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Exam 5
Ecology |
Study of relationships between organisms and there environment |
Population |
Group of individuals of a single species inhabiting a specific area |
Fundamental Characteristics to population |
Density- How many indiv per unit area
Abundance- How many total individuals are present
Population Dynamics- Changes in the distribution and abundance of populations
|
Survivorship curve |
Type 1- High survivorship of young, high mortality of old (flowers)
Type 2- constant rate (Humans)
Type 3- High mortality of young (sea Turtles) |
Birthrate |
Number of offspring produced per female in a period of time |
Rates of pop change |
Life tables and fecundity schedule allows us to calc:
R0: Net Reproductive Rate
T: Generation time
r: per capita rate of increase |
Net Reproductive rate |
average number of offspring produced by an individual |
Discrete generation |
One generation finishes before the next begins
Annual plants
Insects with one generation per year |
Overlapping Generations- |
More than one breeding generation is present at a given time
Humans
Most birds and mammals
many Plants |
Generation Time: |
The average time from birth to birth
|
r
|
per capita rate of increase
=birthrate-deathrate
less than 0= declining
0=stable
Greater than 0=growing |
Kt or Cretaceous-Paleogne Extinction |
Extinction that killed off many of large dinosaurs.
Gave rise to placental mammals
Rapid radiation of mammals
66 MYA |
Divergence of Humans and Chimps |
6-8 MYA
short amount of time |
Common Ancestor of humans and chimps |
Arboreal- adept tree climbers
hairy
small brain
quadrupedal- used all four limbs to move
|
Bipedalism |
humans
Advantage bc lets organism use forelimbs to for another function |
Anatomy of bipedalism |
Anterior foramen magnum
S shape spine
broad pelvis
Foot- human big toe non grasping (for stability)
arched feet- turned foot into propulsive lever
brain size significantly larger humans 1350 cm3
Chimps 375 cm3 |
Earliest humans
|
Ethiopia africa
4ft tall
5.8 MYA |
Ardipithecus
|
First human
brain small
cranium very ape like
pelvis starts to broaden
gripping foot but curved bones |
Australopithicus |
4.2-1.9 MYA
LUCY skeleton
big toe not divergent in line with other toes
foot arch
|
First Homos |
2.3 MYA
500-800cc brain- bigger brains
evidence of cognitive function tools |
Modern Humans |
.2 MYA
|
Cambrien Explosion |
First large and complex organisms appear.
543-495 MYA |
Cambrien Fauna |
Most major animal phyla represented in some form |
Origin of Amniotes |
after first tetrapods
small agile, insectivorous
amniotic egg
waterproof skin
coastal ventilation via ribs |
Amniotic egg |
Albumin-resevoir for water and protein
Yolk- energy supply for the embryo
provides protection
allows passage of respiratory gases and water vapor |
Sauropsids |
Turtles, lizards, snakes,
many extinct species (dinosaurs)
|
Synapsids |
Mammal like reptiles
mammals |
Largest Mass extinction
|
Permian Triassic
252 MYA
gave rise to age of the dinosaurs
thought to be due to volcanic activity
|
Cretaceuos Paleogene Extinction or KT |
killed off many of large dines
gave rise to mammals |
How did life begin |
1. Earths early atmosphere was capable of spontaneously producing AA
2. Replicating molecules evolved and began undergo natural selection
3. Replicating molecules became enclosed in a cell membrane |
Evidence for single common ancestor |
LUCA
genetic code is shared among all organisms
rRNA exists in all living cells and is highly conserved |
Earliest LIFE |
3.5 BYA |