Chapter 8 - Evidence for evolution Flashcards
Species
A group of interbreeding organisms with similar characteristics capable of producing fertile offspring
evolution
The process of cumulative, gradual, and heritable change in a population of organisms that occurs over many generations
What is lamarks theory of transmutation of species
Organisms pass onto their offspring characteristics that they acquire during their life times. That is, individual behaviours during the lifetimes of organisms were the mechanism that drives adaptation
phylogeny
evolutionary relationships that exist between species. Expressed in a tree like diagram
How can the study of bio geography provide evidence of evolution
By looking at the pattern of distribution of plants and animals and fossils today
Molecular homologies
The identification of shared bimolecular elements (generally genes) used to test the closeness of relationships between organisms. Can demonstrate common ancestry
Homology
The existence of shared ancestry between a pair of structures or between genes
Comparative genomics
Comparing the genome sequence of different species. The more similar in sequence the genes and genomes of two species are then more closely related those species are
DNA hybridisation
A method used to analyse relatedness. Similarities in the base pairing of DNA strands are analysed to show evolutionary links between organisms. Can be unreliable when comparing closely related species
Bioinformatics
Digital storage, retrieval, organisation and analysis of large volume of biological data
Molecular phylogeny
The study of evolutionary relationships using comparative genomics
steps of DNA hybridisation
DNA is extracted from two organisms, purified and cut into fragments. It is unwound and the hydrogen bonds joining the two sugar phosphate backbones is broken. The resulting single strands of DNA from the two organisms are mixed making hybrid DNA. Some lengths of DNA will not pair up because the bases do not match. The hybrid strands will bind together more strongly and be more resistant to separating when heated. Resistance is measured as % to work out relatedness
Convergent evolution
A process whereby unrelated organisms evolve similar adaptations in response to similarity in their environments
Mutation rate
The number of changes per gene copy in a population over period of time
Comparative biochemistry
Analysis of the similarities and differences in the cellular chemistry of different species. Particularly includes study of proteins (especially enzymes) and the DNA that encodes them. Results enable relatedness between species to be measured
Principle of superposition
States that the oldest rock layer is found in the deepest position, and each consecutive layer above it is a relatively younger. Indicates the relative ages of the rock layers and the fossils within them
Stratum
The layers of rock in an area. Occur in order, with the oldest layers of the bottom
Absolute dating
The process of determining the age of rocks and fossils they contain on the basis of physical or chemical properties of materials in the rock (Radioactive elements that occur naturally or organic matter)
gradualism
Theoretical model of evolution the proposes that has been a steady, slow divergence of lineages, irrespective gaps in fossil records. Evolution only appears as a burst because of the absence of settlements containing fossils that document a transition. If a small section of fossil bearing sediments were absent this may account for missing millions of years in the fossil record. Gradualism states that if these fossils were still present it would show a divergent pattern that is gradual
Punctuated equilibrium
Theory of evolution that proposes new organisms evolve quickly after a long period of no change rather than evolving by gradual change
What are the two main types of fossil dating methods
Comparative dating and absolute dating
What are the three main types of absolute stating
Radiometric dating, electrons spin resonance and luminescence
Comparative dating
Process of determining the age of rocks that contain fossils relative to one another, allowing an estimation of the oldest to youngest without assigning actual age in years
Radiometric dating
Uses the known rates of decay of naturally occurring radioactive isotopes present in rock or fossil to obtain an absolute date for its age
Process of fossilisation
organism dies in a watery environment and is buried in mud and silt. Soft tissues quickly decompose leaving the hard bones or shells behind. Over time sediment builds over the top and hardens into rock.
Comparative anatomy
study of similarities and differences in structure between different organisms. A larger number of similar features indicate some more recent common ancestor
Morphological features
Structural features
Homologous structure
Feature that has the same general structure but different functions and different organisms
example of a homologous structure
All lizards have scaly skin, however scales can differ in colour, hardness and shape in response to conditions in the habitat that they occupy, serving varying functions of defence, temperature maintenance or camouflage
Adaptive radiation
Process by which species is rapidly diversify into many taxes with differing adaptations. Triggered by factors such as reproductive barriers, changes in availability of resources, new challenges and new opportunities. Is a type of divergent evolution
Vestigial structures
Biological structures that have lost the original function in the course of evolution. In ancestral organisms the structure served a purpose but in their descendants the structures become rudimentary. E.g. pelvic bone in a whale, human appendix
Analogous structures
Features of organisms that have the same function but not the same structure e.g. the eyes of octopuses and vertebrates
Speciation
The evolution of one or more new species from ancestral species. Divergent and convergent evolution
Divergent evolution
Process where they related species evolve new traits over time spent living in different habitats, becoming increasingly different from the common ancestor and from one another giving rise to a new species
convergent evolution
When unrelated organisms evolve similar adaptations in response to similarity in their environments
What can cause divergent evolution
Populations may be separated by physical barriers such as mountains or rivers or other factors such as changes in reproductive timing
