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This chapter explores the multifaceted evidence of evolution, highlighting fossil records, biogeography, and anatomical similarities. It discusses relative and absolute dating methods, the geographical distribution of species, and the significance of homologous and vestigial structures. Additionally, it delves into molecular biology, comparing DNA and protein sequences to establish evolutionary relationships. Concepts such as coevolution, convergent evolution, and divergent evolution are examined, demonstrating how species adapt over time, either in response to one another or to distinct environments.
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Evidence of Evolution Chapter 15 Part II
1. Fossil Record • Are able to observe links between modern forms and ancestors (ex. transition species) • Relative age- age compared to other fossils by referring to the geologic time scale and records of known fossils • Absolute age- use of radiometric dating to date rocks
2. Biogeography • Geographical distribution of species • New organisms arise in same geographic area where similar forms already lived • Example) Australia – has native wolves, cats, mice, moles, and anteaters. Most mammals are marsupials (animals evolved in isolation)
3. Anatomy and Embryology • Homologous structures- anatomical structures that occur in different species that originated in most recent common ancestor • may have different functions but look similar
Common Ancestor: Bat Human
Analogous Structures-a body part similar in function to another organism due to environmental pressuresEx) the wings of a fly, a moth, and a bird developed independently as adaptations to a common function – flying
Vestigial structures- a part of an organism with little or no function but which had a function in an ancestral species
Comparative Embryology- Study of structures that appear during embryonic development • Ex)All vertebrate embryos go though a stage in which they have gill pouches on the sides of their throats
4. Molecular Biology (DNA and Proteins) • Comparison of DNA, RNA, and amino acid sequences • Greater the number of similarities, the more closely the species are related through a common ancestor • Shows the common descent of the most diverse organisms.
Evidence of Evolution:fossil evidence, homologous structures, embryology, vestigial organs, biochemical • Bones in bird’s wing and human’s arm are similar in structure. • All organisms use ATP to transfer energy. • There are similarities in structure among the early stages of fish, birds and humans. • Humans, unlike rabbits, have no known use for their appendix. • Horses have increased in size and decreased in number of toes since the Eocene.
Patterns of Evolution • 1. Coevolution • 2. Convergent Evolution • 3. Divergent Evolution
1. Coevolution • When two or more species have evolved adaptations that influence each other (evolutionary “arms race”) • Examples: • Predator-prey • Parasite-host • Plant-animal pollinator (bee and flower) • Humans have developed and used antibiotics to kill bacteria, bacteria have evolved to become antibiotic resistant
2. Convergent Evolution • Organisms appear to be similar but are not closely related at all • The environment selects similar traits • Result in analagousstructures • Ex) dolphin and shark
3. Divergent Evolution • Two or more biological characteristics become more and more dissimilar in response to different habitats
Adaptive radiation- a new population in a new environment (island) will undergo evolution until the population fills many parts of the environment Ex) Galapagos finches
Artificial Selection • The intentional breeding (by humans) of certain traits, or combination of traits, over others
