BSC 1010 Chapter Notes - Chapter 21: Medium Ground Finch, Melanism, Daphne Major

85 views2 pages
Published on 8 Feb 2017
School
Course
Professor
Chapter 21: The Evidence for Evolution
Natural Selection requires the following conditions:
Phenotypic variation must exist in the population
Variation must lead to differences among individuals in lifetime reproduction success
Phenotypic variation among individuals must be genetically transmissible to the next generation
Peter & Rosemary Grant studied medium ground finch on Daphne Major
Found beak depth variation among members of the population
Average beak depth changed from one year to the next in a predictable fashion
Droughts: birds with deeper, more powerful beaks survived better
Normal rains: average beak depth decreased to its original size
Industrial melanism: phrase used to describe the evolutionary process in which initially light-colored organisms become dark as a
result of natural selection
Artificial selection: change in the genetic structure of population due to selective breeding by humans
Many domestic animal breeds & crop varieties have been produced through artificial selection
Has produced substantial change in almost every case in which it has been applied
Operates by favoring individuals with certain phenotypic traits, allowing them to reproduce & pass their genes on to the next
generation
Should result in evolutionary change
Vestigial structures: a morphological feature that has no apparent current function & is thought to be an evolutionary relic
Example: the vestigial hip bones of boa constrictors
Have no apparent function, but resemble structures their ancestors possessed
Fossil genes (pseudogenes): copy of a gene that is not transcribed
Biogeography: the study of the geographic distribution of species
Reveals that different geographical areas sometimes exhibit groups of plants & animals of strikingly similar appearance
Natural selection appears to have favored parallel evolutionary adaptations in similar environments
Convergent evolution: the independent development of similar structures in organisms that are not directly relates
Often found in organisms living in similar environments
Best known case is the two major groups of mammalsmarsupials & placentalshave evolved in very similar ways in different
parts of the world
Anatomical evidence for Evolution:
Homologous structures
Structures with different appearances & functions that all derived from the same body part in a common ancestor
o Example: the bones in the forelimb of mammals
Imperfections
Some organisms do not appear perfectly adapted
Workable but imperfect solutions
Most animals with long necks have many vertebrae for flexibility
Early embryonic development
Strongest anatomical evidence supporting evolution comes from comparisons of how organisms develop
Embryos of different types of vertebrates
Possess pharyngeal pouches that develop into:
o In humans: glands & ducts
o In fish: gill slits
7 principle objections that critics raise of the teaching of evolution as biological fact:
Evolution is not solidity demonstrated
There are not fossil intermediates
Many fossil intermediates in vertebrate evolution have indeed been found
Intelligent design argument
Evolution by natural selection is not a random process
Favoring those variations that lead to the highest reproductive fitness, natural selection is a nonrandom process that can
construct highly complex organs
Evolution violates the Second Law of Thermodynamics
Argument ignores what the second law really says: disorder increases in a closed system, which the Earth mostly certainly
is not
Proteins are too improbable
Illustrates a lack of understanding of probability & statistics
Unlock document

This preview shows half of the first page of the document.
Unlock all 2 pages and 3 million more documents.

Already have an account? Log in

Document Summary

Variation must lead to differences among individuals in lifetime reproduction success. Phenotypic variation among individuals must be genetically transmissible to the next generation. Peter & rosemary grant studied medium ground finch on daphne major. Found beak depth variation among members of the population. Average beak depth changed from one year to the next in a predictable fashion. Droughts: birds with deeper, more powerful beaks survived better. Normal rains: average beak depth decreased to its original size. Industrial melanism: phrase used to describe the evolutionary process in which initially light-colored organisms become dark as a result of natural selection. Artificial selection: change in the genetic structure of population due to selective breeding by humans. Many domestic animal breeds & crop varieties have been produced through artificial selection. Has produced substantial change in almost every case in which it has been applied.

Get OneClass Grade+

Unlimited access to all notes and study guides.

YearlyMost Popular
75% OFF
$9.98/m
Monthly
$39.98/m
Single doc
$39.98

or

You will be charged $119.76 upfront and auto renewed at the end of each cycle. You may cancel anytime under Payment Settings. For more information, see our Terms and Privacy.
Payments are encrypted using 256-bit SSL. Powered by Stripe.