Microevolution Flashcards
(11 cards)
What is microevolution?
Evolution on a small scale within a single population, involving changes in gene frequency in that population
What defines a single population in evolutionary terms?
A group of organisms that interbreed with each other and share a common gene pool
How is species defined biologically?
A group of individuals that actually or potentially interbreed in nature, representing the largest gene pool possible under natural conditions
What are some problems with the biological species concept?
It is difficult to apply to organisms that reproduce asexually (e.g., many bacteria) and to plants or animals that form hybrids naturally
What is speciation?
A lineage-splitting event producing two or more separate species
What often triggers speciation?
A natural disaster or other event that isolates populations leading to divergence in morphology, behavior, and genetics
What is allopatric speciation?
Speciation caused by geographic isolation, such as rivers changing course or mountains rising, dividing a continuous population
How does a reduction in gene flow occur over a large range?
When a population spreads over a broad geographic area with non-random mating and different selection pressures at the edges, gene frequencies diverge
What other barriers can reduce gene flow besides geography?
Natural selection, sexual selection, genetic drift, or evolution of different mating locations, times, rituals, or incompatible sexual organs
What evidence supports speciation over geological time?
Earth formed ~4.6 billion years ago, life ~3.6 billion years ago, and first humans appeared ~100,000 years ago, showing long evolutionary processes
How does speciation often occur on islands?
Species may evolve smaller body size due to energy requirements or larger size to outcompete for resources, driven by unique island selection pressures
