Biodiversity- Evolution & Taxonomy

Flashcards for Biodiversity's Unit 1: Evolution & Taxonomy

Biological Evolution

The heritable change in one or more characteristics of a population or species from one generation to the next

Evolution

 Any change in allele frequency over time; can be random

Genetic Drift

Random phenotype/allelic change

Adaptive change

Non random change in evolution

Adaptation

Organisms adapting to their environment to survive/better suited for environment through changes in traits, enhancing fitness

Microevolution

Evolution on a small scale, relating to changes in a single gene in a population over time

Macroevolution

Larger-scale evolution, relating to formation of new species or groups of species; leads to the emergence of new species or body forms 

Darwinism’s 5 Major Theories

1. Perpetual Change

2. Common Descent

3. Multiplication of Species

4. Gradualism

5. Natural Selection

Perpetual Change

All species are always changing from generation to generation, change is never static

Common Descent

The idea that if you go far back enough, there is a common ancestor among all species

Multiplication of Species

When species evolve into two or more separate species

Gradualism

Refers to the idea that complex traits have to be built one adaptive step at a time; each step HAS to be advantageous to the individual that has it; change in genes is not random but gradual

Natural Selection

The process where organisms with traits best suited to their environment survive and reproduce more often than others; this is not survival of the fittest, you just have to not be the worst

What does eliminating the slowest organisms lead to?

The mean of the trait shifts over generations

Things needed for Natural Selection to happen

1. Variation in phenotype

2. Must be heritable

3. Must lead to differential reproductive success (refers to whole species, not individuals)

Evolutionary Arms Race

Where competing species or genes develop escalating adaptations and counter-adaptations in response to each other

Adaptive Radiation

Ecologically distinct species that occurs in an evolutionary short time

Evidence for Evolution by Natural Selection

1. Variation in traits, many are inherited

2. More offspring than can survive; resources are limited; organisms compete

Better (relative to environment) traits =

= higher survival & reproduction

Charles Darwin

Came up with the theory of natural selection; shaped by several different fields of study & experiences including: geology, economics etc.

Alfred Russel Wallace

Studied beetles, co-published with Darwin Origin of Species

Thomas Malthus

Believed due to food growth being only linear versus population growth being exponential, food supply would eventually run out and humans would starve

Finite Food Supply/ Scarcity

Organisms/species must compete for food because more individuals are produced than can be supported by the environment 

Evidence of Evolutionary Change

1. Fossil Records

2. Biogeography

3. Observation of natural and artificial selection

4. Homologies

Fossil Record

The collection of all discovered fossils and their placement in chronological order within Earth's rock layers; shows how organisms have changed/evolved throughout generations

Biogeography

As landmasses move apart, each new landmass undergoes an individual speciation; physical barriers change species; selection acts on that and drives them to be different

Convergent Evolution 

When completely unrelated or distantly related organisms independently evolve similar traits or physical features because they adapt to similar environmental pressures or ecological roles

Anatomical Homology 

The similarity in physical structures between different species that comes from a shared evolutionary ancestor; even if those structures now have different uses

Developmental Homology

During development we all share characteristics, and most are lost afterwards

Molecular/sequence Homology

The relationship between DNA, RNA, or protein sequences that share a common evolutionary ancesto