Lecture 3 Flashcards
what is science
a process of generating knowledge
what is the process of generating knowledge
observation hypothesis data collection experimentation conclusions?
what must a scientific theory be
a scientific theory is a falsifiable explanation derived from the scientific process
what is a theory
theory is the best possible explanation at the time and based on the experiments done/data collected
who was Erasmus Darwin (1731-1802)
A freethinking physician and poet, he wrote widely on the natural sciences and medicine
He subscribed to a concept of transmutation, which he believed resulted from inheritance of derived traits
He likely impacted his grandson’s thinking on inheritability
where did darwin first go to school
University of Edinburgh in Scotland for medicine- but he didn’t like it
where did darwin go to school after
Cambridge where he began studying for the ministry– but he didn’t like that much either
what sparked darwins interest in evolution
Darwin starts collecting beetles
why is William Paley (1743-1805) important
Darwin read and admired Paley’s seminal work, Natural Theology
Highly influential in his day, Paley’s work was empirically grounded, yet religious in nature
Watchmaker analogy = design implies a designer
why is John Stevens Henslow (1796-1861) important
a professor of botany at Cambridge, he was a major influence on Darwin, and served as a mentor for many years
The two regularly set out on specimen-hunting excursions to the local countryside
what was the initial purpose of darwin’s voyage
to conduct an extensive hydrographic survey of Patagonia, Tierra de Fuego and Chile
During the voyage, Darwin began to consider two key geological questions
what were they about
- the relationship between volcanism and seismic activity
2. the relative ages of mountain ranges and rock formations
In addition to living plant and animal specimens, Darwin collected what
the bones of a number of extinct species
did darwin actively look to prove a theory
It is important to note that Darwin was not actively building a theory of transmutation during the Beagle voyage. By 1836, he had some well-developed geological theories, but evolution by natural selection would – appropriately enough – develop slowly over several years
During this time, Darwin would reflect on two key conclusions he’d drawn from his time on the Beagle, what were they
- in nature, there is fierce competition for resources
2. minute differences among individuals maybe advantageous
what type of work did darwin first publish
He published and presented on his geological findings, but not on his theories of transmutation (evolution)
what was this was the foundation of natural selection as a theory
Darwin’s 1837 sketch outlined his theory of all life’s descent from an original ancestor
Though the details would not be worked out for some years, this was the foundation of natural selection as a theory
who was Alfred Russel Wallace (1823-1913)
An English naturalist, he conducted years of fieldwork in Brazil and the Malay Archipelago
He independently devised a theory of natural selection
Without his knowledge, his research —along with Darwin’s—was presented to the Linnean Society of London in 1858
when was On the Origin of Species by Means of Natural Selection published
One year after the joint paper with Wallace was presented at the Linnean Society of London, Darwin published On the Origin of Species by Means of Natural Selection (1859)
It was immediately popular and controversial
what are the 6 Principles of Natural Selection
Overproduction Competition Variation Adaptation Natural selection Speciation
what is Overproduction
An organism’s potential rate of reproduction is higher than the rate of food and resource production
what is Competition
There is a struggle for survival
what is variation
Variations exist within a population
what is adaptation
Variations can be favourable and may offer a selective advantage (Adaptation)
the white and black moth example during the industrial revolution
what is natural selection
Those best suited to their environment survive and have more offspring and so will be better represented in the next generation
what is speciation
With enough accumulated differences, a new species may arise
that is needed in order for something to be considered “fit”
Reproductive Success
what did the Galapogos Finches help darwin to conclude
Natural selection does not always result in unidirectional change
what are the Types of Variation
Continuous variation
Discontinuous variation
what is Discontinuous variation
involves “either-or traits” that are confined to set categories and do not fall on a continuum
Discontinuous variation is usually not a significant factor in evolutionary adaptation
what is Continuous variation
is variation with a relative value on a continuum between extremes. Height is an example, as is hand span, shoe size, weight, skin color, etc
what are Complex Adaptations
The development of complex mechanisms such as the eye is the result of continuous variation, with multiple intermediate steps
Natural Selection will take place ONLY if:
the trait is heritable
the trait displays variation among individuals
the trait must be subject to selective pressure
What are selective pressures?
Competition for food/energy
Competition for a mate**
important to note… some features do not have anything to do with the environment… it is just to help attract and mate to pass not heir genes
Environmental changes
Predators
Parasites
Darwin believed in “blending inheritance”, what is that
where characteristics from each parent mixed like liquids
what was one thing that darwin got wrong
blending inheritance
who proved blending inheritance wrong
In 1867, Fleeming Jenkin showed statistically that with blending inheritance, single favorable mutations would be diluted out of existence over time
what didn’t darwin know
- What is the source of individual variation?
2. How are characteristics inherited?
