Core concepts of evolutionary biology and the evidence supporting it
20 cards · science
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| Front | Back |
|---|---|
| Natural Selection | Differential survival and reproduction by heritable traits Individuals with advantageous traits leave more offspring, shifting trait frequencies. |
| Fitness | Reproductive success relative to others Fitness measures contribution to the next generation, not strength; it is environment-dependent. |
| Adaptation | Heritable trait that increases fitness in a given environment Cactus spines reduce water loss and deter herbivores, aiding survival in arid regions. |
| Mutation | Random change in DNA creating new genetic variation Mutations supply the raw material for selection and drift to act upon. |
| Genetic Drift | Random change in allele frequencies, strongest in small populations Chance events can fix or eliminate alleles regardless of advantage. |
| Gene Flow | Movement of genes between populations Migration mixes alleles and can counteract divergence among populations. |
| Speciation | Formation of new species from ancestral populations New species arise when evolving lineages become reproductively isolated. |
| Reproductive Isolation | Barriers preventing gene flow between populations Prezygotic and postzygotic barriers maintain species boundaries. |
| Common Ancestry | All life descends from a shared ancestral population A branching tree of life is inferred from fossils, anatomy, and molecular data. |
| Homologous Structures | Similar traits from shared ancestry despite different functions Vertebrate forelimbs share a bone pattern inherited from a common ancestor. |
| Analogous Structures | Similar traits evolved independently due to similar selection Bat and insect wings perform flight but evolved separately (convergence). |
| Vestigial Structures | Reduced traits inherited from ancestors with lost original function Human tailbones and whale pelvic bones reflect evolutionary history. |
| Fossil Record | Preserved remains documenting evolutionary change through time Transitional forms like Archaeopteryx and Tiktaalik link major groups. |
| Biogeography | Geographic distribution of species reflects evolutionary history Island endemics and continental drift patterns support descent with modification. |
| DNA Evidence | Shared genetic sequences indicate common ancestry The universal genetic code and conserved genes reveal evolutionary relationships. |
| Individuals Evolve | Populations evolve; individuals do not Evolution is a change in allele frequencies across generations. |
| Purposeful Evolution | Evolution has no goal or foresight Selection favors current fitness; changes are not directed toward future needs. |
| Charles Darwin | Proposed natural selection as a mechanism of evolution Origin of Species (1859) synthesized evidence for descent with modification. |
| Alfred Russel Wallace | Independently conceived natural selection His 1858 manuscript prompted joint presentation with Darwin. |
| Gregor Mendel | Discovered particulate inheritance via pea experiments Mendel's laws clarified heredity and later merged with evolutionary theory. |