Evolution - Joshua Trees and Evolution - Solution - Joshua... · flowering plants Monocotyledons (Monocots) Dicotyledons (Dicots) # of species living today approximately 60 000 species
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WORKSHEET FOR THE VIDEO: JOSHUA TREES AND EVOLUTION
Topic: Evolution
Notes/Vocabulary:
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This worksheet accompanies the video “Joshua Trees and Evolution”, which is available for free on YouTube. (https://youtu.be/mibrOhcuqDM)
1. Joshua trees (Yucca brevifolia) belong to the group of monocotyledons (monocots). Complete the comparison of monocots and dicots in the following table.
flowering plants
Monocotyledons (Monocots) Dicotyledons (Dicots)
# of species living today approximately 60 000 species approximately 200 000 species
Age up to 150 million years multiple groups evolved independently at
different times
Characteristics seedlings possess one embryonic leaf (cotyledon)
seedlings possess two embryonic leaves (cotyledons)
2. While Joshua trees inhabited a significantly larger area in the past, today they can only be found in small patches in the southwestern US. Explain which factors contributed to the shrinkage of the Joshua tree habitat.
The climate in the southwestern United States has
changed since the Pleistocene. The previously much more
humid climate allowed the Joshua trees to grow in places
where they can no longer occur due to the lack of water.
In addition, increasing competition is another reason why
the distribution of the Joshua trees has shrunk
considerably. A number of plant species that compete with
the Joshua trees today didn’t exist in the Pleistocene, or
they weren’t as numerous as they are today.
Distribution of Joshua Trees Picture altered from: https://commons.wikimedia.org/wiki/File:US_map_-_states-ca.png
public domain
3. Give a description of what the term ‘coevolution’ refers to.
Coevolution is a process during which two or more species undergo interlinked evolutionary change. These changes or
adaptations causes these species to become more specialized in their mutual interactions.
4. At the time signature 3:30, the video „Joshua Trees and Evolution“ contains a brief intermission. It asks you to pause
the video for a few minutes to work on this task: Form a hypothesis on how the relationship between Yucca moths and Joshua trees might have evolved.
[different answers possible]
assumed distribution of Joshua trees during Pleistocene