Lecture 8 Flashcards
Speciation
evolutionary process that bridges the scales of micro and macro evolution
Speciation is __ an event. It is a __
NOT; PROCESS
Microevolution
Occurs at short timescales, usually from one generation to the next
Macroevolution
Occurs over long timescales that span many, many generations
Adaptive Radiation
Relatively rapid expansion and diversification of life forms into new ecological niches. Initial phenotypic diversity due to relaxed selection. Radiations usually end with increased selection pressures in the newly filled niches.
Ecological Niches
a term for the position of a species within an ecosystem
Species
set of organisms that are similar to each other, and distinguished from other species, by their behavior, morphology, and ability to create viable offspring. A group of interbreeding organisms, connected through gene flow
Speciation occurs through __
reproductive isolation
Biological Species Concept
a group of organisms that can interbreed in nature and produce fertile offspring, while being reproductively isolated from other such groups;
Ecological Species Concept
defines a species as a group of organisms that share a specific set of resources, or niche, in their environment
Allopatric Speciation
Geographic Isolation. Combination of reproductive isolation and natural selection. Geological Barrier.
Parapatric Speciation
No geographic barrier, partial spatial isolation, or separation. Hybrid zones my arise.
Sympatric Speciation
No geographic isolation. Genetic mutation or specialization to distinct niches may allow species to diverge over time.
Barriers to Hybridization
Geographic, temporal incompatibility, behavioral incompatibility, functional incompatibility, mate recognition, gametic incompatibility, hybrid sterility, or inviability, reduced hybrid fitness
Geographic Incompatibility
When two populations are physically separated by a geographic barrier (such as mountains, rivers, or oceans), preventing them from interbreeding.
Temporal Incompatibility
When two populations reproduce at different times (e.g., different seasons, times of day, or years), preventing mating.
Behavioral Incompatibility
When differences in mating behaviors (such as courtship rituals, songs, or pheromones) prevent individuals from recognizing each other as potential mates.
Functional Incompatibility
When structural or physiological differences prevent successful mating or reproduction, such as differences in reproductive organs.
Mate Recognition
The ability of individuals to identify and select appropriate mates based on species-specific signals, such as appearance, sounds, or chemical cues.
Gametic Incompatibility
When the sperm and egg of different species cannot successfully fuse due to biochemical or genetic differences, preventing fertilization.
Hybrid Sterility or Inviability
When offspring resulting from the mating of two different species are either sterile (unable to reproduce) or inviable (fail to develop properly or die early in life).
Reduced Hybrid Fitness
When hybrid offspring have lower survival or reproductive success compared to purebred individuals, leading to fewer hybrids in future generations.
Phylogenetics
Important for understanding how our species evolved
Homology
Traits shared due to common ancestry
Homoplasy
Traits shared due to convergent evolution
Phylogenetic Trees
depict hypotheses about evolutionary relationships
Shared Derived Trait
a characteristic that is shared by two or more species and inherited from a common ancestor. they can only sort relationships within a group.
Convergence Trait
a similar feature that evolves independently in different species.
Ancestral Trait
a characteristic that is passed down from a common ancestor to a group of organisms.
Derived Trait
a characteristic that evolved from an ancestral form and is present in a more recent group of organisms
Outgroup
a distantly related organism that serves as a reference group to determine the evolutionary relationships between a set of species. they can root the phylogenetic tree in evolutionary time.
