In a lizard population, those with longer legs can run faster and escape predators. Over time, long-legged lizards become more common.
Natural Selection
Hunters over-harvest a fish population, leaving just a few fish with rare striping patterns. Now, most of that species has stripes.
Bottleneck effect
Five birds accidentally get trapped in a shipping container and are transported to a new continent. Their descendants look and behave differently than the original population.
Founder Effect
In a desert, lizards that blend in with the sand survive more often. Over time, fewer bright green lizards are born.
Natural Selection
Cheetahs today have incredibly low genetic diversity. Scientists believe this is due to a past event where only a few individuals survived, possibly due to climate change or overhunting.
Bottleneck effect
On Pingelap, a small Pacific island, a typhoon reduced the population to about 20 people. One survivor carried a rare gene for color blindness, which is now unusually common in the population.
Bottleneck and Founder Effect (possibly)
In industrial England, dark-colored moths became more common due to pollution blackening tree bark, giving dark moths better camouflage.
Natural Selection
Modern Icelanders are genetically very similar, with many traits traceable to original Viking settlers.
Founder effect
Elephant seals were hunted nearly to extinction in the 1800s. All current northern elephant seals descend from about 20 individuals, and now they have very little genetic variation.
Bottleneck effect
In regions with high malaria, individuals with one sickle cell allele are more likely to survive malaria. Over time, this trait became more common in those populations.
Natural Selection
Several genetic disorders (e.g., Tay-Sachs) are more common in Ashkenazi Jewish populations due to a small ancestral population and historical isolation.
Founder Effect
During El Niño events, food becomes scarce and smaller-bodied marine iguanas tend to survive better than larger ones, leading to a noticeable shift in body size in following generations.
Natural Selection
On one Galápagos island, droughts reduced soft-seed plants. Only finches with longer, stronger beaks could crack the tougher seeds, so that trait became more common in the next generation.
Natural Selection
On lava flows in the southwestern U.S., dark-colored rock pocket mice became more common than light-colored ones due to camouflage and predator pressure.
Natural Selection
Island Foxes on California’s Channel Islands have several islands that were colonized by small groups that migrated to them and have unique traits on each island
Founder Effect
A contagious cancer wiped out large portions of the Tasmanian devil population, leaving a few survivors with genetic resistance—those individuals have begun repopulating the area.
Bottleneck effect
