CLE: 1-5 Flashcards
how long has life existed on earth
3.5 billion years
abiogenesis
3.8 billion years ago, natural process of life arising from non-living matter, such as simple organic compounds
when dd the earth form
4.6 billion years ago
timeline of life on earth
earth forms, abiogenesis, photosynthetic bacteria release oxygen, eukaryotes, fish, plants, amphibians, reptiles, largest mass extinction, dinosaurs, mammals, birds, flowering plants, dinosaurs and ammonites become extinct
when did dinosaurs and ammonites become extinct
65 million years ago
cambrian explosion
rapid diversification of life forms on earth that produced most of the major phyla known today
last universal ancestor
the ancestor of all life on earth today
events leading to life on earth
abiogenesis, last universal ancestor, oxygen rich atmosphere, cambrian explosion
fossils
preserved remains and traces of once living organisms
fossil record (palaeontology)
fossils preserved in rock of different ages provide a record, or time scale, of life on earth
the law of superposition
in a sequence of rock layers, a higher rock layer is younger than a lower one
evidence for evolution
fossil record, comparative analogy (structures and embryology), comparative genomics
transitional fossil example
archaeopteryx - mixture of reptile and bird
fossil record link to evolution
provides evidence of past life and change in organisms over time (progressively more complex organisms found in younger layers)
comparative analogy
establishing evolutionary relationships between groups of organisms on the basis of structural similarities
homologous structures
structures that have developed from the same part
examples of homologous structure
pentadactyl limb
embryology
study of the development of embryos
embryology (ontogeny)
study of the development of embryos
homologous structure link to evolution
indicates groups of organisms shared a common ancestor
comparative genomics (molecular evidence)
use of molecular information to determine evolutionary relationships between organisms
DNA hybridisation
technique used to compare similarities between DNA samples from different species
Phylogeny
the evolutionary history and relationships among groups of organisms
examples of comparative genomics
comparing differences in amino acid sequence in the blood protein haemoglobin of primates, comparison of DNA sequences
comparative genomics link to evolution
indicates evolutionary relationships between organisms, a small difference indicates a recent divergence
relative age
the age of a fossil relative to another fossil
radioactive dating
measuring radioactive traces of certain elements present in the rock to determine the age of the rock and any fossils in it
stratigraphy
the science of rock strata, or layers
divergent evolution
results in a group of related species that share a recent common ancestor
convergent evolution
results in organisms that do not share a recent common ancestor, but may find themselves adapting in similar ways to similar environments
analogous structure
independently evolved structure which has a similar function
bioinformatics
an interdisciplinary field that develops methods and software tools for understanding biological data
phylogenetic trees
shows the evolutionary interrelationships among various species or other entities that are believed to have a common ancestor
clade
a common ancestor and all of its descendants
phylogeny
the study of the evolutionary relationships between groups of organisms
macroevolution
descent of different species from a common ancestor over many generations
speciation
the formation of new and distinct species in the course of evolution
microevolution
changes in gene/allelic frequency in a population from one generation to the next
evolution
descent with modification from a common ancestor
natural selection process
ESRA. Exisiting variation, differential Selection, differential Reproduction, Adaption
differential selection
driven by changes in environment called selection pressures. individuals are differentially selected to survive based on whether they have geno/phenotypic characteristics to survive
variation in a population (existing)
due to independent assortment, crossing over, random mating and fertilisation, gene flow and mutations
differential reproduction
individuals that are ‘selected for’ are most likely to survive and grow to maturity and have the most offspring. this passes on the allelic version to succeeding generations
fitness
word to describe how good a particular individual is at leaving offspring in the next generation relative to how good other individuals are at it
example of natural selection
peppered moth
allopatric speciation
macroevolution through natural selection
allopatric speciation process
VISS. Variation, isolation, selection, speciation
differences which cause reproductive isolation
behavioural (mating calls and courtship behaviour), temporal (breeding seasons), mechanical (body structures)
desirable characteristics
those that increase the change of an individuals survival when environmental selection pressures change
desirable characteristics improve an individuals ability to:
compete for resources, avoid predators, resist disease, survive changes in environmental factors
isolation (speciation)
a barrier has formed which prevents gene flow (or interbreeding) between the two poulations
variation (speciation)
a range or variety of characteristics exist within a population, they share a common gene pool
selection (speciation)`
in each population, over a number of generations, different selection pressures will act to bring about a change in the gene frequencies of each gene pool
allopatric speciation example
galapagos islands, darwins finches
adaptive radiation
a process in which organisms diversify rapidly from an ancestral species into a multitude of new forms
modification
refers to changes in the frequency of existing allelic versions of genes, and/or the introduction of beneficial mutations
mechanisms of evolution
mutation, gene flow, genetic drift, natural selection, sexual selection
gene flow
any movement of individuals, and/or the genetic material they carry, from one population to another
genetic drift
refers to differences in allelic frequency due to random events that change the members of a population. its affects are much more important in small populations (eg endangered species)
sexual selection
natural selection arising through preference by one sex for certain characteristics in individuals of the other sex
sexual selection works in two ways:
male competition, female choice
mutations
affect the fitness of individuals, germ line
mutation examples
venomous snake, gray tree frog
gene pool
all the allelic versions of all genes from a population
types of genetic drift events
bottleneck effect, founder effect
bottleneck effect
describes genetic drift that occurs when there is a disaster of some sort that reduces a population to a small handful, which rarely represents the actual genetic makeup of the initial popualtion
bottleneck effect example
northern elephant seals. Hunting reduced population to about 20, now about 30,000 but genes still carry the marks of the bottleneck
founder effect
occurs when a new colony is started by a few members of the original population
founder effect example
macaroni penguins. Majority are black faced but one island only had white faced
artificial selection
when people instead of nature select which organisms get to reproduce
purpose of artificial selection
to enhance certain characteristics of an original wild type through a controlled breeding program
artificial selection in animals example
domestic dog. causes undesirable characteristics such as short life span in great dane, epilepsy in Alsatians
artificial selection in plants example
mustard plant. broccoli and cauliflower come from it
biogeography
the study of the distribution of species and ecosystems in geographic space and through geological time
conservation planning to maintain viable gene pool in terms of gene flow
1 - monitoring and identification of species and their population locations, 2 - active involvement between stake holders to reduce barriers for migration, 3 - trapping and translocating, 4 - captive breeding
conservation planning to maintain viable gene pool in terms of ensuring geographical spread in case of disease or catastrophe
1 - captive breeding, 2 - zoos, 3 - seed banks
conservation planning to maintain viable gene pool in terms of reproductive behaviour
1 - breeding season, 2 - number of offspring, 3 - sexual selection
conservation planning to maintain viable gene pool in terms of population dynamics
1 - population density, fluctuations and distribution, 2 - male to female ratios, 3 - age structure, 4 - offspring survival rates
Why is the history of life on earth still incompletely documented
fossil record is incomplete - dead bodies decompose quickly, few bodies are suitable for preservation, earth movements and erosion destroys preserved material, some fossils remain buried, soft-bodied animals not suitable for fossilisation
