evolutionary bio lecture 1

lecture 1

misconception #1,evolution is entirely random

• evolutionists rarely attempt to calculate the probability of chance occurrence in their imagined evolutionary scenarios

• infinite monkey theorem: given enough time, a monkey randomly on a typewriter could produce all the works of Shakespeare

• mutations are random; natural selection is the nonrandom spread of particular mutations

infinite monkey theorem

Given enough time, a monkey bashing randomly on a typewriter could produce all the works of Shakespeare

mutations

are random

natural selection

is the non-random spread of particular mutations

misconception #2,evolution is just natural selection

• natural selection is just one mechanism of evolutionary change

• other mechanisms: sexual selection, genetic drift

sexual selection

an evolutionary mechanism where individuals compete for access to mates or choose partners based on specific traits to maximize their reproductive success

genetic drift

Genetic drift is a mechanism of evolution where the frequencies of gene variants (alleles) in a population change randomly over time due to pure chance rather than natural selection

• has a much stronger affect on small population size

types of genetic drift

bottle neck effect and founder effect

bottleneck effect

A random disaster (like a fire or flood) sharply reduces the size of a population, leaving only a few survivors whose genetic makeup may not match the original group

founder effect

A small group separates from a larger population to establish a new colony, carrying only a small, random sample of the original genetic diversity.

misconception #3,organisms simply evolve what they “need”

• mutations do not occur because they would be adaptive in an environment

• if beneficial mutations happen to occur, they may increase in frequency through natural selection

ascertainment bias

a bias in which data is collected in such a way that it is not representative of the true distribution because of non-random reasons

survivorship bias

you don’t see all the things lived and didn’t have what they “needed? and died out completely

Misconception #4,organisms simply evolve what they “need”

No, evolution is a population-level process

misconception #5, evolution explains the origin of life

• evolution deals with how life has changed after it originated

• other scientific fields address the origin of life

misconception #6, evolution is a march of progress

Evolution is hierarchical, not a straight line

misconception #7, evolution always simple to complex

• evolution can also move from complex to simple

• e.g, mitochondria evolved from free-living bacteria

• “simple” and complex” can be hard to define

misconception #8, evolution acts for the good of the species

• evolution selects traits that are beneficial for individuals or their genes

• traits that are good for individuals (or genes) may not be good for the species

misconception #9, evolution is just a theory

• “just” implies mere speculation, a guess, something not entirely legitimate

• a well-thought-out group of propositions meant to explain facts about the natural world

theory

statement of what are held to be the general laws, principles, or causes of something known or observed

other theories

• gravity: objects with mass attract based on distance between them

• relativity: speed of light and curvature of space-time continuum

• evolution: extensively documented set of principles that explain how and why evolution happens; not just “we think evolution happened”

what is science

• Explores and addresses questions about the natural world
  leading to valid and reliable generalizations and
  explanations

• The methods and resulting evidence are open to review by
  others

indirect evidence

from experiments and observation

e.g., physicists and electrons, geologists and earthquakes, epidemiologists and flu, the TSA and plane crashes

uniformitarianism

the fundamental geological and scientific principle that the natural laws and processes operating in the universe today have always operated in the past and apply everywhere in the cosmos. “the present is the key of the past”

science

explores and addresses questions about the natural world leading to valid and reliable generalizations and explanations

• provides a conceptual framework for understanding out observations and experiences

• results are tenetive and subject to revision

religion

• infuses experiences with meaning

• eternal truths, generally not considered tentative or revisionary