Topic 5-7 Flashcards
(31 cards)
Adaptive Radiation
When one common ancestor has evolved rapidly into multiple descendant species that have adaptations for that environment.
Disruptive Selection
Decreases the mean phenotype but increases the extreme phenotypes.
Stabilizing Selection
Stabilizes the population around the mean instead of pushing it away from the mean.
Directional Selection
The mean changes, but the variation stays the same.
Microevolution
Change in allele frequencies over time.
Macroevolution
Broad pattern of evolutionary change that occurs over a long time.
Allopatric Speciation
Occurs when a physical barrier separates the population, resulting in two species evolving if separated long enough.
Sympatric Speciation
Occurs when something changes in the population, causing reproductive isolation.
Morphological Species
Individuals of a species share measurable traits that distinguish them from individuals of other species.
Biological Species
Groups of interbreeding natural populations reproductively isolated from/do not produce fertile offspring with other such groups.
Phylogenetic Species
A phylogenetic species comprises populations with a recent evolutionary history.
Hybrid Zone: Reinforcement
Pre-zygotic: The evolution of a pre-zygotic barrier to reproduction that prevents the formation of a zygote in the first place as it can recognize its species.
Post-zygotic: Mixed variations do poorly because they don’t do well in the habitat of either parent species.
Hybrid Zone: Fusion
Occurs when there’s not enough genetic divergence for reproductive isolation to occur.
Hybrid Zone: Stability
Hybrids continue to be produced within the hybrid zone but don’t survive long.
Genetic Divergence
If a parent has a few genes that are very significant in the hybrids they produce, then those genes could have quite a large impact and maintain reproductive isolation.
Ecological isolation
Species live in different habitats
Temporal Isolation
Species breed at different times, never encountering one another.
Behavioural Isolation
Species cannot communicate, limiting mating between species that have different behaviours.
Mechanical Isolation
Species cannot physically mate due to different genitalia.
Gametic Isolation
Species have non-matching receptors on gametes, which have proteins able to recognize the same species.
Hybrid Inviability
Hybrid offspring do not complete development.
Hybrid Sterility
Hybrid offspring cannot produce gametes.
Hybrid Breakdown
Hybrid offspring have reduced survival or fertility.
Homologous Structures
Anatomical resemblances representing variations of a structural theme present in a common ancestor.
