Evidence of Macroevolution

Question 1

Evidence for Macroevolution: Fossils

Answer 1

Remains of traces of an organism or it’s activity.

→ These form when bodies of organisms get trapped in sediments that soon become sedimentary rock

→ Most common are hard body parts like shells, bones and teeth
↪ Can include footprints and chemical remains
→ Fossils in young layers of rock are more similar to today’s species than those found in older, deeper layers of rock
→ Not all types of organisms appear in the fossil record at the same time
↪ E.g. fish found in older layers
↪ Amphibians appear in younger layers
↪ Supports theory that amphibians evolved from ancestral fish
→ There are many ‘gaps’ in the fossil record
↪ This is a point that is often focused on by evolution critics

Question 2

Evidence for Macroevolution: Molecular/Biochemical

Answer 2

→ Eukaryotic cells have noncoding genes (i.e. ‘junk DNA’) that can be thought of as evidence of evolution
↪ 2% of the human genome is in use while 98% is nonfunctional (thought to be used by an ancestral species)
→ DNA of different species is compared and the number of similarities in genes and genetic sequences can determine how closely related they are
↪ Humans and chimps share 98% of their DNA (doesn’t mean that humans evolved from chimps; rather that we share a recent common ancestor)

Question 3

Evidence For Macroevolution: Anatomical Features

Answer 3

There are three types of Anatomical Features…

1) Homologous Features
2) Analogous Features
3) Vestigial Features

Question 4

Anatomical Structures: Homologous Structures

Answer 4

Structures that have a common ancestor
↪ May serve the same or different function

→ Due to Divergent Evolution

Ex: The pentadactyl limb is a similar bone structure found throughout many species but are evolved to have different functions

Question 5

Anatomical Structures: Analogous Features

Answer 5

Due to similar selective pressures, animals develop features with similar function (These structures do not have a common ancestor and mostly don’t have similar structures)

→ Similarity is due to convergent evolution
↪ Process in which two distinct lineages evolve a similar characteristic independently of one another.
↪ This often occurs because both lineages face similar environmental challenges and selective pressures.

Question 6

Anatomical Structure: Vestigial Features

Answer 6

These are structures that serve no use to the organism
↪ Like the appendix

→ Vestigial genes are found in DNA, which serve no function but consists of similar sequences

Question 7

Evidence for Macroevolution: Embryonic Development

Answer 7

→ In early development, the embryos of all vertebrates, including humans, possess a short, bony tail (homologous structure)

→ All vertebrate embryos have paired pouches that become gills. Humans (and other land animals) further develop the gills into ears and throat
↪ This shows common ancestry

Question 8

Evidence for Macroevolution: Coevolution

Answer 8

Process in which one species evolves in response to the evolution of another species. (Can happen within the same species: Battle of the sexes)

→ Likely to occur when species have close ecological interactions with one another
↪ Predator-prey
↪ Competitive species
↪ Can happen with Sexual Dimorphism? (Look into this)

Ex: When Darwin saw the orchids in Madagascar, he predicted the existence of a moth with a tongue long enough to reach the nectar. Decades later, the giant hawk moth was discovered

Question 9

Convergent Evolution

Answer 9

The development of similar structures within different species that live in the same environment is known as the convergent evolution.

→ Development of Analogous Structures

Question 10

Divergent Evolution

Answer 10

Divergent evolution is a process of developing two or more species from a common ancestor.

→ Development of Homologous Structures