Chapter 24 and 25 Flashcards
Species
Defined as an evolutionarily independent population or group of populations
Biological species concept
members of populations that actually or potentially interbreed in nature, not according to similarity of appearance
Prezygotic isolation
mechanisms of separation of different species to keep them from creating offspring by preventing the gametes from forming a zygote.
Postzygotic isolation
Reproductive isolation in which the hybrid offspring does not survive or reproduce
Morphospecies concept
Researches identify evolutionarily independent lineages by differences in size, shape, or other morphological features
Polymorphic species
A species that over 2 distinct phenotypes in the same interbreeding population
Cryptic species
Differ in tratis other than morphology
Phylogenetic species concept
Identifies species based on evolutionary history of populations
Definition that species are the smallest monophyletic group in a phylogenetic tree
Monophyletic group (lineage, clade)
include a single common ancestor and all of its descendants
Synapomorphy
Trait that is found in certain groups of organisms and their common ancestor but is missing more distant ancestors
These are what identifies monophyletic groups
Three common species concepts
Biological species
Morphospecies
Phylogenetic species
Allopatry
describes a population or species that is physically isolated from other similar groups by an extrinsic barrier to dispersal
Allopatric speciation
Speciation occurs when populations of the same species become geographically isolated
Starts in two ways called dispersal and vicariance
Dispersal
Movement of individuals from one place to another from place of origin to place of living and breeding
Vicariance
The physical splitting of a habitat by a geographic barrier
Biogeography
Study of how species and populations are distributed geographically
Sympatry
Condition in which two or more populations live in the same geographical area or close enough to permit interbreeding
Sympatric speciation
Speciation that occurs even though populations live within the same geographical area
Niche
Range of resources that a species can use and the range of conditions that it can tolerate
Polyploidy
Condition of possessing more than two complete sets of chromosomes, is caused by a massive error in mitosis or meiosis
Two types of polyploids
Autopolyploid
Allopolyploid
Autopolyploid
Individuals are produced when a mutation results in a doubling of chromosome number and the chromosomes all come from the same species
Allopolyploid
Individuals are created when parents of different species mate and then an error in mitosis occurs and it results in viable offspring with two full sets of chromosomes
Reinforcement
The natural selection for traits that prevent interbreeding among recently diverged species
Sympathic
2 species live in the same area
Allopatric
2 species live in different areas
Hybrid zone
Geographic area where interbreeding occurs and hybrid offspring is common
Hybrid sterility
Postzygotic mechanism occurs when the offspring of two different species are sterile or have reduced fertility
Unable to produce viable offspring themselves
Habitat isolation
Prezygotic mechanism that refers to species being isolated by differences in their habitats or ecological niches, reducing the chance of encountering and mating with each other
Mechanical isolation
Prezygotic mechanism involves structural differences in reproductive organs that prevent successful mating between different species
Temporal isolation
Prezygotic mechanism that involves differences of reproductive activates such as breeding seasons, flowering times, or mating rituals, preventing the interbreeding of different species.
Phylogeny
Evolutionary history of a group of organisms
Phylogenetic tree
Branching diagram that depicts the evolutionary relationships among species or other taxa
Systematics
Discipline of biology that characterizes and classifes relationships among all organisms on earth
tree of life
phylogenetic tree that includes all organisms
taxa
Any named group of organisms at any level of a classification system