natural selection & evidence of evolution Flashcards
What is meant by the concept of natural selection ?
the process by which advantageous traits become more frequent in populations, survival of the fittest
What are the main principles of natural selection?
variation, differential survival and reproduction,heredity,adaptation
describe variation
individuals in a population or group differ in some trait of interest
describe differential survival and reproduction
those with advantageous traits tend to be eaten less by predators and become more frequent in populations, predators weed out the less advantageous traits as they get hunted more frequently leading to less reproduction of that trait, resulting in not all individuals reproducing to their full potential
describe heredity
surviving organisms have offspring of the same (advantageous) trait
describe adaptation
the frequency of the advantageous trait will increase in population over time, advantageous trait- more likely survival- more reproduction of offspring with that trait due to more survival- eventually all individuals will have the trait
How can natural selection result in the evolution of populations?
By having variation, differential in survival & reproduction and heredity, natural selection will result in evolution as an outcome
Explain why populations of organisms and not individual organisms evolve.
An individual organism either has the genes good enough to survive or it doesn’t and cannot just change it’s traits, a population however can gradually change overtime as populations with genetic variation allows some individuals to survive better than others, then those individuals will have more offspring, and the population evolves
What are sources of variation that can lead to natural selection and evolution?
sexual reproduction, mutation, gene flow
describe sexual reproduction’s meaning contribution to natural selection and evolution
can introduce new gene combinations in a population, this genetic shuffling is another important source of genetic variation
describe mutation’s meaning and contribution to natural selection and evolution
mutation- changes in DNA, evolutionary change is based on the accumulation of many mutations
describe gene flow’s meaning and contribution to natural selection and evolution
gene flow- any movement of genes from one population to another and is an important source for genetic variation, occurs when individuals migrate into a population
what are all the types of evidence used to suggest evolutionary pathways
anatomy, fossil record, geography, embryology, molecular and genetic evidence, direct observation
describe anatomy and the different structures studied
studies the structures of organisms and their parts, homologous, analogous, vestigial
describe homologous structures
structures that many other species share due to a common ancestor with this physical feature, structures may be similar, but do not always have the same function, evidence of a common ancestor
describe analogous structures
having similar function but not similar evolutionary origin, are not evidence of a common ancestor, may develop independently due to similar environments of ways of life, not because of shared ancestry, also known as convergent evolution (when distantly related species seem to converge in appearance)
describe vestigial structures
remnants of organs or structures that had a function in an early ancestor, but no longer do
describe fossil record
fossils are traces of organisms from the past, fossil records provides a picture of the past and shows evolutionary change over time, the fossils in bottom layer rocks are older than the newer top layer fossils in rocks, transitional fossils provide evidence of a common ancestor and shows an organism in between 2 species and they indicate that one group may have given rise to the other by evolutionary processes.
describe geography evidence
study of distribution of organisms around the world, species in discrete geographic areas may be more closely related to each other than to species in distant areas, populations can show variation from one place to another because of different ecosystems
describe embryology
study of embryo development and comparison, species with similar traits in embryo development are likely to share a common ancestor, comparing early embryos reveal many structures not seen in adult form
describe genetic and molecular evidence
supports fossil and anatomical evidence, two closely related organisms will have similar DNA sequences, protein comparisons- comparing amino acid sequences reveals similarities in different organisms
describe direct observation
direct observation of change over time/organisms evolving. Ex: antibiotic resistance in bacteria
How are phylogenetic trees used to depict evolutionary relationships?
Shows the shared common ancestor and the common trait that was passed on to more species
What do the nodes mean? What do the branches mean?
Nodes are where 2 lines meet, representing a connection between primates, branches are the lines that connect to the primates to the common ancestor
