Download Evidence of Evolution—clues from living things

Evidence of Evolution—clues
from living things
• Homologous structures—similar features
that originated in a shared ancestor.
--Homologous
structures derive from the same
embryonic structure
--The presence of homologous structures in
different species indicates that the species
shared a fairly recent common ancestor.
--Analogous structures—structures that
serve the same function and look somewhat
alike.
-Analogous structures may have different
internal anatomy and derive from different
embryonic structures.
What 2 parts are
homologous
structures in the bat
and human? Are
those structures also
analogous?
Vestigial Structures
• Definition—features that were useful to an
ancestor, but do not serve the same use in
the modern organism that has them.
• Examples: the human appendix, snakes
with pelvic and limb bones.
• Some whales have vestigial leg bones…
• Does this mean they evolved from an
ancestor that lived on land?
• Vestigial features may come from conserved
genes that are not fully turned off.
Examples of Vestigial Structures
Examples of transitional
fossils. See the reduction
in hindlimbs (these would
have hindered then animal
from power swimming.
Similarities in Embryology
• During the early stages of
development, all vertebrate embryos
look similar.
• Does this mean they share a common
ancestor?
Similarities in Macromolecules
• Homologous proteins—the same proteins
that are found in different species.
• These proteins are similar but not identical
between species.
• The more similar the protein, the more recent
the two species’ common ancestor.
• Human and gorilla hemoglobin have one
different amino acid, human and frog
hemoglobin have 67 different amino acids.
Patterns of Evolution
• Coevolution—the change of two or more
species in close association with one
another. (They become completely
dependent on each other)
•
•
– Example: flowers and their pollinators
Coevolution example:
Flower has long, thin
opening that matches
butterfly proboscis.
Flower advantage:
less wasted pollen
(butterfly moves from
flower to flower)
Butterfly advantage:
steady food source
Examples of convergent evolution. All animals
serve same niche but are not directly related.
Divergent Evolution
• Definition—when two or more related
populations or species become more and
more different.
• Adaptive radiation—when many related
species evolve from a single species
– Galapagos island finches and mustard
plant are examples
• Artificial selection--purposeful selection of
traits to create a useful variation.
– Farm crops are an example.
Adaptive Radiation (Divergent evolution
Another example
of Adaptive
RadiationHawaiian
Honeycreepers
Artificial Selection at Work (~ 10,000 years)
Artificial Selection in plants – all from wild
mustard
Are these examples
of convergent
evolution,
coevolution or
divergent evolution?
Is this an example of
convergent evolution,
coevolution or divergent
evolution
Are these examples of
convergent evolution,
coevolution or
divergent evolution