Adapted to have a thicker shell in order to protect

 Population Ecology
o How do you define members of that population? It’s easy for unitary forms. It

o EX: Aspen Clones: each tree is interconnected and genetically identical. They are
all males. What is the individual?
Lecture 3:
 Characterizing Populations
o Size: Big organism – small population size. Small organism – large population size.
o Density: uneven distribution of space. American crow: widespread distribution
and variability.
o Rare species are common and common species are rare.
 EX. Butterflies. Lots of rare species and not that many common species
o Spatial distribution: random, evenly, clumped. Uniform are territorial and do not
want to compete. Clumped are social, maybe resources are clumped or maybe
they benefit from one another. Clumped is the opposite of uniform. Random is
somewhere in between.
o Clumped: EX. Schooling fish – protection against predators, they trade off
spots on the edge. EX. Yellow poplar – distribute in dense clumps,
overtime they will compete and eventually die out. EX. Woodland caribou
– protection from wolves.
o Uniform: EX. Emperor Penguins – nesting territory. EX. Golden eagles –
breeding site. EX. Plants such as bunchgrass – stronger uniform at smaller
scales, they are stronger competitors.
o Random: EX. Topical trees – new trees don’t emerge unless enough space
is created, there is a lot of randomness that occurs. EX. Dandelions –
random dispersal modes (wind, water, etc) & Juvenile oysters.
o Age distribution: newborn vs juvenile vs adults
o Genetic structure: fragments environments (who closely related are they in each
clump?)
o Natality: how many individuals are being born in a given time period?
o Mortality:
o Emigration:
o Immigration:
 Population ecology – black-capped chickadees. The population fluctuates throughout the
years. This is due to BIDE also known as r. If r is 0, there is no change in population size. If
r is negative, there was a decrease in population size.
 Population demography – age structure. France – urn shape pattern is typical of
developed countries like the US. There’s a lot of senior citizens. India – This pyramidal
age structure is typical of underdeveloped countries. There’s a lot of babies, don’t live