Bio Ch 17 Flashcards
Macroevolution
evolution on a large scale
Speciation
splitting of one species into 2 or more species; or transformation of one species into new species over time
Taxonomist
scientist that classifies organisms into groups
Species concepts
different ways in which a species is defined
Morphology
species identified by differences in their appearance
Morphological Species Concept
each species is defined by one or more distinct physical characteristics (diagnostic traits) that distinguish one species from another
Diagnostic traits
distinct physical characteristics that distinguish one species from another
Cryptic Species
species that look almost identical but are very different in other traits, such as habitat use or courtship behaviors
Evolutionary Species Concept
proposed to explain speciation in the fossil record; relies on identification of certain morphological diagnostic traits to distinguish one species from another; requires that the members of a species share the same, distinct, evolutionary pathway
Phylogenetic Species Concept
an evolutionary family tree (phylogeny) is used to identify species based on a common ancestor, that is, a single ancestor for two or more different groups
Monophyletic
a branch that contains all of the descendants of a common ancestor; main criterion for defining species in the phylogenetic species concept
Node
a phylogenetic tree term; point at which two branches or lineages intersect
Root
a phylogenetic tree term; point to which all species in the phylogeny can trace their ancestry; the origin of their shared common ancestry
Extinction
taxon that is represented in the fossil record but is no longer in it; represented by a shortened branch on the phylogenetic tree correlated with the time the ___ occurred
Biological Species Concept
relies primarily on reproductive isolation rather than trait differences or shared evolutionary history to define a species
Reproductive Isolation
physiological, behavioral, and genetic processes that inhibit interbreeding
Prezygotic Isolation
reproductive isolation before fertilization
Postzygotic Isolation
reproductive isolation after fertilization
Zygote
first cell that results when a sperm fertilizes an egg
Prezygotic Isolating Mechanisms
prevent reproductive attempts or make it unlikely that fertilization will be successful if mating is attempted
Hybridization
mating between 2 species
Habitat Isolation
when 2 species occupy different habitats, even within the same geographic range, they are less likely to meet and attempt to reproduce
Temporal Isolation
several related species can live in the same locale, but if each reproduces at a different time of year, they do not attempt to mate
Behavioral Isolation
many animal species have courtship patterns that allow males and females to recognize one another
Mechanical Isolation
when animal genitalia or plant floral structures are incompatible, reproduction cannot occur
Gamete Isolation
even if the gametes of 2 different species meet, they may not fuse to become a zygote
Postzygotic Isolating Mechanisms
those that operate after formation of the zygote, preventing hybrid offspring from developing, even if reproduction attempts have been successful
Hybrid Inviability
a hybrid zygote may not be viable, and so it dies
Hybrid Sterility
the hybrid zygote may develop into a sterile adult
Allopatric Speciation
eventual result of populations separated by a geographic or some other physical barrier
Reinforcement
process of natural selection that reinforces reproductive isolation; occurs when 2 populations, formerly of the same species, come back in contact after being isolated
Sympatric Speciation
speciation without the presence of a geographic barrier
Polyploidy
a chromosome number beyond the diploid (2n) number; type of sympatric speciation
Autoploidy
occurs when a diploid plant produces diploid gametes due to nondisjunction during meiosis
Alloploidy
requires a more complicated process that autoploidy because it requires that two different but related species of plants hybridize; hybridization is followed by doubling of the chromosomes
Adaptive Radiation
type of speciation that occurs when a single ancestral species rapidly gives rise to a radiation of new species as each adapts to a specific environment
Ecological Release
freedom for a species to expand its use of resources within habitats where competition has been removed
Convergent Evolution
said to occur when a similar biological trait evolves in 2 unrelated species as a result of exposure to similar environments
Analogous
traits that evolve convergently in 2 unrelated lineages because of a response to a similar lifestyle or habitat (ex. wings of birds and bats)
Homologous
traits that are similar because they evolved from a common ancestor
Gradualistic Model of Evolution
proposes that speciation occurs after populations become isolated, with each group continuing slowly on its own evolutionary pathway
Punctuated Equilibrium Model
assembly of species in the fossil record can be explained by periods of equilibrium (stasis), that are punctuated (interrupted) by periods of rapid, abrupt speciation, or change
