Evidence for Evolution/Mechanisms of Evolution Flashcards
What are the 4 mechanisms for evolution??
- Mutations
- Gene flow
- Natural selection (including sexual selection)
- Genetic Drift
Evolution - Definition
change in the (heritable) characteristics of a population over generations
- can be micro or macro
Microevolution
Changes in allele frequencies in POPULATION over short period of time (EX ONE GENERATION)
Macroevolution
occurs at or above the species level - how new species arise. occurs over long time periods
whats the current theory of evolution??
we’re all descended from single celled ancestor (LUCA - Last Universal Common Ancestor) which existed around 3.7 billion years ago
species change through time
species can go extinct
evidence that all species share a common a common ancestor
- all living things are made of cells
- the universality of DNA as the genetic code
- universal flow of biological info (DNA to RNA to amino acids/proteins)
- almost universality of genetic code (codons) and DNA replication/repair
what does all species sharing common ancestor help us do
use bacterial gene editing to edit our genome (CRISPR-Cas9)
crazy things like insert jellyfish gene that codes for green light protein into a cat
evidence that species are related to each other (evolutionary relatedness)
homologies
traits present in two or more organisms INHERITED FROM THEIR COMMON ANCESTOR
homologies can be…
- anatomical/structural
- developmental
- genetic
anatomical/structural homologies
ex in bone structure - human, horse, seal, turtle etc all have a humerus, radius, ulna, carpals, metacarpals, phalanges
homologous structures may not look the same in different species and may not have the same function
developmental homologies
developmental similarities in early embryonic stages (because of inheritance of developmental processes from a common ancestor)
ex humans had gills and tails during development, developmental homology with cats and chickens
genetic homologies
genetic similarities between organisms due to common ancestry
ex. human and chimp DNA is about 99%
since some dna sequences can code for the same proteins, its possible for two species to have around 85% genetic similarity but 100% protein similarity in a specific gene
analogous traits/homologies
occur as an independent solution to an environmental demands - CONVERGENT EVOLUTION
convergent evolution
independant solution to an environmental demand
evidence that species have changed with time
- extinctions in the past and today
- transitional fossils
- vestigial traits
- real time evidence of change
evidence of evolutionary change from fossil record
looking at fossils from the past and comparing to animals now - show that life on earth was once different from life on earth today
evidence of evolutionary change - transitional fossils
transitional/intermediate forms showing intermediate anatomy between early and later forms of species
evidence of evolutionary change - vestigial structures
structures w/ reduced or no function compared to ancestral form due to evolution
ex of vestigial structures
pelvic bones in whales and dolphins from when ancestors walked on land 40 mill years ago
humans - smooth muscles in skin called arrector pili, make us get goosebumps, also ear muscles to change direction of ears
real time evidence of evolutionary change
evolution of antibiotic resistance in bacteria - populations can change overtime but always over generations
mechanisms of evolutionary change
- mutations
- gene flow
- natural selection (inc sexual selection)
- mutations
Mutation definition
any change in the nucleotide sequence of DNA
- can range in size from one nucleotide to large segments of a chromosome that affect multiple genes
point mutation OR ____
SNiP - and mutation that alters a single base pair, or small number of adjacent base pairs