Midterm 2 Flashcards
Exponential growth
dN/dt = rN
(change in population size/per unit time)= equals intrinsic growth rate* current population size
Exponential growth under pop size
Nt=N0e^rt
(pop size at time t)=(starting pop size)(base of natural log: 2.718)(intrinsic growth rate multiplied by time)
r>0
birth rate is higher than death rate, gets steeper as time goes on
r=0
no change
r<0
population declines quickly
Mark-recapture
capture some individuals & visually tag or mark them, release marked animals, wait long enough for them to evenly spread throughout population, recapture 2nd set of individuals, see how many are marked
N=MC/R
N: total population size
M: # caught, marked & released (1st sampling)
C: # caught in (2nd sampling)
Density-independent controls
Factors affecting population size that DO NOT depend on # of organisms in population, usually abiotic factors (Storms, drought)
Density-dependent controls
Factors affecting population size that DO depend on # of organisms, usually biotic factors, prevent population from growing forever, (Disease, predation, limited resources(space))
Logistic Growth
dN/dt = rN0[(K - N0) / K]
change in population equals intrinsic growth rate times current population size times a factor that shrinks as population approaches K
N0 is large
(K-N0)=0, (K-N0)/K=0, growth is slow
N0 is small
(K-N0)/K=1, growth is mostly exponential
Population size under logistic growth
Nt=(K)/1+[(K-N0)/N0]e^-rt
As N0 nears K, (k-N0) becomes 0
Larger r will take less time (t)
K
environmental carrying capacity
Survivorship (I_x)
proportion of individuals surviving from birth to age class x
l_x= N_x / N_0 (# individuals / original population)
Type 1
high survivorship at early ages & survive to old age
Type 2
straight linear line down & similar fraction of individual surviving each age
Type 3
straight linear line down & similar fraction of individual surviving each age
Fecundity (m_x)
average # of offspring an individual will produce during age class x
m_x= N_x offspring / N_x : (# of offspring / individual)
Net reproductive rate (l_x m_x) R_0
mean # of offspring produced per individual across their lifetime
Or average # of offspring per individual
l_x * m_x : (survivorship * fecundity)
Then add all of them together (sigma)
R_0 = (sigma) l_x * m_x
Generation time
average difference btwn age of parents & offspring
xl_xm_x : (age * net reproductive rate)
G= (sigma) xl_xm_x / (sigma) l_x * m_x
result should be around age where organism produces most
Intrinsic growth rate (r)
Growth rate of population as whole
R = ln(R0) / G
Iow R = ln (net reproductive rate) / ((age * net reproductive rate)/net reproductive rate))
Aristotle’s Scala Naturae (350BCE)
very hierarchical & didn’t incorporate any mechanism for change in species through time
Zhyang Zhou (369-286BCE)
“species change over other time, even into other species”
Al-Jahiz & Al-Biruni
organisms seem to fit in their particular environment, world is limited & there is only so much resources
Ibn Khaldun’s Muqaddimah (1377)
Idea that there are processes of decent, individuals down line of descent look diff from ancestors
Descend from monkeys & recognizes inheritance over many generations
Linnaeus’ Systema Naturae (1758)-Linnaeus’ Homo Variant
Shared, systematic way of naming & organizing species & their relationships together
Categorizing diversity: write genus w/ capital letter & specie w/ lowercase letter & they are italicized
Divided things into 3 large groups: animals, plants, minerals
Alexander von Humboldt
Naturalist who brought global human perspective to climate patterns, identified differences & similarities in species in similar climates
Found similar regions have similar species
Thought everyone w/in human was equal
Cuvier & Scientific Racism
Paleontologist who identified patterns of fossils in diff rock layers
His explanation for changes in fossils was that there were period of catastrophes that made 1 species extinct, then another migrated into region
Mary Anning
Amatuear fossil collector
Catastrophism
Earth & life on it primarily shaped by major, sudden events
Sudden changes in fossil records, minerals, volcanic eruptions
Gradualism
Earth & life on it are primarily shaped by long, slow processes
Similar changes, fossils look similar, incremental changes
By mid 1800s
Generally accepted that:
Gradual change is important component of Earth’s history
Earth is very old (Lord Kelvin estimated at 100 my)
Extinction occurs
Jean-Baptiste Lamarck
believed organism passed on traits that acquired through use/disuse
