Evolution Flashcards
What is evolution
Evolution is the process of change of a population over time, over successive generations. The presence of these adaptations allow an organism to better respond to its environment, and hence help it to survive and have more offspring.
What is microevolution
Microevolution refers to a change in allele frequency in a population that gives those with more suitable phenotypes an evolutionary advantage.
What is Macroevolution
Macroevolution is an accumulation of multiple microevolutionary changes that result in a permanent change in a species’ phenotype over a long period of time
Define evolutionary radiation
Describes an increase in taxonomic diversity caused by high rates of speciation from a common ancestor
Define mass extinctions
They are extinctions of a vast number of species within a short geological time frame. They usually correlate with catastrophic global events or widespread environmental changes that occur to rapidly for the majority of species to adapt. These events can have a great impact on biodiversity.
Recognise that natural selection occurs when the pressures of enviromental selection confer a selective advantage on a specific phenotype to enhance its survival (viability) and reproduction (fecundity).
Natural selection is based on the concept that mutations cause variation in phenotypes of organisms, and natural selection acts on this variation in phenotypes
The viability of an organism refers to its chance of survival and ability to reproduce and pass on its genes
The fecundity of an organism is measured by its ability to produce viable offspring
identify that the selection of allele frequency in a gene pool can be positive or negative
allele frequency in a population is determined by selection pressures in the environment
alleles may be positively or negatively selected for in a population - that is, alleles may increase or decrease in frequency
interpret data and describe the three main types of phenotypic selection: stabilising, directional and disruptive
Stabilising selection, directional selection and disruptive selection are the three main types of phenotypic selection
Explain microevolutionary change through the main processes of mutation, gene flow and genetic drift.
recall that specriation and macroevolutionary changes result from accumlation of microevolutionary changes over time
There are four key pathways that evolution can take
speciation is the evolutionary process by which new and distinct species are formed in the course of evolution.
identify that diversification between species can follow one of four pattierns: divergent, convergent, parallel and coevloutionary
Divergent evolution describes when descendants of a common ancestor species develop genetic differences in response to differing enviromental pressures, resulting in two different species.
Convergent evolution is a term used to describe unrelated species developing similar phenotypic traits in response to the same enviromental pressures.
Parallel evolution describes when descendants of a common ancestor species diverge, and then develop similar features independently of each other in response to similar environmental pressures.
Coevolution is a term used to describe the simultaneous evolution of two- species interacting closely with each other. Each species exerts a selection pressure on the other and the other responds in turn, perpetuating the process of coevolution and, in many circumstances, their increasing dependence on each other.
describe the modes of speciation: allopatric, sympatric, parapatric
Allopatric speciation is caused by the geographic isolation of a population, preventing individuals from the two groups from breeding. Over time, the two separated groups respond differently to selection pressures and eventually become two different species that can no longer interbreed.
Sympatric speciation occurs when populations remain in the same geographic area but are subject to varying selectionpressures caused by differing local enviromental conditions. The variation in enviromental conditions cause populations within the same area to adapt and change their temporal or behavioural patterns, isolationg them from the other half of the population
Parapatric speciation occurs where populations occupy the smae geographic area but tend to breed with individuals in close proximity. Over time, individual may become phenotypcially different enough that interbreeding is no longer possible despite their geographcial accessibility.
understand that the different mechanisms of isolation- geographic (including enviromental disasters, habitat fragmentation), reproductive, spatial and temporal - influence gene flow
Population of the same species can become isolated from each other, leading to differing selection pressures on phenotypes and eventually to speciaition.
Several types of isolation can lead to speciation and changes in allele frequencey, including geographic, reproductive, spatial and temporal isolation.
explain how populations with reduced genetic diversity (i.e. those affected by population bottlenecks) face an increased risk of extinction
interpret gene flow and allele frequency data from different populations in order to determine speciation
