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espm 114 midterm two


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study of the distribution patterns of living organisms
study of animal distribution (and richness) patterns
study of plant distribution
total number of species
population size in numbers
3 General patterns of distribution
1) most species occur on only one continent

2) distribution differs across taxonomic groups

3) matches btwn patterns of species occurrence and geographical barriers suggest the world can be divided in zoogeographic realms
endemic species
native and confined to a default area
indigenous species
native to a defined area but also found elsewhere
exotic species
non-native species that are locally or widely introduced
cosmopolitan species
species indigenous to all geographic realms
alfred russel wallace
first scientist to relate species range to geographic features
wallace line
most dramatic change in species composition of any realm boundary:

west: asian fauna and flora
east: australian fauna and flora
3 factors affecting distribution
1) history
2) dispersal
3) adaptive radiation
dispersal factors
1) spread more because of vagility
2) physical barriers
3) biological barriers
connectivity of land masses over geological time
patterns of species richness
1) latitudinal gradient
-richness increases as you go from poles to equator

2) peninsula effect
-richness decreases as you go from base to tip of peninsula

3) richness
-greater in mountainous regions than in flat regions
different climatic events affect different species and different regions of the world
a group of interacting animals of the same species
numbers per unit area
a complete count of all individuals in a population
partial count, could be explanded to an estimate of total population size
function of species, habitat, time of day (light, behavior), observer experience, group size, method of search (speed, height, visibility)
doubling-counting or undercounting
trap-happy vs. trap-shy affects catch-per-unit effort

activity pattern

territorial vs. transient individuals
direct counting technique
aerial- helicopter
group - drives, etc.
live trapping - catch per unit
indirect counting techniques

camera trapping

call stations
quadrats sampling techniques
N = (n/a)A
circular plots sampling techniques
often used for birds

stand at center -> count all within sight of radius
sampling: strip transect
walk in a line, count everything within a width
sampling: distance transect
walking, driving, etc
assumptions of transect
no movement of animals(2x counting, undercount)

sights are independent events

probability of sighting a group is independent of group size

objects directly on line will never be missed
aerial surveys
detectibility varies by:

habitat, time of day, observer, hiegh, speed, species
denser habitat
lower detection
left uncorrected: results in undercount and inflates variance of the population estimate
methods for addressing detectability bias
double sampling: sub-sample plots more intesively

capture-recapture: use more markers

statistical model: RELATE # observed to confounding variable, then set variables to zero
assumptions for mark-recapture
-no emmigration/immigration

-if mortality, = survival of mark/unmarked

-no loss of marker
-= detectability of mark/unmarked
-random mixing of marked/unmarked
-marked individuals are rep. samp of pop.
- all indv. indp. of each other
population of populations
rescue effect
facilitates recolonization of an area following a local extinction

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