Lecture Five ENVS 1500 10/7/2013 6:25:00 AM
1) what did the narrator say wrong at the start?
Finches held the secrete of the origin of species of diversity, not for
the origin of life. It is a model that helps us understand the spices
He should of said it was a hypothesis not theory
2) what did the grants do when they went ashore?
Rinsed everything with seawater to prevent non-native organisms
from establishing themselves on the island
3) primary cause of death or finches?
Lack of food driven from weather. Weather is the main driver
4) 2 species of Finches
Medium ground finch and cactus finch. Focused on medium ground
finch, and could identify every piece of food they eat
5) Major biological process they observed
Evolution by natural selection. They believed these processes were
6) 3 primary question trying to answer?
Trying to understanding species co-op., why populations are
variable, how species are formed
What they found was natural selection was operating under
Galapagos Islands are isolated from other land masses. Darwin never kept
track of which finch’s came from which islands. Finches diversified form one
pair that arrives form South America. Adaptive radiation is the term used to
describe the diversification into 13 types.
Evolution by natural selection: all species have arose form a
common ancestor from 3.5 billion years ago. Not a model for how
life began – model for why we have so many species
Science needed a model to account for diversity + for their inter-
Methodological materialism: must be observable and detectable.
Science is inherently limited by ability to make reliable observation. Dependence on evidence is not a problem of science it is the
essence of science.
1) special creation – cannot be tested (based on faith not
observation) and therefore outside the realm of science. (not for
science to say, needs to be observable and measurable)
2) spontaneous generation – an early hypothesis used to explain
how species arose. (tested and rejected).
A. Lamarck: Inheritance of acquired characteristics of individuals –
hypothesis subject to many tests and failed. (this is largely abandoned by
B. Darwin & Wallace: evolution by natural section – Model repeatedly tested
and refined – supported by the scientific community
Populations were descendants form common ancestors whose
descendants changed – through differential survivals and
reproduction of individuals over time hence evolution of natural
1) Variation – must have variability to have nat. selection
variation exists, some variation has a genetic basis & is therefore
inheritable, all genetic variation arises by change (mutations and
o Ex. Turtles: eggs in moist soil result in longer wider shells
compared to eggs in drier soil.
DNA – basis of information that is passed. Different forms of genes (alleles)