Hello BIS 2B students. Welcome to lab
8: Evidence for Incipient Speciation
What is incipient speciation? Incipient simply means the beginning of
something and speciation is the process
in which species are formed. So today
we're looking at the beginning of the
process of speciation. When species form
that means barriers to reproduction have
also formed. These barriers can be
roughly categorized as prezygotic and
postzygotic barriers. Prezygotic
barriers can be mechanical, geographical,
behavioral, temporal, ecological, or
habitat, and gametic. Postzygotic
barriers include hybrid inviability,
hybrid infertility, or low fitness for
hybrids for any other reason. Our study
organism for this lab is Jadera haematoloma. The soapberry bug. You may have
seen them wandering around in Davis.
Soapberry bugs feed on the seeds of the
plants in the family Sapindaceae. They
use their long beak to pierce the fruit
wall and then bore into the seeds and
liquefy the insides with an enzyme. They
then drink the liquefied plant seed.
The bugs live on the ground below their
host plant and wait for the fruits to
fall before feeding on them.
However, females seeking nutrition for
eggs are likely to climb the plant to
reach fruits before they fall. In Davis
two of the host plants that soapberry
bugs feed on are the golden rain tree
and the balloon vine. Both plants have
different shaped fruits. Fruits of the
balloon vine have a radius of 7 to 11
millimeters and are round. Fruits of the
golden rain tree have a radius of 5 to 9
millimeters and are a wedge shape. Let's
take a look inside. As you can see,
both fruits are similar with 3 hollow
chambers and seeds arranged in the
center of the fruit. Now remember females
may seek early access to food to
reproduce first which in turn affects
fitness. Can you see that natural
selection will favor beaks of certain
lengths depending on the food source? For this lab we have soapberry bugs
collected from local populations of
golden rain tree bugs and balloon vine
bugs. The beak lengths of many
individuals were measured with calipers
and that data was pulled to see the
morphological differences between the
two populations. You will be examining
that data in Google Forms. In addition
you will select one behavior that
relates to incipient speciation and
develop a hypothesis. We will then
provide you with a data set to form a
conclusion with.
As this is the last video in the BIS 2B video series, I would like to address
the question weighing heavily upon your
mind.
What are the names of all the pets that
you have seen? Here we go!
That's it for this video. Good luck on
the practical and have fun with the
Google Forms exercise. And as usual, thank
you for watching!
