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Chapter 4

BIOL 1001 Chapter Notes - Chapter 4: Speciation, Tetrapod, Biogeography

Course Code
BIOL 1001
Tamara Kelly

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Learning Goals- Evidence of Evolutions
1. Describe briefly the general process of fossilization (including conditions for ideal fossilizations),
types of bias in fossil record (and reasons for them) & how dating of fossils is achieved
Methods of fossilization involved rapid burial in such a way that predators & erosional effects
are eliminated. This allows for preservation.
Compression: when organisms die, hard parts of their bodies settle at bottom of sea floors &
are covered by sediments. The process of sedimentations goes on continually & fossils are
2. Describe how continental drift & chance catastrophic events could event affect the evolutionary
history (patterns of speciation & extinction) of species
Continental Drift: a gradual oeet of otiets aross the earth’s surfae through
geologial tie. It’s a theor that eplais ho otiets shift positio o earth’s surfae. It
explains why look-alike animal & plant fossils, similar rock formations are found on different
Rearrangement of landmasses has helped create diversity in animals. Speciation of animals has
lead to ariatio. It’s a pheoeo that orall takes plae he a group of aials of the
same species find themselves isolated from one another. Isolation can occur geographically by
distance, rising mountains, or large bodies of water. Could also be cause of biological or
behavioural barriers.
Continental l drift separates gene pools & exposes each distinct population to different
environmental factors. In time the factors required for survival become very different &
populations evolve in response to these conditions.
3. Distinguish b/t structures similar via common ancestry (homology) & convergent evolution,
justifying your choices and explaining how both phenomena result. Identify examples of each,
including the different types of homologies (vegestial traits, genetic/ developmental/structural
Homology: is the existence of shared ancestry between a pair of structure or genes. A common
example of homologous structures is the forelimbs of vertebrates where the winds of bats, the
arms of primates & front flippers of whales and forelegs of dogs are derived from same
ancestral tetrapod structure. Evolutionary biology explains homologous structures adapted to
different purposes as the result of descent with modification from a common ancestor.
Homology is the relationship between biological structures or sequences that are derived from a
common ancestor.
Vestigial Structures: homologous structures that have no apparent function in the current form
of an organism & appear to be parts from ancestor. These vestigial structures were organs that
performed some important function in organism of the past. Examples include appendix, pelvic,
wings of flightless birds
Structural Homology: Different animals that have bones that appear similar to form or function
& seem to be related
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