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BC Biology 11: Evolution

Terms in this set (43)

Evolution
Process by which modern organisms have descended from ancient organisms; any change in the relative frequencies of alleles in the gene pool of a population.
Fitness
Combination of physical traits and behaviour that help an organism survive and reproduce in its environment,
Common Descent
Idea that species have descended from common ancestors.
Adaptation
Process that enables organisms to become better suited to their environments.
Fossil
Preserved remains or evidence of an ancient organism.
Embryo
Organism at an early stage of development.
Homologous Structure
Parts of different organisms, often quite dissimilar, that developed from the same ancestral body parts.
Vestigial Organ
Structure that serves no useful purpose of function in an organism.
Evolutionary change
A theory first proposed in the nineteenth century by Charles Darwin, according to which the Earth's species have changed and diversified through time under the influence of natural selection. Life on Earth is thought to have evolved in three stages.
reproductive isolation
technique in which the intervention of humans allows only selected organisms to produce offspring. offspring are sterile
Natural Selection
Process in nature that results in the most fit organisms producing offspring.
Gene
segment of DNA that codes for a particular protein.
Allele
one of two or more alternative forms of a gene that arise by mutation and are found at the same place on a chromosome.
Gene flow
also called migration—is any movement of individuals, and/or the genetic material they carry, from one population to another. Gene flow includes lots of different kinds of events, such as pollen being blown to a new destination or people moving to new cities or countries.
Genetic drift
Genetic drift (or allelic drift) is the change in the frequency of a gene variant (allele) in a population due to random sampling.
Gene shuffling
Gene shuffling is the process of recombining the starting pool of sequences to generate new gene-sequences that subsequently can be screened for particular desired characteristics.
Mutation
Change in the genetic material of a cell.
Survival of the fittest
"Survival of the fittest" is a phrase that originated in evolutionary theory as a way of describing the mechanism of natural selection. It is more commonly used today in other contexts, to refer to a supposed greater probability that "fit" as opposed to "unfit" individuals will survive some test.
Population
collection of individuals of the same species in a given area whose members can breed with one another.
Gene pool
common group of genes shared by members of a population.
allele frequency
Number of times an event (allele) occurs compared wit the number of times another event (other alleles for the same gene) occurs.
Speciation
the formation of new and distinct species in the course of evolution.
Niche
combination of an organism's habitat and its role in that habitat.
struggle for existence
The ecological principle that when two species compete for the same critical resources within an environment, one of them will eventually out-compete and displace the other.
geographical isolation
occurs when a physical barrier separates two populations.
Temporal isolation
species that breed during different times of the day, different seasons, or different years cannot mate.
Behavioral isolation
certain behavioral patterns that attract mates or that are unique to a particular species are effective reproductive barriers.
Adaptive radiation
process, also known as divergent evolution, in which one species gives rise to many species that appear different externally but are similar internally.
Divergent evolution
pattern of evolution, also known as adaptive radiation, in which one species gives rise to many species that appear different externally but are similar internally.
Convergent evolution
phenomenon in which adaptive radiations among different organisms produce species that are similar in appearance and behaviour; opposite of divergent evolution.
Analogous structure
structures that are similar in appearance and function but have different origins and usually different internal structures.
Homologous structure
parts of different organisms, often quite dissimilar, that developed from the same ancestral body parts.
gradualism
Pace of speciation: changes
gradually and steadily.
Punctuated equilibrium model
Long term stable periods interrupted by brief periods of change.
the fossil record
records species that are now extinct, modern species are not present in the fossil record, some modern species are similar but not identical to some previous species.
geographical distribution
species of different continents have each descended from different ancestors but have similar features because of similar selection pressures
comparative embryology
study of animal development from egg to fetus (embryos of different organisms look similar early in development, embryos of more closely related organisms will look similar further into development)
comparative biochemistry
all living things have the same basic biochemistry (animals with similar DNA are closely related)
Role of DNA in evolution?
DNA carries on genetic information and causes gradual change by carrying on mutated genes overtime and resulting in more varied genetics.
founder effect
allele frequencies change as a result of migration of a small subgroup of a population
bottleneck effect
most genotypes are prevented from being produced in the next generation; caused by a severe reduction is population size due to a natural disaster, predation or habitat reduction
random mating
all members of a population must have equal chance to reproduce and pass on their alleles
macroevolution
large scale change that takes place over long periods of time.
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