Adaptive radiation
the rapid, divergent evolution of a single ancestral lineage into numerous new species, each uniquely adapted to exploit distinct ecological niches.
Allopatric speciation
the formation of new species due to geographic isolation, where a physical barrier splits a population, preventing gene flow
Anagenesis
the slow, gradual transformation of an entire ancestral species into a new, distinct species over time without branching or splitting
Biological Species concept
defines a species as a group of populations whose members can interbreed in nature to produce viable, fertile offspring, but are reproductively isolated from other such groups
Cladogenesis
an evolutionary process where a parent species splits into two or more distinct, reproductively isolated daughter species, forming new branches (clades) on the tree of life
Ecological Species concept
defines a species as a set of organisms adapted to a specific ecological niche—a particular set of resources and environmental conditions
Macroevolution
large-scale evolutionary changes occurring at or above the species level over geological time
Morphological Sp. cnpt
defines species based on shared, observable physical characteristics—such as size, shape, and structure—rather than reproductive capability, often grouping organisms that look alike.
Paleontological Sp. concept
defines species as groups of organisms, known from fossils, that are morphologically distinct from others, primarily using shared, diagnosable physical characteristics
Phylogenetic Species cnpt
defines a species as the smallest, distinct, and diagnosable cluster of organisms that share a common ancestor, acting as a “tip” on a phylogeny
Post zygotic barriers:
reproductive isolation mechanisms that occur after fertilization, preventing hybrid zygotes from developing into viable, fertile adults
Prezygotic barriers
reproductive isolation mechanisms that prevent fertilization and zygote formation between different species
Punctuated equilibrium
posits that species experience long periods of stability (stasis) interrupted by short, rapid bursts of evolution and speciation
Reproductive Isolation
biological barriers that prevent members of different species from interbreeding and producing fertile offspring
Speciation
the evolutionary process by which new, genetically distinct species arise from existing ones, primarily through reproductive isolation
Species selection
a macroevolutionary process where, similar to natural selection acting on individuals, differential survival and proliferation of entire species (lineages) occur based on emergent traits.
Sympatric speciation
the process by which new species evolve from a single ancestral population while inhabiting the same geographic location, without physical barriers
