐bang  reproduction”:  all  reproduction  concentrated  in  a   single  effort   •e.g.,  agave  =  century  plant   •favored  in  unpredictable  environments:  low  probability  of  adult   survival   –trade-­‐offs:  can’t  maximize  all  reproductive  patterns  at  the  same  time   •e.g.,  more  offspring  means  smaller  offspring  with  less  care     **As  long  as  there  are  more  births  than  deaths,  a  population  will  grow.     •change  in  population  size  =  births  during  time  internal  +  deaths  during  time   interval   –ignore  migration   •ΔN/Δt  =  B  –  D   •ΔN/Δt  =  bN  –  dN  =  (b  –  d)N   –b,  d:  rate  of  births,  deaths  per  capita   •ΔN/Δt  =  rN   –r  =  b  –  d,  per  capita  rate  of  increase   •dN/dt  =  rN   –expressed  as  the  instantaneous  rate  (calculus)   •r  >  0,  population  grows,  r  <  0  population  shrinks   •the  larger  r,  the  faster  the  population  grows   –produces  characteristic  J-­‐shaped  curve   •e.g.,  elephants  in  Kruger  Park   •model  of  exponential  population  growth   –unrealistic  in  most  circumstances     **Population  growth  is  often  regulated  by  feedback.     •carrying  capacity:  number  of  individuals  that  a  habitat  can  sustain   –limiting  factors:  energy,  shelter,  nutrients,  territories,  water,  etc.   –can  vary  over  time   –limiting  resources  can  lower  b,  raise  d   •logistic  population  growth  model:  incorporates  carrying  capacity   –dN/dt  =  rN((K  –  N)/K)   •where  K  =  carrying  capacity   •e.g.,  when  N  is  small,  ((K  –  N)/K)  is  large   •characteristic  S-­‐shaped  curve   •we  can  observe  this  in  real  populations   –e.g.,  paramecium   •most  populations  don’t  fit  exactly   –e.g.,  Daphnia  will  oscillate  around  K   –population  “corrects”  itself   •gives  us  a  way  to  talk  about  life  history  trade-­‐offs   –“K-­selection”  for  traits  that  are  helpful  at  high  densities   •few  relatively  large  offspring;  Type  I  survivorship  curve   –“r-­selection”  for  traits  that  are  helpful  at  low  densities   •many  relatively  small  offspring;  Type  II  survivorship  curve     •when  birth  or  death  rates  change  with  population  size,  they  are  density   dependent   –population  size  regulated  by  feedback   –too  small,  grows;  too  large,  shrinks   •an  equilibrium  can  be  achieved  when  births  equal  deaths   –deviation  from  equilibrium  can  bring  it  back   •causes  of  density-­‐dependent  regulation   –competition:  finite  resources  shared  among  more  individuals   •nutrients,  energy,  space,  etc.   –disease:  pathogens  spread  easier  in  crowded  conditions   –predation:  predator  preferences  my  change  at  high  prey  numbers   –accumulation  of  wastes:  large  population  may  produce  waste  faster  than  it   degrades   –intrinsic  factors:  physiological  responses  to  crowding   •e.g.,  stress  hormones  that  lower  reproductive  rate,  etc.   •Change  in  population  size  from  factors  independent  of  density  is  density-­ independent  regulation   –weather  events  (i.e.,  drought,  tornado,  etc.)       •populations  fluctuate  over  time   –e.g.,  moose,  wolves  on  Isle  Royale   •result  of  biotic  interactions   •there  can  be  long-­‐term  cycles  of  associated  populations   –e.g.,  hare,  lynx  on  10-­‐year  cycle;  why?   •resource  limitation  of  hares  in  winter?  Not  supported  by  the  data.   •predation:  increase  in  hares  leads  to  increase  in  lynx;  overexploitation  by   predators  leads  to  low  prey  densities       •we  have  been  focusing  on  r,  not  migration   –populations  connected  by  dispersal  in  a  metapopulation   •sources:  positive  population  growth  (r  >0),  lots  of  emigration  to  sinks   •sinks:  negative  population  growth  (r  <0)  .,  lots  of  immigration  from  sources   required  to  maintain  population   –populations  blink  in  and  out  over  space  and  time  in  a  mosaic   –habitat  fragmentation  can  yield  a  metapopulation  from  what  originally   was  a  large  continuous  population   –some  species  occur  naturally  in  a  metapopulation  structure   Lecture  39   •Community:  composed  of  two  or  more  species  in  space  and  time     Multiple  ways  in  which  species  interact  within  communities:       1.competition:  -­‐/-­‐  species  compete  for  resources  needed  for  growth,   reproduction,  etc.     2.predation:  +/-­‐  one  animal  eats  another   –predator  adapted  to  locate,  subdue  prey   –prey  adapted  to  hide,  escape   •cryptic  coloration  =  camouflage   •aposematic  coloration:  brightly  colored,  warning   –generally  poisonous,  venomous,  etc.   •Batesian  mimicry:  harmless  resembling  venomous,  etc.   animal   •Müllerian  mimicry:  two  venomous,  etc.  resembling  each   other     3.herbivory:  special  case  of  predation;  animal  eats  a  plant/alga   –plants  adapted  for  defense   •physical  structures  like  spines,  thorns,  etc.   •chemical  protections:  poisons,  nicotine,  caffeine,  spices,  etc.     •niche:  sum  of  the  biotic  and  abiotic  needs  of  a  species;  it’s  place/role  in  a   habitat     •competition  results  from  species  having  overlapping  niches;  various   outcomes   –wide  niche  overlap  leads  to  competitive  exclusion   •weaker  competitor  eliminated  from  local  area   –narrow  niche  overlap  leads  to  resource  partitioning   •species’  “realized  niche”  smaller  than  “fundamental  niche”   –e.g.,  two  barnacle  species  competing  for  space   •spatial  and  temporal  niche  partitioning  leads  to  species   coexistence   –can  lead  to  character  displacement:  resource  partitioning  leads  to   morphological  differences   •e.g.,  Galapagos  finches  in  sympatry  (living  together)  and   allopatry  (living  apart)       •Symbiosis:  close  association  between  species  pairs,  where  at  least  one  species   always  benefits   –beneficial  (+),  negative  (-­‐),  no  effect  (0)     1.mutualism:  +/+  both  species  benefit;  we  have  already  discussed  lots  of   examples   –N-­‐fixing  bacteria  on  legume  roots   –cellulose-­‐digesting  protists  in  cow,  termite  guts   –flowering  plants  and  insect  pollinators   2.commensalism:  +/0  one  benefits,  other  not  affected   –at  least,  not  greatly  affected   –e.g.,  species  that  ride  along  or  follow  others  to  pick  up  leftovers,  etc.   3.parasitism:  +/-­‐  parasite  lives  off  the  host   –inverted  size  relationship,  relative  to  predation   –directly  or  indirectly  affects  host  survival  and  reproduction       •What  do  we  mean  when  we  say  one  community  is  more  diverse  than  another?   •species  richness:  number  of  different  species   •relative  abundance:  proportion  of  individuals  that  belongs  to  each   species   •two  communities  can  have  same  richness  but  different  structures   –various  indices  developed  to  summarize   . –e.g.,  Shannon  Diversity  Index,  H  =  Σ(p   n lnp ) n    •trophic  structure:  feeding  relationships  among  species   –energy  moves  up  from  lower  trophic  levels   –food  chain:  producers  (plants)  →  1°  consumers  (herbivores)  →  2°   consumers  (carnivores)  →  ...   •not  really  linear;  better  represented  as  food  web   –multiple  connections  among  levels   –species  occur  at  multiple  levels;  e.g.,  omnivores  that  eat  producers,  1°   consumers  and  2°  consumers   •most  food  webs  have  <6  trophic  levels   –energetic  hypothesis:  inefficiency  of  energy  transfer  between  levels,  ca.   10%   •takes  100  kg  of  plants  to  support  10  kg  of  herbivore  and  1  kg  of   carnivore       •dominant  species:  most  abundant  or  greatest  biomass  (total  mass  of  entire   population)   –e.g.,  sugar  maples  forests:  determine  shade,  soil  composition,  etc.,  and  thus   other  species   –importance  varies  with  community   •e.g.,  krill  in  arctic  community  support  many  species   •keystone  species:  key  niches  maintaining  community  structure;  not   necessarily  dominant   –e.g.,  without  starfish  (Pisaster),  mussels  would  take  over   •facilitators:  “ecosystems  engineers”   –e.g.,  beavers  create  habitat     •3  possible  relationships  between  Plants  (P)  &  Herbivores  (H)   –P  →  H:  increase  in  P,  increase  in  H   –P  ←  H:  increase  in  H,  decrease  P   –P  ↔  H:  both   •now  we  are  going  to  add  a  Carnivore  (C)  to  the  equation   •bottom-­up  model:  P  →  H  →  C   –increasing  P,  increases  H,  which  increases  C,  etc.   –taking  C  out  should  have  no  effect  on  H  or  V   •top-­down  model:  P  ←  H  ←  C   –removing  C,  raises  H,  which  lowers  P   –increasing  P  should  have  no  effect  on  H  or  C   –“trophic  cascade”     •the  point:  it  is  both,  bottom-­‐up  and  top-­‐down  processes  are  important  in  regulating   communities     •most  communities  are  not  in  a  stable  equilibrium,  that  is  they  are  not  static   entities     •nonequilibrium  model  better  characterizes  most  communities,  they  are  dynamic   with  shifts  in  the  incidence  and  relative  abundance  of  species  over  time   –disturbance  (storms,  fires,  etc.)  keeps  things  in  flux   –E.g.,  Yellowstone  terrestrial  communities  recovering  from  fire     •intermediate  disturbance  hypothesis:  some  disturbance  increases  species   diversity   –low  disturbance:  dominant  species  exclude  others   –high  disturbance:  high  stress;  slow-­‐growing,  slow-­‐colonizing  species   excluded   –intermediate  disturbance:  allows  for  a  mix;  creates  patches  of  different   habitats   –e.g.,  New  Zealand  streams  under  different  flooding  levels,  number  of   invertebrate  taxa  respond  to  disturbance  following  IDH     •ecological  succession:  first  colonizers  replaced  by  other  species,  which  are   replaced  by  other  species   •primary  succession:  beginning  without  soil;  e.g.,  after  a  volcanic  eruption,  glacier   recession   •e.g.,  succession  in  Glacier  Bay,  Alaska     •secondary  succession:  with  soil;  e.g.,  fire  burns  forest   take  less  time  (don’t  need  to  weather  rocks,  create  soils  for  plants,  etc     •so  far,  we  have  mostly  been  considering  biotic  and  local  factors   –also  larger  scale  influences   •larger  areas  have  more  species:  seen  in  species-­area  curve   –larger  area,  more  habitats,  support  more  different  species   •latitudinal  gradient:  more  species  closer  to  the  equator;  higher  tropical  diversity   –historical:  poles  recently  glaciated   –climate:  warmer,  wetter,  so  higher  productivity   •richness  increases  with  evapotranspiration  (evaporation  +  transpiration)        


Buy Material

Are you sure you want to buy this material for

25 Karma

Buy Material

BOOM! Enjoy Your Free Notes!

We've added these Notes to your profile, click here to view them now.


You're already Subscribed!

Looks like you've already subscribed to StudySoup, you won't need to purchase another subscription to get this material. To access this material simply click 'View Full Document'

Why people love StudySoup

Jim McGreen Ohio University

"Knowing I can count on the Elite Notetaker in my class allows me to focus on what the professor is saying instead of just scribbling notes the whole time and falling behind."

Anthony Lee UC Santa Barbara

"I bought an awesome study guide, which helped me get an A in my Math 34B class this quarter!"

Steve Martinelli UC Los Angeles

"There's no way I would have passed my Organic Chemistry class this semester without the notes and study guides I got from StudySoup."

Parker Thompson 500 Startups

"It's a great way for students to improve their educational experience and it seemed like a product that everybody wants, so all the people participating are winning."

Become an Elite Notetaker and start selling your notes online!

Refund Policy


All subscriptions to StudySoup are paid in full at the time of subscribing. To change your credit card information or to cancel your subscription, go to "Edit Settings". All credit card information will be available there. If you should decide to cancel your subscription, it will continue to be valid until the next payment period, as all payments for the current period were made in advance. For special circumstances, please email


StudySoup has more than 1 million course-specific study resources to help students study smarter. If you’re having trouble finding what you’re looking for, our customer support team can help you find what you need! Feel free to contact them here:

Recurring Subscriptions: If you have canceled your recurring subscription on the day of renewal and have not downloaded any documents, you may request a refund by submitting an email to

Satisfaction Guarantee: If you’re not satisfied with your subscription, you can contact us for further help. Contact must be made within 3 business days of your subscription purchase and your refund request will be subject for review.

Please Note: Refunds can never be provided more than 30 days after the initial purchase date regardless of your activity on the site.