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Bellringer What is speciation?
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Speciation
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Learning Targets Explain how populations can become isolated, leading to speciation. Compare and contrast the different types and rates of evolution and extinction
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Speciation The origin of new species is called speciation. Speciation occurs when an ancestral species branches into separate species.
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Species Reminder of a species: Groups of organisms that can successfully reproduce, having viable offspring.
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Speciation is a result of …
Speciation is a result of … Isolation
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How does one group become separated and isolated?
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Reproductive Isolation
Speciation requires reproductive isolation (If they cannot mate, they’re considered different species) Western Meadowlark Eastern Meadowlark
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Reasons For Reproductive Isolation May Be…
Reasons For Reproductive Isolation May Be… Geographical separated by habitat Ex: land & water, mountain & valley, tree & grass separating species from each other.
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Reasons For Reproductive Isolation May Be…
Reasons For Reproductive Isolation May Be… Temporal Separated by time Ex: nocturnal v. diurnal, different mating seasons.
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Reasons For Reproductive Isolation May Be…
Reasons For Reproductive Isolation May Be… Behavioral Ex: mating song or dance is different.
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Reasons For Reproductive Isolation May Be…
Reasons For Reproductive Isolation May Be… Mechanical physically do not fit, cannot mechanically mate
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Discuss with your Partner
What defines a species? Come up with 2 examples of reproductive isolation. Be ready to share!
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Adaptive Radiation Occurs when one common ancestral species evolves into many diverse species adapted to different environments. Usually occurs as a result of the founder effect where organisms migrate from their ancestral population to colonize a new area (island chain) and develop adaptations to the diverse environments on the different islands.
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Macroevolution How then do we get from the mechanism of speciation to evolution on a grand scale; i.e., macroevolution? Two models: Gradualism model change is gradual with the accumulation of unique morphological adaptation. Punctuated Equilibrium model rapid change occurs, with a new species “erupting” from the ancestral lineage and then staying the same thereafter.
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Evolution is not random, it occurs in response to specific environmental conditions:
Convergent evolution = evolution toward similar characteristics in unrelated species Example wings in birds and insects Divergent evolution = when closely related species evolve in different directions Example mammals Co-evolution = when two or more species evolve in response to changes in each other Example flowering plants and their pollinators (insects/birds)
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Species can become extinct…
Permanent loss of a species (Usually followed by adaptive radiation of other species)
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Extinction Background extinctions = occur continuously but at a very low rate Part of the natural cycle of life on Earth, cause local, small-scale changes to ecosystems Mass extinctions = global events that destroy many species Examples asteroid impact, ice age
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Speciation Worksheet Please complete speciation worksheet. Once done make sure your name is on it and turn it in to the tray. If you finish early, you may work on your vocabulary that is due on Tuesday.
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