evolution evidence the theory of evolution states that all organisms on earth have descended from a...
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Evolution Evidence
The theory of evolution states that all organisms on Earth have descended from a common
ancestor
Support for Evolution
1. The Fossil Record (Fig. 15.4 p.
423)–Fossils show that ancient
species share similarities with species that live on Earth today
2. Comparative Anatomy (Fig. 15.6 p. 425)
a) Homologous structures develop from similar tissues in early developmental stages of the organism, but meet different needs in the adult.
Fig. 15.6 on p. 425• Q: What is similar about each of
these?• Similar bone structure, from same
tissue• Q: What is different about each of
these?• Perform different functions – grab,
walk, fly
b) Vestigial structures are features of ancestors that no longer have a function for that species and will become smaller over time until they are lost• Ex: Humans → appendix, tailbone
(Table 15.2 p. 425) Snakes →tiny bones where legs
used to be
c) Analogous structures look similar in appearance and function, but are developed from anatomically different parts–They are used for the same purpose
and similar in construction, but not inherited from a common ancestor.
• Ex: eagle wing vs. beetle wing (Fig. 15.7)
bird wing vs. bat wing
3. Comparative Embryology(Fig. 15.8 p. 426)
• Embryology is the study of embryos• Embryo = early, pre-birth stage of an
organism’s development• Vertebrate embryos have similar
structures during certain stages of development, but become totally different structures in the adult form.
Q: What do similarities in early development indicate?• The organisms have similar genes
controlling early development.Q: What do these similar genes indicate?• These organisms have a common ancestor.Q: Why do the embryos become
different as they develop?• Different genes start to contribute or
become “expressed” in the organism.
4. Comparative Biochemistry(Fig. 15.9 p. 427)
• Evolutionary theory predicts molecules in species with a recent common ancestor should share certain amino acid sequences.• The more closely related the species
are, the more amino acid sequences they have in common.
5. Geographic distribution(Fig. 15.10 p. 427)• Evolution is linked to climate and plate
tectonics which explains many ancestral relationships and geographic distributions seen in fossils and living organisms.–For example: South American animals
are more similar to other South American animals than to animals in Europe.
Adaptation
• An adaptation is a trait influenced by natural selection that increases an organism’s reproductive success.
• Fitness: The ability of an organisms to survive and reproduce–how much a certain trait
appears in the next generation; measured by the amount of offspring
• Camouflage: adaptation that allows a species to blend in with their environment.
• Why? –Hide from predators/prey, more
survive to reproduce• Ex: Arctic fox (Fig. 15.11 p.
428)
•Mimicry: one species changes to look like another species
• Ex: Harmless snake “mimics” a poisonous snake so predators leave it alone (Fig. 15.12 p. 429)
• Antibiotic resistance: –Some species of bacteria that
originally were killed by antibiotics (like penicillin) have evolved to be drug resistant–For nearly every antibiotic, there
is at least one species of resistant bacteria