The Origin of Species Flashcards
Allopatric Speciation
The process by which new species evolve in geographically isolated populations. Physical barriers, prevent gene flow between populations, leading to reproductive isolation and the eventual formation of distinct species.
Allopatric Species
Species that are geographically isolated from one another, often due to physical barriers, leading to divergence over time into separate species.
Allopolyploidy
A type of polyploidy in which an organism has two or more sets of chromosomes derived from different species, often through hybridisation. This can result in the formation of new species.
Autopolyploidy
A type of polyploidy in which an organism has multiple sets of chromosomes from the same species, typically due to errors in cell division (such as failure in meiosis). Autopolyploids may be reproductively isolated from their diploid ancestors.
Behavioural Isolation
A prezygotic isolating mechanism where differences in mating behaviours, such as courtship rituals, vocalisations, or other behavioural cues, prevent individuals from different populations from recognising each other as potential mates.
Cline
A gradual change in a characteristic or trait of a population (such as size, colour, or physiology) across geographical space. Clines often occur due to environmental gradients, such as temperature or altitude
Deme
A population of organisms within which the exchange of genes is completely random
Hybridisation
The process by which two different species, or genetically distinct populations, interbreed to produce offspring, often called hybrids. In some cases, hybrids may be fertile and contribute to the formation of new species.
Geographic Isolation
A form of reproductive isolation where populations of a species become physically separated by geographic barriers (such as rivers, mountains, or oceans), leading to divergence and potential speciation.
Macroevolution
Evolutionary change that occurs on a large scale, typically over long periods of time, leading to the formation of new species, families, or even higher taxonomic groups. Macroevolution encompasses processes such as speciation and extinction.
Microevolution
Evolutionary change within a population or species, occurring over short time scales. It involves small genetic changes, such as shifts in allele frequencies, and is driven by processes like natural selection, genetic drift, and gene flow.
Polyploidy
The condition of having more than two complete sets of chromosomes. Can lead to speciation, particularly when polyploid individuals are reproductively isolated from their diploid ancestors.
Prezygotic Isolating Mechanism
Mechanisms that prevent fertilisation from occurring, such as temporal isolation, behavioural isolation, or mechanical isolation
Postzygotic Isolating Mechanism
Mechanisms that prevent successful reproduction after fertilisation, such as hybrid inviability (where hybrid offspring do not survive to adulthood) or hybrid sterility (where hybrid offspring are sterile)
Speciation
The process by which new species form when groups within a species become reproductively isolated and develop unique characteristics
Reproductive Isolation
When different populations of a species can no longer interbreed and produce fertile offspring, due to prezygotic or postzygotic barriers
Species
A group of organisms that can interbreed and produce fertile offspring under natural conditions.
Subspecies
A distinct population within a species that has unique characteristics (e.g., size, colour, or behaviour) due to geographic or environmental differences, but can still interbreed with other subspecies of the same species.
Sympatric Speciation
The process by which new species evolve from a single ancestral species while inhabiting the same geographic area. This can occur due to ecological or behavioural differences, such as shifts in diet, mating preferences, or habitat use.
Sympatric Species
Species that live in the same geographic area and have overlapping distributions.
Temporal Isolation
A form of prezygotic isolation where different populations or species reproduce at different times (e.g., different seasons, times of day, or years), preventing interbreeding even if they occupy the same geographical area.
