Chapter 26 Flashcards
Species
the fundamental category of taxonomic classification, ranking below a genus or subgenus.
Speciation
the formation of new and distinct species in the course of evolution.
Genetic Isolation
The lack of interbreeding or little genetic mixing between organisms of the same species
Genetic divergence
the process in which two or more populations of an ancestral species accumulate independent genetic changes (mutations) through time, often after the populations have become reproductively isolated for some period of time.
Biological species concept
defines a species as members of populations that actually or potentially interbreed in nature, not according to similarity of appearance. Although appearance is helpful in identifying species, it does not define species.
Reproductive isolation
the inability of a species to breed successfully with related species due to geographical, behavioral, physiological, or genetic barriers or differences
Prezygotic isolation
spatial, behavioral, mechanical and temporal isolation. Keeping two organisms from mating
Postzygotic isolation
A type of reproductive isolation that occurs after members of two different species have mated and produced a hybrid offspring. Such hybrids are usually unable to reproduce.
Temporal isolation
‘isolated in time’, so this is a mechanism that prevents species from mating because they breed at different times. These differences can be time of day, season, or even different years.
Habitat isolation
species live in the same area but different habitats. ( Encounter each other rarely, never technically not geographically isolated, Ex. water vs land snakes)
Behavioral Isolation
An isolating mechanism in which two allopatric species do not mate because of differences in courtship behavior. Also known as ethological isolation.
Gametic barrier
A species is a group of organisms that can interbreed or exchange genes. A hybrid is the result of interspecies mating. Prezygotic barriers prevent fertilization from taking place. Gametic isolation is a type of prezygotic barrier where the gametes (egg and sperm) come into contact, but no fertilization takes place.
Mechanical isolation
This evolutionary mechanism is when different species are isolated by their mechanics - the genitalia of the males and females may have different sizes, shapes, or locations. While mating may still be attempted, evolution has led to genitals that are extremely complex and unique to each species, and this can prevent breeding among even closely related species.
Hybrid viability
When two organisms of different species breed and their offspring is able to reproduce fertile offspring as well.
Hybrid sterility
When two organisms of different species breed and there offspring is not fertile or able to reproduce.
Morphospecies
A group of biological organisms that differs in some morphological respect from all other groups.
Phylogenetic species concept
the smallest set of organisms that share an ancestor and can be distinguished from other such sets. Under this definition, a ring species is a single species that encompasses a lot of phenotypic variation.
Monophyletic group
taxon (group of organisms) which forms a clade, meaning that it consists of an ancestral species and all its descendants. The term is synonymous with the uncommon term holophyly.
Clade
a taxonomic group of organisms classified together on the basis of homologous features traced to a common ancestor.
Lineage
term used to describe cells with a common ancestry, that is developing from the same type of identifiable immature cell. The descendants of one individual; his entire lineage has been warriors.
synapomorphy
a shared, derived trait found in two or more taxa that is present in their most recent common ancestor but is missing in more distant ancestors.(homologous traits)
common ancestry
a group of organisms that share common descent and are usually similar genetically
phylogeny
the evolutionary history of a group of organisms
subspecies
a populations that has distinctive traits and some genetic differences relative to other populations of the same species but that is not distinct enough to be classified as a separate species
allopatric speciation
the divergence of populations into different species by physical isolation of populations in different geographic areas
endangered species act
an act that was put in place to conserve and protect endangered and threatened species and their habitats.
allopatry
refers to species being split up by geographic means
dispersal
the movement of individuals from their place of origin to a new location
vicariance
the physical splitting of a population into smaller isolated populations by a geographic barrier
Biogeography
the study of how species populations are distributed geographically
colonization
by which a species spreads to new areas. Colonisation often refers to successful immigration where a population becomes integrated into a community, having resisted initial local extinction
sympatry
populations or species that live in the same geographic area
sympatric speciation
the divergence of populations living within the same geographic barrier into different species as the result of their genetic isolation
disruptive selection
the pattern of natural selection that favors extreme phenotypes at both ends of the range of phenotypic variation. Maintains overall genetic variation within a population
polyploidy
the state of having more than two full sets of chromosomes
nondisjunction
an error that can occur during meiosis or mitosis in which one daughter cell receives two copies of a particular chromosome, and the other daughter cell receives none
triploid
a cell that has three full sets of chromosomes
tetraploid
cells that contain more than two paired sets of chromosomes, one set coming from each parent
autopolyploidy
the state of having more than two full sets of chromosomes due to a mutation that doubled the chromosome number
allopolyploidy
the state of having more than two full sets of chromosomes due to hybridization between different species
self-fertilization
in plants, the fusion of two gametes from the same individual to form a diploid offspring
hybrid zone
a geographic area where interbreeding occurs between two species, sometimes producing fertile hybrid offspring
secondary contact
the interaction of two diverged species, can often lead to hybridization
hybridization
the crossing of two species that results in a hybrid
backcrossing
cross (a hybrid) with one of its parents or an organism with the same genetic characteristics as one of the parents.
