Evidence of Evolution | Genetics and Evolution - Biology IB23

Fossils

Fossils

Remnants of organisms that lived ages ago are bones, shells and soft tissue today. The C-14 method and Ar-K method can be used to date these remnants.

1. Horse remnants show that horses have an evolved bone structure and evolved a taller structure.

2. Species have gone extinct like mammoths, dodo birds and dinosaurs.

3. Some species show a combination of two species like the archaeopteryx - a combination of reptiles and birds.

Selective Breeding

Choosing particular organisms with specific characteristics to produce offspring with more adaptable or desirable traits.

1. Wolves —> Dogs

2. Milk cows produce more milk today than cows did before.

3. Corn produced today is bigger than original teosinte corn.

Comparative Anatomy

1. Homologous Organs

   Organs with the same structure or shape but with different functions often caused by adaptive radiation.

   a) Finch Beaks - Beaks of finches have changed forms due to being in different environments.

   b) Pentadactylus Limbs - Mammals share the same limb however whales use them to swim, bats need them to fly while humans use hands for grabbing materials.

2. Vestigial Organs

   Organs that are not needed nor used in a species.

   a) Pelvic bones in whales.

   b) Leg bones in snakes.

   c) Wisdom teeth.

3. Comparative Embryology

   Embryos of animals that look similar.

Continuous Variation

Different species can’t mate with each other and produce fertile offspring. Speciation occurs when populations of the same species are separated and their genes can’t mix through sexual reproduction, and if their habitats are different their characteristics might evolve differently.

Recent Evolution

2 or more forms of an insect when presented in a specific condition one will be favored more than the other as they’re more suitable for the environment. The favored characteristics will dominate the population over time.

1. Peppered Moth | Biston Betularia

2. Ladybug | Adalia Bipunctata

New Evidence

1. Antibiotic Resistance in Bacteria

   As bacteria are exposed to antibiotics, some can survive with the help of a resistance gene. The bacteria reproduce and pass on this heritable characteristic to their offspring. This resistance can be transferred through other means, such as plasmids and pili.

2. DDT Resistance in Insects

   Insects have gained resistance to insecticides after high use.

3. Metal Resistance in Plants

   Certain species of plants that live near mining areas are exposed to metal leaching into the soil.