Evolution - Honors Bio

Lamark

The theory that individuals can change their physical characteristics over a lifetime, and those physical characteristics will be passed down to offspring

Darwin

The theory that random mutations either help or hurt an organism, depending on the environment

Darwin’s Research

Darwin created his theory through his study of Galapagos finches. He noticed that each island had their own variety of finch with different characteristics, mainly a difference in beak size. He concluded that there must be a pressure that resulted in this

1 Step of Evolution

Individuals within a population have a variation

2nd Step to Evolution

Individuals are subject to biotic and abiotic pressures

3rd Step to evolution

Variation results in some being more successful than others

4th step to evolution

Those that are successful reproduce and pass down genetically favorable traits

Survival of the fittest

Competition between individuals or their environment

Natural selection

Survival of the fittest within a population

Evolution

Natural selection over time

Fitness

How well a genotype results in future offspring (reproductive success)

Descent with modification

New traits arise from old traits (from a common ancestor)

First influence on natural selection

Genetic variation and mutation lead to adaptation in an environment

Second influence on natural selection

Abiotic factors within an environment can fluctuate, selecting for adaptations over time. Other biotic factors like competition, predation, and disease can also act as a selective pressure on organisms; some survive, some die. The environment does not change the genotypes, they select phenotypes best for survival

3rd influence on natural selection

Chance and random events can also affect evolution

Fossil record

Provides a record of species that lived long ago, and how ancient species are similar to current species, ex: elephant and mammoth, armadillo and glyptodont

Derived trait

A. trait or feature that is present in the current species but was absent in the last common ancestor, does not appear in fossils

Ancestral trait

A trait or feature that is more primitive and was present in a common ancestor, does appear in fossils

Homologous structures

Anatomically similar structures inherited from a common ancestor

Analogous structures

Structures that are similar in unrelated oraganisms

Vestigial structures

Have no apparent function and appear to be residual parts from a past ancestor, ex: wisdom teeth, flightless bird, pelvic bone in whales

Embryo

An early, pre-birth stage in an organism’s development. Embryos share homologous structures during development, ex: gill slits, tails

Comparative biochemistry

The comparison of gene sequences of organisms to determine similarities, fewer differences: more closely related

Geographic distribution

The arrangement of species through different geographical regions over time

Taxonomy

All vertebrates, mammals included, fall into one phylum (Chordata). We organize organisms using taxonomy.

Taxonomy Pyramid

Memorize pyramid

Classes/super classes included in chordata

Agnatha, chondrichthyes, osteichthyes, mammalia, reptilia, amphibia, aves

Notochord

A cartilagenous rod, running parallel to the nerve cord, and providing structural support to all chordates

Other classifying features

nerve cord, pharyngeal slits, post-anal tail, bilateral symmetry, closed circulatory system: having a heart and blood vessels

Genus “homo”

Millions of years ago, there existed many species within the genus “homo.” Such as: H. habilis, H. erectus, H. neanderthalensis, and many others (10-16)

Uncanny valley

Which we feel uneasy about things which closely physically resemble, but are not quite, humans

Adaptation

A trait that increases an organism’s reproductive success

Camouflage

Adaptations allowing organisms to blend into their environment

Mimicry

When come species evolves to resemble another species

Batesian (mimicry)

A harmless species mimics harmful

Mullerian (mimicry)

Two or more harmful species mimic each other

Self (mimicry)

Mimicking a body part

Genetic drift

Random events that cause allele frequencies to change, resulting in evolution

1. Founder effect

A few organisms are isolated from a population and establish a new population

2. Bottleneck effect

A severe drop in population number causes some alleles to become favored, ex: natural disaster

Disruptive selection (look at graph)

Natural selection that favors genes to the left AND right of the mean, favors extremes of the mean

Directional selection (look at graph)

Natural selection that favors genes to the left OR right of the mean

Stabilizing selection (look at graph)

Natural selection that favors the mean genes within a population, genetic diversity decreases

Sexual selection

Form of natural selection driven by mating dances and courting preferences, individuals choose their mate

Hardy-Weinburg principle

Genetic variation in a population will remain constant in the absence of environmental pessures, a baseline, to compare an evolving population with one that remains constant

Hardy-Weinburg assumptions

No selection, no mutation, no migration, large population, random mating

Allele frequency equation

p + q = 1 p=B, q=b

Genotype frequency equation

p² + 2pq + q² = 1 p²= BB, 2pq=Bb, q²=bb

Practice equation

Also practice graphing